AUDIO INTEGRATING SYSTEM ― GENERAL
The Audio Integrating System permits switching microphones to various
radios, distribution of audio to headsets and interphone functionality. In
addition it distributes audio to cabin loudspeakers, to Cockpit Voice
Recorder (CVR, see chapter 31-00 for details) and to optional systems such
as the external loudspeakers.
The Audio Integrating System includes the digital Audio Panels (type AV
900) and the Network Interface Modules (NIM) of the Modular Radio
Cabinets (MRC) as well as the digital audio buses and the PTT control
pushbuttons (cyclic stick trigger, foot-switch).
AUDIO INTEGRATING SYSTEM ― CONTROLS AND
INDICATORS
The Audio Panel has with five rows of pushbuttons each of which has a
green LED annunciator.
The top row of rectangular pushbuttons (MIC) is used to select the
transmitter so they are mutually exclusive (only one of them can illuminate at
a time). The microphone selection button connects the pilot to the
associated radio enabling voice communications and lighting the green
annunciator.
When a MIC pushbutton is pressed to illuminate, the associated AUD round
pushbutton is automatically illuminated for radio monitoring. If a different
radio is then selected for transmission, both MIC and AUD pushbuttons of
the previously selected radio extinguish.
The next three rows of round pushbuttons are for radio audio monitoring
selection. The first of these rows is labelled AUD and is associated to the
MIC pushbuttons.
Multiple radios can be selected for monitoring enabling the pilot to maintain
listening on other radio frequencies while communicating on a selected
primary frequency.
When a COM radio is selected for monitoring by pressing the AUD
pushbutton, the monitoring selection is not cancelled in case that radio is
deselected from transmission: MIC pushbutton extinguishes, AUD
pushbuttons remains illuminated.
The LED at the centre of each button alerts the pilot to the condition of the
radio: when illuminated the radio is selected for monitoring.
The bottom row of round pushbuttons are for intercom handling, both
pilot/co-pilot and cockpit/cabin crew.
A few square shaped puhbuttons provide special functionalities such as
frequency filtering and selective call selections.
The RH column of pushbutton are grouped in a white outlined box labelled
CAB and are used to control audio functions for passengers.
A digital display shows the global headset volume level, or the audio level of
the selected radio or function: a knob permits volume level adjustment.
In the bottom LH the BKUP pop-up knob is used for back-up mode selection
and volume adjustment of the Audio System.