W DOC AIRBUS | AMM A320F

AUDIO MANAGEMENT SYSTEM (AMS) - DESCRIPTION AND OPERATION

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1. General
A. The audio management system provides the means for using:
(1) All the radio communication and radio navigation facilities installed on the aircraft:
  • In transmission mode: it collects the microphone inputs of the various crew stations and directs them to the communication systems.
  • In reception mode : it collects the audio outputs of the communication systems and the navigation receivers and directs them to the various crew stations.
(2) The flight interphone system:
  • Telephone links between the various crew stations in the cockpit.
  • Telephone links between the cockpit and the ground crew from the external power receptacle.
(3) The SELCAL (Selective Calling) system:
  • Visual and aural indication of calls from ground stations equipped with a coding device used by the aircraft installation.
(4) Certain calls:
  • Visual and aural indication of the ground crew and the Cabin Attendants' calls.
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2. System Description
F Audio Management - Block Diagram ** ON A/C NOT FOR ALL
F Audio Management - Block Diagram ** ON A/C NOT FOR ALL
F Audio Management - Block Diagram ** ON A/C NOT FOR ALL
F Audio Management - Block Diagram ** ON A/C NOT FOR ALL
The system comprises:
  • 1 AMU
  • 2 hand microphone receptacles (CAPT and F/O)
  • 2 loud speaker potentiometers with incorporated switches
  • 2 radio PTT switches
  • 1 jack for the ground crew
  • 1 AUDIO SWITCHING selector switch
  • 1 SELCAL code panel.
  • 3 ACPs
  • 1 headset jack (Fourth Occupant)
  • 3 oxygen mask stowage boxes
  • 4 ACPs
  • 1 headset jack (Fourth Occupant)
  • 3 oxygen mask stowage boxes
  • 4 jack panels
  • 3 jack panels
NOTE: In addition, the system uses :
  • 2 loud speakers which are part of the central warning system (Flight Warning Computer, ATA 31-53-00, Circuit WW)
  • 3 oxygen mask microphones which are part of the oxygen system (OXYGEN-ATA 35-00-00, Circuit HM)
  • 4 oxygen mask microphones which are part of the oxygen system (OXYGEN-ATA 35-00-00, Circuit HM)
  • 2 relay boxes which are part of the DMC system (Display Management Computer-ATA 31-63-00, Circuit WT)
  • FLIGHT/GROUND information from the LGCIU (Landing Gear Control and Interface Unit - ATA 32-31-00, Circuit GA).
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3. Component Location
F Audio Management - Component Location (CAPT & F/O Stations) ** ON A/C NOT FOR ALL
F Audio Management - Component Location (CAPT & F/O Stations) ** ON A/C NOT FOR ALL
F Audio Management - Component Location (CAPT & F/O Stations). ** ON A/C NOT FOR ALL
F Audio Management - Component Location (CAPT & F/O Stations) ** ON A/C NOT FOR ALL
F Audio Management - Component Location (3rd Occupant Station) ** ON A/C NOT FOR ALL
F Audio Management - Component Location (3rd Occupant Station) ** ON A/C NOT FOR ALL
F Audio Management - Component Location (3rd Occupant Station) ** ON A/C NOT FOR ALL
F Audio Management - Component Location (4th Occupant Station) ** ON A/C NOT FOR ALL
F Audio Management - Component Location (Avionics Compartment) ** ON A/C NOT FOR ALL
FIN FUNCTIONAL
DESIGNATION		 PANEL ZONE ACCESS
DOOR		 ATA REF
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1RN AMU 81VU 127 23-51-34
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1RN AMU 824 127 23-51-34
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1RN AMU 87VU 127 23-51-34
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2RN1 ACP-CAPT 11VU 210 23-51-12
2RN2 ACP-F/O 11VU 210 23-51-12
2RN3 ACP-3RD OCCPNT 20VU 210 23-51-12
3RN SELCAL CODE PNL 127 23-51-13
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2RN5 ACP-4TH OCCPNT 20VU 210 23-51-12
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10RN1 STOWAGE BOX-OXY MASK, CAPT 101VU 211 35-12-41
10RN2 STOWAGE BOX-OXY MASK, F/O 700VU 212 35-12-41
10RN3 STOWAGE BOX-OXY MASK, 3RD OCCPNT 700VU 212 35-12-41
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10RN5 STOWAGE BOX-OXY MASK, 4TH OCCPNT 101VU 211 23-51-00
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5774HM STOWAGE BOX-OXY MASK, 4TH OCCPNT 211 35-12-41
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11RN SW-RAD PTT, CAPT 191VU 211 23-51-17
12RN SW-RAD PTT, F/O 180VU 212 23-51-17
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14RN JACK-FLT INTPH 108VU 120 23-51-00
15RN1 POT-LOUD SPEAKER, CAPT 301VU 211 23-51-00
15RN2 POT-LOUD SPEAKER, F/O 500VU 212 23-51-00
16RN SEL SW-AUDIO SWITCHING 48VU 210 23-51-00
17RN1 RCPT-BOOMSET, CAPT 61VU 211 23-51-00
17RN2 RCPT-BOOMSET, F/O 60VU 212 23-51-00
17RN3 RCPT-BOOMSET, 3RD OCCPNT 62VU 212 23-51-00
17RN4 RCPT-BOOMSET, AVNCS COMPT 63VU 128 23-51-00
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17RN5 RCPT-BOOMSET, 4TH OCCPNT 15VU 211 23-51-00
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18RN5 JACK-HEADSET, SUPPLEMENTARY 15VU 211 23-51-00
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18RN1 JACK-HEADSET, CAPT 61VU 211 23-51-00
18RN2 JACK-HEADSET, F/O 60VU 212 23-51-00
18RN3 JACK-HEADSET, 3RD OCCPNT 62VU 212 23-51-00
18RN4 JACK-HEADSET, AVNCS COMPT 63VU 128 23-51-00
19RN1 RCPT-HAND MIC, CAPT 17VU 211 23-51-00
19RN2 RCPT-HAND MIC, F/O 16VU 212 23-51-00
19RN3 RCPT-HAND MIC, 3RD OCCPNT 62VU 212 23-51-00
19RN4 RCPT-HAND MIC, AVNCS COMPT 63VU 128 23-51-00
7WW LOUD SPEAKER-CAPT 831 211 31-53-21
8WW LOUD SPEAKER-F/O 831 212 31-53-21
A. Audio Management System - Audio Management Unit (AMU)
The Audio Management Unit (AMU) 1RN is located in the avionics compartment in the aft electronics rack 80VU on shelf 81VU.
The Audio Management Unit (AMU) 1RN is located in the avionics compartment in the aft electronics rack 80VU on shelf 81VU.
B. Audio Management System - Audio Control Panels (ACP)
The three Audio Control Panels (ACP) are identified and located as follows:
  • 2RN1 - center pedestal 11VU, Captain side,
  • 2RN2 - center pedestal 11VU, First Officer side,
  • 2RN3 - overhead panel 20VU.
The four Audio Control Panels (ACP) are identified and located as follows:
  • 2RN1 - center pedestal 11VU, Captain side,
  • 2RN2 - center pedestal 11VU, First Officer side,
  • 2RN3 - overhead panel 20VU,
  • 2RN5 - overhead panel 20VU.
C. Audio Management System - Boomset Receptacle and Headset Jack
These receptacles and jacks panels are identified and located as follows:
  • 17RN1 (boomset receptacle) and 18RN1 (headset jack) on overhead panel 61VU, Captain side,
  • 17RN2 (boomset receptacle) and 18RN2 (headset jack) on overhead panel 60VU, First Officer side,
These receptacles and jack are identified and located as follows:
  • 17RN1 (boomset receptacle) and 18RN1 (headset jack) on overhead panel 61VU, Captain side,
  • 17RN2 (boomset receptacle) and 18RN2 (headset jack) on overhead panel 60VU, First Officer side,
  • 17RN3 (boomset receptacle), 18RN3 (headset jack) and 19RN3 (hand mic receptacle) on panel 62VU on the right rear wall in the cockpit.
  • 17RN3 (boomset jack), 18RN3 (RCVR jack) and 19RN3 (hand mic receptacle) on panel 62VU on the right rear wall in the cockpit.
  • The supplementary headset jack 18RN5 is located on the left rear console, panel 15VU.
  • 17RN5 (boomset receptacle) and 19RN5 (hand mic receptacle) on panel 15VU on the left rear console.
D. Audio Management System - Hand Mic
The two hand mic receptacles are identified and located as follows:
  • 19RN1 on left console, panel 17VU, Captain side,
  • 19RN2 on right console, panel 16VU, First Officer side.
E. Audio Management System - Loud Speaker Potentiometers
The two loud speaker potentiometers with incorporated switches are identified and located as follows:
  • 15RN1 on instrument panel, Captain side, panel 301VU,
  • 15RN2 on instrument panel, First Officer side, panel 500VU.
F. Audio Management System - Radio PTT Switches
The two radio PTT switches are identified and located as follows:
  • 11RN on side stick hand-grip, Captain side, 191VU
  • 12RN on side stick hand-grip, First Officer side, 180VU.
G. Audio Management System - Oxygen-mask Stowage-boxes
The three oxygen-mask stowage-boxes are identified and located as follows:
  • 10RN1 on left side console 101VU, Captain side,
  • 10RN2 on right side console 700VU, First Officer side,
  • 10RN3 on right side console 700VU beside the First Officer oxygen mask.
The three oxygen-mask stowage-boxes are identified and located as follows:
  • 10RN1 on left side console 101VU, Captain side,
  • 10RN2 on right side console 700VU, First Officer side,
  • 10RN3 on right side console 700VU beside the First Officer oxygen mask.
  • 10RN5 on left side console 101VU beside the Captain oxygen mask.
H. Audio Management System - Flight Interphone Jack
The flight interphone jack for the ground crew 14RN is located on the external power panel 108VU.
I. Audio Management System - AUDIO SWITCHING Selector Switch
The AUDIO SWITCHING selector switch 16RN is located on the overhead panel 48VU.
J. Audio Management System - SELCAL Code Panel
The SELCAL code panel 3RN is located in the avionics compartment, above the aft electronics rack 80VU.
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4. Power Supply
F Audio Management - Electrical Power Supply of System ** ON A/C NOT FOR ALL
F Audio Management - Electrical Power Supply of System ** ON A/C NOT FOR ALL
The system components are supplied with 28VDC from busbar 1PP and essential busbar 4PP via 2 sub-busbars 101PP and 401PP respectively.
A. Busbar 101PP
  • Supply of the 3rd Occupant ACP 2RN3 and its associated electronic circuit located in the AMU via 3A circuit breaker 6RN.
  • Supply of the calls card in the AMU via 3A circuit breaker 8RN.
  • Supply of the 3rd Occupant ACP 2RN3 via 3A circuit breaker 6RN.
  • Supply of the Avionics Compartment ACP 2RN4 and its associated electronic circuit (if installed) via 3A circuit breaker 7RN.
  • Supply of the 4th Occupant ACP 2RN5 and its associated electronic circuit (if installed) via 3A circuit breaker 20RN.
  • Circuit breaker 8RN is unused.
B. Busbar 401PP
  • Supply of the Captain ACP 2RN1 and its associated electronic circuit located in the AMU via 3A circuit breaker 4RN.
  • Supply of the first Officer ACP 2RN2 and its associated electronic circuit located in the AMU via 3A circuit breaker 5RN.
  • Supply of the Flight-Interphone Electronic Card located in the AMU via 3A circuit breaker 9RN.
  • Supply of the Captain ACP 2RN1, of the audio board A (capt + bay) and of the SELCAL board via 3A circuit breaker 4RN.
  • Supply of the first Officer ACP 2RN2, of the audio boardB (F/O - 3° occpnt) and of the BITE board via 3A circuit breaker 5RN.
  • Circuit breaker 9RN is unused.
Circuit breakers 4RN, 5RN and 9RN are located on the overhead panel 49VU.
Circuit breakers 6RN and 8RN are located on the rear wall, on panel 121VU.
Circuit breakers 4RN, 5RN and 9RN are located on the overhead panel 49VU.
Circuit breakers 6RN, 8RN and 20RN are located on the rear wall, on panel 121VU.
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5. Component Description
A. Audio Control Panel-Function FIN: 2-RN-1 FIN: 2-RN-2 FIN: 2-RN-3 FIN: 2-RN-5
The ACP supplies the means:
  • To use the various radio communication and radio navigation facilities installed on the aircraft for transmission and reception of the audio signals.
  • To display the various calls (SELCAL, ground crew call and calls from the Cabin Attendants).
The ACP serves only for control and indication.
B. Audio Control Panel-Mechanical description-Front face
F Audio Control Panel - Front Face ** ON A/C NOT FOR ALL
F Audio Control Panel - Front Face ** ON A/C NOT FOR ALL
The front face comprises:
  • 7 rectangular electronic pushbutton switches for selection of the transmission channels. They also display the SELCAL, ground crew and Cabin Attendant calls,
  • 1 rectangular electronic pushbutton switch separated from the other 7 pushbutton switches. This pushbutton switch selects the transmission channel for passenger address (PA) announcements
  • 15 round pushbutton switches with associated potentiometers for selection and adjustment of the audio level on the reception channels
  • 1 INT/RAD selector switch which selects the radio and flight interphone functions. It is a three-position switch : stable in INT and middle position, unstable in RAD position.
  • 1 rectangular VOICE pushbutton switch which connects a filter into the audio circuits of the VOR and ADF navigation systems.
  • 1 RESET rectangular electronic pushbutton switch which is used to cancel the lighted calls.
The ACP is connected to the AMU and to the various aircraft circuits by means of a round 19-pin connector.
C. Audio Control Panel- Functional description
F Audio Control Panel - Functional Description ** ON A/C NOT FOR ALL
F Audio Control Panel - Functional Description ** ON A/C NOT FOR ALL
D. Audio Control Panel- Functional description-Transmission channel selection
F Audio Control Panel - Functional Description ** ON A/C NOT FOR ALL
F Audio Control Panel - Functional Description ** ON A/C NOT FOR ALL
(B)
To connect the microphones and the PTT command to the selected transmitter, push one of the 8 rectangular transmission pushbutton switches (VHF1- VHF2- VHF3- HF1- HF2- INT- CAB- PA).
The three green bars on the transmission pushbutton switch, which indicate that selection has been accepted, come on.
An electronic device inhibits simultaneous selection of several transmitters and therefore several transmission pushbutton switches cannot be selected at the same time.
When a new transmission function is selected, the green bars of the selected pushbutton switch come on and the function is selected. At the same time, the previously selected pushbutton switch is disabled and its green bars go off.
If you push a pushbutton switch which is already selected, the function is disabled.
The green bars which indicate transmission go off and no transmission function is selected on the ACP.
The rectangular PA pushbutton switch is unstable, i.e. it must be held pressed during the complete transmission time. This avoids unwanted transmission on the PA circuit. This unstable operation can be inhibited by the AMU pin-program (Ref. Para. Operation - Pin Program).
E. Audio Control Panel-Functional description-Selection of reception
F Audio Control Panel - Functional Description ** ON A/C NOT FOR ALL
F Audio Control Panel - Functional Description ** ON A/C NOT FOR ALL
(B)
The round reception pushbutton switches serve to select and adjust the audio levels. The three round reception pushbutton switches associated with VHF3,HF and HF2 are not used.
They are of the push-push type: when you push a pushbutton switch (initial position), it moves in then fully out to a level above that of the unselected pushbutton switches. A white skirt on the reception pushbutton switch appears and the selected receiver is connected.
Rotate this pushbutton switch to adjust the reception level.
You can select several reception pushbutton switches simultaneously.
When you push the reception pushbutton switch again, it engages in its initial position: the receiver is disconnected.
F. Audio Control Panel-Functional description-Call indication
F Audio Control Panel - Functional Description ** ON A/C NOT FOR ALL
F Audio Control Panel - Functional Description ** ON A/C NOT FOR ALL
(C, D and E)
During a ground crew or Cabin Attendant or SELCAL call, a legend flashes amber under the green bars of the transmission pushbutton switch concerned.
This occurs whether the transmission pushbutton switch is selected or not:
  • CALL: VHF1-VHF2 pushbutton switches (SELCAL call)
  • MECH : INT pushbutton switch (ground crew call)
  • ATT : CAB pushbutton switch (Cabin Attendant call)
    To switch off the amber legends, push the RESET pushbutton switch.
NOTE: The MECH and ATT legends which flash amber go off automatically. This occurs after 60 seconds of operation if the call is not cancelled by the RESET pushbutton switch (This automatic function can be inhibited by the AMU pin-program (Ref. para. Operation - Pin Program).
G. Audio Control Panel-Functional description-VOICE selection
F Audio Control Panel - Functional Description ** ON A/C NOT FOR ALL
F Audio Control Panel - Functional Description ** ON A/C NOT FOR ALL
(F)
When you push the VOICE pushbutton switch, the ON legend comes on green. This indicates that a filter has been connected into the audio circuits of the ADF and the VOR navigation systems.
When you push this pushbutton switch again, the green ON legend goes off: the filter is no longer in service.
H. Audio Control Panel-Functional description-INT/RAD switch
This switch is used for the transmission function when the boomset or the oxygen mask is in service: it acts as the PTT switch for this equipment which unlike the hand microphone is not equipped with this type of control.
(1) Middle position
The radio transceiver receives no switchover information. It remains in reception function.
(2) RAD position
The radio transceiver receives (via the AMU) a switchover information.
It switches from reception to transmission function.
(3) INT position
This position enables direct use of the flight interphone.
There are two utilization procedures for the flight interphone.
  • Normal mode The user pushes the INT transmission pushbutton switch and uses it like an ordinary radio channel (he places and holds the INT/RAD switch in RAD position).
  • Direct mode If user has selected a radio channel (VHF1, VHF2 etc.), he can, if he so wishes, use the flight interphone. To do this he does not have to release the transmission pushbutton switch. He shall simply place the INT/RAD switch in INT position.
NOTE: When this switch is set to RAD, it performs the same function as the radio switches located on the side-stick hand-grips. If conflicting orders are given by the side-stick switch (RAD position), and the corresponding ACP switch (INT position), the radio function takes priority over the interphone function.
I. Audio Control Panel-Functional description-Lighting
The ACP comprises 2 lighting circuits:
  • The selection accepted (green) and the call (amber) indications can be adjusted by the DIM/BRIGHT circuit (6 V/4.5 VDC) (Ref. ATA 33-14-00-LP).
  • The integral lighting is adjusted by the pedestal integral lighting potentiometer (5 V-0 VAC) (Ref. ATA 33-13-00-LF).
The reception selection pushbutton switches are side-lit by the integral lighting lamps. They are therefore also controlled by the pedestal integral lighting potentiometer.
The ACP comprises 2 lighting circuits:
  • The selection accepted (green) and the call (amber) indications can be adjusted by the DIM/BRIGHT circuit (6 V/4.5 VDC) (Ref. ATA 33-14-00-LP).
  • The integral lighting is adjusted by the pedestal integral lighting potentiometer (5 V-0 VAC) (Ref. ATA 33-13-00-LF).
The reception selection pushbutton switches are side-lit by the integral lighting lamps. They are therefore also controlled by the overhead annunciator light switch.
(1) Operation
(a) General
F Audio Control Panel - Block Diagram ** ON A/C NOT FOR ALL
The ACP is essentially a telecontrol panel.
The internal electronic circuit is structured around a microprocessor. It constantly scans the status of the face controls and transforms them into logic data. It generates serial words from this logic data. These words telecontrol the associated audio card in the AMU after transmission of messages on an ARINC 429 bus line.
An ARINC 429 reception bus line enables the ACP to process the information from the AMU. These information are relevant to the different parameters to be displayed : detected calls, selected transmission channels, selection of the voice filter on. These parameters will be displayed once they have been taken into account by the AMU and acknowledged in return. The system is therefore looped.
(b) Operation
The data is managed and processed by a microcomputer.
There are five separate functions:
  • Reception volume control.
  • Reception selection.
  • Processing of the discrete commands:
    * Selection of transmission channel
    * VOICE filter on/off command
    * RAD/INT command
  • Parameter display management
  • ARINC 429 interfaces
1 Reception volume control
This is achieved by the potentiometers accessible on the front face. The position of each potentiometer is defined by an analog voltage on the slider. The potentiometers are supplied with a reference voltage.
An analog-digital converter makes the 8-bit words correspond to the slider voltages.
The slider voltages are read consecutively. Thus, the digital codes which correspond to the angular positions of the potentiometers are obtained.
2 Reception selection
The potentiometer must be pushes to select a channel. The information is transmitted in the form of a word. This information is taken into account consecutively when the reception volume controls are scanned.
3 Processing of discrete commands
The selection information of the RAD/INT command is constantly available on the switch. It can, therefore, be directly used by the microcomputer.
The transmission selection information (fugitive contacts) is memorized and is therefore available for use by the microcomputer.
The same applies to the VOICE filter control.
4 Parameter display management
The AMU return information is processed in order to make sure that the transmission is correct.
After this check, the display can be performed :
  • The green bars associated with the selected transmission channel comes on
  • The light associated with the VOICE filter comes on
  • The CALL legends go off
A word transmitted by the relevant AMU causes the call lights to come on.
5 ARINC 429 interfaces
The messages are transmitted in conformity with the ARINC 429 standard and at a low frequency (12 kHz).
6 Information exchange protocole between the ACP and the AMU
The ACP transmits 2 types of words :
1st type of word designated word "0" or "status request word" 2nd type of word designated "volume control word".
The AMU transmits a single type of word designated "status word"
  • Word "0"
    b b b b b
    32 31 29 28 11
    ---------------------------------------------------------------------------
    ! P ! ID.FIG. ! ER ER ER ER ER ER ER ER ER ER ER ER ER ER ER ER ER ER !
    ! ! ! 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 !
    ---------------------------------------------------------------------------


