DOC AIRBUS | AMM A320FT/TISS - ATC/MODE S (SELECT) - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The T/TISS-ATC2 system is based on the replies provided by the airborne transponders in response to interrogations from the ATC Secondary Surveillance Radar (SSR). In the following text, T/TISS-ATC2 part may be called "transponder".
T/TISS-ATC2 uses the TCAS antennas for the transponder function.The TCAS and transponder functions thus share RF resources, through the use of a common RF card.
The ground ATC secondary radar uses technics 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:
Moreover, the following functionalities are available:
** ON A/C NOT FOR ALL The T/TISS-ATC2 system is based on the replies provided by the airborne transponders in response to interrogations from the ATC Secondary Surveillance Radar (SSR). In the following text, T/TISS-ATC2 part may be called "transponder".
T/TISS-ATC2 uses the TCAS antennas for the transponder function.The TCAS and transponder functions thus share RF resources, through the use of a common RF card.
The ground ATC secondary radar uses technics 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, new functionalities are required for ATC/Mode S transponders: - elementary surveillance (mandatory after 31 March 2003),
- enhanced surveillance (mandatory after 31 March 2005),
- extended squitters also called Automatic Dependent Surveillance Broadcast (ADS-B) OUT, in compliance with DO-260B.
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 has interface characteristics in compliance with ARINC 718A
- it is backward compatible with Mark III transponder (ARINC 718-4) installations
- its software is fully loadable.
2. System Description
A. Principle
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 ATC/TCAS 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:
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.
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.
T/TISS-ATC2 - PrincipleThe 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 ATC/TCAS 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
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.
3. Component Description
A. Principle of Operation
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 (ADIRU) the FMGCs, the Traffic alert and Collision Avoidance System (TCAS)and other sources (Flight Control Unit (FCU) , Multi-Mode Receiver (MMR) ...) for enhanced surveillance parameters
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.
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 (ADIRU) the FMGCs, the Traffic alert and Collision Avoidance System (TCAS)and other sources (Flight Control Unit (FCU) , Multi-Mode Receiver (MMR) ...) for enhanced surveillance parameters
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.
(1) RF power for XPDR function
There are parameters that are worth considering for the XPDR operation
The nominal MTL for Transponder is -73 dBm for ATCRBS, -74 dBm for Mode S when referenced to the antenna. Accounting for a 3dB cable loss, the sensitivity at the T/TISS computer is -76 and -77dBm respectively.
There are parameters that are worth considering for the XPDR operation
- Minimum transponder transmission for ADS-B OUT or for responses to interrogations
- Minimum Triggering Level (MTL) for reception of interrogations.
The nominal MTL for Transponder is -73 dBm for ATCRBS, -74 dBm for Mode S when referenced to the antenna. Accounting for a 3dB cable loss, the sensitivity at the T/TISS computer is -76 and -77dBm respectively.
(2) Interrogations
Three classes of interrogations are transmitted by the ground interrogator or TCAS equipped aircraft, they are:
Three classes of interrogations are transmitted by the ground interrogator or TCAS equipped aircraft, they are:
- Mode A or C interrogations
- Mode S all-call interrogations
- Mode S interrogations.
(a) 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 P3 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.
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 P3 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.
(b) Mode S All-Call interrogation
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.
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.
(c) Mode S interrogation
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:
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.
(3) Encoded reply
(a) 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).
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).
(b) 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.
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 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 or 112 position modulated pulses.
The replies are PPM coded.
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 or 112 position modulated pulses.
The replies are PPM coded.
(d) Mode S message contents
The transponder must have the following Mode S message capabilities:
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 Automatic Terminal Information Service (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.
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 Airborne Data Link Processor (ADLP) is installed)
- air-to-ground Downlink Extended Length Message (DELM), COMM-D (DF=24). (if external ADLP is installed)
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 Automatic Terminal Information Service (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.
1 Mode S interrogation message formats
All valid Mode S interrogations 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.
All valid Mode S interrogations 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.
