Garmin Cessna Caravan G1000 Manual

G1000
TM
audio panel pilot’s guide

Garmin G1000 Audio Panel Pilot’s Guide 190-00378-02 Rev. A
Record of Revisions
Revision Date of Revision Revision Page Range Description
A 12/01/04 6A-1 – 6A-17 Initial release.

Garmin G1000 Audio Panel Pilot’s Guide190-00378-02 Rev. A 6A-1
INTRODUCTION
6A.1 INTRODUCTION
This manual provides the pilot with a description of
the GMA 1347 and its operating instructions.
The Garmin GMA 1347 is an audio control panel and
marker beacon system. Pressing the audio panel keys
controls audio selection of COM, NAV, telephone and in-
tercom. LED annunciators indicate when a key function
is selected.
NOTE: This audio panel is intended to be used
only as part of the G1000 Integrated Cockpit
System.
The GMA 1347 includes a six-position intercom sys-
tem (ICS) with electronic cabin noise de-emphasis and
two stereo music inputs. Separate knobs for the pilot and
copilot/passenger control intercom audio level. The in-
tercom provides four selectable modes of isolation (All,
Crew, Pilot, Copilot).
A cabin speaker is available to listen to selected aircraft
radios. MASQ (Master Avionics Squelch) processing re-
duces ambient noise from the avionics inputs.
Each microphone input has an automatic squelch
threshold. Manual squelch is available by pressing the
MAN SQ key.
The GMA 1347 provides a digital recorder that can
play back up to two and a half minutes of COM audio.
Recording is automatic when a COM signal is received.
Playback is controlled by pressing the PLAY key. Play-
back can be stopped by pressing the MKR/MUTE key.
The unit controls marker beacon receiver audio and
features marker beacon audio muting.
As part of the G1000 Integrated Cockpit System, the
GMA 1347 also operates the display reversionary mode.
Two GMA 1347 audio panels can be mounted in an
aircraft. In dual panel installations, two (2) units can be
connected to the same radios.
CAUTION: When the GMA 1347 Audio panel is
turned OFF or is inoperative, certain autopilots
are affected. No warning tone is supplied when
the autopilot disengages and the middle marker
sense signal is not supplied.

Garmin G1000 Audio Panel Pilot’s Guide 190-00378-02 Rev. A6A-2
DESCRIPTION
6A.2 UNIT DESCRIPTION
The GMA 1347 features three (3) major groups of keys
as shown in Figure 6A.2.1:
• Communication keys
• Navigation keys
• Intercom system (ICS) keys
Each key is labeled to indicate the name of the func-
tion. The triangular key annunciator above the keys are
white when illuminated.
The knobs at the bottom of the unit control ICS volume
and squelch threshold levels. The small knob adjusts the
volume/squelch level for the pilot. The large knob ad-
justs the volume/squelch level for the copilot/passenger.
The red DISPLAY BACKUP button below the dual vol-
ume/squelch knob controls reversionary mode selection.
FRONT PANEL CONTROLS
• Transceiver audio selector keys
(COM1, COM2, COM3)
• Transmitter (audio/mic) selection keys
(COM1 MIC, COM2 MIC, COM3 MIC)
• Split COM key
(COM 1/2)
• Dedicated telephone interface key
(TEL)
• Passenger address key
(PA)
• Speaker key
(SPKR)
• Marker beacon receiver audio select/mute key
(MKR/MUTE)
• Marker beacon receiver high sensitivity key
(HI SENS)
• Aircraft radio audio selector keys
(NAV1, NAV2, ADF, DME, AUX)
• Intercom manual squelch key
(MAN SQ)
• Digital recording playback key
(PLAY)
• Intercom system (ICS) isolation keys
(PILOT, COPLT)
• Volume/squelch knob
(VOL/SQ)
• Reversionary mode button
(DISPLAY BACKUP)

Garmin G1000 Audio Panel Pilot’s Guide190-00378-02 Rev. A 6A-3
DESCRIPTION
Transmitters Transceiver Audio
Split COM Telephone
Marker Beacon/Mute
Passenger Address
Marker Beacon Signal Sensitivity
Speaker
VOL/SQ
Manual Squelch
Navigation Radio Audio
Reversionary Mode Control
Digital Recording Playback
Navigation Radio Audio
Figure 6A.2.1 Front Panel Controls
ICS Isolation
VOL Annunciation SQ Annunciation