    b b b b
    10 9 8 1
    ---------------------------------------------------------------
    ! SDI ! LABEL 300 !
    ! ! !
    ---------------------------------------------------------------
    b1 to b8 : Label 300 : Byte which defines the type of data
    sent
    b9 to b10 : SDI : Bits at logic 0
    b11 to b28 : Error : Gives the result of a self-test and
    a failure diagnosis
    b29 to b31 : ACP identification bits
    b32 : Parity bit (odd).


  • Volume control word
    b b b b b b b b b b b b b b b b b b
    32 31 30 29 28 27 26 25 24 17 16 15 14 11 10 9 8 1
    -------------------------------------------------------------------------------
    ! ! ! ! ! ! ! ! ! ! ! ! ! !
    !--------------------!! ! ! ! ! ! ! !
    ! ! ! ! ! !R ! !!ON ! ! ! ! ! ! !
    ! !ER!ER!ER!ER!E !V !! ! D D D D D D D D !I !R ! E E E E !S DI ! See label !
    !P ! ! ! ! !S ! !! / ! 7 6 5 4 3 2 1 0!N !A ! 3 2 1 0! ! table !
    ! !21!20!19!18!E !O !! ! !T !D ! ! ! !
    ! ! ! ! ! !T ! !!OFF! ! ! ! ! ! !
    !--------------------!! ! ! ! ! ! ! !
    ! ! ! ! ! ! ! ! ! ! ! ! ! !
    -------------------------------------------------------------------------------
    b1 to b8 : Label : Byte which defines the type of
    transmitted data
    b9 to b10 : SDI : Station identification bits
    b11 to b14 : Status of the transmission keyboard as per the truth
    table below:

    ------------------------------------
    ! BIT ! 11 ! 12 ! 13 ! 14 !
    !----------!-----!-----!-----!-----!
    ! NONE ! 0 ! 0 ! 0 ! 0 !
    !----------!-----!-----!-----!-----!
    ! VHF1 ! 1 ! 0 ! 0 ! 0 !
    !----------!-----!-----!-----!-----!
    ! VHF2 ! 0 ! 1 ! 0 ! 0 !
    !----------!-----!-----!-----!-----!
    ! VHF3 ! 1 ! 1 ! 0 ! 0 !
    !----------!-----!-----!-----!-----!
    ! HF1 ! 0 ! 0 ! 1 ! 0 !
    !----------!-----!-----!-----!-----!
    ! HF2 ! 1 ! 0 ! 1 ! 0 !
    !----------!-----!-----!-----!-----!
    ! INT ! 0 ! 1 ! 1 ! 0 !
    !----------!-----!-----!-----!-----!
    ! CAB ! 1 ! 1 ! 1 ! 0 !
    !----------!-----!-----!-----!-----!
    ! PA ! 0 ! 0 ! 0 ! 1 !
    ------------------------------------
    b15 : Radio PTT switch (active at 1)
    b16 : Interphone PTT switch (active at 1)
    b17 to b24 : Byte which defines the volume control value of the
    channel defined by the label and the SDI.
    b25 : Bit which defines ON or OFF status of the reception
    channel (active at 1)
    b26 : Bit which sets VOICE filter into service (active at 1)
    b27 : Call reset (active at 1)
    b28 to b31 : Error : Bits which give a failure diagnosis
    b32 : Parity bit.

  • Status word
    The AMU transmits a single type of word designated : status word.
    Its structure is as follows :
    b b b b b b b b b b b b b b b
    32 31 30 29 25 24 17 16 15 14 11 10 9 8 1
    -------------------------------------------------------------------------------
    !P !0 !0 ! ! ! ! ! ! !
    ! ! ! ! A A A A A ! ! A A ! E E E E ! 0 0 ! Label 301 !
    ! ! ! ! 4 3 2 1 0! ! 6 5! 3 2 1 0! ! !
    ! ! ! ! ! ! ! ! ! !
    -------------------------------------------------------------------------------
    b1 to b8 : Label 301 : Byte which defines the type of data
    sent
    b9 to b10 : SDI : Set to 0
    b11 to b14 : Return of transmission keyboard status for check in ACP
    (the truth table is the same as the one used in the
    volume control word).
    b15 : Status of ground crew call (active at 1).
    b16 : Status of Cabin Attendant call (active at 1).
    b17 to b24 : Byte which sends the pin-program information to the
    ACPs.
    b17 VHF3
    b18 HF1
    b19 HF2
    b20 ADF2
    b21 MLS
    b22 Lock PA
    b23 Spare
    b24 Spare
    b25 to b29 : Status of the calls VHF1, VHF2, VHF3, HF1 and HF2
    (active at 1)
    b25 : VHF1
    b26 : VHF2
    b27 : VHF3
    b28 : HF1
    b29 : HF2
    b30 : Status of the filter (active at 1)
    b31 : Set to O
    b32 : Parity bit

  • Protocol for data exchange between the ACP and the AMU
    F Protocol for Data Exchange - Flow Diagram ** ON A/C NOT FOR ALL
    After transmission of a word, and in accordance with its label, the ACP receives the status word or collects data. The status word is delivered by the AMU. The collected data is the data present on the ACP face.
    After reception of a word, and in accordance with its label, the AMU transmits the status word or uses the data transmitted by the ACP.
  • Determination of the transmitted word
    The system transmits a word every 10 ms on the ARINC line. The following considerations give the type of word transmitted (VHF1, HF2, status request word, etc):
    In the basic transmission function a word is sent every 10 ms in the following order:
    Word 00: Status request word
    Word 01: VHF1 volume control word
    Word 02: VHF2 volume control word
    Word 03: VHF3 volume control word
    Word 04: HF1 volume control word
    Word 05: HF2 volume control word
    Word 06: INT volume control word
    Word 07: CAB volume control word
    Word 08: PA volume control word
    Word 09: VOR1 volume control word
    Word 10: VOR2 volume control word
    Word 11: MKR volume control word
    Word 12: ILS volume control word
    Word 13: spare volume control word
    Word 14: ADF1 volume control word
    Word 15: ADF2 volume control word
This cyclic transmission continues provided that no volume control modification or any other data modification appears.
As soon as a modification is detected at any data level, the system emits the concerned word every 10 ms until this data is fixed (end of modifications).
However, a complete basic cycle is emitted after 160 ms to up-date, if applicable, other data.
Moreover, the status request word will be emitted systematically every 160 ms irrespective of the data modifications in progress
  • AMU data reception
    During reception, the system reads the word delivered by the associated AMU on the ARINC reception line. This word arrives every 160 ms and gives the SELCAL call status, transmission channel return and pin-programming status.
    A set of checks is made each time a word is received:
    Counting of the number of received words:
    Check of the label
    Check of the SDI, Sign Status, Matrix
    Recalculation of the parity and verification.
  • Displays
    The system updates the parameter displays every 10 ms. The VOICE status is directly displayed. The status of the transmissions is displayed only after acknowledgement by the AMU.
  • Internal test
    This test checks the check-sum of the ROM.
    The RAM is checked at each energization.
    During operation, the microprocessor must cyclically check its peripherals.
  • Label table
    -------------------------------------------------------------------------------
    ! ! ! BINARY ! ! !
    ! ! OCTAL ! b b b b b b b b ! HEX ! SDI !
    ! ! ! 7 6 5 4 3 2 1 0 ! ! !
    -------------------------------------------------------------------------------
    ! Status request word ! 300 ! 0 0 0 0 0 0 1 1 ! 03 ! 00 !
    ! Status word from AMU ! 301 ! 1 0 0 0 0 0 1 1 ! 83 ! 00 !
    ! Volume control word VHF1 ! 210 ! 0 0 0 1 0 0 0 1 ! 11 ! 01 !
    ! Volume control word VHF2 ! 210 ! 0 0 0 1 0 0 0 1 ! 11 ! 10 !
    ! Volume control word VHF3 ! 210 ! 0 0 0 1 0 0 0 1 ! 11 ! 11 !
    ! Volume control word HF1 ! 211 ! 1 0 0 1 0 0 0 1 ! 91 ! 01 !
    ! Volume control word HF2 ! 211 ! 1 0 0 1 0 0 0 1 ! 91 ! 10 !
    ! Volume control word INT ! 215 ! 1 0 1 1 0 0 0 1 ! B1 ! 01 !
    ! Volume control word CAB ! 215 ! 1 0 1 1 0 0 0 1 ! B1 ! 10 !
    ! Volume control word PA ! 212 ! 0 1 0 1 0 0 0 1 ! 51 ! 11 !
    ! Volume control word VOR1 ! 213 ! 1 1 0 1 0 0 0 1 ! D1 ! 01 !
    ! Volume control word VOR2 ! 213 ! 1 1 0 1 0 0 0 1 ! D1 ! 10 !
    ! Volume control word MKR ! 213 ! 1 1 0 1 0 0 0 1 ! D1 ! 11 !
    ! Volume control word ILS ! 217 ! 1 1 1 1 0 0 0 1 ! F1 ! 00 !
    ! Volume control word spare! 220 ! 0 0 0 0 1 0 0 1 ! 09 ! 00 !
    ! Volume control word ADF1 ! 212 ! 0 1 0 1 0 0 0 1 ! 51 ! 01 !
    ! Volume control word ADF2 ! 212 ! 0 1 0 1 0 0 0 1 ! 51 ! 10 !
    -------------------------------------------------------------------------------