2 Mode S message 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.
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)
3 Mode S interrogation data field definition
The following table gives the definition of uplink format message fields:
The table below gives the definition of downlink format message fields:
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 message 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 ! |
| ------------------------------------------------------------------------------- |
(e) Data transmitted for elementary surveillance
The specific data related to the elementary surveillance are the following:
The specific data related to the elementary surveillance are the following:
- 24 bit A/C adress (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)
(f) Data transmitted for enhanced surveillance
The specific parameters related to the enhanced surveillance are:
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
(g) Data transmitted in extended squitters (ADS-B OUT)
The specific parameters related to the extended squitters are:
Extended squitters are automatically broadcast at different rates as shown in the following table.
The specific parameters related to the extended squitters are:
- altitude
- longitude
- latitude
- movement
- heading
- ground track
- flight number
- tail number
- E/W velocity
- N/S velocity
- vertical rate
- GPS height
- airspeed
- version number
- selected heading
- selected altitude
- Barometric Pressure Setting
- integrity
- accuracy
- emergency
- TCAS Resolution Advisories
- A/C category
- length/width code
- Mode A code
- capabilities
Extended squitters are automatically broadcast at different rates as shown in the following table.
B. Peripherals
T/TISS-ATC2 receives information from the following equipment:
T/TISS-ATC2 receives information from the following equipment:
(1) Air Data/Inertial Reference Unit (ADIRU)
The T/TISS computer is linked by:
The T/TISS computer is linked by:
- One ARINC 429 high-speed bus to the ADIRU-IRS2 for position, ground speed, true track angle and pitch/roll angle parameters. IRS2 is the third source of position for T/TISS-ATC2.
- One ARINC 429 low-speed bus to ADIRU-ADR2 for airspeed and barometric parameters
- One ARINC 429 low-speed bus to ADIRU-ADR3 for airspeed and barometric parameters
(2) Flight Control Unit (FCU)
The T/TISS computer is linked by a low-speed ARINC 429 bus to the FCU (First Officer side), for altitude and barometric reference parameters.
The T/TISS computer is linked by a low-speed ARINC 429 bus to the FCU (First Officer side), for altitude and barometric reference parameters.
(3) Multi Mode Receiver (MMR)
The T/TISS computer is linked by two high-speed ARINC 429 buses to the MMR for altitude, position (latitude and longitude), true track angle and ground speed parameters.The MMR is the first source of position for T/TISS-ATC2 part.
The T/TISS computer is linked by two high-speed ARINC 429 buses to the MMR for altitude, position (latitude and longitude), true track angle and ground speed parameters.The MMR is the first source of position for T/TISS-ATC2 part.
(4) Flight Management and Guidance Computer (FMGC)
The T/TISS computer is linked by one high-speed ARINC 429 bus to the FMGC for position (latitude and longitude) parameters.The FMGC is the second source of position for T/TISS-ATC2.
The T/TISS computer is linked by one high-speed ARINC 429 bus to the FMGC for position (latitude and longitude) parameters.The FMGC is the second source of position for T/TISS-ATC2.
(5) Centralized Fault Display Interface Unit (CFDIU)
The T/TISS computer communicates with the CFDS via two low-speed ARINC 429 buses.
The T/TISS computer communicates with the CFDS via two low-speed ARINC 429 buses.
(6) System Data Acquisition Concentrator (SDAC)
The T/TISS-ATC2 is connected to the SDAC 1 and 2 by a low speed ARINC 429 bus. This is the same output bus connected to the CFDIU. SDAC are then connected to Flight Warning Computer (FWC) 1 and 2.
The connection from T/TISS-ATC2 to FWC is used by the transponder to report ADS-B OUT status to the FWC. The FWS in term utilizes this information to provide a cockpit effect when the function is lost.
The T/TISS-ATC2 is connected to the SDAC 1 and 2 by a low speed ARINC 429 bus. This is the same output bus connected to the CFDIU. SDAC are then connected to Flight Warning Computer (FWC) 1 and 2.
The connection from T/TISS-ATC2 to FWC is used by the transponder to report ADS-B OUT status to the FWC. The FWS in term utilizes this information to provide a cockpit effect when the function is lost.
