VHF SYSTEM - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General
The Very High Frequency (VHF) system is used for all the short-range voice communications between:

Different aircraft in flight
The aircraft (in flight or on the ground) and the ground stations.

The VHF system operates within the frequency range defined by ARINC 716 (i.e. 118 to 136.992 MHz with a 8.33 KHz spacing between the channels).
The Very High Frequency (VHF) system is used for all short-range voice communications between:

Different aircraft in flight
Aircraft (in flight or on the ground) and ground stations.

The VHF system requires three VHF channels. Two of the channels are dedicated to voice communication while the third is used primarily for data communications and as a backup for voice communication.
The VHF system operates within the frequency range defined by ARINC 716 (i.e. 118 to 136.975 MHz with 8.33 KHz and 25 KHz spacing between the channels).
The aircraft is equipped with three identical VHF systems which are fully independent: VHF1, VHF2 and VHF3 (VHF3 is optional).
The VHF3 system is also used to transmit data link messages Aircraft Communication Addressing and Reporting System (ACARS) or Air Traffic Service Unit (ATSU)
The aircraft is equipped with three identical VHF systems which are fully independent: VHF1, VHF2 and VHF3.
The VHF3 system is also used to transmit data link messages (Air Traffic Service Unit (ATSU)).
The VHF system has data link functions which are defined by ARINC 750-3:

Mode A
Mode 2.

The VHF system has data link functions which are defined by ARINC 750-4:

Mode A
Mode 2.

A. Mode A:
Many aircraft that use data link communication have a VHF Data Link (VDL) mode A function. This function allows a 2400 bit/s rate throughput through an Amplitude-Minimum Shift Keying (AM-MSK) modulation.
Once the dialogue between the VHF Data Radio (VDR) transceiver and the ATSU is established (exchange protocol Williamsburg V1 initialized), the two systems can exchange data in mode A.
Many aircraft that use data link communication have a VHF Data Link (VDL) mode A function. This function allows a 2400 bit/s rate throughput through an Amplitude-Minimum Shift Keying modulation.
Once the dialogue between the VHF Data Radio (VDR) transceiver and the ATSU is established (exchange protocol Williamsburg V1 initialized), the two systems can exchange data in mode A.

B. Mode 2:
The VDL mode 2 function is used to reduce the channel saturation. With this function, the rate throughput is increased ten times through a D8-PSK modulation (31.5 kbit/s).

NOTE: The VDL mode 2 data link function includes these two ACARS subnetworks: AOA and ATN. The AOA subnetwork is used now and the Air Traffic Network (ATN) subnetwork will be used in the future.

Once the dialogue between the VDR transceiver and the ATSU is established (exchange protocol Williamsburg V3 initialized), the two systems can exchange data in mode 2.
The VDL mode 2 data link function is used to reduce the channel saturation. With this function, the rate throughput is increased 10 times through a D8-PSK modulation (31.5 kbit/s).

NOTE: The VDL mode 2 data link function includes these two Aircraft Communication Addressing and Reporting System (ACARS) sub-networks: Angle Of Attack (AOA) and Air Traffic Network (ATN). The AOA sub-network is used now and the ATN sub-network will be used in the future.

Once the dialogue between the VDR transceiver and the ATSU is established (exchange protocol Williamsburg V3 initialized), it becomes possible to exchange data between the VDL and the ground.

** ON A/C NOT FOR ALL

2. Component Location

VHF System - Component Location ** ON A/C NOT FOR ALL

VHF System - Component Location - A320 A/C ** ON A/C NOT FOR ALL

VHF System - Component Location ** ON A/C NOT FOR ALL

FIN	FUNCTIONAL DESIGNATION	PANEL	ZONE	ATA REF
** ON A/C NOT FOR ALL
1RC1	XCVR-VHF, 1	81VU	127	23-12-33
1RC2	XCVR-VHF, 2	82VU	128	23-12-33
1RC3	XCVR-VHF, 3	81VU	127	23-12-33
4RC1	ANTENNA-VHF, 1		220	23-12-11
4RC2	ANTENNA-VHF, 2		152	23-12-11
4RC3	ANTENNA-VHF, 3		250	23-12-11
3CA1	MCDU-1	11VU	210	22-82-12
3CA2	MCDU-2	11VU	210	22-82-12
1RG1	RMP-COM/NAV FREQ SEL, 1	11VU	210	23-13-13
1RG2	RMP-COM/NAV FREQ SEL, 2	11VU	210	23-13-13
** ON A/C NOT FOR ALL
1RG3	RMP-COM FREQ SEL, 3	20VU	210	23-13-13
** ON A/C NOT FOR ALL
3CA3	MCDU-3	101VU	211	22-82-12

** ON A/C NOT FOR ALL

3. System Description

VHF System - Block Diagram ** ON A/C NOT FOR ALL

Each VHF system is composed of:

A transceiver
A blade antenna.