J. SELCAL Code Panel
(1) Purpose
The SELCAL code panel is used to program the SELCAL code assigned to the aircraft.
(2) Description
F SELCAL Code Panel - FRONT Face ** ON A/C NOT FOR ALL
This panel is a rectangular box in compliance with ARINC 714.
The front face features:
  • 4 knurled knobs for selection of a code made up of 4 letters from amongst the following:
    A - B - C - D - E - F - G - H - J - K - L - M- N - P - Q - R - S.
  • A plexiglass cover over the knurled knobs which protects the displayed code. The operator can read the code through the cover.
    The rear face is equipped with a round connector for connection to the aircraft electrical network.
(3) Operation
F SELCAL Code Panel - Operation of Knurled Knobs ** ON A/C NOT FOR ALL
F SELCAL Code Panel - Operating Diagram ** ON A/C NOT FOR ALL
In accordance with the BCD code, each of the knurled knobs opens the various circuits or connects the various circuits to the ground. This selects the different frequency filters assigned to the considered codes.
  • The Operating Diagram shows the control logic.
  • When this circuit is connected to the ground or supplied with a voltage of +3.5 V a logic 0 is obtained. This corresponds to circuit operation.
  • When the circuit is open or has a resistance greater than 50000 ohms a logic 1 is obtained. This corresponds to non operation of the circuit.
  • The letter-frequency assignment table gives the letter-frequency assignments.
Letter Frequency Assignment Table
-------------------------------------------------------------------------------
! DESIGNATION ! FREQUENCY ! BCD CODE !
-------------------------------------------------------------------------------
! ! ! 8 4 2 1 !
! A ! 312.6 ! 0 0 0 1 !
! B ! 346.7 ! 0 0 1 0 !
! C ! 384.6 ! 0 0 1 1 !
! D ! 426.6 ! 0 1 0 0 !
! E ! 473.2 ! 0 1 0 1 !
! F ! 524.8 ! 0 1 1 0 !
! G ! 582.1 ! 0 1 1 1 !
! H ! 645.7 ! 1 0 0 0 !
! J ! 716.1 ! 1 0 0 1 !
! K ! 794.3 ! 1 0 1 0 !
! L ! 881 ! 1 0 1 1 !
! M ! 977.2 ! 1 1 0 0 !
! P ! 1083.9 ! 1 1 0 1 !
! Q ! 1202.3 ! 1 1 1 0 !
! R ! 1333.5 ! 1 1 1 1 !
! S ! 1479.1 ! 0 0 0 0 !
-------------------------------------------------------------------------------
The SELCAL code panel does not require an electrical power supply.

K. Audio Management Unit
(1) Purpose
The Audio Management Unit (AMU) ensures the interface between the user (jack panel and ACP) and the various radio communication and radio navigation systems. The AMU ensures the following functions:
  • Transmission
  • Reception
  • SELCAL and display of ground crew and Cabin Attendant calls
  • Flight interphone
  • Emergency function for the Captain and First Officer stations
    It also serves to record communications and is equipped with a TEST circuit (BITE). This TEST circuit enables the AMU to be connected to the CFDIU.
(2) Mechanical description
F Audio Management Unit - External Unit ** ON A/C NOT FOR ALL
The AMU is in the form of a 4MCU size box in compliance with ARINC 600 Specifications.
** ON A/C NOT FOR ALL
6. Operation
F Audio Management Unit - Block Diagram ** ON A/C NOT FOR ALL
F Audio Management Unit - Block Diagram ** ON A/C NOT FOR ALL
The AMU comprises 3 independent channels associated with the 3 ACPs.
Each channel comprises :
  • Its reception function
  • Its transmission function
  • Its logic processing function
  • Its power supply.
The SELCAL, BITE and Flight Interphone sections are connected to the different channels.
The basic AMU comprises 4 channels: CAPT, F/O, 3rd OCCPNT and avionics bay station (requires activation of a dedicated pin-programming).
It can receive one additional channel for a 4th cockpit occupant.
A. Transmission Function - General
The transmission function:
  • Sets into service and supplies the various microphones used (boomset, hand microphone, oxygen mask microphone)
  • Selects the transmitter selected by the operator by means of the ACP
  • Ensures the emergency function (for transmission section)
  • Ensures the CAA recording function.
    There is an independent transmission channel for each user of the audio integrating system.
B. Transmission Function - Composition of Circuit
A transmission channel comprises :
  • The various microphone inputs with their power supplies
  • A unit gain amplifier
  • An output transformer
  • A transmitter selection system
  • A module for CAA recording
  • A switching system for emergency function
  • A switching system for use of hand microphone.
C. Transmission Function - Transmission with Boomset
F Audio Management Unit - Block Diagram of Transmitter Circuit ** ON A/C NOT FOR ALL
The analog signals of the boomset microphone are connected to the OdB gain amplifier, then sent to the output transformer.
At the transformer output, the switching module switches these signals to the transmitter selected by the ACP in accordance with information received from the logic processing function.
D. Transmission Function - Transmission with Various Microphones
F Audio Management Unit - Simplified Schematic of Transmission Circuit ** ON A/C NOT FOR ALL
For transmission, each crew member can use either a hand microphone, a boomset or an oxygen mask. The analog signals of these three microphones are adapted and filtered on the adaptation board of the AMU, which also receives the hand microphone PTT and oxygen mask control discretes.
The microphone selection is done by a dedicated circuit according to the following logic:
-----------------------------------------------------
! OXYGEN MASK CONTROL DISCRETE !
!---------------------------------------------------!
! 0 ! 1 !
---------------------!------------------------!--------------------------!
! ! 0 ! Boomset signal valid ! Boomset and oxygen mask !
! HANDMIKE ! ! ! signals valid !
! PTT !-------!---------------------------------------------------!
! ! 1 ! Handmike signal valid !
--------------------------------------------------------------------------