(7) Pin programming
Following discrete pin program inputs are used:
Following discrete pin program inputs are used:
- Mode S address (different on each aircraft)
- Maximum cruising true airspeed (always used)
- SDI.
- System Design Assurance
- Aircraft Category
- Length-width codes
- GPS antenna position
- ADS-B receive capability
- ADS-B Fail Disable (this P/P is always set to 1, i.e. ADS-B function fail is not declared on XPDR fail discretes)
4. Operation
A. Control/Indicating
(1) ATC/TCAS control unit
The transponder function of T/TISS uses the same control unit as T/TISS-TCAS (refer to 34-72-10).
The control unit has:
The transponder function of T/TISS uses the same control unit as T/TISS-TCAS (refer to 34-72-10).
The control unit has:
(a) A switch for system 1/2 active transponder selection.
The 1/2 switch permits selection of the active transponder. The non-selected transponder is placed in standby. ATC2 corresponds to the XPDR function of T/TISS.
The 1/2 switch permits selection of the active transponder. The non-selected transponder is placed in standby. ATC2 corresponds to the XPDR function of T/TISS.
(b) An ATC mode selector switch with the functions given below:
- STBY position. When the transponder is in standby, it does not transmit either squitters or replies to ground station or other aircraft interrogations. This will lead the TCAS to STBY, whatever its selection is.
- AUTO position. In flight, the aircraft transponder operates as in the ON mode: all its functions are active. When the aircraft touches down, the LGCIU sends a "ground" state to the control unit, which conveys this information to the XPDR. This information will then disable the mode A and C replies as well as Mode S all-call of the selected transponder from ground station interrogations. However, the Mode S replies and squitter are not inhibited when the aircraft is on the ground.
- ON position. The Mode S transponder operates permanently, both in flight and on the ground. It periodically transmits squitters (at 1 second intervals) to be detected by other aircraft and replies to their interrogations and those from ground stations. This function permits, on ground, to override the inhibition of replies from interrogations in Mode A or C. It is used by the air traffic controller to check the correct operation of the aircraft Mode A or C transponder prior to takeoff.
(c) An ALT RPTG (Altitude Reporting) selector switch with the functions given below:
- OFF position. Selection of the OFF position has the following results:
* The Mode S transponder continues to transmit squitters and replies to Mode A, C and S interrogations but does not report altitude.
* The TCAS switches to STBY.
* The PFD and ND display corresponds to the standby mode. - ON position. The active transponder replies to interrogations and reports its altitude. The TCAS operates in the mode selected by its logic according to information input from the control unit, ATCRBS/MODE S ground stations and aircraft altitude.
(d) A keyboard and a display window for the identification code in Mode A
The Mode S transponder also replies to Mode A interrogations from ground stations. The keyboard permits the pilot to set the Mode A octal code assigned to the aircraft by the ATC ground station controller and included in the transmitted replies. The display window on the control unit displays this code permanently as long as the content of the digital output message complies with the displayed data.
The Mode S transponder also replies to Mode A interrogations from ground stations. The keyboard permits the pilot to set the Mode A octal code assigned to the aircraft by the ATC ground station controller and included in the transmitted replies. The display window on the control unit displays this code permanently as long as the content of the digital output message complies with the displayed data.
(e) An IDENT pushbutton switch
On ground station request, an additional pulse must be included in the Mode A and Mode C replies transmitted by the transponder to enable a specific distinction from other aircraft. This operation is performed by pressing the IDENT pushbutton switch on the control unit.
On ground station request, an additional pulse must be included in the Mode A and Mode C replies transmitted by the transponder to enable a specific distinction from other aircraft. This operation is performed by pressing the IDENT pushbutton switch on the control unit.
(f) In case of control unit failure, the transponder continues to transmit the last displayed code. No new code selection is possible.
(2) Antennas
For Mode S transmissions, the method for generating an omni directional antenna beam is to provide equal phase, equal amplitude signals to each of the 4 connectors simultaneously. This method has been demonstrated to produce a very uniform omni directional beam whose gain is an average of 2.0 dB less than a matched quarter-wave stub.
