6A.3 UNIT OPERATION
POWER-UP AND FAIL-SAFE OPERATION
Power-up
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.
See the System Overview section for additional power
up information.
Fail-safe Operation
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
The following eight (8) transceiver keys appear at the
top of the GMA 1347 front panel: COM1 MIC, COM2
MIC, COM3 MIC, COM 1/2, COM1, COM2, COM3,
and TEL. COM audio can be selected by pressing either
the desired COM key or by pressing a COM MIC key.
190-00378-02 Rev. A
COM MIC Keys
Pressing the COM1 MIC, COM2 MIC or COM3 MIC
key selects the COM radio as the active transceiver. The
receiver audio key, COM1, COM2, COM3 is also select-
ed. The COM frequency 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.
COM Keys
Pressing the COM1, COM2, or COM3 receiver key
selects the COM radio as an active receiver source. Any
combination of radios can be selected separately or simul-
taneously regardless of the active transceiver selection.
The active COM radio is always heard through the head-
sets.
Garmin G1000 Audio Panel Pilot's Guide
OPERATION
Figure 6A.3.1 Transceivers
6A-5
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