NOTE: Input 6 microphone is valid when PTT6 is activated.
Ground Mech microphone is valid when air/ground discrete is set to GND.
The selected microphone signal is then sent to an output transformer.
At the transformer output, this signal is switched to the transmitter selected by the operator on the ACP, in accordance with information received from the DSP.
This discrete information is consolidated with both hardware and software processings, to avoid permanent transmission.
E. Transmission Function - Transmission with Oxygen Mask Microphone
F Oxygen Mask Microphone - Circuit Block Diagram ** ON A/C NOT FOR ALL
In normal flight configuration, the oxygen mask microphone is not connected to the microphone circuit.
Operation is as follows in flight configuration with use of oxygen mask. This system sets a control switch contained in the stowage box of the oxygen mask to the ground. This activates the relay which sets the oxygen mask into service. The pressurization of the oxygen circuit when masks fall out automatically activates this control switch.
F. Transmission Function - Transmission with Hand Microphone
F Hand Microphone - Circuit Block Diagram ** ON A/C NOT FOR ALL
(1) The hand microphone can be used in two ways:
  • 1st case: Radio transmission
    The logic processing card associated with relay K1 delivers a command. This command supplies relay K1 (AND function between the PTT switch of the hand microphone and the selected radio transmission, except for INT). Relay K1 directly connects the hand microphone to the tranmission selection circuit. The station selected in transmission mode then supplies the hand microphone.
  • 2nd case: Flight Interphone transmission
    When INT transmission is selected, relay K1 is not supplied; the logic processing card associated with relay K2 delivers a command.
    This command supplies relay K2 (AND function between the PTT switch of the hand microphone and the INT transmission selection).
    Relay K2 connects the power supply of the boomset microphone to the hand microphone. This system applies the analog signals of the hand microphone to the OdB amplifier, then to the INT channel via the transmission line. This removes the microphone power supply from the interphone amplifier.
G. Transmission Function - Transmission on Passenger Address Channel
Transmissions can be made on the passenger address channels
in 2 ways:
(1) In normal configuration, use the handset installed aft of the center pedestal to make the PA announcements. This handset is part of the Cabin Intercommunication Data System (Ref. ATA 23-73-00, Circuit RH).
(2) In RADIO configuration, use the rectangular PA pushbutton switch located on each ACP to make the passenger address announcements. This pushbutton switch is unstable, i.e. hold it pushed to make the announcements: this avoids unwanted transmissions. The electronic processing of this channel is identical to that of the other transmission channels.
The operation of this pushbutton switch can be made identical to that of the other transmission channels (stable operation) : to achieve this, modify the AMU pin-program (Ref. Para. Operation - Pin Program).
H. Transmission Function - Muting Circuit
(1) Purpose
F Muting Circuit - Block Diagram ** ON A/C NOT FOR ALL
The feedback produced by the loud speaker-microphone acoustic coupling when the microphones are used (acoustic feedback) is eliminated by a muting circuit. To achieve this, the muting circuit reduces the gain and/or the frequency range of the loud speakers.
This attenuating circuit is controlled by the PTT switch of any of the radio communication microphones.
The attenuating circuit is an integral part of the loud speakers.
(2) Operation
F Direct Muting - Block Diagram ** ON A/C NOT FOR ALL
The logic processing channel receives PTT switch type information.
From this information it activates the muting module. A ground is sent to the loud speaker units which set the direct muting function into service.
I. Reception Function
(1) General
The reception circuit selects and adjusts the volume on the reception channels. The operator selects and adjusts these channels on the ACP.
Each user of the audio integrating system has a separate associated reception-channel.
It ensures the various supplementary functions of the circuit:
  • VOR/DME/ILS/MLS switching
  • VOICE/ON function
  • Emergency function (for reception section).
(2) General
The reception circuit selects and adjusts the volume on the reception channels. The operator selects and adjusts these channels on the ACP.
Each user of the audio integrating system has a separate associated reception-channel.
It ensures the various supplementary functions of the circuit:
  • VOR/DME/LS switching
  • VOICE/ON function
(3) Composition of the circuit
F Audio Circuit - Block Diagram ** ON A/C NOT FOR ALL
The audio circuit comprises:
  • An interface card common to all the audio cards
  • A volume control module assembly
  • A stop-band filter
  • An adder amplifier
  • An emergency switching circuit
  • An output transformer.
(4) Reception mode operation
The audio signals delivered by the various communication and navigation units are connected to the interface card.
This card ensures the adaptation and the connection of the receivers.
This card is a common point to the system and no active components are used (it is mainly comprised of resistors).
The input impedance of a channel is 600 ohms.
The maximum input level is 50 mW/600 ohms (The nominal value is 10 mW/600 ohms).
At the output of the interface card, the signals are applied to the volume control modules.
An analog switch is installed at the input of each volume control. This switch disconnects the audio inputs when :
  • their reception is not selected (information from ACP)
  • their reception level selected on the ACP is at minimum (this condition does not apply to VHF and HF communication channels. A minimum reception level is ensured on the channels even when the potentiometers on the ACP are set to minimum).
When the levels are adjusted in accordance with the information from the logic processing function, the analog signals are sent to an amplifier, then to an output transformer.
The audio signals are available on the secondary of the output transformer. Separate windings send these signals either to the boomset, the loud speaker or the CVR circuit.
Output signal characteristics: 50 mW/600 ohms (the nomimal value is 10 mW/600 ohms).
NOTE: A potentiometer outside the AMU is connected in series between the AMU and the loud speakers. It adjusts the loud speaker audio output level.
(5) Reception function
F Audio Management Unit - Simplified Schematic of Reception Circuit ** ON A/C NOT FOR ALL
The audio signals from the various communication and navigation units are first connected to analog/digital converters, and then to the DSP located on the audio boards.
Dedicated inputs exist on the DSP for filtered signal (ADF and VOR).
The DSP is also connected to a control module which provides information computed from the ACP (potentiometers position, Voice filter selection) and from the FCU (DME coupling to VOR or LS). After digital processing inside the DSP, the resultant signal is converted into analog and sent to the output transformer.
NOTE: A minimum VHF and HF reception level is ensured when the potentiometers on the ACP are set to minimum. The minimum reception level is deleted when the potentiometers are set to OFF.
Minimum reception level is -32 dB with reference to maximum level.
(6) VOR/DME/ILS/MLS switching
F VOR/DME/ILS/MLS Switching - Block Diagram ** ON A/C NOT FOR ALL
(a) Purpose
In normal configuration, the DME reception is coupled with the VOR reception.
However, in certain ILS or MLS approach conditions, the DME used must be aurally identified. The DME reception must therefore be coupled with the ILS or MLS reception.
(b) Operation
The ND (Navigation Display) mode selector switch or the ILS pushbutton switch is used for switching control (REF ATA 31 - DMC circuit (WT)).
Action on one of these commands sends a ground to the switching relays which connect the DME receptions to the ILS or MLS receptions.
(7) DME/VOR/LS switching
(a) Function
In normal configuration, the DME reception is coupled with the VOR reception.
However, in certain landing system approach conditions, the DME used must be aurally identified. The DME reception must therefore be coupled with the MMR reception.
(b) Operation
The LS pushbutton switch is used for switching control (Ref. ATA 31 - DMC circuit (WT)).
Action on this command sends a ground to the AMU which couples the DME receptions to the MMR receptions.
(8) VOICE/ON function
F Navigation Reception Mode - Block Diagram ** ON A/C NOT FOR ALL
(a) Reason
The VOR, ADF navigation ground stations transmit a morse code which is used to identify them. However, certain stations, in addition to their code, transmit recorded voice information. This information informs the crew of subjects such as : latest weather information, state or special information concerning terrains etc. (e.g.: ATIS station).
In order not to hinder the reception of this information, the VOICE/ON function greatly reduces the morse code reception. It is attenuated until it becomes practically inaudible while this information is being transmitted.
(b) Operation
The transmission modulation frequency for ground station codes is 1020 Hz.
However, certain onboard equipment receive a 1020 Hz frequency-modulated signal and at the same time transmit this signal at 1000 Hz to the audio system. The 1000 Hz signal is generated by their synthetizer (the aeronautical standards specify that the ADF ground stations must be modulated at a frequency of 1020 Hz plus or minor 50Hz).
Furthermore, the DME reception is coupled to the VOR reception (in normal operation). Thus the DME marker identification-code is transmitted with a frequency modulation of 1350 Hz. The filtering circuit of the navigation channels therefore comprises an attenuater filter for the reception bands of the ADF and VOR systems.
This filter attenuates the 1000, 1020 and 1350 Hz frequencies by more than 32 dB.
A compensation amplifier is provided to compensate for the insertion losses of this filter.
Action on the VOICE pushbutton switch located on each ACP switches the attenuation filter into or out of service.
(c) Released position: VOICE/ON legend off
The filter is not used, the operator simultaneously receives the marker identification and the voice transmission.
(d) Pressed in position: VOICE/ON legend on
A command from the CPU sets the filter into service. The 1000 - 1020 - 1350 Hz frequencies are greatly attenuated. Only the voice transmissions are audible.
NOTE: The audio outputs of the communication channel and the ILS, MLS, MKR navigation do not transit via the filtering module.
(9) VOICE/ON function
(a) Function
The VOR, ADF navigation ground stations transmit a morse code which is used to identify them. However, certain stations, in addition to their code, transmit recorded voice information. This information informs the crew of subjects such as: latest weather information, state or special information concerning terrains etc. (e.g.: ATIS station).
In order not to hinder the reception of this information, the VOICE/IDENT function greatly reduces the morse code reception. It is attenuated until it becomes practically inaudible while this information is being transmitted.
(b) Operation
The transmission modulation frequency for ground station codes is 1020 Hz.
However, certain onboard equipment (COLLINS ADF) receive a 1020 Hz frequency-modulated signal and at same time transmit this signal at 1000 Hz to the audio system. The 1000 Hz signal is generated by their synthesizer (the aeronautical standards specify that the ADF ground stations must be modulated at a frequency of 1020 Hz plus or minus 50 Hz).
Furthermore, the DME reception is coupled to the VOR reception (in normal operation). Thus the DME marker identification-code is transmitted with a frequency modulation of 1350 Hz. The filtering circuit of the navigation channels therefore comprises an attenuation filter for the reception bands of the ADF and VOR systems.
This digital filter attenuates the 1000 and 1020 Hz frequencies by more than 32 dB.
Action on the VOICE pushbutton switch located on each ACP has the following effects:
  • Released position, VOICE/ON off
    The filters are not used, the operator simultaneously receives the marker identification and the voice transmission.
  • Pressed in position, VOICE/ON on
    The DSP directly processes the filtered signals. The 1000 - 1020 Hz frequencies are greatly attenuated, the DME identified is cut off (1350 Hz). Only the voice transmissions are audible.
NOTE: The audio outputs of the communication channel and the MMR, MKR navigation do not transit via digital filters.
J. Emergency Function
F Microphone Switching - Block Diagram ** ON A/C NOT FOR ALL
F Audio Switching - Block Diagram ** ON A/C NOT FOR ALL
F Emergency Function - Microphone/Reception ** ON A/C NOT FOR ALL
(1) Purpose
The emergency function is used in case of loss of communications on the Captain or the First Officer channels. This function switches the Captain or First Officer communications to the 3rd Occupant station.
In this case, the Captain (or the First Officer) uses the ACP located on the overhead panel to make his microphone or audio selections.
(2) Operation
The AUDIO SWITCHING selector-switch 16RN located on the overhead panel is used to switch to emergency configuration.
Turning this switch, sends a ground to the Captain (or First Officer) and 3rd Occupant switching relays. The various microphone inputs, commands and audio outputs are connected to the microphone inputs, commands and audio outputs of the 3rd Occupant. This switchover is indicated on the upper ECAM display unit (REF ATA 31-54-SDAC).