The VHF system is associated with:

The Radio Management Panels (RMP)
These are centralized systems which enable the frequency display of the VHF system (Ref. 23-13).
The Audio Management Unit (AMU) for connections to the audio integrating and Selective Calling (SELCAL) systems (Ref. 23-51)
The Centralized Fault Display Interface Unit (CFDIU) by the Multipurpose Control & Display Unit (MCDU) which is a centralized maintenance system (Ref. 31-32)
The Landing Gear Control and Interface Unit (LGCIU) which indicates the aircraft status (flight or ground) (Ref. 32-31)
The System Data Acquisition Concentrator (SDAC) which collects transmission data from the VHF system (Ref. 31-54).

Each VHF system is composed of:

A transceiver
An antenna.

Each VHF system has an interface with the following systems and components:

Radio Management Panels (RMP)
Audio Management Unit (AMU)
Centralized Fault Display Interface Unit (CFDIU)
Landing Gear Control and Interface Unit (LGCIU)
System Data Acquisition Concentrators (SDAC)
ATSU.

A. Interface with the RMPs
The RMPs are centralized systems used for the selection of the frequency/channel and the display of the VHF system. They are also used to switch between the voice and data modes (Ref. 23-13).

B. Interface with the AMU
The AMU is used for the connection to the audio integrating and SELCAL systems through the Audio Control Panels (ACP) (Ref. 23-51).

C. Interface with the CFDIU
The CFDIU is a centralized maintenance system (Ref. 31-32). Through its interface with the CFDIU, the VHF3 transceiver sends fault reports to the ground.

D. Interface with the LGCIU
In case of CFDIU failure, the LGCIU gives the aircraft status (in flight or on the ground) to the VHF BITE (Ref. 32-31).

E. Interface with the SDACs
The SDACs receive the transmission information from the VHF system with the KEY EVENT output of the VHF transceiver and record the transmit mode.
When the SDACs sense that the VHF system transmits information (the PTT pushbutton switch is pushed) for 30 seconds:

The "COM VHF1(2)(3) EMITTING" ECAM amber message comes into view on the upper ECAM Display Unit (DU).
A "beep-beep" aural warning is heard each second for five seconds.

After 35 seconds, the transmission automatically stops.
After 25 seconds, if the PTT pushbutton switch stays pushed:

The "COM SINGLE PTT STUCK" ECAM amber message comes into view.
The "COM VHF1(2)(3)EMITTING" ECAM amber message goes out of view.

To start a new transmission, the operator must release the PTT pushbutton switch and push it again.

Data communications stop when the RMP or the MCDU changes from data mode to voice mode.

VHF System - Key Event Data ** ON A/C NOT FOR ALL

NOTE: The Flight Warning System (FWS) standard installed in the aircraft can cause change of the data communication behavior.

F. Interface with the ATSU
If the VHF3 transceiver is in data mode, the ATSU sends data to the VHF system for data communication. In voice mode, the VHF3 transceiver is monitored by the RMP (valid only if the ATSU is available).

** ON A/C NOT FOR ALL

4. Power Supply

VHF Systems - Power Supply ** ON A/C NOT FOR ALL

A. VHF1 System
The VHF1 system is supplied with 28VDC:

From 28VDC ESS BUS 4PP (sub-busbar 401PP)
Through circuit breaker 2RC1 located on overhead panel 49VU, in the cockpit.

In case of emergency, the VHF1 system operates through the DC emergency generation.

B. VHF2 System
The VHF2 system is supplied with 28VDC:

From 28VDC BUS 2 2PP (sub-busbar 204PP)
Through circuit breaker 2RC2 located on rear panel 121VU, in the cockpit.

C. VHF3 System
The VHF3 system is supplied with 28VDC:

From 28VDC BUS 1 1PP (sub-busbar 101PP)
Through circuit breaker 2RC3 located on rear panel 121VU in the cockpit.

** ON A/C NOT FOR ALL

5. Interface

A. Output Interface

(1) Digital outputs
The connection with the CFDIU is a type-1 system. This type of system has an ARINC 429 input from the CFDIU and an ARINC 429 output. This system is thus capable of a two-way communication with the CFDIU (Ref.31-32).
The radio communication equipment receives the frequency data through words from the RMPs. These words have a structure and a refresh rate defined in the ARINC 429 characteristics specification.
On the output bus, each VHF transceiver transmits labels 354, 356, 377, and only the VHF3 transceiver (if installed) transmits labels 270 and 172.

This table contains all the output parameters in the digital form.
They are sorted as per the numerical order of their output label.

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| PARAMETER LIST PARAMETER CHARACTERISTICS (NUMERIC) |

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

! 354 !LRU ! ! ! ! ! ! ! ! !

! !IDENT ! ! ! ! ! 250!ISO5! ! !

! ! ! ! ! ! ! ! ! ! !

