ATC/MODE S (SELECT) - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General
The Air Traffic Control (ATC) system is based on the replies provided by the airborne transponders in response to interrogations from the ATC Secondary Surveillance Radar (SSR).
The ground ATC secondary radar uses technique which provide the air traffic control with information that cannot be acquired by the primary radar.
This system serves to distinguish between aircraft and to maintain effective ground surveillance of the air traffic.
The system provides the air traffic controllers with:

Mode A: Transmission of aircraft identification (code number)
Mode C: Transmission of aircraft barometric altitude
Mode S: Selective calling.
The ATC/Mode S transponder receives interrogations from:
. Mode S and SSR ground stations
. TCAS-equipped aircraft (the Mode S transponder transmits TCAS data from another TCAS-equipped aircraft to its own TCAS computer if installed).
Additional to earlier Air Traffic Control Radar Beacon System (ATCRBS) transponders, the Mode S transponder is capable of providing enhanced surveillance (capability to send and receive data link messages).
The minimum data link transponder supports all surveillance functions, in addition to bidirectional air-to-air data exchange, ground-to-air data uplink (COMM A), air-to-ground data downlink (COMM B) and multisite message protocol. In addition, the transponder is capable of receiving Extended Length Messages (ELMs) from the ground. ELMs are received in the COMM C format. ELM transmittals to the ground use the COMM D format.

NOTE: The ATC is a level 4 transponder.
The transponder is capable of processing COMM A/B/C/D data link messages and can be interfaced to an external Mode S Airborne Data Link Processor (ADLP). The transponder has the ability to be upgraded to a level 5 transponder with an internal ADLP function.

Each (ATC Mode S-equipped) aircraft has its own Mode S address. This address (24-bit) is included in all Mode S transmissions, so that every interrogation can be directed to a specific aircraft, preventing multiple replies.
Also, answers are unequivocal from only one specific aircraft.
If the discrete address is included in an interrogation, the discrete address is also a part of the reply. This is especially important for use in conjunction with TCAS.
For SSR interrogations, the transponder transmits the selectable code number (Mode A) or the barometric altitude (Mode C) if required.
For SSR/Mode S all call interrogations, the transponder transmits the same information.

NOTE: The transponder contains data link capabilities, in addition to Mode S specific services, to function as part of the aircraft telecommunications network.
The transponder has the capability of interfacing to a Global Positioning System (GPS) to provide differential GPS operation.
The transponder is designed with upgrade-ability to meet future requirements which result from Future Air Navigation System (FANS) and aircraft telecommunication network definitions and enhancements.

The Air Traffic Control (ATC) system is based on the replies provided by the airborne transponders in response to interrogations from the ATC Secondary Surveillance Radar (SSR).
The ground ATC secondary radar uses technique which provide the air traffic control with information that cannot be acquired by the primary radar.
This system serves to distinguish between aircraft and to maintain effective ground surveillance of the air traffic.
The system provides the air traffic controllers with:

Mode A: Transmission of aircraft identification (code number)
Mode C: Transmission of aircraft barometric altitude
Mode S: Aircraft selective calling and transmission of flight data for the ground surveillance.
The mode S is fully compatible with the other modes A and C.
The mode S has been designed as an evolutionary addition to the ATC system to provide the enhanced surveillance and communication capability required for air traffic control automation.
Each (ATC Mode S-equipped) aircraft has its own Mode S address. This address (24-bit) is included in all Mode S transmissions, so that every interrogation can be directed to a specific aircraft, preventing multiple replies.
Also, answers are unequivocal from only one specific aircraft.
If the discrete address is included in an interrogation, the discrete address is also a part of the reply. This is especially important for use in conjunction with TCAS.

NOTE: The ATC/mode S will be able to provide the Traffic Collision Avoidance System (TCAS) with the aircraft address.

For SSR interrogations, the transponder transmits the selectable code number (Mode A) or the barometric altitude (Mode C) if required.
For SSR/Mode S all call interrogations, the transponder transmits the same information.
In addition, new functionalities are required for ATC/Mode S transponders:

Elementary surveillance (mandatory in Europe after 31 March, 2003)
Enhanced surveillance (mandatory in Europe after 31 March, 2005).

The transponder meets the requirements for elementary surveillance and has the capability for enhanced surveillance (ref. para. 6.A.(3).). It can also transmit extended squitters. Enhanced surveillance parameters and extended squitters are transmitted if the wiring provisions for enhanced surveillance are installed. Moreover, the following functionalities are available:

Com A/B: capability to receive ground to air data uplink (com A) and to transmit air to ground data downlink (com B) in addition to bidirectional data exchange
Com C: capability to receive Extended Length Messages (ELM)

It also incorporates the following improvements:

It has interface characteristics in compliance with ARINC 718A.
As a Mark IV transponder, this transponder needs additional wiring to perform enhanced surveillance and extended squitters functions. If this wiring is not installed, the transponder will operate as a Mark III transponder. In this case, nor enhanced surveillance parameters neither extended squitters are available.
Its software is fully loadable.

The transponder is a level 3 transponder since it is capable of processing com A/B/C/ data link messages.
The Air Traffic Control (ATC) system is based on the replies provided by the airborne transponders in response to interrogations from the ATC Secondary Surveillance Radar (SSR).
The ground ATC secondary radar uses technique which provide the air traffic control with information that cannot be acquired by the primary radar.
This system serves to distinguish between aircraft and to maintain effective ground surveillance of the air traffic.
The system provides the air traffic controllers with:

Mode A: Transmission of aircraft identification (code number)
Mode C: Transmission of aircraft barometric altitude
Mode S: Aircraft selective calling and transmission of flight data for the ground surveillance.
The mode S is fully compatible with the other modes, A and C.
The mode S has been designed as an evolutionary addition to the ATC system to provide the enhanced surveillance and communication capability required for air traffic control automation.
Each (ATC Mode S-equipped) aircraft has its own Mode S address. This address (24-bit) is included in all Mode S transmissions, so that every interrogation can be directed to a specific aircraft, preventing multiple replies.
Also, answers are unequivocal from only one specific aircraft.
If the discrete address is included in an interrogation, the discrete address is also a part of the reply. This is especially important for use in conjunction with TCAS.

NOTE: The ATC/mode S will be able to provide the Traffic Collision Avoidance System (TCAS) with the aircraft address.

Elementary surveillance (mandatory in Europe after March 31, 2003),
Enhanced surveillance (mandatory in Europe after March 31, 2005).

Com A/B: Capability to receive ground to air data uplink (com A) and to transmit air to ground data downlink (com B) in addition to bidirectional data exchange
Com C: Capability to receive Extended Length Messages (ELM)

It also incorporates the following improvements:

It has interface characteristics in compliance with ARINC 718A.
As a Mark IV transponder, this transponder needs additional wiring to perform enhanced surveillance and extended squitters functions. If this wiring is not installed, the transponder will operate as a Mark III transponder. In this case, nor enhanced surveillance parameters neither extended squitters are available.
Its software is fully loadable.

Mode A: Transmission of aircraft identification (code number)
Mode C: Transmission of aircraft barometric altitude
Mode S: Selective calling.
The ATC/Mode S transponder receives interrogations from:
. Mode S and SSR ground stations
. TCAS-equipped aircraft (the Mode S transponder transmits TCAS data from another TCAS-equipped aircraft to its own TCAS computer).
Each (ATC Mode S-equipped) aircraft has its own Mode S address. This address (24-bit) is included in all Mode S transmissions, so that every interrogation can be directed to a specific aircraft, preventing multiple replies.
Also, answers are unequivocal from only one specific aircraft.
If the discrete address is included in an interrogation, the discrete address is also a part of the reply. This is especially important for use in conjunction with TCAS.
For SSR interrogations, the transponder transmits the selectable code number (Mode A) or the barometric altitude (Mode C) if required.
For SSR/Mode S all call interrogations, the transponder transmits the same information.
In addition, the transponder provides Mode S transponder functions, including Elementary Surveillance (ELS), Enhanced Surveillance (EHS) and Automatic Dependent Surveillance-Broadcast (ADS-B OUT).

The transponder meets the requirements for elementary surveillance and has the capability for enhanced surveillance (Ref. para. 6.A.(3).). It can also transmit extended squitters. Enhanced surveillance parameters and extended squitters are transmitted if the modification related to enhanced surveillance/extended squitters is embodied. This modification consists in connecting avionics peripherals (IR, FCU, ATSU) to the transponder.
Moreover, the following functionalities are available:

Com A/B: Capability to receive ground to air data uplink (com A) and to transmit air to ground data downlink (com B) in addition to bidirectional data exchange
Com C: Capability to receive Extended Length Messages (ELM) if an external Data Link Processor (DLP) is installed
Com D: Capability to transmit ELMs if an external DLP is installed.

It also incorporates the following improvements:

It has interface characteristics in compliance with ARINC 718A
It is backward compatible with Mark III transponders (ARINC 718-4) installations
Its software is fully loadable.

The transponder is a level 4 transponder since it is capable of processing com A/B/C/D data link messages. In addition, it has the capability to be upgraded to a level 5 transponder with an internal Airborne Data Link Processor (ADLP) (software change only) (level 4 plus enhanced protocol for parallel processing of com A/B, up and downlink ELMs).
The Air Traffic Control (ATC) system is based on the replies provided by the airborne transponders in response to interrogations from the ATC Secondary Surveillance Radar (SSR).
The ground ATC secondary radar uses technique which provide the air traffic control with information that cannot be acquired by the primary radar.
This system serves to distinguish between aircraft and to maintain effective ground surveillance of the air traffic.
The system provides the air traffic controllers with:

Mode A: Transmission of aircraft identification (code number)
Mode C: Transmission of aircraft barometric altitude
Mode S: Selective calling.
The ATC/Mode S transponder receives interrogations from:
. Mode S and SSR ground stations
. TCAS-equipped aircraft (the Mode S transponder transmits TCAS data from another TCAS-equipped aircraft to its own TCAS computer).
Each (ATC Mode S-equipped) aircraft has its own Mode S address. This address (24-bit) is included in all Mode S transmissions, so that every interrogation can be directed to a specific aircraft, preventing multiple replies.
Also, answers are unequivocal from only one specific aircraft.
If the discrete address is included in an interrogation, the discrete address is also a part of the reply. This is especially important for use in conjunction with TCAS.
For SSR interrogations, the transponder transmits the selectable code number (Mode A) or the barometric altitude (Mode C) if required.
For SSR/Mode S all call interrogations, the transponder transmits the same information.
In addition, the transponder provides Mode S transponder functions, including Elementary Surveillance (ELS), Enhanced Surveillance (EHS) and Automatic Dependent Surveillance -Broadcast (ADS-B OUT).

Com A/B: Capability to receive ground to air data uplink (com A) and to transmit air to ground data downlink (com B) in addition to bidirectional data exchange

It also incorporates the following improvements:

It has interface characteristics in compliance with ARINC 718A
It is backward compatible with Mark III transponders (ARINC 718-4) installations
Its software is fully loadable.

The transponder is a level 2 transponder since it is capable of processing com A/B data link messages.

** ON A/C NOT FOR ALL

2. Component Location

ATC - Component Location ** ON A/C NOT FOR ALL

FIN	FUNCTIONAL DESIGNATION	PANEL	ZONE	ATA REF
** ON A/C NOT FOR ALL
1SH2	XPDR-ATC/MODE S, 2	82VU	128	34-52-33
** ON A/C ALL
1SH1	XPDR-ATC/MODE S, 1	81VU	127	34-52-33
** ON A/C NOT FOR ALL
7SH2	ANTENNA-ATC BOTTOM, 2		128	34-52-11
** ON A/C ALL
7SH1	ANTENNA-ATC BOTTOM, 1		127	34-52-11
3SH	CTL UNIT-ATC/TCAS	11VU	210	34-52-12
** ON A/C NOT FOR ALL
7SH4	ANTENNA-ATC TOP, 2		233	34-52-11
** ON A/C ALL
7SH3	ANTENNA-ATC TOP, 1		234	34-52-11
** ON A/C NOT FOR ALL
8SH	CTL BOX-REMOTE ATC	88VU	128	34-52-35

** ON A/C NOT FOR ALL

3. System Description

A. Principle

ATC - Principle ** ON A/C NOT FOR ALL

An airborne transponder provides coded reply signals in response to interrogation signals from the ground secondary radar and from aircraft which will be eventually equipped with the TCAS.
This ground interrogation is transmitted in the form of pair of pulses P1 and P3 for the mode A or C and in the form of pulses P1, P3 and P4 for the mode S.
The decoding of the time between the interrogation pulses determines the operating mode of the transponder:

Mode A (identification)
Mode C (altitude range)
Mode S (flight data).

The interrogation frequency is 1030 MHz.
The reply frequency is 1090 MHz.
The system is provided with four antennas:

two antennas are located at the upper part of the fuselage
two antennas are located at the lower part of the fuselage.
According to the aircraft configuration, the transponder selects the antennas (lower or upper) which receive the best transmission signal from the ground ATC secondary radar.

ATC - Principle ** ON A/C NOT FOR ALL

An airborne transponder provides coded reply signals in response to interrogation signals from the ground secondary radar and from aircraft which is equipped with the TCAS.
The ATC/Mode S system has the capability for Modes A, C and S.
Mode A: Identification
Mode C: Altitude range
Mode S: In a Mode S environment, the transponder responds to ATCRBS-formatted interrogations with ATCRBS-formatted replies, but, in addition, it can be discretely addressed directly by Mode S interrogators. Discrete addressing means that only the specifically addressed Mode S transponder replies. Top and bottom antennas and associated antenna switching and signal processing features provide the Diversity Antenna features that allow compatibility with TCAS II. The diversity antenna allows selection of signal receptions from either the top or the bottom antenna based on the characteristics of the received interrogation signals. This improves air-to-air surveillance and communication. The ATC/Mode S transponder, is also used in collision avoidance (if TCAS installed). In this role, the transponder performs as an ATCRBS and Mode S transponder for ATC requirements, while simultaneously serving as an integral part of TCAS. The Mode S transponder has two basic functions related to TCAS:
(1) Approximately every second, a Mode S transponder makes a transmission known as squitter. These transmissions alternate between the top and bottom Mode S antennas. Squitter is coded with the aircraft Mode S address and equipment capabilities. A ground station and airborne TCAS listen for squitter as the initial indication that a Mode S-equipped aircraft has entered the surveillance area.
(2) The communication between two TCAS-equipped aircraft occurs from the TCAS antenna of one aircraft to the Mode S transponder antenna of the other aircraft. Aboard the TCAS-equipped aircraft, data received by the Mode S transponder is passed to a TCAS computer, and the TCAS computer determines the content of reply messages.
The Mode S reply includes the flight number transmitted by the Flight Management and Guidance Computer (FMGC).
The ATC system operates with two frequencies:

Interrogation: 1030 MHz
Reply: 1090 MHz

Modes A, C and "All call" interrogations are transmitted in the form of coded pulses PPM (Pulse Position Modulation).
An "All call" interrogation is an interrogation which generates Mode A or C and Mode S replies.
The transponder contains data link capability, which allows it to receive uplink messages and uplink extended length messages. The transponder can transmit Downlink Messages and Downlink Extended Length Messages (DELM). The transmitter has the capability of transmitting sets of 16 segment DELMs at a rate of 8 per second.

ATC - Principle ** ON A/C NOT FOR ALL

An airborne transponder provides coded reply signals in response to interrogation signals from the ground secondary radar and from aircraft which is equipped with the TCAS.
The ATC/Mode S system has the capability for Modes A, C and S.
Mode A: Identification
Mode C: Altitude range
Mode S: In a Mode S environment, the transponder responds to ATCRBS-formatted interrogations with ATCRBS-formatted replies, but, in addition, it can be discretely addressed directly by Mode S interrogators. Discrete addressing means that only the specifically addressed Mode S transponder replies. Top and bottom antennas and associated antenna switching and signal processing features provide the Diversity Antenna features that allow compatibility with TCAS II. The diversity antenna allows selection of signal receptions from either the top or the bottom antenna based on the characteristics of the received interrogation signals. The transponder selects the antennas (lower or upper) which receive the best transmission signal from the ground ATC secondary radar. This improves air-to-air surveillance and communication. The ATC/Mode S transponder, is also used in collision avoidance. In this role, the transponder performs as an ATCRBS and Mode S transponder for ATC requirements, while simultaneously serving as an integral part of TCAS. The Mode S transponder has two basic functions related to TCAS:
(1) Approximately every second, a Mode S transponder makes a transmission known as squitter. These transmissions alternate between the top and bottom Mode S antennas. Squitter is coded with the aircraft Mode S address and equipment capabilities. A ground station and airborne TCAS listen for squitter as the initial indication that a Mode S-equipped aircraft has entered the surveillance area.
(2) The communication between two TCAS-equipped aircraft occurs from the TCAS antenna of one aircraft to the Mode S transponder antenna of the other aircraft. Aboard the TCAS-equipped aircraft, data received by the Mode S transponder is passed to a TCAS computer, and the TCAS computer determines the content of reply messages.
The Mode S reply includes the flight number transmitted by the Flight Management and Guidance Computer (FMGC).
The ATC system operates with two frequencies:

Interrogation: 1030 MHz
Reply: 1090 MHz

ATC - Principle ** ON A/C NOT FOR ALL

An airborne transponder provides coded reply signals in response to interrogation signals from the ground secondary radar and from aircraft which is equipped with the TCAS.
The ATC/Mode S system has the capability for Modes A, C and S.
Mode A: Identification
Mode C: Altitude range
Mode S: In a Mode S environment, the transponder responds to ATCRBS-formatted interrogations with ATCRBS-formatted replies, but, in addition, it can be discretely addressed directly by Mode S interrogators. Discrete addressing means that only the specifically addressed Mode S transponder replies. Top and bottom antennas and associated antenna switching and signal processing features provide the Diversity Antenna features that allow compatibility with TCAS II. The diversity antenna allows selection of signal receptions from either the top or the bottom antenna based on the characteristics of the received interrogation signals. The transponder selects the antennas (lower or upper) which receive the best transmission signal from the ground ATC secondary radar. This improves air-to-air surveillance and communication. The ATC/Mode S transponder, is also used in collision avoidance. In this role, the transponder performs as an ATCRBS and Mode S transponder for ATC requirements, while simultaneously serving as an integral part of TCAS. The Mode S transponder has two basic functions related to TCAS:
(1) Approximately every second, a Mode S transponder makes a transmission known as squitter. These transmissions alternate between the top and bottom Mode S antennas. Squitter is coded with the aircraft Mode S address and equipment capabilities. A ground station and airborne TCAS listen for squitter as the initial indication that a Mode S-equipped aircraft has entered the surveillance area.
(2) The communication between two TCAS-equipped aircraft occurs from the TCAS antenna of one aircraft to the Mode S transponder antenna of the other aircraft. Aboard the TCAS-equipped aircraft, data received by the Mode S transponder is passed to a TCAS computer, and the TCAS computer determines the content of reply messages.
The Mode S reply includes the flight number transmitted by the Flight Management and Guidance Computer (FMGC).
The ATC system operates with two frequencies:

Interrogation: 1030 MHz
Reply: 1090 MHz

B. System Security
The whole system comprises the following components:

One CAPT pushbutton switch
One F/O pushbutton switch
(For further details about the CAPT and F/O pushbutton switches, refer to AMM 23-73-00 Cabin Intercommunication Data System (CIDS)).

C. System Architecture
The ATC comprises two independent systems. Each system consists of:

One transponder 1SH1 (1SH2),
Two antennas 7SH1,7SH3 (7SH2,7SH4),
One ATC/TCAS control unit 3SH common to the two systems.
In addition, the Centralized Fault-Display Interface-Unit (CFDIU) 1TW enables access to the maintenance part of the ATC system through one Multipurpose Control and Display Unit (MCDU) 3CA1 (3CA2).
ATC - Control & Indicating ** ON A/C NOT FOR ALL

The ATC comprises two independent systems.
Each system consists of:

One transponder 1SH1 (1SH2),
Two antennas 7SH1,7SH3 (7SH2,7SH4),
One ATC/TCAS control unit 3SH common to the two systems.
One remote ATC control box 8SH common to the two systems
One pushbutton switch with protective cover

In addition, the Centralized Fault-Display Interface-Unit (CFDIU) enables access to the maintenance part of the ATC system through one Multipurpose Control and Display Unit (MCDU).