NOTE: When the emergency function is activated, the various audio inputs and outputs at the 3rd Occupant station are no longer connected to their circuit. Therefore, the 3rd Occupant cannot use his audio integrating circuits.
(3) Purpose
The emergency function is used in case of loss of communications on the Captain or the First Officer channels. This function switches the Captain or First Officer communications to the 3rd Occupant station.
In this case, the Captain (or the First Officer) uses the ACP located on the overhead panel to make his microphone or audio selections.
The AUDIO SWITCHING selector-switch 16RN located on the overhead panel is used to switch to emergency configuration.
This switchover is indicated on the upper ECAM display unit (REF ATA 31-54-SDAC).
(4) Pilot emergency function
In case of a failure on the Audio Board A, the pilot's microphones and audio signals are switched through relays in parallel to the 3rd occupant's microphone inputs and audio outputs.
The PTT commands from the pilot's microphones are active.
The pilot's ACP is no longer active.
(5) Copilot In case of a failure on the Audio Board B, the copilot's microphones and audio signals are switched through relays to the Avionics Bay microphone inputs and audio outputs, which are no longer active.
The PTT commands from the copilot's microphones are active.
The copilot's ACP is no longer active.
In addition, the 3rd occupant's micro and audio signals are switched in parallelto the Avionics Bay micro and audio signals, and the 3rd ACP ARINC bus is switched to the AVIONICS bAY acp arinc input/output.
The Avionics Bay ACP ARINC line is cut.
K. FAA/CAA Recording Function
F CAA Certification - Block Diagram ** ON A/C NOT FOR ALL
F Communications - CVR Circuit ** ON A/C NOT FOR ALL
(1) Reason
The Aeronautics Authorities for Federal Navigation request that the communications made onboard the aircraft are recorded on the CVR system (Cockpit Voice Recorder - REF ATA 23-71-RK).
To meet this requirement, the CVR is equipped with 4 recording tracks:
  • 3 tracks for recording the Captain, First Officer, 3rd Occupant communications
  • The 4th track is assigned to an area microphone installed in the cockpit. This microphone picks up the various noises made in the cockpit.
The Captain, First Officer and 3rd Occupant communications are recorded in accordance with the requirements laid down by the FAA (Federal Aviation Authority) and the CAA (Civil Aviation Authorities).
(2) CAA recording
F CAA Certification - Block Diagram ** ON A/C NOT FOR ALL
All the communications heard by the Captain (or the First Officer or the 3rd Occupant) are recorded. This enables, at the same time, to record all the communications sent out by these crew members.
This is achieved by means of the side-tone controls on the various equipment.
Three windings equip the secondary of the output transformer of the reception channel: 2 are allocated to the loud speaker and boomset outputs. The third is reserved for recording the communications heard in the cockpit (CVR). The CAA recording principle requires that the noises picked up by the boomset microphones be recorded even when these microphones are not active i.e. when the push-to-talk switches on the side-sticks or on the ACPs are not activated. This in order to reinforce the sounds picked-up by the area microphone.
A shunt is installed on the pin-programming terminal of the AMU to activate the CAA recording (Ref. Para. Operation - Pin Program).
(3) FAA recording
F FAA Certification - Block Diagram ** ON A/C NOT FOR ALL
All the communications heard by the Captain (or the First Officer or the 3rd Occupant) are recorded. This enables, at the same time, to record all the communications sent out by these crew members.
This is achieved by means of the side-tone controls on the various equipment.
Three windings equip the secondary of the output transformer of the reception channel: 2 are allocated to the loud speaker and boomset outputs. The third is reserved for recording the communications heard in the cockpit (CVR).
(4) FAA recording
All the communications heard by the Captain (or the First Officer or the 3rd Occupant) are recorded. This enables, at the same time, to record all the communications sent out by these crew members.
This is achieved by means of the side-tone controls on the various equipment.
The A/C is basically designed in accordance with this specification.
(5) CAA recording
The principle of CAA recording requires (in addition to the FAA recording principle) that the noises picked up by the boomset microphones be recorded even when these microphones are not active i.e. when the push-to-talk switches on the side-sticks or on the ACPs are not activated. This in order to reinforce the sounds picked-up by the area microphone. This configuration is named "hot-mike".
A shunt is installed on the pin-programming terminal of the AMU to activate the CAA recording (Ref. Para. Operation - Pin Program).
(6) DFDR/CVR Synchronization
The two recorders (CVR and DFDR) are synchronized:
  • The DFDR receives the GMT signal from the FDIU,
  • Also, the CVR receives the GMT signal from the FDIU. This signal is sent to the CVR via the AMU where it is mixed with the 3rd occupant audio signals.
(7) Operation
F CAA Certification - Block Diagram ** ON A/C NOT FOR ALL
Following the AMU pin-program modification, the SELCAL-CALL card generates an information message. This message is sent to the different audio cards and therefore to the various channels of the logic processing function.
This information is taken into account, then the logic processing channel sets the CAA certification module into service. The LF signals are picked-up by the boomset or oxygen mask microphone (when in use) at the output of the 0db gain amplifier. They are sent to the CAA Certification Module and, from there, to the CVR output.
L. Flight Interphone Function
F Flight Interphone - Block Diagram ** ON A/C NOT FOR ALL
F Flight Interphone - Block Diagram ** ON A/C NOT FOR ALL
(1) General
The flight interphone enables:
  • Telephone conversations between the various stations in the cockpit
  • Telephone conversations between the cockpit and the ground crew via the external power panel.
(2) Composition of the circuit
The flight interphone circuit comprises a summing amplifier equipped with:
  • 7 microphone inputs
    input impedance : 150 ohms
    input level : 0.250 V.
  • 3 audio outputs
    impedance : 600 ohms - Power 35 mW plus or minus 5 mW for ground crew reception
    output impedance : 600 ohms - Power 10 mW for AMU external reception, output 6
    internal output impedance : 2.2 kohms for AMU internal reception relevant to the various cards.
This circuit also comprises :
  • 1 power supply for microphones of channels 6 and 7.
  • 1 interface and current detection circuit for channel 6.
  • 1 cut-off circuit for channel 7.
(3) Operation
The input signal from the various microphones used in the aircraft (hand microphone, boomset, mask microphone) is applied to inputs 1 to 7. A specific power supply circuit is provided for the microphones of inputs 6 and 7 (they have no transmission card to supply them). A current detection circuit on channel 6 and a cut-off relay on channel 7 insulates the channels when they are not used. The L/G relay controls this cut-off relay.
The amplified LF output signal is then available on the 3 windings of the secondary of the output transformer:
  • 600 ohm output for ground crew.
  • 600 ohm output for audio output No. 6.
  • 2.2 Kohm output for the various AMU audio cards.
(4) General
The flight interphone enables:
  • Telephone conversations between the various stations in the cockpit
  • Telephone conversations between the cockpit and the ground crew via the external power panel.
(5) Operation
The flight interphone comprises the following functions:
  • microphone inputs
  • amplification and summation
  • audio output.
(a) Microphone inputs
There are two types of microphone inputs:
  • normal inputs: inputs from the CAPT, F/O, 3rd OCCPNT , Avionics Bay (and optionally 5th OCCPNT)
  • protected inputs: they comprise the mechanic input and the Reserve input (input 6).
(b) Protected inputs
The mechanic input is disconnected from the interphone amplifier when the flight/ground information from the LGCIU is present (flight configuration).
The input 6 is disconnected from the interphone amplifier when the PTT input 6 is not activated.
(c) Architecture
The adaptation board perfoms the summing of all the modulation signals. As a security precaution, there are two independent summation circuits.
The output of the first summation circuit is transmitted to the "master" audio board (board A).
The output of the second summation circuit is transmitted to the "slave" audio board (board B).
NOTE: The ouputs of the first summation circuit is also transmitted to the MECH and Audio 6 outputs.
(6) Logic Processing Function
F Logic Processing - Block Diagram ** ON A/C NOT FOR ALL
(a) Purpose
Each user of the audio integrating system has an associated logic-processing channel.
The logic processing function manages the processing channel at AMU level and enables the use of the system.
In particular:
  • It dialogs with the associated ACP, with the BITE circuit or the SELCAL-CALL circuit.
  • It manages the various inputs/outputs of the processing channel.
(b) Composition
The logic processing channel comprises:
  • A computer
  • An interface circuit to ARINC 429 standard
  • A serial interface circuit
  • A control interface circuit.
1 Computer
It comprises the peripherals required for the operation of the microprocessor, clock, monitoring circuit (watchdog), memories, address decoder, etc.
2 ARINC 429 interface
This circuit ensures the interface with the ACP and comprises:
a transmission interface, a reception interface, a microprocessor interface.
  • Transmission interface
    The transmission interface conditions the electrical levels in compliance with ARINC 429 standard.
  • Reception interface
    The reception interface enables the galvanic insulation of the link between the ACP and the AMU. It also reconstitutes the transmission clock and the information.
  • Microprocessor interface
    Transmission: this interface receives data in byte form from the microprocessor. This data is required to transmit the messages and to condition them in compliance with ARINC 429 standard.
    Reception: this interface receives the transmission clock and the data in ARINC message form. It transmits this data to the microprocessor in byte form.
3 Serial interfaces
These interfaces enable data exchange between the logic processing function and the BITE and SELCAL-CALL functions.
These interfaces are mainly comprised of 2 ACIAs (Asynchronous Communication Interface Adaptors).
4 Command interface
This interface comprises PIAs (Peripherals Interface Adaptors) or buffer registers. The microprocessor uses them to acquire discrete information (e.g. PTT switches) or to generate commands. These commands are sent to the various functions (e.g. transmission selection command, setting into service of VOICE/ON filter).
M. SELCAL Function - Mechanic Call - Cabin Attendant Call
(1) Purpose
The SELCAL-CALL system of the audio management system gives :
  • A visual and aural indication of the calls from the ground stations equipped with a coding device which can be used by the aircraft installation (SELCAL system - Selective Calling). The calls are sent on the radio frequencies which link the aircraft to the ground. The communication channels used are : VHF1 - VH2 and VHF3, HF1, HF2 if installed.
  • A visual indication of the calls from the ground crew or from the Cabin Attendants.
NOTE: The ground crew call system is described in chapter 23-42-00:
"Cockpit-to-ground crew call system" (circuit WC).
The Cabin Attendant call system is part of chapter 23-73-00:
"Cabin Intercommunication Data System" (circuit RH).
(2) SELCAL
(a) Ground system
F SELCAL System - Ground System ** ON A/C NOT FOR ALL
The ground system transmits, via VHF or HF transmitters, a selective call code. This code comprises 2 consecutive pulses each containing a mixture of the 2 frequencies. This enables the calls to be differentiated.
The call comprises a single-code transmission without repeat.
(b) Aircraft system
F SELCAL System - Aircraft System ** ON A/C NOT FOR ALL
The aircraft receivers detect and capture the call signals transmitted by the ground stations (VHF or HF). Once detected, the signals are sent to the AMU SELCAL card.
This SELCAL card is equipped with 5 inputs. These inputs correspond to the various communication facilities on the aircraft (VHF1 - VHF2 - VHF3 - HF1 - HF2 in accordance with aircraft definition).
The SELCAL decoder permanently scans the 5 inputs on which the calls may be present. It analyzes the received signals to check if they comprise the frequencies relevant to aircraft code. The operator programs this code on the SELCAL code panel.
If the frequencies and aircraft code correspond, the warning system transmits an aural signal. The CALL legend on each ACP associated to the system which received the call (VHF1 - VHF2 - VHF3 - HF1 - HF2) comes on.
Push the RESET pushbutton switch located on each ACP to reset the aural and lighted call.
(c) Associated peripheral assemblies
The SELCAL system is associated with:
  • The radio communication systems VHF1 - VHF2 - VHF3 - HF1 - HF2 (in accordance with aircraft definition).
  • The Flight Warning Computer (FWC) system.
(d) Operation of the system
F SELCAL System - Block Diagram ** ON A/C NOT FOR ALL
1 Ground crew and Cabin Attendant call system
F Ground Crew and Cabin Attendant Call System - Block Diagram ** ON A/C NOT FOR ALL
  • Operation of ground crew call