For Mode S transmissions, the method for generating an omni directional antenna beam is to provide equal phase, equal amplitude signals to each of the 4 connectors simultaneously. This method has been demonstrated to produce a very uniform omni directional beam whose gain is an average of 2.0 dB less than a matched quarter-wave stub.
(3) Antennas
FOR 7SG1
The directional antenna has four passive vertically-polarized elements. This high-strength composite antenna has a curved base, eight fuselage mounting screws and four color-coded connectors. These connectors coaxially connect the four antenna elements to the Traffic and Terrain Integrated Surveillance System (T/TISS) computer (Traffic Alert and Collision Avoidance System (TCAS) function).
A Teflon gasket is installed between the fuselage and the antenna to make the removal of the antenna easier.
An O-ring seals the antenna to the fuselage. The antenna receives and sends directional information for 1090 MHz mode-S squitters, mode-S and air traffic control radar beacon system replies. A correct phasing of the four antenna elements makes possible the omnidirectional or directional transmission of 1030 MHz broadcast or coordination messages and air traffic control radar beacon system or mode-S interrogations.
FOR 7SG2
The omnidirectional antenna is an L-band antenna with a short stub, all-aluminum blade type which is fully sealed to prevent failure because of moisture.
It is vertically polarized, has an impedance of 50 ohms and a Voltage Standing Wave Ratio (VSWR) less or equal to 1.6. It operates in the 950 MHz to 1260 MHz frequency band. Lightning protection prevents damage to the antenna and the transponder.
FOR 7SG1
The directional antenna has four passive vertically-polarized elements. This high-strength composite antenna has a curved base, eight fuselage mounting screws and four color-coded connectors. These connectors coaxially connect the four antenna elements to the Traffic and Terrain Integrated Surveillance System (T/TISS) computer (Traffic Alert and Collision Avoidance System (TCAS) function).
A Teflon gasket is installed between the fuselage and the antenna to make the removal of the antenna easier.
An O-ring seals the antenna to the fuselage. The antenna receives and sends directional information for 1090 MHz mode-S squitters, mode-S and air traffic control radar beacon system replies. A correct phasing of the four antenna elements makes possible the omnidirectional or directional transmission of 1030 MHz broadcast or coordination messages and air traffic control radar beacon system or mode-S interrogations.
FOR 7SG2
The omnidirectional antenna is an L-band antenna with a short stub, all-aluminum blade type which is fully sealed to prevent failure because of moisture.
It is vertically polarized, has an impedance of 50 ohms and a Voltage Standing Wave Ratio (VSWR) less or equal to 1.6. It operates in the 950 MHz to 1260 MHz frequency band. Lightning protection prevents damage to the antenna and the transponder.
(4) Display on the ECAM DUs
(a) 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.
(b) 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).
(c) In case of "ADS-B reporting fault", a new amber alert "NAV ADS-B RPTG x FAULT" level 2 (amber message on EWD + "single chime" sound + master caution amber light) will be displayed on EWD only if DO260B option is intalled. In addition, a new amber Inop Sys "ADS-B RPTG x" will be displayed on the SD.
Moreover, if the faulty ATC is selected on ATC/TCAS control panel, a new cyan procedure "ATC/XPDR SYS y" will be displayed below the alert level 2.
Moreover, if the faulty ATC is selected on ATC/TCAS control panel, a new cyan procedure "ATC/XPDR SYS y" will be displayed below the alert level 2.
NOTE: In case of double MRR fault, only Inop is displayed (amber alert "NAV ADS-B RPTG x FAULT" and cyan procedure are not displayed due to inhibition in FWC).
NOTE: "x" could be either 1 or 2, "y" could be either 1 (if x = 2) or 2 (if x = 1).
(5) Suppressor connection
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, DME and TCAS systems operate on the same frequency range.
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, DME and TCAS systems operate on the same frequency range.
(6) Reconfiguration switching
In normal configuration, the T/TISS transponder receives the altitude information from ADIRU 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 centre pedestal.
In normal configuration, the T/TISS transponder receives the altitude information from ADIRU 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 centre pedestal.