ATC - Control and Indicating ** ON A/C NOT FOR ALL

The ATC comprises two independent systems. Each system consists of:

One transponder 1SH1,
Two antennas 7SH1,7SH3,
One ATC/TCAS control unit 3SH.
In addition, the Centralized Fault-Display Interface-Unit (CFDIU) 1TW enables access to the maintenance part of the ATC system through one Multipurpose Control and Display Unit (MCDU) 3CA1 (3CA2).
ATC - Control & Indicating ** ON A/C NOT FOR ALL
ATC - Control and Indicating ** ON A/C NOT FOR ALL

D. Warning
The warning related to the ATC is only the FAULT or FAIL indicator light of the ATC control unit : when the system is faulty, the amber FAULT or FAIL indicator light comes on.

** ON A/C NOT FOR ALL

4. Power Supply
Energization of each system is through:

115VAC ESS BUS SHEDDABLE 801XP via circuit breaker 5SH1 for system 1.
115VAC BUS 2 204XP via circuit breaker 5SH2 for system 2.

Energization of the ATC control unit is through the two circuit breakers 5SH1 and 5SH2.
Energization of each system is through:

115VAC ESS BUS SHEDDABLE 801XP via circuit breaker 5SH1 for system 1.
115VAC BUS 2 204XP via circuit breaker 5SH2 for system 2.
115VAC ESS BUS SHEDDABLE 801XP via circuit breaker 10SH for system 1 in hijack mode.
28VDC ESS BUS 801PP via circuit breaker 11SH for remote ATC control box.

Energization of the ATC control unit is through the two circuit breakers and 5SH2.
Energization of each system is through:

115VAC ESS BUS SHEDDABLE 801XP via circuit breaker 5SH1 for system 1.

Energization of the ATC control unit is through the two circuit breakers 5SH1 and 2004SG.

A. Circuit Breakers Table

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	COM NAV/ATC/1	5SH1	G11
** ON A/C NOT FOR ALL
121VU	COM NAV/ATC/2	5SH2	K07
** ON A/C NOT FOR ALL
121VU	T/TISS	2004SG	K07
** ON A/C NOT FOR ALL
106VU	NAV/ATC 1/EMER	10SH	B01
106VU	NAV/REMOTE/ATC/SPLY	11SH	B02

** ON A/C NOT FOR ALL

5. Interface

ATC - Block Diagram ** ON A/C NOT FOR ALL

Two types of ARINC signals, ARINC 429 and ARINC 575, provide a two-way interface between the transponder and other aircraft systems.
The ARINC 429 signals consist of 32-bit data words. The first 8 bits of the word make up a label which specifies the type of information contained in that word.
The ARINC 429 buses provide the following information:

Control data input
Air data input 1 and 2
Maintenance data.
The low-speed 429 buses are repetitive buses that provide the transponder interfaces between:
Control panel
Altitude information from the ADIRUs
CFDIU.
The high-speed 429 buses permit the transfer of data between the transponder and the TCAS (if installed).

The ARINC 429 signals provide a two-way interface between the transponder and other aircraft systems.
The ARINC 429 signals consist of 32-bit data words. The first 8 bits of the word make up a label which specifies the type of information contained in that word.
The ARINC 429 buses provide the interfaces with:

The Traffic Collision Avoidance System (TCAS) computer
The Air Data and Inertial Reference Units (ADIRUs, ADC and IRS)
The Centralized Fault Display Interface Unit (CFDIU)
The Flight Management and Guidance Computer (FMGC)
The Flight Control Unit (FCU)
The ATC/TCAS Control Panel

NOTE: MMR/ATC link, ATSU/ATC link, FCU/ATC link and ADIRU (IR part)/ATC link are installed if the optional wiring provisions for enhanced surveillance/extended squitters are validated.
No data are currently transmitted on ATSU/ATC link; MMR /ATC link are provisions only.

The Traffic Collision Avoidance System (TCAS) computer
The Air Data and Inertial Reference Units (ADIRUs, ADC and IRS)
The Centralized Fault Display Interface Unit (CFDIU)
The Flight Management and Guidance Computer (FMGC)
The Flight Control Unit (FCU)
The ATC/TCAS Control Panel

NOTE: MMR/ATC link, ATSU/ATC link, FCU/ATC link and ADIRU (IR part)/ATC link are installed if the optional wiring provisions for enhanced surveillance are validated.
No data are currently transmitted on ATSU/ATC link; MMR /ATC link are provisions only.

The Traffic Collision Avoidance System (TCAS) computer
The Air Data and Inertial Reference Units (ADIRUs)
The Centralized Fault Display Interface Unit (CFDIU)
The Flight Management and Guidance Computer (FMGC)
The Flight Control Unit (FCU)
The ATC/TCAS Control Unit via the remote ATC control box for transponder 1.

The Traffic Collision Avoidance System (TCAS) computer
The Air Data and Inertial Reference Units (ADIRUs, ADC and IRS)
The Centralized Fault Display Interface Unit (CFDIU)
The Flight Management and Guidance Computer (FMGC)
The Flight Control Unit (FCU)
The ATC/TCAS control panel
The Multi-Mode Receiver (MMR1 and MMR2)
The System Data Acquisition Computer (SDAC).

NOTE: MMR/ATC link, FCU/ATC link and ADIRU (IR part)/ATC link are installed if the optional wiring provisions for enhanced surveillance/extended squitters are validated.

A. Transponder Input Data
Control panel labels which are received from the tuning source are transmitted to the TCAS as periodic labels. Only labels which are received from the control panel are transmitted without modification to the TCAS, however the transponder must receive at least label 016 to be operational.

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| PARAMETER LIST PARAMETER CHARACTERISTICS (NUMERIC) |

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! 013 !CTL WORD 1! ! ! ! ! ! ! !

! 015 !CTL WORD 2! ! ! ! ! ! ! !

! 016 !CTL WORD 3! ! ! ! ! ! ! !

! 031 !CTL WORD 4! ! ! ! ! ! ! !

-------------------------------------------------------------------------------

NOTE: CTL WORD 1: TCAS display mode and range control information
CTL WORD 2: TCAS altitude limit control information
CTL WORD 3: transponder and TCAS control information
CTL WORD 4: transponder control information, and is designed for interface with older ATCRBS control panels.

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! SOURCE ! LABEL ! PARAMETER !

----------------------------------------------------------------------------

! ATC/TCAS ! 013 ! TCAS display control !

! control panel ! 015 ! Display altitude !

! ! 016 ! TCAS/ATC control !

! ! 031 ! ATCRBS control !

! ! disc ! STBY/ON !

! ! disc ! Air/Ground !

-----------------!----------------------------------------------------------

! TCAS ! 273 ! Tx word 1 !

! ! 274 ! Tx word 2 !

! ! 275 ! Tx word 3 !

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! FCU ! 102 ! Selected Altitude !

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! CFDIU ! 227 ! Command to systems !

! ! 125 ! GMT !

! ! 260 ! Date !

! !233 to 236! Flight number !

! !040 to 042! City pair !

! !301 to 304! A/C ident !

! ! 126 ! Flight phase !

! !155 to 157! A/C configuration !

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! ADIRU ! 310 ! Latitude present position !

! (IR part) ! 311 ! Longitude present position !

! ! 312 ! Ground speed !

! ! 313 ! True track angle !

! ! 320 ! Magnetic heading !

! ! 325 ! Roll angle !

! ! 335 ! Track angle rate !

! ! 365 ! Inertial vertical velocity !

! ! 366 ! N/S velocity !

! ! 367 ! E/W velocity !

! ! 076 ! GNSS alt !

! ! 103 ! GNSS track angle !

! ! 110 ! GNSS latitude coarse !

! ! 111 ! GNSS longitude coarse !

! ! 112 ! GNSS ground speed !

! ! 120 ! GNSS latitude fine !

! ! 121 ! GNSS longitude fine !

! ! 130 ! Autonomous Hill !

! ! 150 ! Time !

! ! 165 ! GNSS vertical velocity !

! ! 166 ! GNSS N/S velocity !

! ! 174 ! GNSS E/W velocity !

! ! 247 ! Horizontal figure of merite !

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! ADIRU ! 203 ! Altitude barometric !

! (ADR part) ! 205 ! Mach !

! ! 206 ! Computed airspeed !

! ! 210 ! True airspeed !

! ! 212 ! Altitude rate barometric !

! ! 234 ! Baro correction !

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! FMS ! 233 ! Flight number word 1 !

! ! 234 ! Flight number word 2 !

! ! 235 ! Flight number word 3 !

! ! 236 ! Flight number word 4 !

! ! 310 ! Latitude present position !

! ! 311 ! Longitude present position !

----------------------------------------------------------------------------

! SOURCE ! LABEL ! PARAMETER !

----------------------------------------------------------------------------

! ATC/TCAS ! 013 ! TCAS display control !

! control panel ! 015 ! Display altitude !

! ! 016 ! TCAS/ATC control !

! ! 031 ! ATCRBS control !

! ! disc ! STBY/ON !

! ! disc ! Air/Ground !

-----------------!----------------------------------------------------------

! TCAS ! 273 ! Tx word 1 !

! ! 274 ! Tx word 2 !

! ! 275 ! Tx word 3 !

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! FCU ! 102 ! Selected Altitude !

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! CFDIU ! 227 ! Command to systems !

! ! 125 ! GMT !

! ! 260 ! Date !

! !233 to 236! Flight number !

! !040 to 042! City pair !

! !301 to 304! A/C ident !

! ! 126 ! Flight phase !

! !155 to 157! A/C configuration !

----------------------------------------------------------------------------

! ADIRU ! 310 ! Latitude present position !

! (IR part) ! 311 ! Longitude present position !

! ! 312 ! Ground speed !

! ! 313 ! True track angle !

! ! 320 ! Magnetic heading !

! ! 325 ! Roll angle !

! ! 335 ! Track angle rate !

! ! 365 ! Inertial vertical velocity !

! ! 366 ! N/S velocity !

! ! 367 ! E/W velocity !

! ! 076 ! GNSS alt !

! ! 103 ! GNSS track angle !

! ! 110 ! GNSS latitude coarse !

! ! 111 ! GNSS longitude coarse !

! ! 112 ! GNSS ground speed !

! ! 120 ! GNSS latitude fine !

! ! 121 ! GNSS longitude fine !

! ! 130 ! Autonomous Hill !

! ! 150 ! Time !

! ! 165 ! GNSS vertical velocity !

! ! 166 ! GNSS N/S velocity !

! ! 174 ! GNSS E/W velocity !

! ! 247 ! Horizontal figure of merite !

----------------------------------------------------------------------------

! ADIRU ! 203 ! Altitude barometric !

! (ADR part) ! 205 ! Mach !

! ! 206 ! Computed airspeed !

! ! 210 ! True airspeed !

! ! 212 ! Altitude rate barometric !

! ! 234 ! Baro correction !

----------------------------------------------------------------------------

! FMS ! 233 ! Flight number word 1 !

! ! 234 ! Flight number word 2 !

! ! 235 ! Flight number word 3 !

! ! 236 ! Flight number word 4 !

! ! 310 ! Latitude present position !

! ! 311 ! Longitude present position !

----------------------------------------------------------------------------

! SOURCE ! LABEL ! PARAMETER !

----------------------------------------------------------------------------

! ATC/TCAS ! 013 ! TCAS display control !

! control panel ! 015 ! Display altitude !

! ! 016 ! TCAS/ATC control !

! ! 031 ! ATCRBS control !

! ! disc ! STBY/ON !

! ! disc ! Air/Ground !

-----------------!----------------------------------------------------------

! TCAS ! 273 ! Tx word 1 !

! ! 274 ! Tx word 2 !

! ! 275 ! Tx word 3 !

----------------------------------------------------------------------------

! FCU ! 102 ! Selected Altitude !

----------------------------------------------------------------------------

! CFDIU ! 227 ! Command to systems !

! ! 125 ! GMT !

! ! 260 ! Date !

! !233 to 236! Flight number !

! !040 to 042! City pair !

! !301 to 304! A/C ident !

! ! 126 ! Flight phase !

! !155 to 157! A/C configuration !

----------------------------------------------------------------------------

! ADIRU ! 310 ! Latitude present position !

! (IR part) ! 311 ! Longitude present position !

! ! 312 ! Ground speed !

! ! 313 ! True track angle !

! ! 320 ! Magnetic heading !

! ! 325 ! Roll angle !

! ! 335 ! Track angle rate !

! ! 365 ! Inertial vertical velocity !

! ! 366 ! N/S velocity !

! ! 367 ! E/W velocity !

! ! 076 ! GNSS alt !

! ! 103 ! GNSS track angle !

! ! 110 ! GNSS latitude coarse !

! ! 111 ! GNSS longitude coarse !

! ! 112 ! GNSS ground speed !

! ! 120 ! GNSS latitude fine !

! ! 121 ! GNSS longitude fine !

! ! 130 ! Autonomous Hill !

! ! 150 ! Time !

! ! 165 ! GNSS vertical velocity !

! ! 166 ! GNSS N/S velocity !

! ! 174 ! GNSS E/W velocity !

! ! 247 ! Horizontal figure of merite !

----------------------------------------------------------------------------

! ADIRU ! 203 ! Altitude barometric !

! (ADR part) ! 205 ! Mach !

! ! 206 ! Computed airspeed !

! ! 210 ! True airspeed !

! ! 212 ! Altitude rate barometric !

! ! 234 ! Baro correction !

----------------------------------------------------------------------------

! FMS ! 233 ! Flight number word 1 !

! ! 234 ! Flight number word 2 !

! ! 235 ! Flight number word 3 !

! ! 236 ! Flight number word 4 !

! ! 310 ! Latitude present position !

! ! 311 ! Longitude present position !

----------------------------------------------------------------------------

! SOURCE ! LABEL ! PARAMETER !

----------------------------------------------------------------------------

! ATC/TCAS ! 013 ! TCAS display control !

! control panel ! 015 ! Display altitude !

! ! 016 ! TCAS/ATC control !

! ! 031 ! ATCRBS control !

! ! disc ! STBY/ON !

! ! disc ! Air/Ground !

-----------------!----------------------------------------------------------

! TCAS ! 273 ! Tx word 1 !

! ! 274 ! Tx word 2 !

! ! 275 ! Tx word 3 !

----------------------------------------------------------------------------

! FCU ! 101 ! Selected Heading !

! ! 102 ! Selected Altitude !

! ! 272 ! Selected Baro ref and display mode !

----------------------------------------------------------------------------

! CFDIU ! 125 ! GMT !

! ! 126 ! Flight phase !

! !155 to 156! A/C configuration

! ! 227 ! BITE Command Word !

! !233 to 236! Flight number !

! ! 260 ! Date !

! !301 to 304! A/C ident !

----------------------------------------------------------------------------

! ADIRU ! 312 ! Ground speed !

! (IR part) ! 313 ! True track angle !

! ! 314 ! True Heading !

! ! 320 ! Magnetic Heading !

! ! 325 ! Roll angle !

! ! 335 ! Track angle rate !

! ! 365 ! Inertial vertical speed !

! ! 377 ! Equipment ID !

----------------------------------------------------------------------------

! ADIRU ! 203 ! Altitude barometric !

! (ADR part) ! 204 ! Corrected Barometric Altitude !

! ! 205 ! Mach !

! ! 206 ! Computed airspeed !

! ! 210 ! True airspeed !

! ! 212 ! Altitude rate barometric !

! ! 234 ! Baro correction !

! ! 352 ! Aircraft type !

----------------------------------------------------------------------------

! FMS ! 233 ! Flight number word 1 !

! ! 234 ! Flight number word 2 !

! ! 235 ! Flight number word 3 !

! ! 236 ! Flight number word 4 !

----------------------------------------------------------------------------

! MMR1 and MMR2 ! 273 ! GNSS STATUS !

! ! 076 ! GPS MSL altitude !

! ! 103 ! GPS Track anglearse !

! ! 110 ! GPS Latitude coarsee !

! ! 111 ! GPS Longitude coarse !

! ! 112 ! GPS Ground Speede !

! ! 120 ! GPS Latitude fine !

! ! 121 ! GPS Longitude fine !

! ! 130 ! GPS HPLT. INTEGRITY LIMIT !

! ! 133 ! GPS VERT. INTEGRITY LIMITrit (VFOM) !

! ! 136 ! GPS Vertical Figure of Merit (VFOM) !

! ! 165 ! GPS Vertical velocity !

! ! 166 ! GPS N/S Velocity !

! ! 174 ! GPS E/W Velocity Figure of Merit (HFOM) !

! ! 247 ! GPS Horizontal Figure of Merit (HFOM) !

! ! 370 ! Height above ellipsoid !

! ! 140 ! UTC FINE FRACTIONS !

! ! 141 ! UTC FINE FRACTIONS !

! ! 150 ! UTC Time !

----------------------------------------------------------------------------

B. Transponder Buses

TCAS interface
Data between the transponder and the TCAS are transferred on two unidirectional buses. These buses are high-speed ARINC 429 buses.
ADIRU interface
The transponder receives inputs from two ADIRUs. Air data 1 and Air data 2 supply the transponder with barometric altitude data.
CFDIU interface
The Centralized Fault Display Interface Unit (CFDIU) bus consists of two low-speed ARINC 429 buses, one in each direction.

FMGC interface
The transponder receives flight identification on an ARINC 429 low-speed bus in four labels. The Flight identification may be transmitted to the ground.

-------------------------------------------------------------------------------

| PARAMETER LIST PARAMETER CHARACTERISTICS (NUMERIC) |

-------------------------------------------------------------------------------

-------------------------------------------------------------------------------

! 125 !TIME ! ! ! ! ! !BCD ! ! !

! 126 !FLIGHT ! ! ! ! ! !BNR ! ! !

! !PHASE ! ! ! ! ! ! ! ! !

! 155 !AIRCRAFT ! ! ! ! ! !DISC! ! !

! !CONFIGURA ! ! ! ! ! ! ! ! !

! !TION ! ! ! ! ! ! ! ! !

! 271 !WORD 1 ! ! ! ! ! !DISC! ! !

! 272 !WORD 2 ! ! ! ! ! !DISC! ! !

! 273 !WORD 3 ! ! ! ! ! !DISC! ! !

! 203 !WORD 4 ! ! ! ! ! !BCD ! ! !

! 275 !WORD 5 ! ! ! ! ! !DISC! ! !

! 276 !WORD 6 ! ! ! ! ! !DISC! ! !

! 277 !WORD 7 ! ! ! ! ! !DISC! ! !

! 274 !WORD 8 ! ! ! ! ! !DISC! ! !

! 350 !MAINTENAN ! ! ! ! ! !DISC! ! !

! !CE ! ! ! ! ! ! ! ! !

! 356 !BITE ! ! ! ! ! !N/A ! ! !

! !STATUS ! ! ! ! ! ! ! ! !

! ! ! ! ! ! ! ! ! ! !

! 233-236 !FLIGHT ! ! ! ! ! !BNR ! ! !

! !NUMBER ! ! ! ! ! ! ! ! !

! !STATUS ! ! ! ! ! ! ! ! !

-------------------------------------------------------------------------------

NOTE: WORD 1: TCAS broadcast coordination data 1
WORD 2: TCAS broadcast coordination data 2
WORD 3: Mode S ground uplink sensitivity level command
WORD 4: Baro corrected altitude
WORD 5: Mode S address part 1
WORD 6: Mode S address part 2
WORD 7: Acknowledgement of non periodic message
WORD 8: TCAS broadcast coordination data

----------------------------------------------------------------------------

! DESTINATION ! LABEL ! PARAMETER !

----------------------------------------------------------------------------

! TCAS ! 271 ! TCAS coordination data 1 !

! ! 272 ! TCAS coordination data 2 !

! ! 273 ! Mode S ground uplink !