Garmin G1000 Audio Panel Pilot’s Guide 190-00378-02 Rev. A6A-4
DESCRIPTION
TRANSCEIVERS
The GMA 1347 handles three different transceivers:
• COM1 MIC
• COM2 MIC
• COM3 MIC
NOTE: A push-to-talk (PTT) switch must be
pressed to transmit on the selected radio.
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 GMA 1347 can accommodate up to six (6) head-
sets, pilot, copilot and up to four (4) passengers.
NOTE: The use of stereo headsets is highly rec-
ommended.
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 Audio Panel Pilot’s Guide190-00378-02 Rev. A 6A-5
OPERATION
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.
Figure 6A.3.1 Transceivers
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 190-00378-02 Rev. A
6A-6
OPERATION
Transmitting
When a transmitter is keyed, the active transceiver
MIC key annunciator blinks approximately once per sec-
ond. A white TX indication appears next to the active
COM frequency on both the PFD and the MFD during
transmission.
NOTE: Audio level of the COM radio(s) is con-
trolled by the COM volume controls located on
both the PFD and MFD (see the VHF NAV/COM
Pilot’s Guide).
COM SWAP
A remotely mounted switch can be used to transfer the
active transceiver between COM1 MIC and COM2 MIC.
Pressing the switch has no effect if COM3 is the active
transceiver.
OPTIONAL COM MUTING
COM muting on receive and COM muting on trans-
mit options can each be disabled if desired. Contact a
Garmin-authorized service center for details.
COM Muting on Receive
When COM muting on receive is enabled, all second-
ary COM audio is muted during detection of received pri-
mary COM audio.
NOTE: If COM muting on receive option is
enabled, only primary COM radio reception is
recorded by the digital clearance recorder.
COM Muting on Transmit
When COM muting on transmit is enabled, all sec-
ondary COM audio is muted during transmission over the
primary COM radio.
TELEPHONE INTERFACE
The GMA 1347 contains a dedicated telephone inter-
face that is closely linked to the ICS operation. It is con-
trolled by the TEL key. See Table 6A.3.3 for a summary
of the telephone distribution and the various ICS isolation
modes.
NOTE: The ringer to the TEL channel is muted
during COM radio transmissions.
SPLIT COM FUNCTION
Pressing the COM 1/2 key selects the split COM func-
tion. During split COM operation, the COM1, COM1
MIC, COM2 and COM2 MIC keys are active.
When the COM 1/2 key is selected, COM1 is used by
the pilot for transmission and COM2 is used by the copi-
lot. The COM1 MIC annunciator blinks when the pilot’s
microphone is keyed and the COM2 MIC annunciator
blinks when the copilot’s microphone is keyed.
In this mode, both the pilot and the copilot can trans-
mit simultaneously over separate radios. The pilot can
still monitor COM3, NAV1, NAV2, DME, ADF, AUX and
MKR audio as selected, but the copilot is only able to
monitor COM2.
Split COM mode is cancelled by pressing the COM 1/2
key again.
NOTE: Split COM performance varies significantly
across installations and is affected by both the
distance between the antennas and the separa-
tion of the tuned frequencies.

Garmin G1000 Audio Panel Pilot’s Guide190-00378-02 Rev. A 6A-7
OPERATION
PA FUNCTION
A passenger address function is provided by pressing
the PA key. Push-to-talk (PTT) must be used to deliver PA
announcements over the headsets.
SPEAKER
All of the radios can be heard over the cabin speaker.
Pressing the SPKR key selects and deselects the cabin
speaker. Speaker audio is muted when the PTT switch
is keyed.
The speaker volume is adjustable above and below a
nominal value. Contact a Garmin-authorized service cen-
ter for details.
MARKER BEACON RECEIVER
Description and Operation
The GMA 1347 marker beacon is used as part of the
ILS system. The marker beacon receiver is always ON and
receives at 75 MHz. The GMA 1347 provides a marker
audio muting capability.
The receiver detects the three (3) marker tones, outer,
middle and inner, and illuminates the appropriate mark-
er beacon indicators. The marker indicators are located to
the left of the Altimeter on the PFD (Figure 6A.3.3). The
outer marker frequency is 400 Hz with a blue indicator,
the middle marker frequency is 1,300 Hz with an amber
indicator and the inner marker frequency is 3,000 Hz with
a white indicator. Refer to Table 6A.3.1 for a summary of
the marker beacon signal characteristics.
When the MKR/MUTE key is selected, the annun-
ciator light illuminates and the audio signal can be heard
over the speaker or headsets during marker reception.
When the MKR/MUTE key is annunciated and a mark-
er beacon tone is received, pressing the MKR/MUTE key
mutes the audio but does not affect the annunciators. The
audio returns when the next marker signal is received. If
the MKR/MUTE key is pressed during signal reception,
while marker beacon audio is muted, marker audio and
the MKR/MUTE key annunciator light are turned off.
NOTE: The marker beacon receiver lights operate
independently of the marker beacon audio and
cannot be turned off.
The marker beacon audio output level is adjustable by
a Garmin-authorized service center.
NOTE: The GMA 1347 is capable of driving
external marker beacon lamps.
Marker Beacon Signal Sensitivity
The HI SENS key can be pressed for increased marker
beacon signal sensitivity. The HI SENS function is used
to receive an earlier indication of nearing a marker during
an approach.
Figure 6A.3.2 Marker Beacon