    This circuit displays the call from the ground crew in the cockpit.
NOTE: Chapter ATA 23-42 (Cockpit-to-Ground Crew Call System - Circuit WC) gives the operation of the ground crew call circuit.
  • Operation
    When a call is made from the Cabin Attendant station, the CIDS generates ground information. This information is sent to the calculating unit via the input stages.
    The information is processed then sent via the output stages to the various audio cards and then to the ACPs. On the ACPs, this causes ATT legend to flash (coupled with CAB pushbutton switch) for 60 seconds. After 60 seconds or when the RESET pushbutton switch is pushed, like the SELCAL system, the calculating unit re-initializes the circuit.
    It also sends information to the CIDS for re-initialization via the output stages.
NOTE: It is possible to inhibit the automatic function which causes the MECH and ATT flashing call legends to stop. (Ref. Para. Operation - Pin Program)
2 Other functions
  • Pin-program
    The calculating unit collects the information given by the pin-program. It processes this information then sends it:
    .to the various audio cards and then to the ACPs.
    .to the BITE circuit to enable this circuit to generate a data message which is sent to the CFDIU system.
  • BITE circuit
    The BITE system sends a test request message to the SELCAL-CALL card via the input stages.
    A test unit comprised of an LF-signal generator circuit, output status-check circuits and input forcing circuits is integrated into this card.
    The calculating unit processes the messages then triggers the test program.
    The result is sent in message form to the BITE circuit.
(3) SELCAL
(a) Ground system
F SELCAL System - Ground System ** ON A/C NOT FOR ALL
The ground system transmits, via VHF or HF transmitters, a selective call code. This code comprises 2 consecutive pulses each containing a mixture of the 2 frequencies. According to the ARINC 714 specification, this enables the calls to be differentiated.
The call comprises a single-code transmission without repeat.
(b) Aircraft system
F SELCAL System - Aircraft System ** ON A/C NOT FOR ALL
The aircraft receivers detect and capture the call signals transmitted by the ground stations (VHF or HF). Once detected, the signals are sent to the AMU SELCAL board.
This SELCAL card is equipped with 5 inputs. These inputs correspond to the various communication facilities on the aircraft (VHF1 - VHF2 - VHF3 - HF1 - HF2 in accordance with aircraft definition).
The SELCAL function continuously monitors the digital data of the five radio communication channels. It analyzes the received signals to check if they comprise the frequencies relevant to aircraft code. The operator programs this code on the SELCAL code panel.
If the frequencies and aircraft code correspond, the warning system transmits an aural signal. The CALL legend on each ACP associated to the system which received the call (VHF1 - VHF2 - VHF3 - HF1 - HF2) comes on.
Push the RESET pushbutton switch located on each ACP to reset the aural and lighted call.
(c) Associated peripheral assemblies
The SELCAL system is associated with:
  • The radio communication systems VHF1 - VHF2 - VHF3 - HF1 - HF2 (in accordance with aircraft definition).
  • The Flight Warning Computer (FWC) system.
(d) Operation of the system
1 Operation
The SELCAL signal issued by the various communication assemblies is applied, depending on its source, to one of the 5 input channels (VHF1, VHF2, VHF3, HF1, HF2).
The calculating unit:
  • Recognizes if the code of the signals received corresponds to the code given by the SELCAL code panel
  • Interprets and manages the various information received from the input circuits: ground crew call, Cabin Attendant call.
  • Generates the various messages transmitted to the output circuits.
The calculating unit checks the concordance between the code selected on the SELCAL code panel and the received code. It then generates a digital message. This message is sent to the audio boards which transmit the information to the various ACPs via their connecting bus in order to switch on the associated lights.
Likewise, data is sent to the FWC system.
This enables audio indication of the call.
When an operator pushes the RESET pushbutton switch on one of the ACPs, data is sent to the associated audio card. This data is transmitted via the input stages to the calculating unit. This calculating unit re-initializes the system.
2 Ground crew and Cabin Attendant call system
F SELCAL System - Aircraft System ** ON A/C NOT FOR ALL
3 Operation
The SELCAL signal issued by the various communication assemblies is applied, depending on its source, to one of the 5 input channels (VHF1, VHF2, VHF3, HF1, HF2).
An input compressor-filter first processes this signal:
  • The input compressor (comprises a high gain amplifier and a deviation detector amplifier) delivers an LF signal with constant amplitude irrespective of input signal level
  • The filter eliminates all frequencies above 3 Khz to enable further processing of the signals by digital filtering.
At output of the 5 filters, the signals are sent to an analog-digital converter. This converter has 2 functions:
  • It constantly scans the 5 analog inputs under the control of the calculating unit.
  • It selects the channel on which a call is transmitted (multiplexing function).
  • It converts the analog signals into 8-bit digital signals so that they can be used by the calculating unit.
At the output of the converter, an 8-bit data bus transmits the digital signals to the calculation unit.
The calculating unit:
  • Recognizes if the code of the signals received corresponds to the code given by the SELCAL code panel
  • Interprets and manages the various information received from the input circuits: ground crew call, Cabin Attendant call, pin-program information, test request, etc.
  • Generates the various messages transmitted to the output circuits.
    When the system operates correctly, this enables the indication of calls, the link with the BITE circuit, etc.
The calculating unit checks the concordance between the code selected on the SELCAL code panel and the received code. It then generates a digital message. This message is sent via the output stages to the various audio cards. The audio cards transmit the information to the various ACPs via their connecting bus in order to switch on the associated lights.
Likewise, data is sent to the FWC system.
This enables audio indication of the call.
When an operator pushes the RESET pushbutton switch on one of the ACPs, data is sent to the associated audio card. This data is transmitted via the input stages to the calculating unit. This calculating unit re-initializes the system.
4 Ground crew and Cabin Attendant call system
  • Operation of ground crew call
    This circuit displays the call from the ground crew in the cockpit.
NOTE: Chapter ATA 23-42 (Cockpit-to-Ground Crew Call System - Circuit WC) gives the operation of the ground crew call circuit.
  • Operation
    When a call is made from the Cabin Attendant station, the CIDS generates ground information. This information is sent to the calculating unit via the input stages.
    The information is processed then sent via the output stages to the various audio cards and then to the ACPs. On the ACPs, this causes ATT legend to flash (coupled with CAB pushbutton switch) for 60 seconds. After 60 seconds or when the RESET pushbutton switch is pushed, like the SELCAL system, the calculating unit re-initializes the circuit.
    It also sends information to the CIDS for re-initialization via the output stages.
NOTE: It is possible to inhibit the automatic function which causes the MECH and ATT flashing call legends to stop. (Ref. Para. Operation - Pin Program)
N. Pin-Program
F Pin-Program - Block Diagram ** ON A/C NOT FOR ALL
F Pin-Program - Block Diagram ** ON A/C NOT FOR ALL
In a simple way, the pin-program adapts the AMU to suit the various configurations of the audio system.
The pin-programm:
  • Inhibits the function selection annunciators located on the face of the ACP which correspond to the uninstalled optional equipment (VHF3, HF1, HF2)
  • Sends, after processing in the AMU, installation information relevant to the previous equipment and information relevant to the optional navigation equipment (ADF2 - MLS). It sends this information to the CFDIU via an output bus.
  • Inhibits the automatic reset function after the Cabin Attendant and ground crew calls have operated for 60 seconds.
  • Enables change from FAA certification to CAA certification.
  • Enables the PA transmission pushbutton switch located on each ACP to be given stable operation (i.e. same as the other transmission pushbutton switches).
Operation
It is possible to modify the programming of these functions by installing specific shunts. This generates a message which (after it has been processed) is sent to the various ACPs, to the CFDIU or to the management microprocessor.
O. Electrical Power Supply
F Electrical Power Supplies of the AMU - Block Diagram ** ON A/C NOT FOR ALL
Seven separate power-supply networks supply the AMU:
  • One +28 V input for each processing channel (5 in maximum configuration)
  • One +28 V input which supplies the flight interphone function.
  • One +28 V input which supplies the SELCAL-CALL and BITE function.
Each network is equipped with its own protection, filter and regulation systems.
P. Additional cockpit occupant function (optional)
On AMU 4031SB, all the audio circuits and interfaces for the optional 5th Occupant (located in cockpit) are implemented on the BITE board :
  • power supply interface
  • microphone supply interface
  • selection and input of audio signals from the 5th Occupant microphones
  • digital to analog conversion of reception signals
  • amplification and impedance matching of audio output interface
  • radio PTT selection interface
  • discrete interface
  • ARINC 429 interface with the 5th Occupant ACP
NOTE: For the other crew members, these circuits and interfaces are located on the audio boards and adaptation board.
** ON A/C NOT FOR ALL
7. BITE Test
A. Purpose
The audio system BITE (Built-In Test Equipment) serves as an aid for line maintenance in workshop and Service Department.
It is used when faulty units are to be detected, replaced or repaired.
It limits the number of unwanted removals of the system components.
The BITE:
  • Constantly transmits the actual status of the system (availability-unavailability).
  • Memorizes any failures which occurred during the 63 previous flight segments or up to memory capacity.
  • Monitors the data exchanges between the system components.
  • Centralizes the triggered tests or self-test results.
  • Dialogs with the CFDIU by means of menus.
  • An additional function is the transmission of the pin-program and a message which serve to identify the system.
The Audio Management Unit (AMU) is equipped with a Type 1 BITE circuit.
B. General Operation
(1) Normal mode
This mode cyclically interrogates the AMU cards in order to know their status and the status of the associated ACP. It transmits this information to the CFDIU and if a failure is detected, records this information in the failure memory.
It interrogates the cards one after each other every 13 ms. The processing card generates information with respect to the self-test of this card and the data from the associated ACP. This information is sent to the BITE. This information is sent to CFDIU cyclically every 200 ms under label 356.
(2) Menu mode
This mode is used only on the ground. It enables dialog between the AMU and an operator via the Multipurpose Control and Display Unit (MCDU).
An air-ground discrete gives the ground-flight information.
The LGCIU (Landing Gear Control and Interface Unit - ATA 32-31-00 - Circuit GA) delivers the air-ground discrete.
C. Functional description
F MCDU - Location ** ON A/C NOT FOR ALL
The operator uses the 2 MCDUs 3CA1 and 3CA2 installed on the center pedestal to manage the BITE system (REF ATA 22-82-00).
For the various operations to be performed and the displays obtained, Ref.following figures
F MCDU - Functional Description ** ON A/C NOT FOR ALL
F Audio Integrating System (AIS) - LAST LEG REPORT - (Sheet 2/2) ** ON A/C NOT FOR ALL
F Audio Integrating System (AIS) - PREVIOUS LEGS REPORT - (Sheet 2/2) ** ON A/C NOT FOR ALL
F Audio Integrating System (AIS) - LRU IDENTIFICATION - (Sheet 2/2) ** ON A/C NOT FOR ALL
F Audio Integrating System (AIS) - TEST - (Sheet 2/2) ** ON A/C NOT FOR ALL
F Audio Integrating System - BITE Description ** ON A/C NOT FOR ALL
The two AUDIO boards, the SELCAL board, the BITE board and the ACPs are the elements monitored by the AMU BITE.
D. Function
The main purpose of the AUDIO system BITE is to supply maintenance assistance. The integrated maintenance function has two levels :
  • a real time maintenance, which is active during the operation of the unit
  • a ground maintenance, which brings into operation tests that cannot be performed during the flight.
    The BITE board manages the dialogue with the CFDIU. It dates and stores in an EPROM memory all the faults detected in the system during the previous 63 flight legs.
    The BITE board transmits to the CFDIU the data and information that follow :
  • functional status of the system (AMU and ACPs)
  • results of the Built-in tests and of the CFDIU-requested tests
  • unit ATA identifier code - part number and serial number of the unit
  • part number of the ACPs
  • pin programming, which is a constant data stored in the EPROM memory.
E. Operation
(1) Normal mode
The normal mode of operation consists in monitoring cyclically the status of the AMU cards and the status of the associated ACP, transmitting data to the CFDIU and, if any failure is detected, storing it in the fault memory.