! ! 203 ! Barometric altitude !

! ! 275 ! Mode S adress part 1 !

! ! 276 ! Mode S adress part 2 !

! ! 277 ! Acknowledgement !

! ! 274 ! Lock confirmation !

! ! 204 ! Baro corrected altitude !

! ! 013 ! TCAS display control !

! ! 015 ! Display altitude limit !

! ! 016 ! TCAS/ATC control !

! ! 210 ! Airspeed !

! ! 212 ! Altitude rate !

! ! 350 ! Maintenance word !

----------------------------------------------------------------------------

! CFDIU ! 356 ! Normal mode !

----------------------------------------------------------------------------

! DESTINATION ! LABEL ! PARAMETER !

----------------------------------------------------------------------------

! TCAS ! 271 ! TCAS coordination data 1 !

! ! 272 ! TCAS coordination data 2 !

! ! 273 ! Mode S ground uplink !

! ! 203 ! Barometric altitude !

! ! 275 ! Mode S adress part 1 !

! ! 276 ! Mode S adress part 2 !

! ! 277 ! Acknowledgement !

! ! 274 ! Lock confirmation !

! ! 204 ! Baro corrected altitude !

! ! 013 ! TCAS display control !

! ! 015 ! Display altitude limit !

! ! 016 ! TCAS/ATC control !

! ! 210 ! Airspeed !

! ! 212 ! Altitude rate !

! ! 350 ! Maintenance word !

! ! 354 ! Program pin status !

----------------------------------------------------------------------------

! CFDIU ! 356 ! Normal mode !

----------------------------------------------------------------------------

** ON A/C NOT FOR ALL

6. Component Description

A. ATC Transponder FIN: 1-SH-1 FIN: 1-SH-2

(1) External Description

ATC - Transponder ** ON A/C NOT FOR ALL

The face of the transponder is fitted with a handle, two attaching parts, a PUSH TO TEST pushbutton switch, six LEDs and a DATA LOADER plug.
The PUSH TO TEST pushbutton switch is used to initiate the LED test and transponder self-test. All LEDs are on for approximately three seconds following self-test initiation. After three seconds, the front panel LEDs indicate the current condition of the unit.
If the PUSH TO TEST pushbutton switch is not pushed again, the LEDs go off.
If the PUSH TO TEST pushbutton switch is pushed while the LEDs are still on, the next previous flight leg is displayed.
The transponder has the capability to store 10 flight legs. To display all stored flight legs, the PUSH TO TEST pushbutton switch must be pushed when the previous flight leg is being displayed. When all flight legs are displayed, all LEDs flash to indicate the end of the routine. All LEDs go off within 10 s after self-test is completed.
The functions of the LEDs are indicated on the table below:

-------------------------------------------------------------------------

! LEDs ! FUNCTION !

-------------------------------------------------------------------------

! XPDR PASS (green) ! On after test indicates normal operation. !

!----------------------!------------------------------------------------!

! XPDR FAIL (red) ! On after test indicates malfunction. !

!----------------------!------------------------------------------------!

! CNTL PNL (red) ! On after test indicates abnormal input of 429 !

! ! word data from control unit, or associated !

! ! circuitry. !

!----------------------!------------------------------------------------!

! TOP ANT (red) ! Indicates that the upper antennas are !

! ! incorrectly connected or are failed (comes on !

! ! during BITE self-test). !

!----------------------!------------------------------------------------!

! BOT ANT (red) ! Indicates that the lower antennas are !

! ! incorrectly connected or are failed (comes on !

! ! during BITE self-test). !

!----------------------!------------------------------------------------!

! ALT SIG (red) ! On after test indicates abnormal input from !

! ! ALT data system bus, or associated circuitry. !

!----------------------!------------------------------------------------!

The back of the transponder contains an ARINC 600, shell-size connector to provide electrical connections to the aircraft wiring via mount. Contact grouping is as follows:

Top contact set - ATE interface
Center contact set - System interconnections
Bottom contact set - Power supply and bonding.

(2) External Description

ATC - Transponder ** ON A/C NOT FOR ALL

The face of the transponder is fitted with a handle, two attaching parts, a TEST pushbutton switch and five LEDs.
The TEST pushbutton switch is used to initiate the BITE self-test. During the self-test, the transponder performs the following functions:
With TEST pushbutton switch pressed for less than 5 seconds:

Stops normal processing
Performs test of full-time ROM checksum status
Performs RAM tests
Stimulates receiver noise sources and monitors results
Checks antenna integrity
Injects simulated ATCRBS/Mode S all-call into top and bottom receivers
Samples transmitter monitor, following transmission, and verifies reply is correct
Samples power supply monitor
Performs test on non-active serial buses (TCAS, COM A/B and C/D)
Updates maintenance portion of nonvolatile memory
Returns unit to normal operation
Performs receiver test: All LEDs come on red for 2 seconds. Then the LRU status LED becomes green and the other LEDs remain red for 2 seconds. Then all LEDs go off for 2 seconds, then the test results are displayed for 30 seconds:
LRU status - green for LRU with no fault, red for LRU fault; all other LEDs are off for no fault, red for fault.

Instead of self-test, the unit reads nonvolatile memory fault data for the last four flight legs and the applicable LEDs come on.

The functions of the LEDs are indicated on the table below:

-------------------------------------------------------------------------

! LEDs ! FUNCTION !

-------------------------------------------------------------------------

! LRU STATUS (green) ! On after test indicates normal operation. !

!----------------------!------------------------------------------------!

! LRU STATUS (red) ! On after test indicates malfunction. !

!----------------------!------------------------------------------------!

! ANTENNA TOP (red) ! Indicates that the upper antennas are !

! FAIL ! incorrectly connected or are failed (comes on !

! ! during BITE self-test). !

!----------------------!------------------------------------------------!

! ANTENNA BOT (red) ! Indicates that the lower antennas are !

! FAIL ! incorrectly connected or are failed (comes on !

! ! during BITE self-test). !

!----------------------!------------------------------------------------!

! ALTITUDE FAIL(red) ! Indicates abnormal input from ALT data system !

! ! bus, or associated circuitry (comes on during !

! ! BITE self-test). !

!----------------------!------------------------------------------------!

! CONTROL FAIL (red) ! Indicates abnormal input of 429 word data from !

! ! control unit, or associated circuitry (comes !

! ! on during BITE self-test). !

-------------------------------------------------------------------------

The back of the transponder contains an ARINC 600, shell-size connector to provide electrical connections to the aircraft wiring via mount. Contact grouping is as follows :

Top contact set and Center contact set - System interconnections
Bottom contact set - Power supply and bonding.

(3) Internal Description

ATC Transponder - Simplified Block Diagram ** ON A/C NOT FOR ALL

Input signals (1030 MHz interrogations/uplinks) are received at one or both of the antennas. Each received antenna signal is pulse demodulated and sent to the processing circuits where the diversity selection is made. The diversity selection determines which receiver provides the stronger (or first) signal. The selected received signal is then applied through a demodulator circuit to the processing circuits. The processing circuits determine if the interrogation is an ATCRBS interrogation, a mode S interrogation addressed to the particular aircraft or a mode S addressed to another aircraft. Depending upon the type of the interrogation, the processing circuits determine the proper reply ( if one is required) and send the appropriate reply through a message processing circuit to the diversity switching circuits. The diversity switching circuits select the antenna through which the reply will be transmitted. The reply message is transmitted through the same antenna from which the selected received signal originated.
The I/O circuit is an interface circuit to receive serial ARINC 429 data, the 24 bit address input, the code altitude input and various discretes. The CPU provides the link between the I/O and the signal processing circuits.
The signal processing circuits consist of a video processor, a PAM decoder and a message processor. The video processor analyzes the received signals (pulses and pulse amplitude). If the received signal is valid, the PAM decoder determines the type of interrogation. Then the decoder output is sent to the message processor where appropriate reply format is generated.
The message processor output is amplified and the resultant 1090 MHz transmit signal is applied to the antennas through a diplexer/diversity switch.
The received signals from the antennas are sent to the receiver stage. The 60 MHz IF output is used to drive the video processor and the message processor (DSPK function). The input of the receiver stage is filtered to reduce the susceptibility to HIRF signals.
The power supply is a pulse-width modulated switching regulator. It supplies all the necessary DC voltages required by the internal circuitry. An integrated monitoring function gives protection to the power supply circuits and reset signals to the CPUs each time primary power is applied.

(4) External Description

ATC - Transponder ** ON A/C NOT FOR ALL

Stops normal processing
Performs test of full-time ROM checksum status
Performs RAM tests
Stimulates receiver noise sources and monitors results
Checks antenna integrity
Injects simulated ATCRBS/Mode S all-call into top and bottom receivers
Samples transmitter monitor, following transmission, and verifies reply is correct
Samples power supply monitor
Performs test on non-active serial buses (TCAS, COM A/B and C/D)
Updates maintenance portion of nonvolatile memory
Returns unit to normal operation
Performs receiver test: All LEDs come on red for 2 seconds. Then the LRU status LED becomes green and the other LEDs remain red for 2 seconds. Then all LEDs go off for 2 seconds, then the test results are displayed for 30 seconds:
LRU status - green for LRU with no fault, red for LRU fault; all other LEDs are off for no fault, red for fault.

Instead of self-test, the unit reads nonvolatile memory fault data for the last four flight legs and the applicable LEDs come on.

The functions of the LEDs are indicated on the table below:

-------------------------------------------------------------------------

! LEDs ! FUNCTION !

-------------------------------------------------------------------------

! LRU STATUS (green) ! On after test indicates normal operation. !

!----------------------!------------------------------------------------!

! LRU STATUS (red) ! On after test indicates malfunction. !

!----------------------!------------------------------------------------!

! ANTENNA TOP (red) ! Indicates that the upper antennas are !

! FAIL ! incorrectly connected or are failed (comes on !

! ! during BITE self-test). !

!----------------------!------------------------------------------------!

! ANTENNA BOT (red) ! Indicates that the lower antennas are !

! FAIL ! incorrectly connected or are failed (comes on !

! ! during BITE self-test). !

!----------------------!------------------------------------------------!

! ALTITUDE FAIL(red) ! Indicates abnormal input from ALT data system !

! ! bus, or associated circuitry (comes on during !

! ! BITE self-test). !

!----------------------!------------------------------------------------!

! CONTROL FAIL (red) ! Indicates abnormal input of 429 word data from !

! ! control unit, or associated circuitry (comes !

! ! on during BITE self-test). !

-------------------------------------------------------------------------

The back of the transponder contains an ARINC 600, shell-size connector to provide electrical connections to the aircraft wiring via mount. Contact grouping is as follows :

Top contact set and Center contact set - System interconnections
Bottom contact set - Power supply and bonding.

(5) Internal description

ATC Transponder - Simplified Block Diagram ** ON A/C NOT FOR ALL

(6) External description

ATC - Transponder ** ON A/C NOT FOR ALL

The face of the transponder is fitted with a handle, two attaching parts, a TEST pushbutton switch and ten LEDs.
The TEST pushbutton switch initiates the LED test and transponder self-test. When pressed and held, it initiates the LED test: - three seconds on and three seconds off. After the LED test, the LEDs indicate unit operational status and any current major malfunctions.
The functions of the LEDs are indicated on the table below:

-------------------------------------------------------------------------

! LEDs ! FUNCTION !

-------------------------------------------------------------------------

! TPR (green) ! On after test indicates normal operation. !

!----------------------!------------------------------------------------!

! TPR (red) ! On after test indicates malfunction. !

!----------------------!------------------------------------------------!

! ALT (red) ! On after test indicates abnormal input from !

! ! ALT data system bus, or associated circuitry. !

!----------------------!------------------------------------------------!

! DATA IN (red) ! On after test indicates abnormal input of 429 !

! ! word data from control unit, or associated !

! ! circuitry. !

!----------------------!------------------------------------------------!

! TOP (red) ! On after test indicates malfunctioning top !

! ! transponder antenna (if installed), !

! ! or associated circuitry. !

!----------------------!------------------------------------------------!

! BOT (red) ! On after test indicates malfunctioning bottom !

! ! transponder antenna, or associated circuitry. !

!----------------------!------------------------------------------------!

! TCAS (red) ! On after test indicates abnormal input of 429 !

! ! word data from the TCAS unit (if installed), !

! ! or associated circuitry. !

!----------------------!------------------------------------------------!

! MAINTENANCE (red) ! On after test indicates abnormal input from !

! ! Maintenance data system bus, or associated !

! ! circuitry. !

-------------------------------------------------------------------------

The back is equipped with one ARINC 600 electrical receptacle and a slot for the test connector.

(7) Internal Description

ATC Transponder - Simplified Block Diagram ** ON A/C NOT FOR ALL

(a) Antenna switch and low pass filter board:
The antenna switch and low pass filter board routes and filters the received or transmitted RF signal.

(b) Pin diode driver board:
The pin diode driver board selects the antenna and receives a transmit mode according to its inputs.
The pin diode contains BITE which monitors the antenna, modulator and pin diode driver.

(c) Receive function:
The receive function consists of the RF/IF board and the video/DPSK board.
The RF/IF board filters, amplifies and converts the antenna signals into IF frequency. Two outputs are generated:

The top/bottom video signal which is processed by the video processing circuit in order to determine whether it is correct or a parasite signal.
A top/bottom IF signal which is sent to the DPSK demodulator circuit which converts it into TTL logic level and transmits it to the I/O processor board.

(d) The transmit function consists of:

The modulator board
The transmitter board
The band pass filter
The RF interconnect board

The I/O processor board transmits an information signal which is converted into a pulsed output. The pulsed output is applied to the pulsed oscillator of the transmitter board then amplified, filtered and fed to the antenna through the RF interconnect board.

(e) Test function:
The test function consists of:

The test oscillator modulator board
The test oscillator board.

It allows generation of test signals applied to the antenna.

(f) I/O processor board
The heart of the I/O processor board is an 80186 microprocessor (16 bits). This microprocessor is connected with interface circuits to various A/C systems. The microprocessor controls:

The input/output requirement of the transponder
The receive/transmit function
The BITE of the transponder.

(8) External Description

ATC - Transponder ** ON A/C NOT FOR ALL

The front face of the transponder has a handle, two attaching parts, a PUSH TO TEST pushbutton switch and six LEDs. The name, color and function of the six LEDs are as follows:

XPDR P/F (green): no faults are detected on the transponder during the reply.
XPDR P/F (red): faults are detected on the transponder during the reply.
ADS-B (red): faults are detected on automatic dependent surveillance-broadcast.
TOP ANT (red): the top antenna(s) is(are) incorrectly connected or is(are) defective.
BOT ANT (red): the bottom antenna(s) is(are) incorrectly connected or is(are) defective.
CTRL (red): the control panel is incorrectly connected.
ALT (red): the altitude is not in the correct format.

The rear of the transponder has an ARINC 600, shell-size connector for electrical connections to the aircraft wiring with a mount.

(9) Principle of Operation

ATC - Block Diagram ** ON A/C NOT FOR ALL

Mode A interrogations
Mode C interrogations
Mode S all call interrogations
Mode S interrogations.

After receiving these pulses, the transponder identifies and decodes the interrogations. Depending on the detected interrogation mode, the transponder transmits the identification of the aircraft or its barometric altitude. The transponder is provided with the Mode S Data Link capability. The transmission of the replies to the ground takes place on a carrier frequency of 1090 MHz.

(a) Interrogations

ATC - Principle ** ON A/C NOT FOR ALL

Four classes of interrogations are transmitted by the ground interrogator, they are:

1 Mode A or C interrogations
A mode A or C interrogation consists of two pulses labelled P1 and P3. These pulses are transmitted by the directional antenna of the Secondary Surveillance Radar (SSR) and spaced according to the SSR mode of operation. A control pulse P2 is radiated by the omnidirectional antenna of the SSR two microseconds after the pulse P1 is transmitted from the directional antenna of the SSR.
Amplitude of pulses P1 and P3 varies according to the position of the directional antenna. P1 and P3 are at higher amplitude than P2 when the aircraft flies in the antenna main beam. Amplitude of the pulse P2, also called side lobe suppression pulse, is constant whichever the position of the omnidirectional antenna.
The aircraft receives the P1 pulse at a higher amplitude than P2. The aircraft transponder detects this amplitude difference and determines the interrogation to be a valid interrogation. When the transponder detects that P2 is within 6 dB of P1, in amplitude, it determines that the interrogation is not valid.

2 Mode S all call interrogation

ATC - Mode S All Call Pulse Characteristics ** ON A/C NOT FOR ALL

A mode S all call interrogation consists of three pulses labelled P1, P3 and P4. They are transmitted by a directional antenna. A control pulse P2 (Side Lobe Suppression Pulse) is transmitted following P1 by an omnidirectional antenna.
The detection of pulse P1, P2 and P3 is the same as for mode A or C interrogation.
The transponder initiates a reply until the presence of the pulse P4 is detected. Upon detection of the pulse P4, the reply is terminated. If the width of the pulse P4 is 0.8 microseconds (mode A or mode C only all-call), no reply is transmitted. If the width of the pulse is 1.6 microseconds (mode S all-call), a mode S reply is generated 128 microseconds after the leading edge of the pulse P4.

3 Mode S interrogation

ATC - Mode S Pulse Characteristics ** ON A/C NOT FOR ALL

A mode S interrogation consists of a preamble followed by a data block.
The preamble consists of two equal transmitted pulses labelled P1 and P2 and spaced by two microseconds.
The data block consists of a single pulse P6 with a synchro phase reversal modulation.

Pulse P6 duration : short 15.5 microseconds,

long 29.5 microseconds,

Data block : 56 or 112 bits.

The pulse P5, which is radiated by the omnidirectional antenna may be overlaid on P6 by the ground interrogator as a Side Lobe Suppression (SLS) signal in any mode S interrogation. The pulse P5 is spaced 0.4 microsecond from the synchro phase reversal.

(b) Encoded reply

1 Mode A or C reply
A mode A or C reply consists of two framing pulses F1 and F2, separated by a 20.3 microseconds time interval. The encoding of the reply is done by means of the presence (1) or absence (0) of 13 reply pulses (12 pulses plus X pulse).

2 Mode S all call reply
A mode S all call reply consists of a four-bit preamble followed by a data block.
The data block contains 56 position modulated pulses.

3 Mode S reply
A mode S reply occurs after a mode S interrogation or a mode S all call interrogation (P4 duration 1.6 microseconds).
A mode S reply consists of a four-bit preamble followed by a data block. The data block contains 56 (short) or 112 (long) position modulated pulses.

4 Mode S message content
The minimum data link transponder supports all surveillance functions, in addition to bidirectional air-to-air data exchange, ground-to-air data uplink (Comm A), air-to-ground data downlink (Comm B), and multisite message protocol. In addition, the transponder is capable of receiving Extended Length Messages (ELMs) from the ground. ELMS are received in the Comm C format. ELM transmittals to the ground use the Comm D format (Note: Comm C and Comm D are future applications; Comm D is not available with this transponder). All discrete Mode S interrogations and replies (except the all-call reply) contain the 24-bit discrete address of the Mode S transponder upon which 24 error detection parity check bits are overlaid. In the all-call reply, the 24 parity check bits are overlaid on the Mode S interrogation address and the transponders' discrete address is included in the text of the reply.
The main function of Mode S is surveillance. To accomplish this function, the Mode S transponder uses the 56-bit transmissions (in each direction). In the 56-bit transmissions, the aircraft reports its altitude or ATCRBS 4096 code, and the flight status (airborne, on-ground, alert, Special Position Identification (SPI), etc.
The discrete addressing and digital encoding of Mode S transmissions permit their use as a digital data link. The interrogation and reply formats of the Mode S system contain sufficient coding space to permit the transmission of data. These data transmissions may be used for air traffic control purposes, air-to-air data interchange for collision avoidance, or to provide flight advisory services such as weather reports, or Automated Terminal Information System (ATIS).
Most Mode S data link transmissions will be handled as one 56-bit message included as part of a long 112-bit interrogation or reply.
These transmissions include the message in addition to the surveillance data.
Longer messages are transmitted using the Extended Length Message (ELM) capability. The ELM is capable of transmitting up to sixteen 80-bit message segments, either ground-to-air or air-to-ground. The ELM can be acknowledged with a single reply or interrogation. ELMs uplinked need not be replied to individually, but can be acknowledged in a reply containing a summary of the received interrogations.
ELMs do not contain surveillance data.
The following table gives the definition of uplink format message fields:

-------------------------------------------------------------------------------

! DESIGNATOR ! FIELD ! INDICATION !

