-
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.
1EFF : ALL 1 23-51-00Page 91 1 1 May 01/05 1 1 1CES 1
SELCAL System - Block Diagram
Figure 034
R 1EFF : 001-049, 051-099, 101-105, 151-199, 1 23-51-00Page 92 1201-220, 1May 01/05 1 1 1CES 1 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.
2 Ground crew and Cabin Attendant call system
_
(Ref. Fig. 035)
R **ON A/C 106-149, 221-299, 301-399, 401-499,
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
_
(Ref. Fig. 033A)
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Ground Crew and Cabin Attendant Call System - Block Diagram
Figure 035
R 1EFF : 001-049, 051-099, 101-105, 151-199, 1201-220, 1 1CES 1 111 23-51-00 Page 94 May 01/05
R **ON A/C 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 pushbutton switch 10WC (located on external power panel 108VU) is pushed, it sends ground information to the calculating unit via the input stages. The information is processed then a message is sent via the output stages to the various audio cards and then to the ACPs. This causes the MECH legend to flash (coupled with INT transmission pushbutton switch) for 60 seconds. After 60 seconds, or when the RESET pushbutton switch is pressed, like the SELCAL system, the circuit is re-initialized.
-
Operation of Cabin Attendant Call This circuit displays calls made from the cabin by the Cabin Attendants in the cockpit.
NOTE : Chapter ATA 23-73 (Cabin Intercommunication Data System
____ -Circuit RH) gives the operation of the 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.
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