! 377 !EQUIP ! ! ! ! ! ! ! ! !

! !IDENT ! ! ! ! !1000! BCD! ! !

! ! ! ! ! ! ! ! ! ! !

! 356 !FAULT ! ! ! ! ! ! ! ! !

! !MESSAGE ! ! ! ! ! 250!ISO5! ! !

! ! ! ! ! ! ! ! ! ! !

! 270 !STATUS ! ! ! ! !1000!BOO-! ! !

! ! ! ! ! ! ! !LEAN! ! !

! ! ! ! ! ! ! !WORD! ! !

! 172 !SAL MODE ! ! ! ! !1000! BNR! ! !

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The equipment code of the VHF transceiver is 016.
An ARINC 429 HS bus between the VHF3 (VDR3 if installed) transceiver and the ATSU is used to transmit user data and control data.

(2) Output discretes
These output discretes are the same for each VHF circuit.

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NAME ELECTRICAL LEVEL TO SIGNAL STATUS

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KEY EVENT GND/O.C. SDAC GND=EMISSION

(3) Output analog signals
These output analog signals are the same for each VHF circuit.

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NAME ELECTRICAL LEVEL TO SIGNAL STATUS

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AUDIO SIDETONE OUTPUT MODULATION AMU

SELCAL OUTPUT MODULATION AMU

(4) Digital outputs
The connection with the CFDIU is a type-1 system. This type of system has an ARINC 429 input from the CFDIU and an ARINC 429 output. This system is thus capable of two-way communication with the CFDIU (Ref. 31-32).
The radio communication equipment receives the frequency data through words from the RMPs. These words have a structure and a refresh rate defined in ARINC 429 characteristics specification.
On the output bus, each VHF transceiver transmits labels 354, 356, 377.

This table contains all the output parameters in the digital form.
They are sorted as per the numerical order of their output label.

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| PARAMETER LIST PARAMETER CHARACTERISTICS (NUMERIC) |

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

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

! 354 !LRU ! ! ! ! ! ! ! ! !

! !IDENT ! ! ! ! ! 250!ISO5! ! !

! ! ! ! ! ! ! ! ! ! !

! 377 !EQUIP ! ! ! ! ! ! ! ! !

! !IDENT ! ! ! ! !1000! BCD! ! !

! ! ! ! ! ! ! ! ! ! !

! 356 !FAULT ! ! ! ! ! ! ! ! !

! !MESSAGE ! ! ! ! ! 250!ISO5! ! !

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The equipment code of the VHF transceiver is 016.

(5) Output discretes
These output discretes are the same for each VHF circuit.

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NAME ELECTRICAL LEVEL TO SIGNAL STATUS

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KEY EVENT GND/O.C. SDAC GND=EMISSION

(6) Output analog signals
These output analog signals are the same for each VHF circuit.

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NAME ELECTRICAL LEVEL TO SIGNAL STATUS

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AUDIO SIDETONE OUTPUT MODULATION AMU

SELCAL OUTPUT MODULATION AMU

(7) Digital outputs
The connections with the CFDIU are of type-1 system. This type of system has an ARINC 429 input from the CFDIU and an ARINC 429 output. This system is thus capable of two-way communication with the CFDIU (Ref.31-32).
The radio-communication equipment receives the frequency data through words from the RMPs. These words have a structure and a refresh rate defined in ARINC 429 characteristics specification.
On the output bus, each VHF transceiver transmits the labels 354, 356, 377, and only the VHF3 transceiver (if installed) transmits the labels 270, 172 and 304.

This table contains all the output parameters in the digital form.
They are sorted as per the numerical order of their output label.

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

| PARAMETER LIST PARAMETER CHARACTERISTICS (NUMERIC) |

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

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

! 354 !LRU ! ! ! ! ! ! ! ! !

! !IDENT ! ! ! ! ! 250!ISO5! ! !

! ! ! ! ! ! ! ! ! ! !

! 377 !EQUIP ! ! ! ! ! ! ! ! !

! !IDENT ! ! ! ! !1000! BCD! ! !

! ! ! ! ! ! ! ! ! ! !

! 356 !FAULT ! ! ! ! ! ! ! ! !

! !MESSAGE ! ! ! ! ! 250!ISO5! ! !

! ! ! ! ! ! ! ! ! ! !

! 270 !STATUS ! ! ! ! !1000!BOO-! ! !

! ! ! ! ! ! ! !LEAN! ! !

! ! ! ! ! ! ! !WORD! ! !

! 172 !SAL MODE ! ! ! ! !1000! BNR! ! !

! ! ! ! ! ! ! ! ! ! !

! 304 !A/C IDENT ! ! ! ! !1000!ISO5! ! !

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

The equipment code of the VHF transceiver is 016.
An ARINC 429 HS bus between the VHF3 transceiver (if installed) and the ATSU is used to transmit user's data and control data.