-------------------------------------------------------------------------------

! AP ! address parity ! 24-bit address and parity overlaid !

! ! ! !

! AQ ! acquisition ! differentiates acquisition from non-acquisi- !

! ! ! tion interrogations !

! ! ! !

! DI ! designator ! identifies the coding contained in the SD !

! ! identification ! field !

! ! ! !

! II ! interrogator ! identifies the interrogator !

! ! identification ! !

! ! ! !

! MA ! message ! 56-bit MA field contains messages directed !

! ! Comm A ! to the A/C !

! ! ! !

! MC ! message ! 80-bit MC field contains one segment of a !

! ! Comm C ! sequence of segments transmitted in ELM mode. !

! ! ! !

! MU ! message ! 56-bit MU messages contain information used !

! ! Comm U ! in air-to-air exchanges !

! ! ! !

! NC ! number of C ! number of segments transmitted in ELM mode !

! ! segments ! !

! ! ! !

! PC ! protocol ! operating commands of the transponder !

! ! ! !

! PR ! probability ! contains commands to the transponder to !

! ! of reply ! specify the reply probability to the mode S !

! ! ! only all-call interrogations (Allows !

! ! ! operators to acquire closely spaced A/C). !

! ! ! !

! RC ! reply ! designates the transmitted segment as initial,!

! ! control ! intermediate or final !

! ! ! !

! RL ! reply ! indicates if message is short or long !

! ! length ! !

! ! ! !

! RR ! reply ! length and content of the reply information !

! ! request ! requested by the interrogator !

! ! ! !

! SD ! special ! contains control codes affecting the link !

! ! designator ! protocol !

-------------------------------------------------------------------------------

The table below gives the definition of downlink format message fields:

-------------------------------------------------------------------------------

! DESIGNATOR ! FIELD ! INDICATION !

-------------------------------------------------------------------------------

! AA ! address ! contains the A/C mode S address !

! ! announced ! !

! ! ! !

! AC ! altitude ! information containing the A/C altitude !

! ! code ! !

! ! ! !

! AP ! address ! 24-bit address and parity overlaid !

! ! parity ! !

! ! ! !

! CA ! transponder ! reports transponder capability !

! ! capability ! !

! ! ! !

! DR ! downlink ! requests extraction of downlink messages from !

! ! request ! the transponder by the interrogator !

! ! ! !

! FS ! flight ! flight status !

! ! status ! !

! ! ! !

! ID ! identification ! contains the Mode A identification code !

! ! ! !

! MB ! message ! 56-bit MB field contains the message !

! ! Comm B ! transmitted to the interrogator !

! ! ! !

! MD ! message ! 80-bit MD field contains one segment of a !

! ! Comm D ! sequence of segments in the ELM Mode !

-------------------------------------------------------------------------------

(10) Operation

ATC Transponder - Simplified Block Diagram ** ON A/C NOT FOR ALL

(a) Introduction
The transponder is capable of operating with ATC Radar Beacon System interrogators, as well as mode S interrogators and is also designed to accept two antenna inputs for diversity operation. Diversity operation in a Mode S transponder is an added feature to improve air to air surveillance as part of a collision avoidance system.
An additional feature of a Mode S transponder is the ability to send and receive data link messages via the reply and interrogation mode S message formats.

(b) Simplified theory
The transponder consists of four principal assemblies: the transmitter, the receiver, the I/O and processor circuit card and the power supply.
Input signals (1030 MHz interrogations/uplinks) are received at one or both of the antennas. Each received antenna signal is pulse demodulated and sent to the processing circuits, where the diversity selection is made. The diversity selection determines which receiver provides the stronger (or first) signal. The selected received signal is then applied through a demodulator circuit to the processing circuits. The processing circuits determine if the interrogation is an ATC Radar Beacon System interrogation, a mode S interrogation addressed to the particular aircraft, or a mode S interrogation addressed to another aircraft. Depending upon the type of the interrogation, the processing circuits determine the proper reply (if one is required) and send the appropriate reply through a message processing circuit to the diversity switching circuits. The diversity switching circuits select the antenna that the reply will be transmitted through. The reply message is transmitted through the same antenna from which the selected received signal originated.

The I/O circuit is an interface circuit to receive serial ARINC 429 data, the 24 bit address input, the code altitude input and various discretes. The CPU provides the link between the I/O and the signal processing circuits.
The signal processing circuits consist of a video processor, a PAM decoder and a message processor. The video processor analyzes the received signals (pulses and pulse amplitude). If the received signal is valid, the PAM decoder determines the type of interrogation. Then the decoder output is sent to the message processor where appropriate reply format is generated.
The message processor output is amplified and the resultant 1090 MHz transmit signal is applied to the antennas through a diplexer/diversity switch.
The received signals from the antennas are sent to the receiver stage. The 60 MHz IF output is used to drive the video processor and the message processor (DSPK function). The input of the receiver stage is filtered to reduce the susceptibility to HIRF signals.
The power supply is a pulse-width modulated switching regulator. It supplies all the necessary DC voltages required by the internal circuitry. An integrated monitoring function gives protection to the power supply circuits and reset signals to the CPUs each time primary power is applied.

-------------------------------------------------------------------------------

NAME ELECTRICAL LEVEL TO SIGNAL STATUS

-------------------------------------------------------------------------------

XPNDR FAIL OC/5VDC CTL UNIT - ATC 5VDC = FAULT

-------------------------------------------------------------------------------

(11) Principle of Operation

ATC - Block Diagram ** ON A/C NOT FOR ALL

(a) Interrogations
Three classes of interrogations are transmitted by the ground interrogator; they are:

Mode A or C interrogations
Mode S all-call interrogations
Mode S interrogations.

1 Mode A or C interrogation
A mode A or C interrogation consists of two pulses labelled P1 and P3. A control pulse P2 is transmitted following the first interrogation pulse. P1 and P3 are radiated by a narrow rotating beam antenna.
P2, also called the Side Lobe Suppression (SLS) pulse, is radiated by an omnidirectional antenna with an amplitude of 9 dB below P1 and P2 within the main lobe.
P1 amplitude is greater than or equal to P2 amplitude from the greatest side lobe transmission of the antenna radiating P1.

2 Mode S all-call interrogation

ATC - Mode S All Call Pulse Characteristics ** ON A/C NOT FOR ALL

A Mode S all-call interrogation consists of three transmitted pulses labelled P3 and P4. A control pulse P2 (Side Lobe Suppression Pulse) is transmitted following P1. P1 amplitude is greater than or equal to P2 amplitude from the greatest side lobe transmission of the antenna radiating P1.
P2 amplitude is at a level lower than 9 dB below P1 amplitude within the main lobe.
P4 duration is 0.8 or 1.6 microseconds depending on the interrogation mode.
If P4 is equal to 0.8 microseconds, this means that the interrogation only concerns conventional ATC mode A or C transponders, and consequently the Mode S transponder should not reply.
If P4 is equal to 1.6 microseconds, this means that the mode S transponder should reply with mode S information.

3 Mode S interrogation

ATC - Mode S Pulse Characteristics ** ON A/C NOT FOR ALL

A Mode S interrogation consists of a two-bit preamble followed by a data block.
The preamble consists of two transmitted pulses labelled P1 and P2. The characteristics of P1 and P2 are the same as for the mode S all call interrogation, except that P2 amplitude is equal to P1.
The data block consists of a single pulse P6 with a Differential Phase Shift Keying (DPSK) modulation.
. Pulse duration: short 15.5 microseconds / long 29.5 microseconds
. Data block: 56 or 112 bits.

(b) Encoded reply

1 Mode A or C reply
A Mode A or C reply consists of two framing pulses F1 and F2, separated by a 20.3 microsecond time interval. The encoding of the reply is done by means of the presence (1) or absence (0) of 13 reply pulses (12 pulses plus X pulse).

2 Mode S all-call reply
A Mode S all-call reply consists of a four-bit preamble followed by a data block.
The data block contains 56 position modulated pulses.

3 Mode S reply
A Mode S reply occurs after a mode S interrogation or a mode S all-call interrogation (P4 duration 1.6 microseconds).
A mode S reply consists of a four-bit preamble (duration 8 microseconds) followed by a data block. The data block contains 56 or 112 position modulated pulses.
The replies are PPM coded.

(c) Mode S message content
The minimum data link transponder supports all surveillance functions, in addition to bidirectional air-to-air data exchange, ground-to-air data uplink (Comm A), air-to-ground data downlink (Comm B), and multisite message protocol. In addition, the transponder is capable of receiving Extended Length Messages (ELMs) from the ground. ELMS are received in the Comm C format. ELM transmittals to the ground use the Comm D format. (Note: The ATC Collins is capable of comm A(B) C data-link operation). All discrete Mode S interrogations and replies (except the all-call reply) contain the 24-bit discrete address of the Mode S transponder upon which 24 error detection parity check bits are overlaid. In the all-call reply, the 24 parity check bits are overlaid on the Mode S interrogation address and the transponders7 discrete address is included in the text of the reply. The main function of Mode S is surveillance. To accomplish this function, the Mode S transponder uses the 56-bit transmissions (each direction). In the 56-bit transmissions, the aircraft report its altitude or ATCRBS 4096 code, and the flight status (airborne on-ground, alert, Special Position Identification (SPI), etc. The discrete addressing and digital encoding of Mode S transmission permit their use as a digital data link. The interrogation and r formats of the Mode S system contain sufficient coding space to permit the transmission of data. These data transmissions may be for air traffic control purposes, air-to-air data interchange of collision avoidance, or to provide flight advisory services such weather reports, or Automated Terminal Information System (ATIS) Most Mode S data link transmissions will be handled as one 56-bi message included as part of a long 112-bit interrogation or reply these transmission include the message in addition to the surveillance data.
Longer messages are transmitted using the Extended Length Message (ELM) capability. The ELM is capable of transmitting up to sixteen 80-bit message segments, either ground-to-air or air-to-ground. The ELM can be acknowledged with a single reply or interrogation. ELMs uplinked need not be replied to individually, but can be acknowledged in a reply containing a summary of the received interrogations.
ELMs do not contain surveillance data.

1 Mode S interrogation message formats
All valid Mode S interrogation are listed here.
The first 5 bits of the message indicate a UF message format.
Items in brackets, e.g (AP:24) represent the NAPN field code, and the number of bits in the field N24N.
Underscored numbers represent unused fields and should not be processed.

TCAS Surveillance:
UF=0 (0 0000) 3_ (RL:1) 4_ (AQ:1) 18_ (AP:24)
Surveillance, Altitude Request:
UF=4 (0 0100) (PC:3) (RR:5) (DI:3) (SD:16) (AP:24)
Surveillance, Identity Request:
UF=5 (0 0101) (PC:3) (RR:5) (DI:3) (SD:16) (AP:24)
Mode S All-Call Interrogation:
UF=11 (0 1011) (PR:4) (II:4) 19_ (AP:24)
Long TCAS Interrogation (COMM-U):
UF=16 (1 0000) 3_ (RL:1) 4_ (AQ:1) 18_ (MU:56) (AP:24)
COMM-A Interrogation, Altitude:
UF=20 (1 0100) (PC:3) (RR:5) (DI:3) (SD:16) (MA:56) (AP:24)
COMM-A Interrogation, Identity:
UF=21 (1 0101) (PC:3) (RR:5) (DI:3) (SD:16) (MA:56) (AP:24)
Uplink Extended Length Message (UELM)/COMM-C Interrogation:
UF=24 (1 1) (RC:2) (NC:4) (MC:80) (AP:24)

NOTE: PC, RR, DI and SD subfields are undefined for UF=20/21 broadcast interrogations.

2 Mode S messages downlink formats
All valid Mode S replies are listed here.
The first 5 bits of the message indicate a UF message format.
Items in brackets, e.g (AP:24) represent the NAPN field code, and the number of bits in the field N24N.
Underscored numbers represent unused fields are shall be set to zero.

TCAS Surveillance:
DF=0 (0 0000) (VS:1) 2_ (SL:3) 2_ (RI:4) 2_ (AC:13) (AP:24)
Surveillance, Altitude:
DF=4 (0 0100) (FS:3) (DR:5) (UM:6) (AC:13) (AP:24)
Surveillance, Identity:
DF=5 (0 0101) (FS:3) (DR:5) (UM:6) (ID:13) (AP:24)
Mode S All-Call Reply, ATCRBS/Mode S All-Call Reply, Mode S Squitter:
DF=11 (0 1011) (CA:3) (AA:24) (PI:24)
Long TCAS Reply (COMM-V):
DF=16 (1 0000) (VS:1) 2_ (SL:3) 2_ (RI:4) (AC:13) (MV:56) (AP:24)
Extended Squitters:
DF=17 (1 0001) (CA:3) (AA:24) (ME:56) (PI:24)
COMM-B Reply, Altitude:
DF=20 (1 0100) (FS:3) (DR:5) (UM:6) (AC:13) (MB:56) (AP:24)
COMM-B Reply, Identity:
DF=21 (1 0101) (FS:3) (DR:5) (UM:6) (ID:13) (MB:56) (AP:24)
Downlink Extended Length Message (DELM)/COMM-D:
DF=24 (1 1) 1_ (KE:1) (ND:4) (MD:80) (AP:24)

3 Mode S interrogation data field definition
The following table gives the definition of uplink format message fields:

-------------------------------------------------------------------------------

! DESIGNATOR ! FIELD ! INDICATION !

-------------------------------------------------------------------------------

! AP ! address parity ! 24-bit address and parity overlaid !

! ! ! !

! AQ ! acquisition ! differentiates acquisition from non-acquisi- !

! ! ! tion interrogations !

! ! ! !

! DI ! designator ! identifies the coding contained in the SD !

! ! identification ! field !

! ! ! !

! II ! interrogator ! identifies the interrogator !

! ! identification ! !

! ! ! !

! MA ! message ! 56-bit MA field contains messages directed !

! ! Comm A ! to the A/C !

! ! ! !

! MC ! message ! 80-bit MC field contains one segment of a !

! ! Comm C ! sequence of segments transmitted in ELM mode. !

! ! ! !

! MU ! message ! 56-bit MU messages contains information used !

! ! Comm U ! in air-to-air exchanges !

! ! ! !

! NC ! number of C ! number of segments transmitted in ELM mode !

! ! segments ! !

! ! ! !

! PC ! protocol ! operating commands of the transponder !

! ! ! !

! PR ! probability ! contains commands to the transponder to !

! ! of reply ! specify the reply probability to the mode S !

! ! ! only all-call interrogations (Allows !

! ! ! operators to acquire closely spaced A/C). !

! ! ! !

! RC ! reply ! designates the transmitted segment as initial,!

! ! control ! intermediate or final !

! ! ! !

! RL ! reply ! indicates if message is short or long !

! ! length ! !

! ! ! !

! RR ! reply ! length and content of the reply information !

! ! request ! requested by the interrogator !

! ! ! !

! SD ! special ! contains control codes affecting the link !

! ! designator ! protocol !

-------------------------------------------------------------------------------

The table below gives the definition of downlink format message fields:

-------------------------------------------------------------------------------

! DESIGNATOR ! FIELD ! INDICATION !

-------------------------------------------------------------------------------

! AA ! address ! contains the A/C mode S address !

! ! announced ! !

! ! ! !

! AC ! altitude ! information containing the A/C altitude !

! ! code ! !

! ! ! !

! AP ! address ! 24-bit address and parity overlaid !

! ! parity ! !

! ! ! !

! CA ! transponder ! reports transponder capability !

! ! capability ! !

! ! ! !

! DR ! downlink ! requests extraction of downlink messages from !

! ! request ! the transponder by the interrogator !

! ! ! !

! FS ! flight ! flight status !

! ! status ! !

! ! ! !

! ID ! identification ! contains the Mode A identification code !

! ! ! !

! MB ! message ! 56-bit MB field contains the message !

! ! Comm B ! transmitted to the interrogator !

! ! ! !

! MD ! message ! 80-bit MD field contains one segment of a !

! ! Comm D ! sequence of segments in the ELM Mode !

-------------------------------------------------------------------------------

4 Data transmitted for elementary surveillance
The specific data related to the elementary surveillance are the following:

24 bits A/C address (coded in AA field of DF11)
flight number (MB field of DF20 or DF21 filled in with Binary Data Stores (BDS) 2.0
transponder capability report (coded in CA field of DF11)
altitude/ground reporting (coded in AC field of DF4 or DF20)
flight status (coded in FS field of DF4)
RA report (MB field of DF20 or DF21 filled in with BDS 3.0)
Surveillance Identifier (SI) (coded in PI field of DF11)

5 Data transmitted for enhanced surveillance (if the optional wiring provisions for enhanced surveillance/extended squitters are validated)
The specific parameters related to the enhanced surveillance are:

Selected altitude
Barometric pressure setting
Roll angle
Track angle rate
True track angle
Ground speed
True air speed
Magnetic heading
Indicated airspeed
Mach
Barometric altitude rate
Inertial vertical velocity

Data is transmitted in MB field of BDS 4.0, 5.0 or 6.0 in DF20 or DF21, upon request from ground station.

6 Data transmitted in extended squitters (if the optional wiring provisions for enhanced surveillance/extended squitters are validated)
The specific parameters related to the extended squitters are:

Altitude
Longitude
Latitude
Movement
Ground track
Flight number
E/W velocity
N/S velocity
Vertical rate

These data are transmitted in ME field of BDS 0.5, 0.6, 0.7, 0.8 or 0.9 in DF17.
Extended squitters are automatically broadcast at different rates as shown in the following table.

ATC - Extended Squitters (Automatic Dependent Surveillance Broadcast (ADS-B)) DF17 Format ** ON A/C NOT FOR ALL

(12) Principle of Operation

ATC - Block Diagram ** ON A/C NOT FOR ALL

Each ground interrogator transmits its interrogations at the frequency of 1030 MHz in the form of a series of two pulses.
Depending on the pulse intervals and numbers, they define three different interrogation modes. After receiving these pulses, the transponder identifies and decodes the interrogations. Depending on the detected interrogation mode, the transponder transmits either the identification of the aircraft or its barometric altitude or flight data.
To perform these functions, the transponder is associated with a control unit defining the aircraft identification code, the Air Data/Inertial Reference Units (ADIRUs) the Flight Management and Guidance Computers (FMGCs) and the Traffic Collision Avoidance System (TCAS)(if installed).
The transmission of the replies to the ground takes place on a carrier frequency of 1090 MHz. If the interrogation is sent by the side lobe of the radar a characteristic signal is sent allowing the transponder to disregard the interrogation.
In addition to its specific transponder functions, it enables communication between the TCAS and a detected aircraft if equipped with the TCAS.

(a) Interrogations

ATC - Principle ** ON A/C NOT FOR ALL

Three classes of interrogations are transmitted by the ground interrogator, they are:

Mode A or C interrogations
Mode S all call interrogations
Mode S interrogations.

1 Mode A or C interrogation
A mode A or C interrogation consists of two pulses labelled P1 and P3. A control pulse P2 is transmitted following the first interrogation pulse. P1 and P3 are radiated by a narrow rotating beam antenna.
P2, also called the Side Lobe Suppression (SLS) pulse, is radiated by an omnidirectional antenna with an amplitude of 6 dB below P1 and P2 within the main lobe.
P1 amplitude is greater than or equal to P2 amplitude from the greatest side lobe transmission of the antenna radiating P1.