5. Test
A. CFDIU Interface
The BITE facilitates maintenance on in-service aircraft. It detects and identifies the faults related to the T/TISS-ATC2. It reports also to the CFDIU the potential faulty LRU(s) (internal or external to the system) when a failure is detected.
The BITE:
The BITE facilitates maintenance on in-service aircraft. It detects and identifies the faults related to the T/TISS-ATC2. It reports also to the CFDIU the potential faulty LRU(s) (internal or external to the system) when a failure is detected.
The BITE:
- Continuously transmits the T/TISS-ATC2 (full configuration only) status (good health or failure messages), equipment ID and LRU identification messages to the CFDIU.
- Memorizes LRU(s) accusations (failure messages) and their associated Trouble Shooting Data (TSD = monitoring result, snapshot when the event is detected) of the last 64 flight legs including the current one.
- Launches manual system tests from the CFDIU via the MCDU and reports results of these tests.
- Normal mode: In case of fault detection or no reported failure, it transmits its information to the CFDIU during the given flight. These items of information are transmitted to the CFDIU every 100 ms by an ARINC 429 message with label 356. The BITE stores the information in the internal fault memories for access in interactive mode.
- Interactive mode (on ground, to get access to T/TISS-ATC2 internal fault logs and unit status information) to get access to BITE memory (failure messages and associated LRU ID, TSD) and to launch test.
NOTE: No modification has been introduced in the CFDIU, therefore T/TISS-ATC2 onboard mantenance interface can be accessed through the "ATC 2" prompt.
(1) Normal mode
During normal mode, the results of monitoring of the status of the T/TISS-ATC2 part are sent to the BITE function in order to determine the corresponding failure messages.
During normal mode, the results of monitoring of the status of the T/TISS-ATC2 part are sent to the BITE function in order to determine the corresponding failure messages.
(2) Interactive mode
To get access to the BITE, it is necessary to use one MCDU. All information displayed on the MCDU during the BITE TEST configuration can be printed. The interactive mode can only be activated on the ground. This mode enables communication between the CFDIU and the T/TISS-ATC2 BITE by means of the MCDU.
The SYSTEM REPORT/TEST function enables access to all the electronic systems and to the T/TISS-ATC2 part.
The T/TISS-ATC2 menu is composed of:
To get access to the BITE, it is necessary to use one MCDU. All information displayed on the MCDU during the BITE TEST configuration can be printed. The interactive mode can only be activated on the ground. This mode enables communication between the CFDIU and the T/TISS-ATC2 BITE by means of the MCDU.
The SYSTEM REPORT/TEST function enables access to all the electronic systems and to the T/TISS-ATC2 part.
The T/TISS-ATC2 menu is composed of:
- LAST LEG REPORT
- PREVIOUS LEGS REPORT
- LRU IDENTIFICATION
- GROUND SCANNING
- TROUBLE SHOOTING DATA
- CLASS 3 FAULTS
- GROUND REPORT
- DISCRETE CONFIG
- TEST.
(a) LAST LEG REPORT
The LAST LEG REPORT (also called CURRENT LEG REPORT) contains the overall internal and external class 1 failures reported to the CFDIU in flight during the last leg. The failures are displayed in the chronological order (oldest first).
Select LAST LEG REPORT by pressing line key 1L on the T/TISS-ATC2 menu page. The T/TISS-ATC2/LAST LEG REPORT page will be displayed as follows:
The LAST LEG REPORT (also called CURRENT LEG REPORT) contains the overall internal and external class 1 failures reported to the CFDIU in flight during the last leg. The failures are displayed in the chronological order (oldest first).
Select LAST LEG REPORT by pressing line key 1L on the T/TISS-ATC2 menu page. The T/TISS-ATC2/LAST LEG REPORT page will be displayed as follows:
NOTE: The class 3 faults are stored in the LAST LEG CLASS 3 FAULT menu.
When a new flight is detected, the content of "LAST LEG REPORT" is transferred into the "PREVIOUS LEGS REPORT" with a "flight leg counter" equal to 1. The "flight leg counters" of the other fault messages stored in "PREVIOUS LEGS REPORT" is incremented by 1.