(8) Output discretes
These output discretes are the same for each VDR circuit.

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NAME ELECTRICAL LEVEL TO SIGNAL STATUS

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KEY EVENT GND/O.C. SDAC GND=EMISSION

(9) Output analog signals
These output analog signals are the same for each VDR circuit.

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NAME ELECTRICAL LEVEL TO SIGNAL STATUS

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AUDIO SIDETONE OUTPUT MODULATION AMU

SELCAL OUTPUT MODULATION AMU

B. Input Interfaces

(1) Digital input
The VHF transceivers receive frequency data through words from the RMPs. These words have a structure and a refresh rate defined in ARINC 429 specification.
The equipment code of the VHF transceiver is 016. The ATSU transmits labels to the VHF3 transceiver (if installed) through an ARINC 429 HS bus.

This table contains all the input parameters in the digital form.
They are listed according to the input label number (ascending order).

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| PARAMETER LIST PARAMETER CHARACTERISTICS (NUMERIC) |

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

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! 030 !FREQ/ ! ! ! ! ! 150! BCD! ! !

! !CHANNEL ! ! ! ! ! ! ! ! !

! !TUNNING ! ! ! ! ! ! ! ! !

! ! ! ! ! ! ! ! ! ! !

! 047 !FREQ/ ! ! ! ! ! 150! BCD! ! !

! !CHANNEL ! ! ! ! ! ! ! ! !

! !TUNNING ! ! ! ! ! ! ! ! !

! ! ! ! ! ! ! ! ! ! !

! 125 !UTC ! ! ! ! !1000! BCD! ! !

! ! ! ! ! ! ! ! ! ! !

! 126 !FLIGHT ! ! ! ! !1000! BNR! ! !

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

! ! ! ! ! ! ! ! ! ! !

! 155 !AIRCRAFT ! ! ! ! !1000!DISC! ! !

! !CONFIG 1 ! ! ! ! ! !RETE! ! !

! ! ! ! ! ! ! ! ! ! !

! 156 !AIRCRAFT ! ! ! ! !1000!DISC! ! !

! !CONFIG 2 ! ! ! ! ! !RETE! ! !

! ! ! ! ! ! ! ! ! ! !

! 157 !AIRCRAFT ! ! ! ! !1000!DISC! ! !

! !CONFIG 3 ! ! ! ! ! !RETE! ! !

! ! ! ! ! ! ! ! ! ! !

! 227 !COMMAND ! ! ! ! ! 120!DISC! ! !

! ! ! ! ! ! ! !RETE! ! !

! ! ! ! ! ! ! ! ! ! !

! 233 !FLIGHT ! ! ! ! !5000!ISO5! ! !

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

! ! ! ! ! ! ! ! ! ! !

! 234 !FLIGHT ! ! ! ! !5000!ISO5! ! !

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

! ! ! ! ! ! ! ! ! ! !

! 235 !FLIGHT ! ! ! ! !5000!ISO5! ! !

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

! ! ! ! ! ! ! ! ! ! !

! 236 !FLIGHT ! ! ! ! !5000!ISO5! ! !

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

! ! ! ! ! ! ! ! ! ! !

! 237 !FLIGHT ! ! ! ! !5000!ISO5! ! !

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

! ! ! ! ! ! ! ! ! ! !

! 253 !SAL MODE ! ! ! ! !ASYN!ISO5! ! !

! ! ! ! ! ! !CHRO! ! ! !

! ! ! ! ! ! !NOUS! ! ! !

! ! ! ! ! ! ! ! ! ! !

! 260 !DATE ! ! ! ! !1000! BCD! ! !

! ! ! ! ! ! ! ! ! ! !

! 301 !A/C IDENT ! ! ! ! !4000!ISO5! ! !

! ! ! ! ! ! ! ! ! ! !

! 302 !A/C IDENT ! ! ! ! !4000!ISO5! ! !

! ! ! ! ! ! ! ! ! ! !

! 303 !A/C IDENT ! ! ! ! !4000!ISO5! ! !

! ! ! ! ! ! ! ! ! ! !

! 304 !A/C IDENT ! ! ! ! !4000!ISO5! ! !

! ! ! ! ! ! ! ! ! ! !

! 377 !EQUIP ! ! ! ! ! 480! BCD! ! !

! !IDENT ! ! ! ! ! ! ! ! !

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

(2) Input discretes
These input discretes are the same for each VDR circuit.

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NAME ELECTRICAL LEVEL FROM SIGNAL STATUS

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AMU PTT GROUND/OPEN

ATSU/RMP PORT SELECT GROUND/OPEN

LGCIU LGCIU GROUND/OPEN

ATSU VOICE/DATA GROUND/OPEN

(3) Input analog signals
These input analog signals are the same for each VDR circuit.