2 Mode S all call interrogation

ATC - Mode S All Call Pulse Characteristics ** ON A/C NOT FOR ALL

A mode S all call interrogation consists of three transmitted pulses labelled P1, P3 and P4. A control pulse P2 (Side Lobe Suppression Pulse) is transmitted following P1. P1 amplitude is greater than or equal to P2 amplitude from the greatest side lobe transmission of the antenna radiating P1.
P2 amplitude is at a level lower than 6 dB below P1 amplitude within the main lobe.
P4 duration is 0.8 or 1.6 microseconds depending on the interrogation mode.
If P4 is equal to 0.8 microseconds, this means that the interrogation only concerns conventional ATC mode A or C transponder, and consequently the Mode S transponder must not reply.
If P4 is equal to 1.6 microseconds, this means that the mode S transponder must reply with mode S information.

3 Mode S interrogation

ATC - Mode S Pulse Characteristics ** ON A/C NOT FOR ALL

A mode S interrogation consists of a two-bit preamble followed by a data block.
The preamble consists of two transmitted pulses labelled P1 and P2. The characteristics of P1 and P2 are the same as for the mode S all call interrogation, except that P2 amplitude is equal to P1.
The data block consists of a single pulse P6 with a Differential Phase Shift Keying (DPSK) modulation.

Pulse duration : short 15.5 microseconds,

long 29.5 microseconds,

Data block : 56 or 112 bits.

(b) Encoded reply

2 Mode S all-call reply
A mode S all-call reply consists of a four-bit preamble followed by a data block.
The data block contains 56 position modulated pulses.

4 Mode S message contents
The transponder must have the following Mode S message capabilities:

Surveillance functions of both ATCRBS and Mode S ground sensors (UF=4.5 / DF=4.5)
Surveillance functions of airborne interrogators (UF=0 /DF=0)
Bi-directional air-to-air information exchange, COMM-U/V (UF=16 / DF=16)
Ground-to-air data uplink, COMM-A (UF=20.21)
Air-to-ground data downlink, COMM-B (DF=20.21)
Ground-to-air Uplink Extended length message (UELM), COMM-C (UF=24) (if external ADLP is installed)
Air-to-ground Downlink Extended length message (DELM), COMM-D (DF=24). (if external ADLP is installed)

All discrete Mode S interrogations and replies (except the all-call reply) contain the 24-bit discrete address of the Mode S transponder upon which 24 error detection parity check bits are overlaid. In the all-call reply, the 24 parity check bits are overlaid on the Mode S interrogation address and the transponders' discrete address is included in the text of the reply. The main function of Mode S is surveillance. To accomplish this function, the Mode S transponder uses the 56-bit transmissions (in each direction). In the 56-bit transmissions, the aircraft reports its altitude or ATCRBS 4096 code, and the flight status (airborne, on-ground, alert, Special Position Identification (SPI), etc.
The discrete addressing and digital encoding of Mode S transmissions permit their use as a digital data link. The interrogation and reply formats of the Mode S system contain sufficient coding space to permit the transmission of data. These data transmissions may be used for air traffic control purposes, air-to-air data interchange for collision avoidance, or to provide flight advisory services such as weather reports, or Automated Terminal Information System (ATIS). Most Mode S data link transmissions will be handled as one 56-bit message included as part of a long 112-bit interrogation or reply. These transmission include the message in addition to the surveillance data.
Longer messages are transmitted using the Extended Length Message (ELM) capability (if external ADLP is installed). The ELM is capable of transmitting up to sixteen 80-bit message segments at a rate of 8 per second, either ground-to-air or air-to-ground. The ELM can be acknowledged with a single reply or interrogation. ELMs uplinked need not be replied to individually, but can be acknowledged in a reply containing a summary of the received interrogations.
ELMs do not contain surveillance data.

a Mode S interrogation message formats
All valid Mode S interrogation are listed here.
The first 5 bits of the message indicate a UF message format.
Items in brackets, e.g (AP:24) represent the "AP" field code, and the number of bits in the field "24".
Underscored numbers represent unused fields and must not be processed.

TCAS Surveillance:
UF=0 (0 0000) 3_ (RL:1) 4_ (AQ:1) 18_ (AP:24)
Surveillance, Altitude Request:
UF=4 (0 0100) (PC:3) (RR:5) (DI:3) (SD:16) (AP:24)
Surveillance, Identity Request:
UF=5 (0 0101) (PC:3) (RR:5) (DI:3) (SD:16) (AP:24)
Mode S All-Call Interrogation:
UF=11 (0 1011) (PR:4) (II:4) 19_ (AP:24)
Long TCAS Interrogation (COMM-U):
UF=16 (1 0000) 3_ (RL:1) 4_ (AQ:1) 18_ (MU:56) (AP:24)
COMM-A Interrogation, Altitude:
UF=20 (1 0100) (PC:3) (RR:5) (DI:3) (SD:16) (MA:56) (AP:24)
COMM-A Interrogation, Identity:
UF=21 (1 0101) (PC:3) (RR:5) (DI:3) (SD:16) (MA:56) (AP:24)
Uplink Extended Length Message (UELM)/COMM-C Interrogation:
UF=24 (1 1) (RC:2) (NC:4) (MC:80) (AP:24)

NOTE: PC, RR, DI and SD subfields are undefined for UF=20/21 broadcast interrogations.

b Mode S reply message formats
All valid Mode S replies are listed here.
The first 5 bits of the message indicate a UF message format.
Items in brackets, e.g (AP:24) represent the "AP" field code, and the number of bits in the field "24".
Underscored numbers representing unused fields must be set to zero.

TCAS Surveillance:
DF=0 (0 0000) (VS:1) 2_ (SL:3) 2_ (RI:4) 2_ (AC:13) (AP:24)
Surveillance, Altitude:
DF=4 (0 0100) (FS:3) (DR:5) (UM:6) (AC:13) (AP:24)
Surveillance, Identity:
DF=5 (0 0101) (FS:3) (DR:5) (UM:6) (ID:13) (AP:24)
Mode S All-Call Reply, ATCRBS/Mode S All-Call Reply, Mode S Squitter:
DF=11 (0 1011) (CA:3) (AA:24) (PI:24)
Long TCAS Reply (COMM-V):
DF=16 (1 0000) (VS:1) 2_ (SL:3) 2_ (RI:4) (AC:13) (MV:56) (AP:24)
COMM-B Reply, Altitude:
DF=20 (1 0100) (FS:3) (DR:5) (UM:6) (AC:13) (MB:56) (AP:24)
COMM-B Reply, Identity:
DF=21 (1 0101) (FS:3) (DR:5) (UM:6) (ID:13) (MB:56) (AP:24)
Downlink Extended Length Message (DELM)/COMM-D:
DF=24 (1 1) 1_ (KE:1) (ND:4) (MD:80) (AP:24)

c Mode S interrogation data field definition
The following table gives the definition of uplink format message fields:

-------------------------------------------------------------------------------

! DESIGNATOR ! FIELD ! INDICATION !

-------------------------------------------------------------------------------

! AP ! address parity ! 24-bit address and parity overlaid !

! ! ! !

! AQ ! acquisition ! differentiates acquisition from non-acquisi- !

! ! ! tion interrogations !

! ! ! !

! DI ! designator ! identifies the coding contained in the SD !

! ! identification ! field !

! ! ! !

! II ! interrogator ! identifies the interrogator !

! ! identification ! !

! ! ! !

! MA ! message ! 56-bit MA field contains messages directed !

! ! Comm A ! to the A/C !

! ! ! !

! MC ! message ! 80-bit MC field contains one segment of a !

! ! Comm C ! sequence of segments transmitted in ELM mode. !

! ! ! !

! MU ! message ! 56-bit MU messages contains information used !

! ! Comm U ! in air-to-air exchanges !

! ! ! !

! NC ! number of C ! number of segments transmitted in ELM mode !

! ! segments ! !

! ! ! !

! PC ! protocol ! operating commands of the transponder !

! ! ! !

! PR ! probability ! contains commands to the transponder to !

! ! of reply ! specify the reply probability to the mode S !

! ! ! only all-call interrogations (Allows !

! ! ! operators to acquire closely spaced A/C). !

! ! ! !

! RC ! reply ! designates the transmitted segment as initial,!

! ! control ! intermediate or final !

! ! ! !

! RL ! reply ! indicates if message is short or long !

! ! length ! !

! ! ! !

! RR ! reply ! length and content of the reply information !

! ! request ! requested by the interrogator !

! ! ! !

! SD ! special ! contains control codes affecting the link !

! ! designator ! protocol !

-------------------------------------------------------------------------------

The table below gives the definition of downlink format message fields:

-------------------------------------------------------------------------------

! DESIGNATOR ! FIELD ! INDICATION !

-------------------------------------------------------------------------------

! AA ! address ! contains the A/C mode S address !

! ! announced ! !

! ! ! !

! AC ! altitude ! information containing the A/C altitude !

! ! code ! !

! ! ! !

! AP ! address ! 24-bit address and parity overlaid !

! ! parity ! !

! ! ! !

! CA ! transponder ! reports transponder capability !

! ! capability ! !

! ! ! !

! DR ! downlink ! requests extraction of downlink messages from !

! ! request ! the transponder by the interrogator !

! ! ! !

! FS ! flight ! flight status !

! ! status ! !

! ! ! !

! ID ! identification ! contains the Mode A identification code !

! ! ! !

! MB ! message ! 56-bit MB field contains the message !

! ! Comm B ! transmitted to the interrogator !

! ! ! !

! MD ! message ! 80-bit MD field contains one segment of a !

! ! Comm D ! sequence of segments in the ELM Mode !

-------------------------------------------------------------------------------

(c) Data transmitted for elementary surveillance
The specific data related to the elementary surveillance are the following:

24 bits A/C address (coded in AA field of DF11)
Flight number (MB field of DF20 or DF21 filled in with Binary Data Stores (BDS) 2.0
Transponder capability report (coded in CA field of DF11)
Altitude/ground reporting (coded in AC field of DF4 or DF20)
Flight status (coded in FS field of DF4)
RA report (MB field of DF20 or DF21 filled in with BDS 3.0)
Surveillance Identifier (SI) (coded in PI field of DF11)

(d) Data transmitted for enhanced surveillance (if modification 32467 is validated)
The specific data related to the enhanced surveillance are the following:

Selected altitude
Barometric pressure setting
Roll angle
Track angle rate
True track angle
Ground speed
True air speed
Magnetic heading
Indicated airspeed
Mach
Barometric altitude rate
Inertial vertical velocity

These data are transmitted in MB field of BDS 4.0, 5.0 or 6.0 in DF20 or DF21.

(e) Data transmitted in extended squitters (if modification 32467 is validated)
The specific data related to the extended squitters are the following:

Altitude
Longitude
Latitude
Movement
Ground track
Flight number
E/W velocity
N/S velocity
Vertical rate

These data are transmitted in ME field of BDS 0.5, 0.6, 0.8 or 0.9 in DF17.

(13) Operation

ATC Transponder - Simplified Block Diagram ** ON A/C NOT FOR ALL

The transponder consists of a receiver, a transmitter, an interface/Central Processing Unit (CPU) assembly and a power supply/modulator assembly.

(a) Receiver
The receiver (top and bottom receiver channels), which consists of a ceramic pre-selector filter, self-test coupler, low noise amplifier, mixer, Intermediate Frequency (IF) amplifier and band-pass filter, logarithmic amplifier (log amp) detectors and a Differential Phase Shift Keying (DPSK) demodulator, has the circuitry required to accept the Radio Frequency (RF) signal and convert it into a voltage signal to be used by the signal processing elements.

(b) Transmitter
The transmitter, which consists of a 1090 MHz local oscillator, RF transmitter gain stages, transmit/receive pin diode switches, forward power and antenna monitors and a low-pass harmonic filter, is unique in that it is an all solid-state unit with the capability for the Mode S message requirements, which impose increased operating requirements on the transmitter.

(c) Interface/CPU assembly
The interface/CPU assembly contains a microprocessor and supporting memory and logic circuitry. The support circuitry includes Flash EPROM memory devices for the operational program, boot program and system data, system RAM memory for program execution, and an EEPROM memory for calibration and self-test error logging. The assembly contains Application Specific Integrated Circuits (ASICs) for the RF processing functions (interrogations and replies), and communication over ARINC 429 data buses. In addition to the RF ASIC the assembly contains circuitry for processing receiver video signals. The assembly supports all external interface functions, including processing discrete inputs/outputs and analog synchro interfaces.

(d) Power supply/modulator assembly
The transponder has its own internal self-contained power supply. The 115V, 400 Hz power supply input is applied through the rear connector of the unit.
The power supply modulator assembly has an EMI filter, 115VAC to DC converter, power interrupt monitor, +60VDC switching supply for transmitter energy storage, a fly-back supply for generating internal unit voltages, and a +35VDC and +28VDC regulator for supplying transmitter voltages. The assembly contains PIN diode driver circuitry for driving the RF transmit/receive switches, pulse and envelope modulator circuitry for modulating the RF transistors. The assembly also contains a self-test modulator and power supply monitors.

(14) Theory of operation
Interrogations which are received by the transponder are filtered and amplified by the 1030MHz receiver, converted to a 60MHz IF by the mixer and IF filter on the receiver. The interrogations (pulses) are then converted to a base-band analog video signals by the log amps. The DPSK portion of a Mode S interrogation is turned into a digital video signal by the DPSK demodulator. The analog video signal is then processed by the video processor circuit on the interface/CPU assembly, where it is converted to a digital video signal. The digital video signals and DPSK video signals are then processed by the RF ASIC, which determines the validity and type of interrogation. If a valid interrogation is received, the RF ASIC in conjunction with the microprocessor and software generates a reply. The RF ASIC generates digital pulses which are used to modulate the transmitter. The digital signals are converted to analog modulator signals by the pulse and envelope modulator circuitry on the power supply/modulator. The analog modulator signals are then used to turn the transmitter stages on or off as is appropriate to generate the pulsed replies.

(15) Principle of Operation

ATC - Block Diagram ** ON A/C NOT FOR ALL

(a) Interrogations
Three classes of interrogations are transmitted by the ground interrogator; they are:

Mode A or C interrogations
Mode S all-call interrogations
Mode S interrogations.

2 Mode S all-call interrogation

ATC - Mode S All Call Pulse Characteristics ** ON A/C NOT FOR ALL

3 Mode S interrogation

ATC - Mode S Pulse Characteristics ** ON A/C NOT FOR ALL

(b) Encoded reply

2 Mode S all-call reply
A Mode S all-call reply consists of a four-bit preamble followed by a data block.
The data block contains 56 position modulated pulses.

(c) Mode S message content
The minimum data link transponder supports all surveillance functions, in addition to bidirectional air-to-air data exchange, ground-to-air data uplink (Comm A), air-to-ground data downlink (Comm B), and multisite message protocol. In addition, the transponder is capable of receiving Extended Length Messages (ELMs) from the ground. ELMS are received in the Comm C format. ELM transmittals to the ground use the Comm D format. (Note: The ATC Collins is capable of comm A(B) C data-link operation). All discrete Mode S interrogations and replies (except the all-call reply) contain the 24-bit discrete address of the Mode S transponder upon which 24 error detection parity check bits are overlaid. In the all-call reply, the 24 parity check bits are overlaid on the Mode S interrogation address and the transponders7 discrete address is included in the text of the reply. The main function of Mode S is surveillance. To accomplish this function, the Mode S transponder uses the 56-bit transmissions ( each direction). In the 56-bit transmissions, the aircraft report its altitude or ATCRBS 4096 code, and the flight status (airborn on-ground, alert, Special Position Identification (SPI), etc. The discrete addressing and digital encoding of Mode S transmissions permit their use as a digital data link. The interrogation and r formats of the Mode S system contain sufficient coding space to permit the transmission of data. These data transmissions may be for air traffic control purposes, air-to-air data interchange fo collision avoidance, or to provide flight advisory services such weather reports, or Automated Terminal Information System (ATIS) Most Mode S data link transmissions will be handled as one 56-bi message included as part of a long 112-bit interrogation or reply these transmission include the message in addition to the surveillance data.
Longer messages are transmitted using the Extended Length Message (ELM) capability. The ELM is capable of transmitting up to sixteen 80-bit message segments, either ground-to-air or air-to-ground. The ELM can be acknowledged with a single reply or interrogation. ELMs uplinked need not be replied to individually, but can be acknowledged in a reply containing a summary of the received interrogations.
ELMs do not contain surveillance data.

TCAS Surveillance:
UF=0 (0 0000) 3_ (RL:1) 4_ (AQ:1) 18_ (AP:24)
Surveillance, Altitude Request:
UF=4 (0 0100) (PC:3) (RR:5) (DI:3) (SD:16) (AP:24)
Surveillance, Identity Request:
UF=5 (0 0101) (PC:3) (RR:5) (DI:3) (SD:16) (AP:24)
Mode S All-Call Interrogation:
UF=11 (0 1011) (PR:4) (II:4) 19_ (AP:24)
Long TCAS Interrogation (COMM-U):
UF=16 (1 0000) 3_ (RL:1) 4_ (AQ:1) 18_ (MU:56) (AP:24)
COMM-A Interrogation, Altitude:
UF=20 (1 0100) (PC:3) (RR:5) (DI:3) (SD:16) (MA:56) (AP:24)
COMM-A Interrogation, Identity:
UF=21 (1 0101) (PC:3) (RR:5) (DI:3) (SD:16) (MA:56) (AP:24)
Uplink Extended Length Message (UELM)/COMM-C Interrogation:
UF=24 (1 1) (RC:2) (NC:4) (MC:80) (AP:24)

NOTE: PC, RR, DI and SD subfields are undefined for UF=20/21 broadcast interrogations.

TCAS Surveillance:
DF=0 (0 0000) (VS:1) 2_ (SL:3) 2_ (RI:4) 2_ (AC:13) (AP:24)
Surveillance, Altitude:
DF=4 (0 0100) (FS:3) (DR:5) (UM:6) (AC:13) (AP:24)
Surveillance, Identity:
DF=5 (0 0101) (FS:3) (DR:5) (UM:6) (ID:13) (AP:24)
Mode S All-Call Reply, ATCRBS/Mode S All-Call Reply, Mode S Squitter:
DF=11 (0 1011) (CA:3) (AA:24) (PI:24)
Long TCAS Reply (COMM-V):
DF=16 (1 0000) (VS:1) 2_ (SL:3) 2_ (RI:4) (AC:13) (MV:56) (AP:24)
Extended Squitters:
DF=17 (1 0001) (CA:3) (AA:24) (ME:56) (PI:24)
COMM-B Reply, Altitude:
DF=20 (1 0100) (FS:3) (DR:5) (UM:6) (AC:13) (MB:56) (AP:24)
COMM-B Reply, Identity:
DF=21 (1 0101) (FS:3) (DR:5) (UM:6) (ID:13) (MB:56) (AP:24)
Downlink Extended Length Message (DELM)/COMM-D:
DF=24 (1 1) 1_ (KE:1) (ND:4) (MD:80) (AP:24)

3 Mode S interrogation data field definition
The following table gives the definition of uplink format message fields:

-------------------------------------------------------------------------------

! DESIGNATOR ! FIELD ! INDICATION !

-------------------------------------------------------------------------------

! AP ! address parity ! 24-bit address and parity overlaid !

! ! ! !

! AQ ! acquisition ! differentiates acquisition from non-acquisi- !

! ! ! tion interrogations !

! ! ! !

! DI ! designator ! identifies the coding contained in the SD !

! ! identification ! field !

! ! ! !

! II ! interrogator ! identifies the interrogator !

! ! identification ! !

! ! ! !

! MA ! message ! 56-bit MA field contains messages directed !

! ! Comm A ! to the A/C !

! ! ! !

! MC ! message ! 80-bit MC field contains one segment of a !

! ! Comm C ! sequence of segments transmitted in ELM mode. !

! ! ! !

! MU ! message ! 56-bit MU messages contains information used !

! ! Comm U ! in air-to-air exchanges !

! ! ! !

! NC ! number of C ! number of segments transmitted in ELM mode !

! ! segments ! !

! ! ! !

! PC ! protocol ! operating commands of the transponder !

! ! ! !

! PR ! probability ! contains commands to the transponder to !

! ! of reply ! specify the reply probability to the mode S !

! ! ! only all-call interrogations (Allows !

