Unit Operation; Microphones; Mono/Stereo Headsets; Unmuted/Unswitched Inputs - Garmin G1000 Reference Manual

4.4 UNIT OPERATION

Microphones

The GMA 1347 features two different microphone
channeling modes:
• COM1 MIC
• COM2 MIC
NOTE: A push-to-talk (PTT) switch must be
pressed to transmit on the selected channel.
Each audio panel can accept up to six (6) microphone
inputs, allowing for a two-person crew and up to four (4)
passenger intercom stations in the aircraft.

Mono/Stereo Headsets

The Cessna 172 and Cessna 182 are equipped with
four (4) stereo headset jacks (pilot, copilot and two pas-
sengers). The Cessna 206 is equipped with six (6) stereo
headset jacks (pilot, copilot and four passengers).
Use of a monaural headset in a stereo jack shorts the
right headset channel output to ground. A person listen-
ing on a monaural headset hears only the left channel in
both ears. If a monaural headset is used at one of the pas-
senger positions, any other passenger listening on a stereo
headset hears audio in the left ear only, unless the headset
has a mono/stereo switch that is set to mono.

Unmuted/Unswitched Inputs

The unit provides four (4) unmuted/unswitched in-
puts that are always present on the headsets or speaker.
These inputs are the following aural warnings:
• ALTITUDE WARNING
• UNSWITCHED 1
• UNSWITCHED 2
• UNSWITCHED 3
Garmin G1000 Cockpit Reference Guide for Cessna Nav III
SECTION 4 – AUDIO PANEL

Power-up Settings

The GMA 1347 performs a self-test during power-up.
All panel annunciator lights illuminate for approximately
two (2) seconds. Once the self-test is completed, the set-
tings are restored to the ones in use before the unit was
last turned off.

Fail-safe Mode

A fail-safe circuit connects the pilot' s headset and mi-
crophone directly to COM1 in case power is interrupted
or the unit is turned off. In this case, audio is not available
on the speaker.

Selecting and Deselecting Keys

LED annunciators indicate when a key function is se-
lected. Pressing a key activates and deactivates the func-
tion, turning the annunciator light on and off.

Lighting

LED key annunciators and backlighting are controlled
automatically by the G1000 Control Display Unit (CDU).

Transceiver Keys

Pressing the COM1 MIC or COM2 key selects the
COM radio as the active transceiver. The receiver audio
key, COM1 or COM2 is also selected. The COM frequen-
cy is highlighted green in the active frequency field of the
PFD and MFD.
Only one microphone source can be selected at a time.
If COM2 MIC is pressed when COM1 MIC is active, the
unit switches to COM2.
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