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NAME ELECTRICAL LEVEL FROM SIGNAL STATUS

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MIKE INPUT MODULATION AMU

** ON A/C NOT FOR ALL

6. Component Description

A. VHF Transceiver - Description FIN: 1-RC-1 FIN: 1-RC-2 FIN: 1-RC-3
The VHF (VHF Data Radio (VDR)) transceiver agrees with the ARINC 600 specifications.
The case size is 3MCU.

VHF Transceiver ** ON A/C NOT FOR ALL

(1) VHF transceiver face
The face features:

VHF Transceiver ** ON A/C NOT FOR ALL

two jacks (PHONE and MIC)
a self-test pushbutton
a LCD screen to display messages in simple language in one of four modes (normal operation, BITE display, maintenance, S/W loading).
two pushbutton switches.
a handle

(2) VHF transceiver face
The face features:

VHF Transceiver ** ON A/C NOT FOR ALL

Two jacks (PHONE and MIC)
A TEST pushbutton switch
A red/green warning light: LRU STATUS
A red indicator light: CONTROL FAIL
A red warning light: ANTENNA FAIL
A handle
An identification plate.

(3) VHF (VDR) transceiver face
The face features:

VHF Transceiver ** ON A/C NOT FOR ALL

A manual TEST pushbutton switch
An RS 232 connector
A VDR STATUS LED
A CTRL FAULT LED
An ANT FAULT LED.

The VDR STATUS LED comes on 'yellow' while the VHF (VDR) transceiver is performing the self-test, either on power-up or when the operator initiated it.
After completion of the self-test, the VDR STATUS LED comes on as follows:

'Green' if no internal faults are present or
'Red' if a fault is present.

After the completion of the self-test, the frequency CTRL FAULT LED or ANT FAULT LED comes on 'yellow' if the selected frequency control input is missing or an antenna fault is present.

(4) VHF transceiver back
The back comprises three connectors to enable connection with:

The automatic test circuits (Top Plug (TP))
The peripheral systems (Middle Plug (MP))
The antenna and the power supply circuits (Bottom Plug (BP)).

(5) VHF transceiver back
The back comprises three connectors to enable connection with:

The vendor specific test equipment (Top Plug (TP))
The peripheral systems (Middle Plug (MP))
The antenna and the power supply circuits (Bottom Plug (BP)).

(6) VHF transceiver back
The back comprises three connectors to enable the connection with:

The automatic test circuits (Top Plug (TP))
The peripheral systems (Middle Plug (MP))
The antenna and the power supply circuits (Bottom Plug (BP)).

(7) VHF (VDR) transceiver back

VDR Transceiver Rear Connector 2/2 ** ON A/C NOT FOR ALL

The VHF (VDR) transceiver back includes:

The Top Plug (TP) for connection to the automatic test circuits
The Middle Plug (MP) for connection to the antenna and peripheral systems
The Bottom Plug (BP) for connection to the power supply circuits.

B. VHF (VDR) Transceiver - Characteristics
The VHF transceiver complies with the standards defined in ARINC 716.
The transmission and reception of coded messages between the various control units (CFDIU, RMP) comply with ARINC 429.
The transceiver operates at a frequency range between 118.000 and 136.975 MHz with a 8,33 KHz spacing between the channels (it can use 2.278 channels).
The VHF (VDR) transceiver complies with the standards defined in ARINC 716.
The transmission and reception of coded messages between the various control units (CFDIU, RMP) comply with ARINC 429.
The transceiver operates within the frequency range between 118.000 and 136.975 MHz with 8,33 KHz and 25KHz spacing between the channels (it has a possibility of 2278 and 760 channels respectively).

C. VHF (VDR) Transceiver - Operation

(1) General operation
The VHF transceiver ensures its primary functions through:

RF module
Main processor module
Power supply module
HIRF/Rear interconnect
Front panel display assembly
Memory card interface module.

(2) General operation
The VHF transceiver ensures its primary functions through:

The receiver
The transmitter
The synthesizer
The FM immunity filter, which is a high-pass filter with a stop band attenuation at 108 MHz greater than 10 dB. This filter prevents interference with the high-power FM broadcast-stations.

The antenna switch and final filter assembly:

Route the input signal from the antenna to the receiver in receive mode
Connect the transmitter RF output to the antenna in transmit mode.

Self-test:
The purpose of this test is to test the front panel LEDs and the functioning of the radio. The color of the LEDs in the fourth phase indicates the result of theself-test. The duration of the LED illumination is for reference only.

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! PHASE ! LRU STATUS ! CONTROL FAIL ! ANTENNA FAIL ! DURATION !

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! 1 ! RED ! RED ! RED ! 1-3 sec !

! 2 ! GREEN ! RED ! RED ! 1-3 sec !

! 3 ! OFF ! OFF ! OFF ! 1-3 sec !

! 4 ! GREEN ! OFF ! OFF ! 20-40 sec !