! ! ! operators to acquire closely spaced A/C). !

! ! ! !

! RC ! reply ! designates the transmitted segment as initial,!

! ! control ! intermediate or final !

! ! ! !

! RL ! reply ! indicates if message is short or long !

! ! length ! !

! ! ! !

! RR ! reply ! length and content of the reply information !

! ! request ! requested by the interrogator !

! ! ! !

! SD ! special ! contains control codes affecting the link !

! ! designator ! protocol !

-------------------------------------------------------------------------------

The table below gives the definition of downlink format message fields:

-------------------------------------------------------------------------------

! DESIGNATOR ! FIELD ! INDICATION !

-------------------------------------------------------------------------------

! AA ! address ! contains the A/C mode S address !

! ! announced ! !

! ! ! !

! AC ! altitude ! information containing the A/C altitude !

! ! code ! !

! ! ! !

! AP ! address ! 24-bit address and parity overlaid !

! ! parity ! !

! ! ! !

! CA ! transponder ! reports transponder capability !

! ! capability ! !

! ! ! !

! DR ! downlink ! requests extraction of downlink messages from !

! ! request ! the transponder by the interrogator !

! ! ! !

! FS ! flight ! flight status !

! ! status ! !

! ! ! !

! ID ! identification ! contains the Mode A identification code !

! ! ! !

! MB ! message ! 56-bit MB field contains the message !

! ! Comm B ! transmitted to the interrogator !

! ! ! !

! MD ! message ! 80-bit MD field contains one segment of a !

! ! Comm D ! sequence of segments in the ELM Mode !

-------------------------------------------------------------------------------

4 Data transmitted for elementary surveillance
The specific data related to the elementary surveillance are the following:

24 bits A/C address (coded in AA field of DF11)
Flight number (MB field of DF20 or DF21 filled in with Binary Data Stores (BDS) 2.0
Transponder capability report (coded in CA field of DF11)
Altitude/ground reporting (coded in AC field of DF4 or DF20)
Flight status (coded in FS field of DF4)
RA report (MB field of DF20 or DF21 filled in with BDS 3.0)
Surveillance Identifier (SI) (coded in PI field of DF11)

Selected altitude
Barometric pressure setting
Roll angle
Track angle rate
True track angle
Ground speed
True air speed
Magnetic heading
Indicated airspeed
Mach
Barometric altitude rate
Inertial vertical velocity

Data is transmitted in MB field of BDS 4.0, 5.0 or 6.0 in DF20 or DF21, upon request from ground station.

6 Data transmitted in extended squitters (if the optional wiring provisions for enhanced surveillance/extended squitters are validated)
The specific parameters related to the extended squitters are:

Altitude
Longitude
Latitude
Movement
Ground track
Flight number
E/W velocity
N/S velocity
Vertical rate

These data are transmitted in ME field of BDS 0.5, 0.6, 0.7, 0.8 or 0.9 in DF17.
Extended squitters are automatically broadcast at different rates as shown in the following table.

ATC - Extended Squitters DF17 Format ** ON A/C NOT FOR ALL

(16) Principle of Operation

ATC - Block Diagram ** ON A/C NOT FOR ALL

Each ground interrogator transmits its interrogations at the frequency of 1030 MHz in the form of a series of two pulses.
Depending on the pulse intervals and numbers, they define three different interrogation modes. After receiving these pulses, the transponder identifies and decodes the interrogations. Depending on the detected interrogation mode, the transponder transmits either the identification of the aircraft or its barometric altitude or flight data.
To perform these functions, the transponder is associated with a control unit defining the aircraft identification code, the Air Data/Inertial Reference Units (ADIRUs) the Flight Management and Guidance Computers (FMGCs) and the Traffic Collision Avoidance System (TCAS)(if installed) and others sources for enhanced surveillance parameter (FCU, MMR, ...).
The transmission of the replies to the ground takes place on a carrier frequency of 1090 MHz. If the interrogation is sent by the side lobe of the radar a characteristic signal is sent allowing the transponder to disregard the interrogation.
In addition to its specific transponder functions, it enables communication between the TCAS and a detected aircraft if equipped with the TCAS.

(a) Interrogations

ATC - Principle ** ON A/C NOT FOR ALL

Three classes of interrogations are transmitted by the ground interrogator, they are:

Mode A or C interrogations
Mode S all call interrogations
Mode S interrogations.

1 Mode A or C interrogation
A mode A or C interrogation consists of two pulses labelled P1 and P3. A control pulse P2 is transmitted following the first interrogation pulse. P1 and P3 are radiated by a narrow rotating beam antenna.
P2, also called the Side Lobe Suppression (SLS) pulse, is radiated by an omnidirectional antenna with an amplitude of 6 dB below P1 and P2 within the main lobe.
P1 amplitude is greater than or equal to P2 amplitude from the greatest side lobe transmission of the antenna radiating P1.

2 Mode S all call interrogation

ATC - Mode S All Call Pulse Characteristics ** ON A/C NOT FOR ALL

3 Mode S interrogation

ATC - Mode S Pulse Characteristics ** ON A/C NOT FOR ALL

Pulse duration : short 15.5 microseconds,

long 29.5 microseconds,

Data block : 56 or 112 bits.

(b) Encoded reply

2 Mode S all-call reply
A mode S all-call reply consists of a four-bit preamble followed by a data block.
The data block contains 56 position modulated pulses.

4 Mode S message contents
The transponder must have the following Mode S message capabilities:

Surveillance functions of both ATCRBS and Mode S ground sensors (UF=4.5 / DF=4.5)
Surveillance functions of airborne interrogators (UF=0 /DF=0)
Bi-directional air-to-air information exchange, COMM-U/V (UF=16 / DF=16)
Ground-to-air data uplink, COMM-A (UF=20.21)
Air-to-ground data downlink, COMM-B (DF=20.21)
Ground-to-air Uplink Extended length message (UELM), COMM-C (UF=24) (if external ADLP is installed)
Air-to-ground Downlink Extended length message (DELM), COMM-D (DF=24). (if external ADLP is installed)

TCAS Surveillance:
UF=0 (0 0000) 3_ (RL:1) 4_ (AQ:1) 18_ (AP:24)
Surveillance, Altitude Request:
UF=4 (0 0100) (PC:3) (RR:5) (DI:3) (SD:16) (AP:24)
Surveillance, Identity Request:
UF=5 (0 0101) (PC:3) (RR:5) (DI:3) (SD:16) (AP:24)
Mode S All-Call Interrogation:
UF=11 (0 1011) (PR:4) (II:4) 19_ (AP:24)
Long TCAS Interrogation (COMM-U):
UF=16 (1 0000) 3_ (RL:1) 4_ (AQ:1) 18_ (MU:56) (AP:24)
COMM-A Interrogation, Altitude:
UF=20 (1 0100) (PC:3) (RR:5) (DI:3) (SD:16) (MA:56) (AP:24)
COMM-A Interrogation, Identity:
UF=21 (1 0101) (PC:3) (RR:5) (DI:3) (SD:16) (MA:56) (AP:24)
Uplink Extended Length Message (UELM)/COMM-C Interrogation:
UF=24 (1 1) (RC:2) (NC:4) (MC:80) (AP:24)

NOTE: PC, RR, DI and SD subfields are undefined for UF=20/21 broadcast interrogations.

b Mode S messages downlink formats
All valid Mode S replies are listed here.
The first 5 bits of the message indicate a UF message format.
Items in brackets, e.g (AP:24) represent the "AP" field code, and the number of bits in the field "24".
Underscored numbers representing unused fields must be set to zero.

TCAS Surveillance:
DF=0 (0 0000) (VS:1) 2_ (SL:3) 2_ (RI:4) 2_ (AC:13) (AP:24)
Surveillance, Altitude:
DF=4 (0 0100) (FS:3) (DR:5) (UM:6) (AC:13) (AP:24)
Surveillance, Identity:
DF=5 (0 0101) (FS:3) (DR:5) (UM:6) (ID:13) (AP:24)
Mode S All-Call Reply, ATCRBS/Mode S All-Call Reply, Mode S Squitter:
DF=11 (0 1011) (CA:3) (AA:24) (PI:24)
Long TCAS Reply (COMM-V):
DF=16 (1 0000) (VS:1) 2_ (SL:3) 2_ (RI:4) (AC:13) (MV:56) (AP:24)
Extended Squitters:
DF=17 (1 0001) (CA:3) (AA:24) (ME:56) (PI:24)
COMM-B Reply, Altitude:
DF=20 (1 0100) (FS:3) (DR:5) (UM:6) (AC:13) (MB:56) (AP:24)
COMM-B Reply, Identity:
DF=21 (1 0101) (FS:3) (DR:5) (UM:6) (ID:13) (MB:56) (AP:24)
Downlink Extended Length Message (DELM)/COMM-D:
DF=24 (1 1) 1_ (KE:1) (ND:4) (MD:80) (AP:24)

c Mode S interrogation data field definition
The following table gives the definition of uplink format message fields:

-------------------------------------------------------------------------------

! DESIGNATOR ! FIELD ! INDICATION !

-------------------------------------------------------------------------------

! AP ! address parity ! 24-bit address and parity overlaid !

! ! ! !

! AQ ! acquisition ! differentiates acquisition from non-acquisi- !

! ! ! tion interrogations !

! ! ! !

! DI ! designator ! identifies the coding contained in the SD !

! ! identification ! field !

! ! ! !

! II ! interrogator ! identifies the interrogator !

! ! identification ! !

! ! ! !

! MA ! message ! 56-bit MA field contains messages directed !

! ! Comm A ! to the A/C !

! ! ! !

! MC ! message ! 80-bit MC field contains one segment of a !

! ! Comm C ! sequence of segments transmitted in ELM mode. !

! ! ! !

! MU ! message ! 56-bit MU messages contains information used !

! ! Comm U ! in air-to-air exchanges !

! ! ! !

! NC ! number of C ! number of segments transmitted in ELM mode !

! ! segments ! !

! ! ! !

! PC ! protocol ! operating commands of the transponder !

! ! ! !

! PR ! probability ! contains commands to the transponder to !

! ! of reply ! specify the reply probability to the mode S !

! ! ! only all-call interrogations (Allows !

! ! ! operators to acquire closely spaced A/C). !

! ! ! !

! RC ! reply ! designates the transmitted segment as initial,!

! ! control ! intermediate or final !

! ! ! !

! RL ! reply ! indicates if message is short or long !

! ! length ! !

! ! ! !

! RR ! reply ! length and content of the reply information !

! ! request ! requested by the interrogator !

! ! ! !

! SD ! special ! contains control codes affecting the link !

! ! designator ! protocol !

-------------------------------------------------------------------------------

The table below gives the definition of downlink format message fields:

-------------------------------------------------------------------------------

! DESIGNATOR ! FIELD ! INDICATION !

-------------------------------------------------------------------------------

! AA ! address ! contains the A/C mode S address !

! ! announced ! !

! ! ! !

! AC ! altitude ! information containing the A/C altitude !

! ! code ! !

! ! ! !

! AP ! address ! 24-bit address and parity overlaid !

! ! parity ! !

! ! ! !

! CA ! transponder ! reports transponder capability !

! ! capability ! !

! ! ! !

! DR ! downlink ! requests extraction of downlink messages from !

! ! request ! the transponder by the interrogator !

! ! ! !

! FS ! flight ! flight status !

! ! status ! !

! ! ! !

! ID ! identification ! contains the Mode A identification code !

! ! ! !

! MB ! message ! 56-bit MB field contains the message !

! ! Comm B ! transmitted to the interrogator !

! ! ! !

! MD ! message ! 80-bit MD field contains one segment of a !

! ! Comm D ! sequence of segments in the ELM Mode !

-------------------------------------------------------------------------------

(c) Data transmitted for elementary surveillance
The specific data related to the elementary surveillance are the following:

24 bits A/C address (coded in AA field of DF11)
Flight number (MB field of DF20 or DF21 filled in with Binary Data Stores (BDS) 2.0
Transponder capability report (coded in CA field of DF11)
Altitude/ground reporting (coded in AC field of DF4 or DF20)
Flight status (coded in FS field of DF4)
RA report (MB field of DF20 or DF21 filled in with BDS 3.0)
Surveillance Identifier (SI) (coded in PI field of DF11)

(d) Data transmitted for enhanced surveillance (if the optional wiring provisions for enhanced surveillance/extended squitters are validated).
The specific parameters related to the enhanced surveillance are:

Selected altitude
Barometric pressure setting
Roll angle
Track angle rate
True track angle
Ground speed
True air speed
Magnetic heading
Indicated airspeed
Mach
Barometric altitude rate
Inertial vertical velocity

Data is transmitted in MB field of BDS 4.0, 5.0 or 6.0 in DF20 or DF21, upon request from ground station.

(e) Data transmitted in extended squitters (if the optional wiring provisions for enhanced surveillance/extended squitters are validated).
The specific parameters related to the extended squitters are:

Altitude
Longitude
Latitude
Heading
Movement
Ground track
Flight number
E/W velocity
N/S velocity
Vertical rate
GPS height
Airspeed
Version number
Selected Heading
Selected Altitude
Integrity
Accuracy
Emergency
TCAS RA
A/C category
Length/Width code
Mode A code
Capabilities

Data is transmitted in ME field of BDS 0.5, 0.6, 0.7, 0.8 or 0.9, 6.1, 6.2, 6.5 in DF17.
Extended squitters are automatically broadcast at different rates as shown in the following table.

ATC - Extended Squitters (Automatic Dependent Surveillance Broadcast (ADS-B)) DF17 Format ** ON A/C NOT FOR ALL

ATC - Extended Squitters (Automatic Dependent Surveillance Broadcast (ADS-B OUT)) DF17 Format ** ON A/C NOT FOR ALL

(17) Operation

ATC Transponder - Simplified Block Diagram ** ON A/C NOT FOR ALL

The transponder consists of a receiver, a transmitter, an interface/Central Processing Unit (CPU) assembly and a power supply/modulator assembly.

(18) Theory of operation
Interrogations which are received by the transponder are filtered and amplified by the 1030MHz receiver, converted to a 60MHz IF by the mixer and IF filter on the receiver. The interrogations (pulses) are then converted to a base-band analog video signals by the log amps. The DPSK portion of a Mode S interrogation is turned into a digital video signal by the DPSK demodulator. The analog video signal is then processed by the video processor circuit on the interface/CPU assembly, where it is converted to a digital video signal. The digital video signals and DPSK video signals are then processed by the RF ASIC, which determines the validity and type of interrogation. If a valid interrogation is received, the RF ASIC in conjunction with the microprocessor and software generates a reply. The RF ASIC generates digital pulses which are used to modulate the transmitter. The digital signals are converted to analog modulator signals by the pulse and envelope modulator circuitry on the power supply/modulator. The analog modulator signals are then used to turn the transmitter stages on or off as is appropriate to generate the pulsed replies.

B. Control Unit

ATC/TCAS - Control Unit ** ON A/C NOT FOR ALL

The processor based unit conforms to the ARINC 718 specification. The face is integrally lit by clear 5V lamps and features:

A liquid crystal display window, in which the identification code is displayed
An XPDR FAIL indicator light
An IDNT pushbutton switch which is used to generate additional identification pulses in the reply signal
Two double control knobs to select the four-digit transmit code
The code range is 0000 to 7777.
An ALT RPT ON/OFF switch which inhibits altitude information when in the OFF position
An XPDR 1/2 switch which enables the selection of the ATC 1 or ATC 2 system
An SBY/ON/TA/RA/TA switch:
* when in SBY position, it inhibits the answers. In SBY position, TCAS advisory generation and surveillance functions are inhibited.
* when in ON position, it transmits the answers of the selected transponder when the aircraft is in flight only. In ON position, TCAS advisory generation and surveillance functions are inhibited.
* when in TA position, the TCAS computer is fully operational, but only in TA mode. No resolution advisories are generated. TA intruders are displayed on the NDs.
* when in RA/TA position, the TCAS performs all TA/RA mode functions. TA and RA intruders are displayed on the NDs. Preventive/corrective vertical resolution advisories are displayed on the PFDs. Aural messages are heard on the cockpit loudspeakers.
A TRAFFIC AUTO/ON switch
* When in AUTO mode, PROXIMATE, TA and RA visual/aural alerts are generated.
* When in ON mode, OTHER, PROXIMATE, TA and RA visual/aural alerts are generated.

NOTE: At the present time, the DMCs are not capable of displaying OTHER intruders.

The processor controls the function of the unit and:

Converts the identification code selected into ARINC 429 format transmission to the transponder
Provides selected code data to drive the liquid crystal display
Activates the appropriate light when a fault signal is received.

ATC/TCAS - Control Unit ** ON A/C NOT FOR ALL

The processor-based unit conforms to the ARINC 718 specification.
The front panel is integrally lit by clear 5V lamps and features :

A liquid crystal display window in which the identification code is displayed
An ATC FAIL indicator light which indicates a transponder failure
A IDENT pushbutton switch
An ALT RPTG/ON/OFF switch which controls the transmission of altitude data from the transponder to the ATC ground control stations
A keyboard to select the four-digit transmit code (from 0000 to 7777)
A 1/2 selector switch which enables the operation of the ATC system 1 or 2
A STBY/AUTO/ON selector switch which enables the ATC operating modes
A TCAS mode selector switch (STBY/TA/TA-RA) which enables the ATC/TCAS operating modes (Ref. 34-43-00 for more details).
A THRT/ALL/ABV/BLW selector switch which controls the type of traffic to be displayed as well as the above and below vertical altitude for traffic advisory.
According to the 1/2 selection, the processor 1 or 2 controls the functions of the unit. Each processor can compensate for the other in case of failure. The selected processor reads the switch selections and :
Drives the LCD display
Formats the ARINC control word.
In case of transponder failure, two independent circuits control :
The failure indicator light
The failure mode of the processor.

ATC/TCAS - Control Unit ** ON A/C NOT FOR ALL

The processor-based unit conforms to the ARINC 718 specification.
The front panel is integrally lit by clear 5V lamps and features:

A liquid crystal display window in which the identification code is displayed,
An ATC FAIL indicator light which indicates a transponder failure,
An IDENT pushbutton switch,
A keyboard to select the four-digit transmit code (from 0000 to 7777),
A SYS 1/2 switch which enables the operation of the ATC system 1 or 2,
A THRT/ALL switch which is used for TCAS system,
A BLW/N/ABV (Below/Normal/Above) selector switch which enables the TCAS surveillance envelope above/below the TCAS equipped aircraft,
an ATC/TCAS mode selector switch with five positions:
. In STBY position, ATC and TCAS are operative but not responding to any interrogations,
. In ALT RPTG OFF position, ATC operates in mode A and TCAS is still in standby mode,
. In XPNDR position, ATC operates in mode A or C and TCAS operates in standby mode (no replies/interrogations),
. In TA ONLY or TA/RA positions, the TCAS operates in the selected mode (Ref. 34-43-00 for more details).
According to the 1/2 selection, the processor 1 or 2 controls the functions of the unit. Each processor can compensate for the other in case of failure. The selected processor reads the switch selections and:
Drives the LCD display,
Formats the ARINC control word.
In case of transponder failure, two independent circuits control:
The failure indicator light,
The failure mode of the processor.

C. Antenna

ATC - Antenna ** ON A/C NOT FOR ALL

The L-band antenna is a short stub, all aluminum blade type which is completely sealed to prevent failure from moisture incursion.
It is vertically polarized, has an impedance of 50 ohms, a Voltage Standing Wave Ratio (VSWR) of 1,5 : 1 and operates in the 960 MHz to 1220 MHz frequency band. Lightning protection is provided to prevent damage to the antenna and the transponder.
Four antennas must be provided on the aircraft. The desire for improved upper hemisphere coverage usually leads to a choice of upper and lower mounting locations for the transponder antennas on the aircraft.

ATC - Antenna ** ON A/C NOT FOR ALL

The L-band antenna is an aluminum-alloy cast blade. It is sealed to prevent moisture which can cause failures. The antenna has the properties that follow:

Vertical polarization
Impedance of 50 ohms
Voltage standing wave ratio less than or equal to 1.6
Operating frequency range between 950 MHz and 1260 MHz.