When a new flight is detected, the content of "LAST LEG REPORT" is transferred into the "PREVIOUS LEGS REPORT" with a "flight leg counter" equal to 1. The "flight leg counters" of the other fault messages stored in "PREVIOUS LEGS REPORT" is incremented by 1.
(b) PREVIOUS LEGS REPORT
The "PREVIOUS LEGS REPORT" gathers the 63 previous legs internal and external class 1 failures that occured during the 63 previous legs. The legs are displayed in reverse chronological order (oldest last) whereas within one leg the failures are reported in chronological order (oldest first for a same leg). The displayed messages are identical to the ones presented in the previous paragraph.
Select PREVIOUS LEGS REPORT by pressing line key 2L on the T/TISS-ATC2 menu page. The T/TISS-ATC2 PREVIOUS LEGS REPORT page will be displayed as follows:
The "PREVIOUS LEGS REPORT" gathers the 63 previous legs internal and external class 1 failures that occured during the 63 previous legs. The legs are displayed in reverse chronological order (oldest last) whereas within one leg the failures are reported in chronological order (oldest first for a same leg). The displayed messages are identical to the ones presented in the previous paragraph.
Select PREVIOUS LEGS REPORT by pressing line key 2L on the T/TISS-ATC2 menu page. The T/TISS-ATC2 PREVIOUS LEGS REPORT page will be displayed as follows:
NOTE: A memory capacity of at least 30 failures is required. If the system has been installed on several aircraft and faults have been detected, the display of the "previous legs report" is:
- new A/C ident on new page
- or new A/C ident on same page if there is enough space.
(c) LRU IDENTIFICATION
This item presents the Part Number (PN), Serial Number (SN) and Software Number (SW/N) of the component.
Select LRU IDENT by pressing line key 3L on the T/TISS-ATC2 menu page. The T/TISS-ATC2 LRU IDENT page will be displayed as follows:
This item presents the Part Number (PN), Serial Number (SN) and Software Number (SW/N) of the component.
Select LRU IDENT by pressing line key 3L on the T/TISS-ATC2 menu page. The T/TISS-ATC2 LRU IDENT page will be displayed as follows:
(d) GROUND SCANNING
This function reports in real time, all failures detected by the system (T/TISS-ATC2 part) without a predetermined time frame. It reactivates the monitoring and fault analysis used during flight by reports in interactive mode instead of normal mode.
All failures detected while using this function are only shown on the MCDU and are not memorized in a non-volatile memory. In addition, this function enables intermittent failures to be detected.
The T/TISS-ATC2 peripherals monitoring and the T/TISS-ATC2 internal cyclic tests are used to detect transient anomalies
This function reports in real time, all failures detected by the system (T/TISS-ATC2 part) without a predetermined time frame. It reactivates the monitoring and fault analysis used during flight by reports in interactive mode instead of normal mode.
All failures detected while using this function are only shown on the MCDU and are not memorized in a non-volatile memory. In addition, this function enables intermittent failures to be detected.
The T/TISS-ATC2 peripherals monitoring and the T/TISS-ATC2 internal cyclic tests are used to detect transient anomalies
(e) TROUBLE SHOOTING DATA
This function analyzes the snapshot of the recorded failure to detect the software bugs.
Two types of data are displayed:
This function analyzes the snapshot of the recorded failure to detect the software bugs.
Two types of data are displayed:
- Some correlation parameters, which are the date and the UTC available in plain English.
- Some snapshot data delivered in hexadecimal code.
NOTE: Trouble Shooting Data can also be reached by pressing the line key corresponding to a failure message (e.g. ">1").
(f) CLASS 3 FAULTS
This report gathers the last leg class 3 failures (external or internal) detected in flight.
This report gathers the last leg class 3 failures (external or internal) detected in flight.
(g) GROUND REPORT
This item presents the class 1, 2 or 3 internal failures when they are detected on the ground.
This item presents the class 1, 2 or 3 internal failures when they are detected on the ground.
(h) DISCRETE CONFIGURATION
This item presents many information of program pins dedicated to the ATC system installation.
This item presents many information of program pins dedicated to the ATC system installation.
