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The reception selection pushbutton switches are side-lit by the integral lighting lamps. They are therefore also controlled by the pedestal integral lighting potentiometer.
(4) Operation
(a)
General (Ref. Fig. 010) 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 potent iometers 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.
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Audio Control Panel - Block Diagram Figure 010
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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"
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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 | ---------------------------------------------------------------------------
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