(2) Menu mode
The menu mode of operation is only activated on the ground and it consists in a dialogue between the AMU and the operator through one of the three MCDUs. Flight/ground data is given by the CFDIU and when there is no data from a ground circuit (flight/ground discrete), it is given by the LGCIU.
For the Audio Integrating System (AIS), the menu mode consists of the following:
F MCDU - Functional Description ** ON A/C NOT FOR ALL
(3) Other functions
The AMU BITE circuit ensures two additional functions
  • It transmits the status of the pin-program
  • It transmits an identification message.
(a) Transmission of PIN-PROGRAM*
  • The BITE circuit generates a message giving the installation status of certain equipment (VHF3 - HF1 - HF2 - ADF2 - MLS). This message is generated from the information sent by the SELCAL card which receives the pin-program. It is sent to the CFDIU.
  • The CFDIU system requires this information in order to transmit this information to the relevant circuits such as the RMPs (Radio Management Panels) and the SDAC (System Data Acquisition Concentrator).
  • This information is transmitted in 32-bit word form in compliance with ARINC 429 with label 350.
    Word structure is as follows:
    b32 b31 b30 b23 b16 b15 b14 b13 b12 b11 b10 b9 b8 b1
    -------------------------------------------------------------------------------
    ! ! !M !A !H !H !V ! ! ! !
    P ! 0 0 !0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0! L ! D ! F ! F ! H ! 0 ! 0!LABEL!
    ! ! ! S! F ! 2! 1! F ! ! ! 350 !
    ! ! ! ! 2! ! ! 3! ! ! !
    -------------------------------------------------------------------------------