Garmin G1000 Audio Panel Pilot’s Guide 190-00378-02 Rev. A
6A-8
OPERATION
Beacon Audio Frequency Audio Keying Rate Lamp Color
Outer Marker 400 Hz — — — 2 dashes per second Blue
Middle Marker 1,300 Hz • — • — 95 dot-dash combinations
per minute Amber
Airway/Inner Marker 3,000 Hz • • • • 6 dots per second White
Table 6A.3.1 Marker Beacon Signal Characteristics
Inner Marker Middle Marker Outer Marker
Figure 6A.3.3 Marker Beacon Signal Indicator Lights on the PFD

Garmin G1000 Audio Panel Pilot’s Guide190-00378-02 Rev. A 6A-9
OPERATION
NAVIGATION RADIOS
Pressing DME, ADF, AUX, NAV1, or NAV2 selects
and deselects the radio source and activates the annuncia-
tor. Selected audio can be heard over the headset and the
speakers. All radio keys can be selected individually or
together.
Figure 6A.3.4 Navigation Radios
When no further navigation radio audio is heard, the
amount of background noise is reduced by the Master Avi-
onics Squelch (MASQ) feature.
ENTERTAINMENT INPUTS
The current ICS isolation mode affects the distribution
of the entertainment inputs MUSIC 1 and MUSIC 2.
NOTE: MUSIC 1 and MUSIC 2 cannot be com-
pletely turned off. Audio level for these inputs
can be set above and below a nominal value.
Contact a Garmin-authorized service center for
adjustment.
MUSIC 1
MUSIC 1 can be heard by the pilot in COPILOT mode
and in ALL mode, and can be heard by the copilot in
PILOT mode and in ALL mode.
MUSIC 1 Muting
MUSIC 1 muting occurs when aircraft radio, marker
beacon or ICS activity is heard.
NOTE: MUSIC 1 muting during ICS activity can be
disabled. Contact a Garmin-authorized service
center for details.
Muting of MUSIC 1 is also triggered by marker beacon
activity when in ALL, CREW or COPILOT mode. After
muting ceases, MUSIC 1 gradually returns to its original
volume level. This characteristic is known as “soft mute.”
The time required for MUSIC 1 to return to its original
volume level at the headset outputs is between 0.5 and
4 seconds.
NOTE: If the MKR/MUTE key is pressed and held
for three (3) seconds, the GMA 1347 toggles
music muting ON and OFF during radio signal
reception. Upon toggling, either one (1) or two
(2) beeps can be heard; one (1) beep indicates
that music muting is enabled and two (2) beeps
indicate that music muting is disabled.
MUSIC 2
MUSIC 2 can be heard only by the passengers and is
never muted.

