INTERCOMMUNICATION, PASSENGER ADDRESSING AND
AURAL WARNINGS
Intercommunication between crew members (Interphone) normally takes
place digitally either in the “Cold Mike” or “VOX Hot Mike” mode as follows:
1 If in “Cold Mike” mode, press the Press To Talk button (the trigger on
the cyclic stick, 1st detent)
2 Analog voice signal from the headset microphone is converted into
digital by the Audio Panel and distributed via the two MIC digital
buses
3 All Audio Panels convert the selected audio into analog and send it to
the associated headset
Intercommunication between crew and cabin attendant takes place as
follows:
1 Select intercommunication by acting on the Audio Panel and the
Cabin Audio Panel
2 When the crew member is talking, analog voice signal from the
headset microphone is converted into digital by the Audio Panel and
distributed via the two MIC digital buses. The NIM of MRC 2 converts
the digital audio into analog audio and sends it to the attendant’s
headset via the Cabin Audio Panel
3 When the cabin attendant is talking, analog voice signal from the
attendant’s headset microphone is converted into digital by the NIM of
MRC 2 and distributed via the relevant AUDIO digital bus. The Audio
Panel converts the selected audio into analog and sends it to the crew
member headset.
Any crew member or the cabin attendant can address passengers via the
cabin loudspeakers. Passenger addressing takes place as follows:
1 Select the PA (Passenger Addressing) function on the Audio Panel
and press the PTT button (the trigger on the cyclic stick or the foot
switch) to connect the headset microphone to the passenger
compartment public address system.
2 Analog voice signal from the microphone is sent to the cabin
loudspeakers via the Passenger Speaker Amplifier. The same signal
is returned to the headset as sidetone.
The audio provided by the Aural Warning Generator (AWG, see chapter 31
00), is handled by the digital circuitry of the Audio Panels and sent to the
crew member headset.