The L-band antenna has lightning protection to prevent damage to the antenna and the transponder. The aircraft has two antennas: one is installed on the top and the other one on the bottom of the aircraft fuselage. This gives better coverage of the upper hemisphere.

D. Display on the ECAM DUs

(1) In case of "XPDR stand-by", a new amber "NAV ATC/XPDR STBY" level 2 alert is displayed on the upper ECAM DU. Green memo "TCAS STBY" is only a consequence of XPDR stand-by.

T/TISS-ATC2 - XPDR STBY Messages Displayed on Upper ECAM DU ** ON A/C NOT FOR ALL

(2) In case of "XPDR fault", a new amber Inop Sys "ATC/XPDR x"alert is displayed on the lower ECAM DU. In addition, a new amber "NAV ATC/XPDR x FAULT" level 2 alert is displayed on the upper ECAM DU (green memo"TCAS STBY"is only a consequence of XPDR fault). Moreover, if the faulty ATC is selected on the ATC/TCAS control unit, a new cyan procedure "ATC/XPDR SYS y" is displayed below the level 2 alert.

NOTE: "x" could be either 1, 2 or 1+2 and "y" could be either 1 (if x = 2) or 2 (if x = 1).

T/TISS-ATC2 - XPDR Fault Message on ECAM Display Units ** ON A/C NOT FOR ALL

E. Reconfiguration switching

(1) In normal configuration, the T/TISS transponder receives the altitude information from ADIRU 2.

(2) In case of ADIRU 2 failure, the pilot can select the altitude information from ADIRU 3 with the AIR DATA selector switch installed on the center pedestal.

F. Remote ATC Control Box

Remote ATC Control Box ** ON A/C NOT FOR ALL

The remote ATC control box is a 2MCU size unit with mounting requirements in compliance with ARINC 600 specification.

** ON A/C NOT FOR ALL

7. Operation

A. Control

ATC - Control & Indicating ** ON A/C NOT FOR ALL

ATC - Control and Indicating ** ON A/C NOT FOR ALL

(1) In normal operation, you select the ATC 1(2) through the XPDR 1/2 selector switch on the control unit in either position 1 or 2.
A switch SBY/ON/TA/RA/TA enables the functions given below :

In SBY position : the answers of the two transponders are inhibited
In ON position : the selected transponder answers are valid when the aircraft is in flight or on the ground.
In TA or RA/TA position : the corresponding TCAS modes are operated (if installed).

(2) Upon energization of the aircraft or modification of system selection, the last ATC code selected is displayed before the new code selection. This code comes into view on the display window of the control unit. When you set the ALT RPT ON/OFF switch to ON, the altitude information transmission of the selected transponder is enabled.

(3) When you push the IDNT pushbutton switch (ON configuration), this generates an additional identification pulse in the reply signal.

(4) With failure of the ATC control unit, the transponder continues to transmit the last displayed code. No new code selection is possible.

(5) In addition, a suppressor coaxial connects the ATC transponders to the Distance Measuring Equipment (DME) interrogators and the TCAS computer (if installed). This prevents transmission from one system while the others are in reception mode. This is necessary because the ATC, the DME and the TCAS systems operate on the same frequency range.

(6) In normal operation, you select ATC 1(2) through the 1/2 switch on the control unit in either position 1 or 2.
A STBY/AUTO/ON selector switch enables the functions given below:

In STBY position: the two transponders are electrically supplied but do not operate
In AUTO position: the selected transponder operates in flight but operates only in mode S on ground
In ON position: the selected transponder operates when the aircraft is in flight.

(7) Upon energization of the aircraft or modification of system selection, the last ATC code selected is displayed before the new code selection. This code comes into view on the display window of the control unit. When you set the ALT RPTG/ON/OFF switch to ON, the altitude information transmission of the selected transponder is enabled.

(8) When you push the IDENT pushbutton switch (ON configuration), this generates an additional identification pulse in the reply signal.

(9) With failure of the ATC/TCAS control unit, the transponder continues to transmit the last displayed code. No new code selection is possible.

(10) In addition, a suppressor coaxial connects the ATC transponders to the Distance Measuring Equipment (DME) interrogators. This prevents transmission from one system while the other is in reception mode. This is necessary because the ATC and the DME systems operate on the same frequency range.

(11) In normal operation, you select the ATC 1(2) through the XPNDR 1/2 selector switch on the control unit in either position 1 or 2.
A switch STBY/XPNDR/TA ONLY/TA/RA enables the functions given below :

In STBY position : the answers of the two transponders are inhibited
In XPNDR position : the selected transponder answers are valid when the aircraft is in flight.
In TA ONLY or TA/RA positions select the TCAS modes.

(12) Upon energization of the aircraft or modification of system selection, the last ATC code selected is displayed before the new code selection. This code comes into view on the display window of the control unit. When you set the ALT RPTG/OFF switch to ALT RPTG, the altitude information transmission of the selected transponder is enabled.

(13) When you push the IDENT pushbutton switch (ON configuration), this generates an additional identification pulse in the reply signal.

(14) With failure of the ATC control unit, the transponder continues to transmit the last displayed code. No new code selection is possible.

(15) In addition, a suppressor coaxial connects the ATC tranponders to the Distance Measuring Equipment (DME) interrogators and the TCAS computer. This prevents transmission from one system while the others are in reception mode. This is necessary because the ATC, the DME and the TCAS systems operate on the same frequency range.

(16) In normal operation, you select the ATC 1(2) through the SYS 1/2 switch on the control unit in either position 1 or 2.

(17) An ATC/TCAS mode selector switch enables the functions given below:

In STBY position, all ATC and TCAS functions are inhibited,
In ALT RPTG OFF position, TCAS is still inhibited and ATC replies only in mode A,
In XPNDR position, TCAS is inhibited and ATC replies in mode A or C,
In TA ONLY position, TCAS is fully operative but only in TA mode. TA intruders are displayed on the NDs. No resolution advisories are generated,
In TA/RA position, TA and RA intruders are displayed on the NDs. Preventive/corrective resolution advisories are displayed on the PFDs. Aural messages are heard on the cockpit loudspeakers.

(18) The THRT/ALL (Treat, All) selector switch which is used for Full Time Display mode for the aircraft equipped with the TCAS (Ref. 34-43-00 for more details).

(19) The ABV/N/BLW (Above/Normal/Below) selector switch enables the altitude field of surveillance above/below the TCAS equipped aircraft (Ref. 34-43-00 for more details).

(20) Upon energization of the aircraft or modification of system selection, the last ATC code selected is displayed before the new code selection. This code comes into view on the display window of the control unit.

(21) When you push the IDENT pushbutton switch, this generates an additional identification pulse in the reply signal.

(22) In case of control unit failure, the transponder continues to transmit the last displayed code. No new code selection is possible.

(23) In addition, a suppressor coaxial connects the ATC transponders to the Distance Measuring Equipment (DME) interrogators. This prevents transmission from one system while the other is in reception mode. This is necessary because the ATC and the DME systems operate on the same frequency range.

B. Reconfiguration Switching

ATC - Control & Indicating ** ON A/C NOT FOR ALL

ATC - Control and Indicating ** ON A/C NOT FOR ALL

In normal configuration, each ATC receives the altitude information from its corresponding Air Data/Inertial Reference Unit (ATC1 from ADIRU1, ATC2 from ADIRU2).
With failure of the ADIRU corresponding to the serviceable transponder, the pilot can select the altitude information from the ADIRU 3. This selection is through the AIR DATA selector switch installed on panel 8VU on the center pedestal.

** ON A/C NOT FOR ALL

8. Test

A. CFDIU Interface

(1) BITE description
The BITE facilitates maintenance on in-service aircraft. It detects and identifies a failure related to the ATC system.
The BITE of the ATC transponder is connected to the CFDIU.
The unit tested is the ATC transponder.
The BITE:

Transmits permanently ATC system status and its identification message to the CFDIU
Memorizes the faults which occurred during the last 63 flight legs
Monitors data inputs from the various peripherals (FMGC, ADIRU, ATC CTL UNIT and CFDIU)
Transmits to the CFDIU the result of the tests performed and self-tests
Can communicate with the CFDIU through the menus.

The BITE can operate in two modes:

The normal mode
The interactive mode.

(a) Normal mode
During the normal mode the BITE monitors cyclically the status of the ATC system. It transmits its information to the CFDIU during the flight concerned.
In case of fault detection, the BITE stores the information in the fault memories.
These items of information are transmitted to the CFDIU every 100 ms by an ARINC 429 message with label 350.

(b) Interactive mode:
The interactive mode can only be activated on the ground.
This mode enables communication between the CFDIU and the ATC transponder BITE by means of the MCDU.

ATC Maintenance Test Procedure - ATC Menu ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Last Leg Report - Previous Legs Report - LRU Ident ** ON A/C NOT FOR ALL

All the information displayed on the MCDU during the BITE TEST configuration can be printed by the printer.
The ATC interactive mode is composed of:

LAST LEG REPORT
The purpose of this item is to present the fault messages (class 1 and 2, internal and external) that appeared during the last flight.
PREVIOUS LEGS REPORT
The purpose of this item is to present the fault messages (class 1 and 2, internal and external) that appeared during the previous flights.
When no fault has been detected during the last 63 flights, the NO FAULT DETECTED message is displayed.
LRU IDENTIFICATION
The purpose of this item is to present the Part Number (PN), the Serial Number (SN) and the Software Number (SW/N) of the component.
TROUBLE SHOOTING DATA
This item allows to analyze the snapshot of the recorded failure to detect the software bugs.
CLASS 3 FAULTS
The purpose of this item is to present the class 3 fault messages that appeared during the last flight.
There is no date and no failure classification.
GROUND REPORT
The purpose of this item is to present the class 1, 2 or 3 internal failures when they are detected on ground.
CONFIGURATION DATA
The purpose of this item is to present in three pages, each formatted differently, the current configuration and discrete data and format the data for display on the MCDU.
TEST
The activation of this manual test shall only be allowed on the ground. The results of the test are transmitted to the CFDIU but are not memorized.

--------------------------------------------------------------------------

! REPORTED INTERNAL FAILURES !

!------------------------------------------------------------------------!

! MESSAGE (i = 1 or 2) ! CLASS ! ATA !

!---------------------------------------------!---------!----------------!

! ATCi (1SHi) ! 1 ! 34-52-33 !

! ATC1 TOP ANTENNA (7SH3) ! 1 ! 34-52-11 !

! ATC1 BOT ANTENNA (7SH1) ! 1 ! 34-52-11 !

! ATC2 TOP ANTENNA (7SH4) ! 1 ! 34-52-11 !

! ATC2 BOT ANTENNA (7SH2) ! 1 ! 34-52-11 !

! WRG : MODE S ADRESS/ATCi (1SHi) ! 1 ! 34-52-33 !

--------------------------------------------------------------------------

! REPORTED EXTERNAL FAILURES !

!------------------------------------------------------------------------!

! MESSAGE (i = 1 or 2) ! CLASS ! ATA !

!---------------------------------------------!---------!----------------!

! ATC CTL PNL (3SH)/ATCi (1SHi) ! 1 ! 34-52-12 !

! ADIRU i/3(1FPi/3)/ATCi (1SHi) ! 1 ! 34-12-34 !

! TCAS(1SG)/ATCi(1SHi) ! 3 ! 34-43-34 !

! CFDIU(1TW)/ATCi(1SHi) ! 3 ! 31-32-34 !

! FMGC1(1CA1)/ ATC i (1SHi) ! 3 ! 22-83-34 !

! POWER SUPPLY INTERRUPT ! 1 ! 24-00-00 !

! LGCIUi(5GAi)/ATCi(1SHi) ! 3 ! 32-31-71 !

--------------------------------------------------------------------------

(2) BITE description
The BITE facilitates maintenance on in-service aircraft. It detects and identifies a failure related to the ATC system.
The BITE of the ATC transponder is connected to the CFDIU.
The unit tested is the ATC transponder.
The BITE:

Transmits permanently ATC system status and its identification message to the CFDIU
Memorizes the faults which occurred during the last 63 flight legs
Monitors data inputs from the various peripherals (FMGC, ADIRU, ATC CTL UNIT and CFDIU)
Transmits to the CFDIU the result of the tests performed and self-tests
Can communicate with the CFDIU through the menus.

The BITE can operate in two modes:

The normal mode
The interactive mode.

(b) Interactive mode:
The interactive mode can only be activated on the ground.
This mode enables communication between the CFDIU and the ATC transponder BITE by means of the MCDU.

ATC Maintenance Test Procedure - ATC Menu ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Last Leg Report - Previous Legs Report - LRU Ident ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Ground Scanning ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Discrete Configuration 2/4 ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Discrete Configuration 3/4 ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Discrete Configuration 4/4 ** ON A/C NOT FOR ALL

All the information displayed on the MCDU during the BITE TEST configuration can be printed by the printer.
The ATC interactive mode is composed of:

LAST LEG REPORT
The purpose of this item is to present the fault messages (class 1 and 2, internal and external) that appeared during the last flight.
PREVIOUS LEGS REPORT
The purpose of this item is to present the fault messages (class 1 and 2, internal and external) that appeared during the previous flights.
When no fault has been detected during the last 63 flights, the NO FAULT DETECTED message is displayed.
LRU IDENTIFICATION
The purpose of this item is to present the Part Number (PN), the Serial Number (SN) and the Software Number (SW/N) of the component.
GROUND SCANNING
This item is based on the monitoring and fault analysis used during the flight.
The system peripherals monitoring and system internal cyclic tests are used to detect transient anomalies.
TROUBLE SHOOTING DATA
This item allows to analyze the snapshot of the recorded failure to detect the software bugs.
CLASS 3 FAULTS
The purpose of this item is to present the class 3 fault messages that appeared during the last flight.
There is no date and no failure classification.
GROUND REPORT
The purpose of this item is to present the class 1, 2 or 3 internal failures when they are detected on ground.
DISCRETE CONFIGURATION
The purpose of this item is to present many information of program pins dedicated to the ATC system installation.
TEST
The activation of this manual test shall only be allowed on the ground. The results of the test are transmitted to the CFDIU but are not memorized.

--------------------------------------------------------------------------

! REPORTED INTERNAL FAILURES !

!------------------------------------------------------------------------!

! MESSAGE (i = 1 or 2) ! CLASS ! ATA !

!---------------------------------------------!---------!----------------!

! ATCi (1SHi) ! 1 ! 34-52-33 !

! ATC1 TOP ANTENNA (7SH3) ! 1 ! 34-52-11 !

! ATC1 BOT ANTENNA (7SH1) ! 1 ! 34-52-11 !

! ATC2 TOP ANTENNA (7SH4) ! 1 ! 34-52-11 !

! ATC2 BOT ANTENNA (7SH2) ! 1 ! 34-52-11 !

! WRG : MODE S ADRESS/ATCi (1SHi) ! 1 ! 34-52-33 !

--------------------------------------------------------------------------

! REPORTED EXTERNAL FAILURES !

!------------------------------------------------------------------------!

! MESSAGE (i = 1 or 2) ! CLASS ! ATA !

!---------------------------------------------!---------!----------------!

! ATC CTL PNL (3SH)/ATCi (1SHi) ! 1 ! 34-52-12 !

! ADIRU i/3(1FPi/3)/ATCi (1SHi) ! 1 ! 34-12-34 !

! TCAS(1SG)/ATCi(1SHi) ! 3 ! 34-43-34 !

! CFDIU(1TW)/ATCi(1SHi) ! 3 ! 31-32-34 !

! FMGC1(1CA1)/ ATC i (1SHi) ! 3 ! 22-83-34 !

! POWER SUPPLY INTERRUPT ! 1 ! 24-00-00 !

! LGCIUi(5GAi)/ATCi(1SHi) ! 3 ! 32-31-71 !

--------------------------------------------------------------------------

(3) BITE description
The BITE facilitates maintenance on in-service aircraft. It detects and identifies a failure related to the ATC system.
The BITE of the ATC transponder is connected to the CFDIU.
The unit tested is the ATC transponder.
The BITE:

Transmits permanently ATC system status and its identification message to the CFDIU
Memorizes the faults which occurred during the last 63 flight legs
Monitors data inputs from the various peripherals (FMGC, ADIRU, ATC CTL UNIT and CFDIU)
Transmits to the CFDIU the result of the tests performed and self-tests
Can communicate with the CFDIU through the menus.

The BITE can operate in two modes:

The normal mode
The interactive mode.

(b) Interactive mode:
The interactive mode can only be activated on the ground.
This mode enables communication between the CFDIU and the ATC transponder BITE by means of the MCDU.

ATC Maintenance Test Procedure - ATC Menu ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Last Leg Report - Previous Legs Report - LRU Ident ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Discrete Configuration 2/4 ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Discrete Configuration 3/4 ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Discrete Configuration 4/4 ** ON A/C NOT FOR ALL

All the information displayed on the MCDU during the BITE TEST configuration can be printed by the printer.
The ATC interactive mode is composed of:

LAST LEG REPORT
The purpose of this item is to present the fault messages (class 1 and 2, internal and external) that appeared during the last flight.
PREVIOUS LEGS REPORT
The purpose of this item is to present the fault messages (class 1 and 2, internal and external) that appeared during the previous flights.
When no fault has been detected during the last 63 flights, the NO FAULT DETECTED message is displayed.
LRU IDENTIFICATION
The purpose of this item is to present the Part Number (PN), the Serial Number (SN) and the Software Number (SW/N) of the component.
TROUBLE SHOOTING DATA
This item allows to analyze the snapshot of the recorded failure to detect the software bugs.
CLASS 3 FAULTS
The purpose of this item is to present the class 3 fault messages that appeared during the last flight.
There is no date and no failure classification.
GROUND REPORT
The purpose of this item is to present the class 1, 2 or 3 internal failures when they are detected on ground.
DISCRETE CONFIGURATION
The purpose of this item is to present many information of program pins dedicated to the ATC system installation.
TEST
The activation of this manual test shall only be allowed on the ground. The results of the test are transmitted to the CFDIU but are not memorized.

--------------------------------------------------------------------------

! REPORTED INTERNAL FAILURES !

!------------------------------------------------------------------------!

! MESSAGE (i = 1 or 2) ! CLASS ! ATA !

!---------------------------------------------!---------!----------------!

! ATCi (1SHi) ! 1 ! 34-52-33 !

! ATC1 TOP ANTENNA (7SH3) ! 1 ! 34-52-11 !

! ATC1 BOT ANTENNA (7SH1) ! 1 ! 34-52-11 !

! ATC2 TOP ANTENNA (7SH4) ! 1 ! 34-52-11 !

! ATC2 BOT ANTENNA (7SH2) ! 1 ! 34-52-11 !

! WRG : MODE S ADRESS/ATCi (1SHi) ! 1 ! 34-52-33 !

--------------------------------------------------------------------------

! REPORTED EXTERNAL FAILURES !

!------------------------------------------------------------------------!

! MESSAGE (i = 1 or 2) ! CLASS ! ATA !

!---------------------------------------------!---------!----------------!

! ATC CTL PNL (3SH)/ATCi (1SHi) ! 1 ! 34-52-12 !

! ADIRU i/3(1FPi/3)/ATCi (1SHi) ! 1 ! 34-12-34 !

! TCAS(1SG)/ATCi(1SHi) ! 3 ! 34-43-34 !

! CFDIU(1TW)/ATCi(1SHi) ! 3 ! 31-32-34 !

! FMGC1(1CA1)/ ATC i (1SHi) ! 3 ! 22-83-34 !

! POWER SUPPLY INTERRUPT ! 1 ! 24-00-00 !

! LGCIUi(5GAi)/ATCi(1SHi) ! 3 ! 32-31-71 !