Garmin G1000 Audio Panel Pilot’s Guide 190-00378-02 Rev. A
6A-10
OPERATION
INTERCOM SYSTEM (ICS) ISOLATION
The intercom system (ICS) provides four (4) isolation
modes: ALL, PILOT, COPILOT and CREW. The desired
mode can be selected or deselected using the PILOT and
COPLT keys.
The possible ICS isolation states are summarized in the
table below. Table 6A.3.3 summarizes the ICS operation
for the four (4) ICS isolation modes and telephone distri-
bution.
PILOT Mode
PILOT mode is selected when only the PILOT key
is annunciated. In PILOT mode, the pilot can hear the
selected radios, the copilot can hear MUSIC 1, the pas-
sengers can hear MUSIC 2, and the copilot and passengers
can communicate with each other.
COPILOT Mode
COPILOT mode is selected when only the COPLT key
is annunciated. In COPILOT mode, the copilot is isolated
from everyone else. The pilot and passengers can hear the
selected radios and communicate with each other. In this
mode, the pilot can hear MUSIC 1, while the passengers
can hear MUSIC 2.
Current ICS Isolation State
Input PILOT COPILOT CREW ALL
PILOT Key Press ALL CREW COPILOT PILOT
COPLT Key Press CREW ALL PILOT COPILOT
Table 6A.3.2 ICS Isolation Mode Transitions
Figure 6A.3.5 ICS Isolation Keys
CREW Mode
CREW mode is selected when both the PILOT and
COPLT keys are annunciated. In CREW mode, both the
pilot and copilot can hear the selected radios
and com-
municate with each other, while the passengers can only
hear MUSIC 2.
ALL Mode
ALL mode is selected when the PILOT and the
COPLT keys are not annunciated. In ALL mode, everyone
hears the selected radios and is able to communicate with
everyone else. In this mode, both the pilot and copilot
can hear MUSIC 1, while the passengers hear MUSIC 2.

Garmin G1000 Audio Panel Pilot’s Guide190-00378-02 Rev. A 6A-11
OPERATION
Mode PILOT
LED
COPLT
LED
TEL
LED Pilot Hears Copilot Hears Passenger
Hears Input to Phone
ALL
OFF OFF OFF
Selected radios;
pilot; copilot;
passengers;
MUSIC 1
Selected radios;
pilot; copilot;
passengers;
MUSIC 1
Selected radios;
pilot; copilot;
passengers;
MUSIC 2
None
OFF OFF ON
Selected radios;
pilot; copilot;
passengers;
MUSIC 1;
TEL audio
Selected radios;
pilot; copilot;
passengers;
MUSIC 1;
TEL audio
Selected radios;
pilot; copilot;
passengers;
MUSIC 2;
TEL audio
Pilot; copilot;
passengers
PILOT
ON OFF OFF Selected radios;
pilot
Copilot;
passengers;
MUSIC 1;
TEL audio
Copilot;
passengers;
MUSIC 2;
TEL audio
Copilot;
passengers
ON OFF ON Selected radios;
pilot; TEL audio
Copilot;
passengers;
MUSIC 1
Copilot;
passengers;
MUSIC 2
Pilot
COPILOT
OFF ON OFF
Selected radios;
pilot; passengers;
MUSIC 1
Copilot;
TEL audio
Selected radios;
pilot; passengers;
MUSIC 2
Copilot
OFF ON ON
Selected radios;
pilot; passengers;
MUSIC 1;
TEL audio
Copilot
Selected radios;
pilot; passengers;
MUSIC 2;
TEL audio
Pilot; passengers
CREW
ON ON OFF Selected radios;
pilot; copilot
Selected radios;
pilot; copilot
Passengers;
MUSIC 2;
TEL audio
Passengers
ON ON ON
Selected radios;
pilot; copilot;
TEL audio
Selected radios;
pilot; copilot;
TEL audio
Passengers;
MUSIC 2 Pilot; copilot
Table 6A.3.3 ICS Isolation Modes & Telephone Distribution

Garmin G1000 Audio Panel Pilot’s Guide 190-00378-02 Rev. A
6A-12
OPERATION
VOLUME/SQUELCH CONTROL
When the GMA 1347 MAN SQ key is selected, press-
ing the VOL/SQ knob toggles between volume and
squelch adjustment. When the unit is in volume adjust-
ment mode, the VOL annunciation on the lower left of the
VOL/SQ knob is lit and volume can be adjusted. When
the unit is in squelch mode, the SQ annunciation on the
lower right of the VOL/SQ knob is lit and squelch thresh-
old level can be adjusted.
Figure 6A.3.6 Volume/Squelch Control
Current VOL/SQ State
Input Auto, VOL selected Manual, VOL selected Manual, SQ selected
MAN SQ
Key Press
Previous State:
Manual, VOL
selected
Manual, VOL
selected
Auto, VOL selected Auto, VOL selected
Previous State:
Manual, SQ
selected
Manual, SQ
selected
GMA 1347 VOL/SQ Knob Press Auto, VOL selected Manual, SQ selected Manual, VOL selected
Table 6A.3.5 Transitioning from Auto to Manual Squelch Mode
NOTE: When the MAN SQ key is not selected
(auto-squelch is active), pressing the VOL/SQ
knob has no effect on the VOL/SQ selection state
and VOL is automatically annunciated.
When transitioning from auto to manual squelch, the
unit returns to the previous VOL/SQ selection (see table
below).
NOTE: The volume and squelch controls for the
COM and NAV radios are located on the PFD and
MFD bezels (refer to the VHF NAV/COM Pilot’s
Guide for details).
Intercom VOL/SQ
Intercom Volume Control
Intercom volume can be controlled with the VOL/SQ
knob. The small knob controls the pilot ICS volume.
The large knob controls the copilot/passenger ICS vol-
ume. Turning either knob clockwise increases audio
level. Turning either knob counterclockwise decreases
audio level. When MAN SQ is off (key not annunciated)
volume adjustment is automatically selected and the VOL
annunciation is lit.