(3) Power supply
The power supply provides four voltages to the transceiver: +12 Vdc, -12 Vdc, +35 Vdc and 5 Vdc. The power supply will be shut down by over/undervoltage circuits when the input voltage is not within limits. The power supply monitors a power supply over/under voltage output to the system processor. Energy-storage circuits provide operation during input power interrups of 200 msec or less.

(4) Frequency synthesizer
A dual loop digital synthesizer is used. The first loop operates at 50 kHz spacing. This output is divided by a fixed divide of 128 digital divider to produce a variable reference in the 3.6 to 5 mHz band. The output loop Voltage Controlled Oscillator (VCO) operates directly at the required VHF frequency, 118 to 158 mHz. This VCO output is divided by a fixed divide of 32 digital divider to the variable reference frequency range of 3.6 to 5 mHz. This signal is then compared in a phase detector with the variable frequency from the reference loop. Any phase or frequency error is corrected by the negative feedback of the loop.
Two VCOs are used: one to operate at the output range of 118 to 158 mHz and one to operate at the reference range of 472 to 632 mHz. A tuning voltage of approximately 5 to 10 Vdc is used to cover the tuning range of each VCO. A common-emitter RF amplifier amplifies the output loop VCO to the +20-dBm level where it is routed via a pin diode switch to either the transmitter or the receiver RF assembly.
A separate BITE is used during self-test and alignment modes to monitor the transmit signal with the receiver. The BITE synthesizer is a single loop indirect phase-locked loop providing mixer injection in 25 kHz frequency steps. A single phase-locked loop combining dual modulus prescaler and programmable divider provides the phase-locked loop function. The BITE synthesizer is powered off when not in use to eliminate any possibility of spurious outputs feeding to the output of the main synthesizer. When in the self-test or alignment mode, a command from the system processor connects the self-test synthesizer to the receiver mixer while the main synthesizer remains connected to the transmitter.

(5) Audio processing

VHF Transceiver - Block Diagram of the Audio Processing ** ON A/C NOT FOR ALL

The microphone input-circuit provides excitation and couples voice modulation to the compressor circuits. The compressor circuits level the range of input signal amplitudes to maintain a high level of modulation without overmodulating. The compressed signal is amplified and applied to the modulator located on the transmitter assembly. Data inputs are similarly processed and applied to the modulator.
In addition to the transmitted audio or the data control, final receiver audio amplification and filtering are performed on this circuit board. Service adjustments are provided for data and voice audio output levels in accordance with the ARINC requirements.

D. VHF (VDR) Transceiver - Test

The purpose of this test is to test the front panel LEDs and to test the functioning of the radio. The color of the LEDs in the fourth phase indicate the result of the self-test. The duration of the LED illumination is for reference only.

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! PHASE ! LRU STATUS ! CONTROL FAIL ! ANTENNA FAIL ! DURATION !

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! 1 ! RED ! RED ! RED ! 1-3 sec !

! 2 ! GREEN ! RED ! RED ! 1-3 sec !

! 3 ! OFF ! OFF ! OFF ! 1-3 sec !

! 4 ! GREEN ! OFF ! OFF ! 20-40 sec !

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E. VHF Antenna

(1) Description

VHF Antenna ** ON A/C NOT FOR ALL

The VHF antenna is a white blade antenna. It weighs 1,2 kg.
This antenna is composed of:

An aluminum base plate
A laminated radome
A duralinox leading edge
A C-type coaxial connector surrounded by a seal.

The antenna is connected to the transceiver with a coaxial cable. It is screwed on to the fuselage. The attachment screws ensure the electrical bonding.

(2) Operation
The VHF antenna, the height of which corresponds to a quarter of the wavelength, provides a quasi-omnidirectional radiation.
This antenna allows the transmission and reception of VHF signals over the 116 to 156 MHz frequency range. Its impedance is 50 ohms and its standing-wave ratio is lower than 2 over the 118 to 137 MHz VHF frequency range.

** ON A/C NOT FOR ALL

7. Operation

A. Receive Function
The antenna picks up the VHF radio-communication signals from the stations. These signals are transmitted to the transceiver by a coaxial cable.
The transceiver, tuned on the frequency selected on one RMP (Ref. 23-13) demodulates the VHF received signals into AF signals.
The AF signals are transmitted via the AMU to the audio equipment or SELCAL system.
The antenna picks up the VHF radio-communication signals from the stations. These signals are transmitted to the transceiver with a coaxial cable.
In voice mode, the transceiver, tuned to the frequency selected on one RMP (Ref. 23-13), demodulates the VHF received signals into Audio Frequency (AF) signals.
The AF signals are transmitted to the audio equipment or SELCAL system through the AMU.
In data mode, the transceiver (tuned to the frequency selected on one MCDU, transmitted to the transceiver through an ARINC 429 HS bus,) demodulates the VHF3 received signals into digital information.
This information is transmitted to the ATSU through an ARINC 429 HS bus.