--------------------------------------------------------------------------

(4) BITE Description

ATC Maintenance Test Procedure - ATC Menu ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Last Leg Report - Previous Legs Report - LRU Ident ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Ground Scanning ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Discrete Configuration 2/4 ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Discrete Configuration 3/4 ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Discrete Configuration 4/4 ** ON A/C NOT FOR ALL

The BITE makes the maintenance on an in-service aircraft easier. It detects and finds a failure related to the ATC system.
The BITE of the ATC transponder is connected to the CFDIU.
The unit tested is the ATC transponder.
The BITE:

Transmits permanently the ATC system status and its identification message to the CFDIU.
Keeps in memory the faults that occurred during the last 63 flight legs.
Monitors data inputs from many peripherals (FMGC, ADIRU, ATC CTL UNIT and CFDIU).
Transmits the results of the tests and the self-tests to the CFDIU.
Uses the menus to communicate with the CFDIU.

The BITE can operate in two modes:

The normal mode
The interactive mode.

(a) Normal mode
During the normal mode, the BITE monitors in cycles the status of the ATC system. It transmits its information to the CFDIU during the flight.
If a fault is detected, the BITE keeps the information in the fault memory.
These items of information are transmitted to the CFDIU every 100 ms by an ARINC 429 message with label 350.

(b) Interactive mode:
The interactive mode can only be activated on the ground.
This mode makes the communication between the CFDIU and the ATC transponder BITE possible with the MCDU.
It is possible to print all the information shown on the MCDU during the BITE TEST configuration with the printer.
The ATC interactive mode includes:

LAST LEG REPORT
The function of this item is to show the fault messages (class 1 and 2, internal and external) that came into view during the last flight.
PREVIOUS LEGS REPORT
The function of this item is to show the fault messages (class 1 and 2, internal and external) that came into view during the previous flights.
If no fault was detected during the last 63 flights, the NO FAULT DETECTED message is shown.
LRU IDENTIFICATION
The function of this item is to show the Part Number (PN), the Serial Number (SN) and the Software Number (SW/N) of the component.
GROUND SCANNING
This item is based on the monitoring and fault analysis used during the flight.
The system peripherals monitoring and system internal cyclic-tests are used to find transient anomalies.
TROUBLE SHOOTING DATA
With this item it is possible to do an analysis of the recorded failure to detect the software bugs.
CLASS 3 FAULTS
The function of this item is to show the class 3 fault messages that came into view during the last flight.
There is no date and no failure classification.
GROUND REPORT
The function of this item is to show the class 1, 2 or 3 internal failures when they are detected on the ground.
DISCRETE CONFIGURATION
The function of this item is to show the information of program pins dedicated to the ATC system installation.
TEST
You can do this manual test only on the ground. The results of the test are transmitted to the CFDIU but are not kept in memory.

--------------------------------------------------------------------------

! REPORTED INTERNAL FAILURES !

!------------------------------------------------------------------------!

! MESSAGE (i = 1 or 2) ! CLASS ! ATA !

!---------------------------------------------!---------!----------------!

! ATCi (1SHi) ! 1 ! 34-52-33 !

! ATCi TOP ANTENNA (7SH3) ! 1 ! 34-52-11 !

! ATCi BOT ANTENNA (7SH1) ! 1 ! 34-52-11 !

! WRG : MODE S ADRESS/ATCi (1SHi) ! 1 ! 34-52-33 !

--------------------------------------------------------------------------

! REPORTED EXTERNAL FAILURES !

!------------------------------------------------------------------------!

! MESSAGE (i = 1 or 2) ! CLASS ! ATA !

!---------------------------------------------!---------!----------------!

! ATC CTL PNL (3SH)/ATCi (1SHi) ! 1 ! 34-52-12 !

! ADIRU i/3(1FPi/3)/ATCi (1SHi) ! 1 ! 34-12-34 !

! TCAS(1SG)/ATCi(1SHi) ! 3 ! 34-43-34 !

! T2CAS(100SG)/ATCi(1SHi) if installed ! 3 ! 34-43-34 !

! CFDIU(1TW)/ATCi(1SHi) ! 3 ! 31-32-34 !

! FMGCi(1CAi)/ATCi(1SHi) ! 3 ! 22-83-34 !

! POWER SUPPLY INTERRUPT ! 1 ! 24-00-00 !

! LGCIUi(5GAi)/ATCi(1SHi) ! 3 ! 32-31-71 !

! MMRi(40RTi)/ATCi(1SHi) ! 3 ! 34-36-31 !

! MMR1+2(40RT1+2)/ATCi(1SHi) ! 3 ! 34-36-31 !

! WRG : MODE S ADRESS/ATCi (1SHi) ! 3 ! 34-52-00 !

--------------------------------------------------------------------------

(5) BITE description
The BITE facilitates maintenance on in-service aircraft. It detects and identifies a failure related to the ATC system.
The BITE of the ATC transponder is connected to the CFDIU.
The unit tested is the ATC transponder.
The BITE:

Transmits permanently ATC system status and its identification message to the CFDIU
Memorizes the faults which occurred during the last 63 flight legs
Monitors data inputs from the various peripherals (FMGC, ADIRU, ATC CTL UNIT and CFDIU)
Transmits to the CFDIU the result of the tests performed and self-tests
Can communicate with the CFDIU through the menus.

The BITE can operate in two modes:

The normal mode
The interactive mode.

(b) Interactive mode:
The interactive mode can only be activated on the ground.
This mode enables communication between the CFDIU and the ATC transponder BITE by means of the MCDU.

ATC Maintenance Test Procedure - ATC Menu ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Last Leg Report - Previous Legs Report - LRU Ident ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Discrete Configuration 2/4 ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Discrete Configuration 3/4 ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Discrete Configuration 4/4 ** ON A/C NOT FOR ALL

All the information displayed on the MCDU during the BITE TEST configuration can be printed by the printer.
The ATC interactive mode is composed of:

LAST LEG REPORT
The purpose of this item is to present the fault messages (class 1 and 2, internal and external) that appeared during the last flight.
PREVIOUS LEGS REPORT
The purpose of this item is to present the fault messages (class 1 and 2, internal and external) that appeared during the previous flights.
When no fault has been detected during the last 63 flights, the NO FAULT DETECTED message is displayed.
LRU IDENTIFICATION
The purpose of this item is to present the Part Number (PN), the Serial Number (SN) and the Software Number (SW/N) of the component.
TROUBLE SHOOTING DATA
This item allows to analyze the snapshot of the recorded failure to detect the software bugs.
CLASS 3 FAULTS
The purpose of this item is to present the class 3 fault messages that appeared during the last flight.
There is no date and no failure classification.
GROUND REPORT
The purpose of this item is to present the class 1, 2 or 3 internal failures when they are detected on ground.
DISCRETE CONFIGURATION
The purpose of this item is to present many information of program pins dedicated to the ATC system installation.
TEST
The activation of this manual test shall only be allowed on the ground. The results of the test are transmitted to the CFDIU but are not memorized.

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! REPORTED INTERNAL FAILURES !

!------------------------------------------------------------------------!

! MESSAGE ! CLASS ! ATA !

!---------------------------------------------!---------!----------------!

! ATC1 (1SH1) ! 1 ! 34-52-33 !

! ATC1 TOP ANTENNA (7SH3) ! 1 ! 34-52-11 !

! ATC1 BOT ANTENNA (7SH1) ! 1 ! 34-52-11 !

! WRG : MODE S ADRESS/ATC1 (1SH1) ! 1 ! 34-52-33 !

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! REPORTED EXTERNAL FAILURES !

!------------------------------------------------------------------------!

! MESSAGE (i = 1 or 2) ! CLASS ! ATA !

!---------------------------------------------!---------!----------------!

! ATC CTL PNL (3SH)/ATC1 (1SH1) ! 1 ! 34-52-12 !

! ADIRU i/3(1FPi/3)/ATC1 (1SH1) ! 1 ! 34-12-34 !

! TCAS(1000SG)/ATC1(1SH1) ! 3 ! 34-72-34 !

! CFDIU(1TW)/ATC1(1SH1) ! 3 ! 31-32-34 !

! FMGC1(1CA1)/ ATC i (1SHi) ! 3 ! 22-83-34 !

! POWER SUPPLY INTERRUPT ! 1 ! 24-00-00 !

! LGCIUi(5GAi)/ATC1(1SH1) ! 3 ! 32-31-71 !

! MMRi(40RTi)/ATC1(1SH1) ! 3 ! 34-36-31 !

! MMR1+2(40RT1+2)/ATC1(1SH1) ! 3 ! 34-36-31 !

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(6) BITE description
The BITE facilitates maintenance on in-service aircraft. It detects and identifies a failure related to the ATC system.
The BITE of the ATC transponder is connected to the CFDIU.
The unit tested is the ATC transponder.
The BITE:

Transmits permanently ATC system status and its identification message to the CFDIU
Memorizes the faults which occurred during the last 63 flight legs
Monitors data inputs from the various peripherals (FMGC, ADIRU, ATC CTL UNIT and CFDIU)
Transmits to the CFDIU the result of the tests performed and self-tests
Can communicate with the CFDIU through the menus.

The BITE can operate in two modes:

The normal mode
The interactive mode.

(b) Interactive mode:
The interactive mode can only be activated on the ground.
This mode enables communication between the CFDIU and the ATC transponder BITE by means of the MCDU.

ATC Maintenance Test Procedure - ATC Menu ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Last Leg Report - Previous Legs Report - LRU Ident ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Discrete Configuration 2/4 ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Discrete Configuration 3/4 ** ON A/C NOT FOR ALL

ATC Maintenance Test Procedure - Discrete Configuration 4/4 ** ON A/C NOT FOR ALL

All the information displayed on the MCDU during the BITE TEST configuration can be printed by the printer.
The ATC interactive mode is composed of:

LAST LEG REPORT
The purpose of this item is to present the fault messages (class 1 and 2, internal and external) that appeared during the last flight.
PREVIOUS LEGS REPORT
The purpose of this item is to present the fault messages (class 1 and 2, internal and external) that appeared during the previous flights.
When no fault has been detected during the last 63 flights, the NO FAULT DETECTED message is displayed.
LRU IDENTIFICATION
The purpose of this item is to present the Part Number (PN), the Serial Number (SN) and the Software Number (SW/N) of the component.
TROUBLE SHOOTING DATA
This item allows to analyze the snapshot of the recorded failure to detect the software bugs.
CLASS 3 FAULTS
The purpose of this item is to present the class 3 fault messages that appeared during the last flight.
There is no date and no failure classification.
GROUND REPORT
The purpose of this item is to present the class 1, 2 or 3 internal failures when they are detected on ground.
DISCRETE CONFIGURATION
The purpose of this item is to present many information of program pins dedicated to the ATC system installation.
TEST
The activation of this manual test shall only be allowed on the ground. The results of the test are transmitted to the CFDIU but are not memorized.

--------------------------------------------------------------------------

! REPORTED INTERNAL FAILURES !

!------------------------------------------------------------------------!

! MESSAGE (i = 1 or 2) ! CLASS ! ATA !

!---------------------------------------------!---------!----------------!

! ATCi (1SHi) ! 1 ! 34-52-33 !

! ATCi TOP ANTENNA (7SH3) ! 1 ! 34-52-11 !

! ATCi BOT ANTENNA (7SH1) ! 1 ! 34-52-11 !

! WRG : MODE S ADRESS/ATCi (1SHi) ! 1 ! 34-52-33 !

--------------------------------------------------------------------------

! REPORTED EXTERNAL FAILURES !

!------------------------------------------------------------------------!

! MESSAGE (i = 1 or 2) ! CLASS ! ATA !

!---------------------------------------------!---------!----------------!

! ATC CTL PNL (3SH)/ATCi (1SHi) ! 1 ! 34-52-12 !

! ADIRU i/3(1FPi/3)/ATCi (1SHi) ! 1 ! 34-12-34 !

! TCAS(1SG)/ATCi(1SHi) ! 3 ! 34-43-34 !

! T2CAS(100SG)/ATCi(1SHi) if installed ! 3 ! 34-43-34 !

! CFDIU(1TW)/ATCi(1SHi) ! 3 ! 31-32-34 !

! FMGC1(1CA1)/ ATC i (1SHi) ! 3 ! 22-83-34 !

! POWER SUPPLY INTERRUPT ! 1 ! 24-00-00 !

! LGCIUi(5GAi)/ATCi(1SHi) ! 3 ! 32-31-71 !

! MMRi(40RTi)/ATCi(1SHi) ! 3 ! 34-36-31 !

! MMR1+2(40RT1+2)/ATCi(1SHi) ! 3 ! 34-36-31 !

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B. BITE Implementation

(1) Internal test processing

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! TEST ! TESTED INTERNAL COMPONENTS ! DURATION ! ACTIVATION !

! DESIGNATION ! ! ! CONDITIONS !

----------------------------------------------------------------------------

! Power-up test ! Power supply module ! 3 s ! Power interrupt!

! ! ROM - RAM ! ! > 200 ms !

!---------------!------------------------------!----------!----------------!

! MCDU system ! - NAV receiver ! ! Relevant MCDU !

! test ! - BITE circuitry ! ! menu and line !

! ! - SYS failure LED indication ! ! key selection !

! ! on the ATC control unit ! ! !

!---------------!------------------------------!----------!----------------!

! Face test ! - ROM, RAM check ! ! Relevant P/BSW !

! ! - Antenna integrity ! ! activated on !

! ! - Receiver (top/bottom) ! ! XPDR face. !

! ! - Transmitter ! ! !

! ! - Reply format ! ! !

! ! - Power supply monitor ! ! !

! ! - I/O bus check ! ! !

! ! - Non-Volatile Memory ! ! !

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(2) Activation of the test on the indicators
The ATC 1(2) test function can be activated in ground conditions only by pressing the TEST key on the ATC 1(2) maintenance sub-menu or by pressing the pushbutton switch on the face of the transponder.
The following sequence is then generated on the output of the equipment:

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! DURATION ! MESSAGE ! ATC CONTROL UNIT AND FACE OF ATC TRANSPONDER !

-------------------------------------------------------------------------

! FOR 3 s ! Failure ! - Failure light comes on control unit !

! ! ! - all LEDs come on transponder face !

! AFTER 3 s ! ! - ATC Transponder LEDs indicate the current !

! ! ! condition of the unit !

! FOR 10 s ! ! - The LEDs associated with the self-test results!

! ! ! come on. Afterwards, all LEDs go off. !

-------------------------------------------------------------------------

When the selected system on the ATC control unit is different from the system under test, this causes illumination of a message on the MCDU after the TEST selection. This message is: PLEASE CHECK IF THE CONTROL PANEL SWITCH IS ON SYSTEM (1 OR 2) AND PRESS TEST KEY.
Reminder: The TEST pushbutton switch is used to initiate the LED test and transponder self-test. When this pushbutton switch is pressed while the LEDs are still on, the next previous flight leg is displayed. The transponder has the capability to store 10 flight legs. To display all stored flight legs, the pushbutton switch must be pushed when the previous flight leg is being displayed. When all flight legs are displayed, all LEDS flash to indicate the end of the routine.

(3) Internal test processing

----------------------------------------------------------------------------

! TEST ! TESTED INTERNAL COMPONENTS ! DURATION ! ACTIVATION !

! DESIGNATION ! ! ! CONDITIONS !

----------------------------------------------------------------------------

! Power-up test ! Power supply module ! 3 s ! Power interrupt!

! ! ROM - RAM ! ! > 200 ms !

!---------------!------------------------------!----------!----------------!

! MCDU system ! - NAV receiver ! ! Relevant MCDU !

! test ! - BITE circuitry ! ! menu and line !

! ! - SYS failure LED indication ! ! key selection !

! ! on the ATC control unit ! ! !

!---------------!------------------------------!----------!----------------!

! Face test ! - ROM, RAM check ! ! Relevant P/BSW !

! ! - Antenna integrity ! ! activated on !

! ! - Receiver (top/bottom) ! ! XPDR face. !

! ! - Transmitter ! ! !

! ! - Reply format ! ! !

! ! - Power supply monitor ! ! !

! ! - I/O bus check ! ! !

! ! - Non-Volatile Memory ! ! !

----------------------------------------------------------------------------

(4) Activation of the test on the indicators
The ATC 1(2) test function can be activated in ground conditions only by pressing the TEST key on the ATC 1(2) maintenance sub-menu or by pressing the pushbutton switch on the face of the transponder.
The following sequence is then generated on the output of the equipment:

-------------------------------------------------------------------------

! DURATION ! MESSAGE ! ATC CONTROL UNIT AND FACE OF ATC TRANSPONDER !

-------------------------------------------------------------------------

! FOR 1 s ! Failure ! - Failure light comes on control unit !

! ! ! - all LEDs come on transponder face !

! AFTER 1 s ! ! - All indicator lights go off !

! FOR 10 s ! ! - The indicator lights associated with the !

! ! ! self-test results come on. Afterwards, all !

! ! ! indicator lights go off. !

-------------------------------------------------------------------------

When the selected system on the ATC control unit is different from the system under test, this causes illumination of a message on the MCDU after the TEST selection. This message is: PLEASE CHECK IF THE CONTROL PANEL SWITCH IS ON SYSTEM (1 OR 2) AND PRESS TEST KEY.
Reminder: The TEST pushbutton switch is used to initiate the LED test and transponder self-test. When this pushbutton switch is pressed for more than five seconds, the transponder reads the Non-Volatile Memory fault data for last four legs and the applicable fault indicator lights come on.

(5) Internal test processing

----------------------------------------------------------------------------

! TEST ! TESTED INTERNAL COMPONENTS ! DURATION ! ACTIVATION !

! DESIGNATION ! ! ! CONDITIONS !

----------------------------------------------------------------------------

! Power-up test ! Power supply module ! 3 s ! Power interrupt!

! ! ROM - RAM ! ! > 200 ms !

!---------------!------------------------------!----------!----------------!

! MCDU system ! - NAV receiver ! ! Relevant MCDU !

! test ! - BITE circuitry ! ! menu and line !

! ! - SYS failure LED indication ! ! key selection !

! ! on the ATC control unit ! ! !

!---------------!------------------------------!----------!----------------!

! Face test ! - ROM, RAM check ! ! Relevant P/BSW !

! ! - Antenna integrity ! ! activated on !

! ! - Receiver (top/bottom) ! ! XPDR face. !

! ! - Transmitter ! ! !

! ! - Reply format ! ! !

! ! - Power supply monitor ! ! !

! ! - I/O bus check ! ! !

! ! - Non-Volatile Memory ! ! !

----------------------------------------------------------------------------

(6) Activation of the test on the indicators
The ATC 1(2) test function can be activated in ground conditions only by pressing the TEST key on the ATC 1(2) maintenance sub-menu or by pressing the pushbutton switch on the face of the transponder.
The following sequence is then generated on the output of the equipment:

-------------------------------------------------------------------------

! DURATION ! MESSAGE ! ATC CONTROL UNIT AND FACE OF ATC TRANSPONDER !

-------------------------------------------------------------------------

! FOR 1 s ! Failure ! - Failure light comes on control unit !

! ! ! - all LEDs come on transponder face !

! AFTER 1 s ! ! - All indicator lights go off !

! FOR 10 s ! ! - The indicator lights associated with the !

! ! ! self-test results come on. Afterwards, all !

! ! ! indicator lights go off. !

-------------------------------------------------------------------------

When the selected system on the ATC control unit is different from the system under test, this causes illumination of a message on the MCDU after the TEST selection. This message is: PLEASE CHECK IF THE CONTROL PANEL SWITCH IS ON SYSTEM (1 OR 2) AND PRESS TEST KEY.
Reminder: The TEST pushbutton switch is used to initiate the LED test and transponder self-test. When this pushbutton switch is pressed for more than five seconds, the transponder reads the Non-Volatile Memory fault data for last four legs and the applicable fault indicator lights come on.

C. Power-up Tests Initialization and Cockpit Repercussions

(1) Conditions of power-up tests initialization

How long the computer must be de-energized: 1 s.
A/C configuration: whatever the A/C configuration on ground

(2) Duration of power-up tests: 3 s approx.

(3) Results of power-up tests
(cockpit repercussions, if any, in case of tests pass/tests failed).

Tests pass: none
Tests failed: on the ATC control unit, FAULT or FAIL indicator light comes on or F indication appears on the display (depending on the type of the control unit).

[Rev.10 from 2021] 2026.04.02 06:23:31 UTC