Garmin G1000 Audio Panel Pilot’s Guide190-00378-02 Rev. A 6A-13
OPERATION
To adjust ICS volume when MAN SQ is OFF
(key not annunciated):
1. Turn the appropriate
VOL/SQ knob.
To adjust ICS volume when MAN SQ is ON
(key annunciated), do one of the following:
1a. If the unit is in manual squelch threshold
adjustment mode (
SQ annunciation at the
lower right of the
VOL/SQ knob is lit), press the
VOL/SQ knob to toggle to ICS volume adjust-
ment mode, and turn the appropriate VOL/SQ
knob.
1b. If the unit is already in ICS volume adjustment
mode ( VOL annunciation at at the lower left
of the
VOL/SQ knob is lit), turn the appropriate
VOL/SQ knob.
Intercom Squelch Control
Each microphone input has an automatic squelch
threshold. Manual squelch override as well as keyed ICS
operation (for noisier cockpits) is also available.
The VOL/SQ knob manually adjusts squelch thresh-
old when the MAN SQ key is annunciated and the SQ an-
nunciation is lit. The small VOL/SQ knob controls pilot
squelch threshold and the large VOL/SQ knob controls
copilot/passenger squelch threshold. Turning either knob
clockwise increases the threshold. Turning either knob
counterclockwise decreases the threshold.
NOTE: In manual squelch mode, when the
VOL/SQ knob is adjusted to minimum, all crew
audio inputs can break squelch. When the
VOL/SQ knob is adjusted to maximum, the
ICS audio is heard only when an ICS PTT is
pressed.
To adjust squelch threshold level manually
when MAN SQ is OFF (key not annunciated):
1. Press the
MAN SQ key:
2a. If the
VOL annunciation is lit, press the VOL/SQ
knob for
SQ annunciation and turn the VOL/SQ
knob.
2b. If the
SQ annunciation is already lit, turn the
VOL/SQ knob.
To adjust squelch threshold level manually
when MAN SQ is ON (key annunciated):
1a. If the
VOL annunciation is lit, press the VOL/SQ
knob for
SQ annunciation and turn the VOL/SQ
knob.
1b. If the
SQ annunciation is already lit, turn the
VOL/SQ knob.
Volume Adjustments
The audio level of various signals can be adjusted if
desired by a Garmin-authorized service center.
MASTER AVIONICS SQUELCH (MASQ)
MASQ (Master Avionics Squelch) reduces ambient
noise from the aircraft radios. When no audio is detected,
MASQ processing further reduces the amount of back-
ground noise from the radios.
The Master Avionics Squelch (MASQ) threshold level
can be adjusted or disabled by a Garmin-authorized ser-
vice center.