B. Transmit Function
The AF signals from the microphones are transmitted to the VHF transceiver through the AMU.
The VHF transceiver tuned on the frequency selected on one RMP transforms the AF signals into VHF modulated signals.
The VHF signals are fed to the antenna by a coaxial cable. They are then transmitted to the various stations.
A connection between the VHF transceiver and the SDAC enables to record the use of the VHF system in transmit mode. The connection is obtained through the PTT switch.
In voice mode, the AF signals from the microphones are transmitted to the VHF transceiver through the AMU.
The VHF transceiver, tuned to the frequency selected on one RMP, modulates the AF signals into VHF signals. These VHF signals are sent to the antenna with a coaxial cable. They are then transmitted to the various stations.
The VHF system sends the transmission information to the SDACs through the KEY EVENT output of the VHF transceiver. The SDACs record the transmit mode.
In data mode, the digital information is transmitted from the ATSU to the VHF3 transceiver (tuned to the frequency selected on one MCDU and transmitted to the transceiver through an ARINC 429 HS bus), which modulates it.
The VHF signals are sent to the antenna with a coaxial cable. They are then transmitted to the various stations.

C. VHF Voice/Data Mode Selection
The system has a direct control over the VHF3 switching between voice and data modes.
A voice/data switching can be requested by:

Any RMP
The MCDU through the Air Traffic and Information Management System (ATIMS) (Ref. 46-21).

D. VDR Voice/Data Mode Selection
The system has direct control of VDR3 switching between voice and data mode.
A switching to voice/data request can be issued from:

any RMPs
the Multipurpose Control and Display Unit (MCDU) through the Air Traffic and Information Management System (ATIMS) (Ref. 46-21).

E. VDL Ground Network
The VDL mode A and mode 2 functions provide a short-range Air/Ground VHF digital communication link (operated mainly by ARINC or SITA and by other secondary ground service providers) for the transmission of digital data. The VDL mode 2 function is available on aircraft in parallel with the VDL mode A function. Switching between the two modes (mode A, mode 2) is automatic without any action from the navigation crew (depending on the capacity of the selected provider and the ATSU configuration).

NOTE: The functions (mode A, mode 2) cannot be used simultaneously.

** ON A/C NOT FOR ALL

8. Test

VHF System - BITE Monitoring ** ON A/C NOT FOR ALL

A. Built-In-Test Equipment (BITE)
The BITE facilitates the maintenance on in-service aircraft.
The BITE detects and determines a failure related to the VHF system.
The BITE of the VHF transceiver is connected to the CFDIU (refer to ATA 31-32).
The BITE:

Transmits permanently the VHF system status and an identification message to the CFDIU
Memorizes the failures that occurred during the last 63 flight legs
Monitors data input from the various peripherals (RMP, CFDIU and ATSU)
Transmits to the CFDIU the result of the tests performed and the result of the self-tests
Can communicate with the CFDIU through menus.

The BITE facilitates maintenance on in-service aircraft.
The BITE detects and determines a failure related to the VHF system.
The BITE of the VHF (VDR) transceiver is connected to the Centralized Fault Display Interface Unit (CFDIU). Refer to ATA 31-32.
The BITE:

Transmits permanently VHF system status and an identification message to the CFDIU
Memorizes the failures occurred during the last 63 flight legs
Monitors data input from the various peripherals (RMP, CFDIU and ATSU for VHF3 transceiver only)
Transmits to the CFDIU the result of the tests performed and self-tests
Can communicate with the CFDIU by the menus in interactive mode.

B. General Operation
The BITE has two operation modes:

The normal mode
The menu mode.

The BITE has two operation modes:

The normal mode
The interactive mode.

(1) Normal mode
In normal mode, the BITE monitors cyclically the temporary status of the VHF system. It transmits these information signals to the CFDIU during the flight.
In case of fault detection, the BITE stores the information signals in the fault memories.
These information signals are transmitted to the CFDIU every 250 ms (maximum) through an ARINC 429 message with label 356.

(2) Menu mode
The menu mode can only be activated on the ground.
This mode enables communication between the CFDIU and the VHF transceiver BITE, through the MCDU (maintenance menu).
In menu mode, the VHF menu gives access to these pages:

LAST LEG REPORT
PREVIOUS LEGS REPORT
LRU IDENTIFICATION
GND SCANNING
TROUBLE SHOOT DATA
CLASS 3 FAULTS
TEST
GROUND REPORT.

(3) Normal mode
During the normal mode, the BITE monitors cyclically the instantaneous status of the VHF system. It transmits these information signals to the CFDIU during the flight concerned.
In case of fault detection, the BITE stores the information signals in the fault memories.
These information signals are transmitted to the CFDIU every 250 ms by an ARINC 429 message with label 356.