(i) TEST
The T/TISS-ATC2 functional test can be initiated on the ground only:
The T/TISS-ATC2 functional test can be initiated on the ground only:
- by pressing the line key adjacent to the TEST indication on the ATC maintenance submenu,
- on Power-On of the unit,
- by pressing the push-button switch on the face of the T/TISS computer.
This manual test can only be activated on the ground.
(3) Reporting functions
(a) Internal failures-summary
| -------------------------------------------------------------------------- |
| ! REPORTED INTERNAL FAILURES ! |
| !------------------------------------------------------------------------! |
| ! MESSAGE ! CLASS ! ATA ! |
| !---------------------------------------------!---------!----------------! |
| ! ATC2 (1000SG) ! 1 ! 34-52-33 ! |
| ! ATC/TCAS TOP ANTENNA (7SG1) ! 1 ! 34-43-11 ! |
| ! ATC/TCAS TOP ANTENNA (7SG1) COAXIAL J1 ! 1 ! 34-43-11 ! |
| ! ATC/TCAS TOP ANTENNA (7SG1) COAXIAL J2 ! 1 ! 34-43-11 ! |
| ! ATC/TCAS TOP ANTENNA (7SG1) COAXIAL J3 ! 1 ! 34-43-11 ! |
| ! ATC/TCAS TOP ANTENNA (7SG1) COAXIAL J4 ! 1 ! 34-43-11 ! |
| ! ATC/TCAS BOT ANTENNA (7SG2) ! 1 ! 34-43-11 ! |
| ! ATC/TCAS BOT ANTENNA (7SG2) COAXIAL J1 ! 1 ! 34-43-11 ! |
| ! ATC/TCAS BOT ANTENNA (7SG2) COAXIAL J2 ! 1 ! 34-43-11 ! |
| ! ATC/TCAS BOT ANTENNA (7SG2) COAXIAL J3 ! 1 ! 34-43-11 ! |
| ! ATC/TCAS BOT ANTENNA (7SG2) COAXIAL J4 ! 1 ! 34-43-11 ! |
| ! WRG : MODE S ADRESS/ATC2 (1000SG) ! 1 ! 34-52-33 ! |
| -------------------------------------------------------------------------- |
(b) External failures-summary
| -------------------------------------------------------------------------- |
| ! REPORTED EXTERNAL FAILURES ! |
| !------------------------------------------------------------------------! |
| ! MESSAGE ! CLASS ! ATA ! |
| !---------------------------------------------!---------!----------------! |
| ! ATC CTL PNL (3SH)/ATC2 (1000SG) ! 1 ! 34-52-12 ! |
| ! ADIRU 2/(1FP2)BUS IR/ATC2 (1000SG) ! 1 ! 34-12-34 ! |
| ! ADIRU 2/(1FP2)BUS ADR/ATC2 (1000SG) ! 1 ! 34-12-34 ! |
| ! ADIRU 2/(1FP2)BUS ADR/ATC2 (1000SG) ! 3 ! 34-12-34 ! |
| ! ADIRU 3/(1FP3)BUS ADR/ATC2 (1000SG) ! 1 ! 34-12-34 ! |
| ! ADIRU 3/(1FP3)BUS ADR/ATC2 (1000SG) ! 3 ! 34-12-34 ! |
| ! FCU(2CA)BUS 2B/ATC2(1000SG) ! 3 ! 22-81-12 ! |
| ! CFDIU(1TW)/ATC2(1000SG) ! 3 ! 31-32-34 ! |
| ! FMGC1(1CA1)BUS OWN C/ATC2(1000SG) ! 3 ! 22-83-34 ! |
| ! POWER SUPPLY INTERRUPT ! 1 ! 24-00-00 ! |
| ! GPS1(40RT1)/ATC2(1000SG) ! 3 ! 34-36-31 ! |
| ! GPS2(40RT2)/ATC2(1000SG) ! 3 ! 34-36-31 ! |
| ! GPS1+2(40RT1+2)/ATC2(1000SG) ! 1 ! 34-36-31 ! |
| ! WRG : PIN PROG/ATC2(1000SG) ! 1 ! 34-43-34 ! |
| -------------------------------------------------------------------------- |