  • Bit at logic 0: the equipment is not installed
  • Bit at logic 1: the equipment is installed
(b) Transmission of identification message
Every component connected to the maintenance centralized system transmits an identification message to facilitate and shorten the test procedures.
The identification code assigned to the AMU is 6A.
This information is transmitted in 32-bit word form in compliance with ARINC 429 with label 377.
Word structure is as follows:
b31 b30 b29 b19 b18 b15 b14 b11 b10 b9 b8 b1
-------------------------------------------------------------------------------
! ! ! ! ! ! ! ! !
! P ! 0 0 ! 0 0 0 0 0 0 0 0 0 0 0 ! 6 ! A ! 0 ! 1 ! LABEL 377 !
! ! ! ! ! ! ! ! !
-------------------------------------------------------------------------------

(4) Other functions
The AMU BITE circuit ensures two additional functions
  • It transmits the status of the pin-program
  • It transmits an identification message.
(a) Transmission of PIN-PROGRAM*
  • The BITE circuit generates a message giving the installation status of certain equipment (VHF3 - HF1 - HF2 - ADF2 - MLS). It is sent to the CFDIU.
  • The CFDIU system requires this information in order to transmit this information to the relevant circuits such as the RMPs (Radio Management Panels) and the SDAC (System Data Acquisition Concentrator).
  • This information is transmitted in 32-bit word form in compliance with ARINC 429 with label 350.
    Word structure is as follows:
    b32 b31 b30 b23 b16 b15 b14 b13 b12 b11 b10 b9 b8 b1
    -------------------------------------------------------------------------------
    ! ! !M !A !H !H !V ! ! ! !
    P ! 0 0 !0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0! L ! D ! F ! F ! H ! 0 ! 0!LABEL!
    ! ! ! S! F ! 2! 1! F ! ! ! 350 !
    ! ! ! ! 2! ! ! 3! ! ! !
    -------------------------------------------------------------------------------

  • Bit at logic 0: the equipment is not installed
  • Bit at logic 1: the equipment is installed
(b) Transmission of identification message
Every component connected to the maintenance centralized system transmits an identification message to facilitate and shorten the test procedures.
The identification code assigned to the AMU is 6A.
This information is transmitted in 32-bit word form in compliance with ARINC 429 with label 377.
Word structure is as follows:
b31 b30 b29 b19 b18 b15 b14 b11 b10 b9 b8 b1
-------------------------------------------------------------------------------
! ! ! ! ! ! ! ! !
! P ! 0 0 ! 0 0 0 0 0 0 0 0 0 0 0 ! 6 ! A ! 0 ! 1 ! LABEL 377 !
! ! ! ! ! ! ! ! !
-------------------------------------------------------------------------------

F. 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) Progress of power-up tests
  • Duration: 1 s.
  • Cockpit repercussions directly linked to power-up test accomplishment (some other repercussions may occur depending on the A/C configuration but these can be disregarded):
    - None
(3) Results of power-up tests (cockpit repercussions, if any, in case of tests pass/tests failed).
  • Tests pass:
    . None
  • Tests failed:
    . None
[Rev.10 from 2021] 2026.04.02 06:49:44 UTC
"WTRUIB" 2025