(4) Interactive mode
The interactive mode can only be activated on the ground.
This mode enables communication between the CFDIU and the VHF (VDR) transceiver BITE. This is by means of the MCDU of the maintenance system.
In interactive mode, the VHF menu gives access to these pages:

LAST LEG REPORT
PREVIOUS LEGS REPORT
LRU IDENTIFICATION
GROUND SCANNING
TROUBLE SHOOTING DATA
CLASS 3 FAULTS
TEST
GROUND REPORT
SPECIFIC DATA.

C. Functional Description

(1) LAST LEG REPORT

VHF System - LAST LEG REPORT ** ON A/C NOT FOR ALL

This report contains the Class 1 and 2 internal and external faults recorded during the last flight.

(2) PREVIOUS LEGS REPORT

VHF System - PREVIOUS LEGS REPORT ** ON A/C NOT FOR ALL

The messages shown on this report are identical to those given in the paragraph above but they are related to the faults that occurred during the last 63 flights.

(3) LRU IDENTIFICATION

VHF System - LRU IDENT ** ON A/C NOT FOR ALL

This report displays the Part Number (P/N) and the Serial Number (S/N).

(4) GROUND SCANNING

VHF System - GND SCANNING ** ON A/C NOT FOR ALL

This function is used to monitor and detect anomalies on the ground.

(5) TROUBLE SHOOT DATA

VHF System - TROUBLE SHOOT DATA ** ON A/C NOT FOR ALL

This function is used to analyze the snapshot of the recorded fault to detect any software bug. Two types of data are displayed on the MCDU:

The correlation parameters, which are the date and the Universal Time Coordinated (UTC).
The snapshot data.

(6) CLASS 3 FAULTS

VHF System - CLASS 3 FAULTS ** ON A/C NOT FOR ALL

This report contains the Class 3 internal and external faults recorded during the last flight.

(7) TEST

VHF System - TEST ** ON A/C NOT FOR ALL

A VHF built-in functional test can be initiated by pushing, on the MCDU, the line key adjacent to the TEST indication on the VHF maintenance sub-menu. The test sequence is shown on the figure.

(8) GROUND REPORT

VHF System - GROUND REPORT ** ON A/C NOT FOR ALL

This function is used to display Class 1, 2 or 3 internal faults when they are detected on the ground. These faults differ from the faults displayed in the LAST LEG REPORT and CLASS 3 FAULTS. The figure shows examples of the internal faults recorded on the ground by the VHF system.
The BITE system is used through one of the two MCDUs 3CA1 and 3CA2 (Ref. ATA 22-82-00).

(9) LAST LEG REPORT

VHF System - LAST LEG REPORT ** ON A/C NOT FOR ALL

This report contains the Class 1 and 2 internal and external faults recorded during the last flight.

(10) PREVIOUS LEGS REPORT

VHF System - PREVIOUS LEGS REPORT ** ON A/C NOT FOR ALL

The messages shown on this report are identical to those given in the paragraph above but they are related to the faults that occurred during the last 63 flights.

(11) LRU IDENTIFICATION

VHF System - LRU IDENTIFICATION ** ON A/C NOT FOR ALL

This report displays the Part Number (P/N) and the Serial Number (S/N).

(12) GROUND SCANNING

VHF System - GROUND SCANNING ** ON A/C NOT FOR ALL

This function is used to monitor and detect anomalies on the ground.

(13) TROUBLE SHOOTING DATA

VHF System - TROUBLE SHOOTING DATA ** ON A/C NOT FOR ALL

This function is used to analyze the snapshot of the recorded fault to detect any software bug. Two types of data are displayed on the MCDU:

Correlation parameters, which are the date and the Universal Time Coordinated (UTC).
Snapshot data.

(14) CLASS 3 FAULTS

VHF System - CLASS 3 FAULTS ** ON A/C NOT FOR ALL

This report contains the Class 3 internal and external faults recorded during the last flight.

(15) TEST

VHF System - TEST ** ON A/C NOT FOR ALL

A VHF built-in functional test can be initiated by pushing, on the MCDU, the line key adjacent to the TEST indication on the VHF maintenance sub-menu. The test sequence is shown on the figure.

(16) GROUND REPORT

VHF System - GROUND REPORT ** ON A/C NOT FOR ALL

This function is used to display Class 1, 2 or 3 internal faults when they are detected on the ground. These faults differ from these faults displayed in the LAST LEG REPORT and CLASS 3 FAULTS. The figure shows examples of internal faults recorded on the ground by the VHF system.
The BITE system is used through one of the two MCDUs 3CA1 and 3CA2 (Ref. ATA 22-82-00).

(17) SPECIFIC DATA

VHF System - SPECIFIC DATA ** ON A/C NOT FOR ALL

This function provides the information about the discrete status, the ARINC 429 status and the aircraft configuration.

[Rev.10 from 2021] 2026.04.02 07:08:48 UTC