Garmin G1000 Audio Panel Pilot’s Guide 190-00378-02 Rev. A
6A-14
OPERATION
DIGITAL CLEARANCE RECORDER WITH
PLAYBACK CAPABILITY
The GMA 1347 provides a digital clearance recorder
with playback capability of up to 2.5 minutes of COM sig-
nal recording. Recorded COM signals are stored in sepa-
rate memory blocks. Signals from all of the selected COM
radios are recorded and can be played back. Anyone able
to hear the selected COM radios is able to hear the COM
signal playback.
Once the 2.5 minutes of recording time have been
reached, the recorder begins recording over the stored
memory blocks, starting from the oldest block. Powering
off the unit automatically clears all recorded blocks.
Figure 6A.3.7 Playback
NOTE: In split COM mode the pilot or copilot
COM audio can be configured for recording and
playback. Contact a Garmin-authorized service
center for details.
The PLAY key controls the playback function.
• Pressing PLAY once plays back the latest recorded
memory block, then returns to normal operation.
• Pressing PLAY during playback of a memory block
halts the playback of this block and plays back the
preceding recorded block. The PLAY key can be
used to backtrack through the recorded memory
blocks to reach and play back any desired block.
NOTE: Pressing the MKR/MUTE key during
playback halts playback and returns the recorder/
playback to normal operation.
During playback, the PLAY annunciator light blinks
approximately once per second. If a COM input signal is
detected during playback, playback is halted and the new
COM input signal is recorded as the latest block.
NOTE: The recorder can be disabled using an
external switch or permanently disabled by a
Garmin-authorized service center.
NOTE: If the COM muting on receive option
is enabled, only the primary COM radio signal
reception is recorded by the digital clearance
recorder.

Garmin G1000 Audio Panel Pilot’s Guide190-00378-02 Rev. A 6A-15
OPERATION
REVERSIONARY MODE
The red DISPLAY BACKUP button selects the rever-
sionary mode for all displays. Reversionary mode opera-
tion displays important flight and engine information on
both the PFD and MFD, in case of display failure.
In dual audio panel configuration the DISPLAY
BACKUP button operates on the pilot side only.
Figure 6A.3.8 Reversionary Mode Button
COCKPIT VOICE RECORDER INTERFACE
The GMA 1347 provides the ability to interface to a
cockpit voice recorder (CVR). The unsquelched pilot mi-
crophone input (all vocal inputs from the pilot) is com-
bined with all audio heard on the pilot’s headset and cabin
speaker and is output to the pilot CVR channel. The un-
squelched copilot microphone input is combined with all
audio heard on the copilot’s headset and the cabin speaker
and is output to the copilot CVR channel.
DUAL PANEL OPERATION
In a dual installation, one GMA 1347 is in the pilot
position, the other is in the copilot position. The units are
referred to as the pilot side and copilot side audio panels.
Both the pilot and the copilot can transmit at the same
time from either the pilot side unit or copilot side unit.
ICS key selections (PILOT and COPILOT) and the
telephone key (TEL) annunciate together in a dual instal-
lation. When a key is pressed on either the pilot side or
the copilot side, both units annunciate the same selection.
COM3 MIC and the TEL have no priority.
NOTE: In dual configuration, the pilot always
hears the audio selected on the pilot’s audio
panel and the copilot always hears the audio
selected on the copilot’s audio panel.
Intercom operation of dual audio panels is identical to
that of single audio panel operation. The passengers hear
selected radios from the pilot or copilot side, depending
on the installation.
When ICS is connected to the copilot side in PILOT
mode, the passengers hear radios selected by the copilot,
the passenger audio, the copilot and MUSIC 2. When
ICS is connected to the copilot side in COPILOT mode,
the passengers hear the passenger audio, the pilot and
MUSIC 2
Simultaneous COM Transmission
Dual GMA 1347 installations allow both the pilot and
copilot to transmit simultaneously over separate radios.
When either COM transmitter is keyed, transmit-inter-
lock shuts off the other COM receiver. This prevents in-
terference from the active COM transmitter.
With two pilots aboard, transmit-interlock may in-
terfere with communications. When either the pilot or
copilot transmits on a COM radio, no audio is heard on
the other COM receiver. This means that if the pilot is
communicating with ATC on COM1, while the copilot is
transmitting on COM2, all of the pilot’s reception is lost
during the time of copilot transmission.

Garmin G1000 Audio Panel Pilot’s Guide 190-00378-02 Rev. A
6A-16
OPERATION
If transmit-interlock is not activated, all the selected
receivers are heard at all times. Without transmit-inter-
lock, during simultaneous transmission, interference may
be heard on the COM receivers. Transmission by one ra-
dio produces static or squeal, resulting in loss of commu-
nication on other radios.
Dual COM performance varies significantly depending
on the distance between the antennas and the tuned fre-
quency separation.

Garmin G1000 Audio Panel Pilot’s Guide190-00378-02 Rev. A 6A-17
OPERATION
Figure 6A.3.9 Dual G1000 Audio Panels (GMA 1347)
Reversionary
mode operates on
pilot side only
Speaker not available
on copilot side
Copilot Side Pilot Side

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190-00378-02 Rev. A © 2004 Garmin Ltd. or its subsidiaries