Dual Panel Operation; Simultaneous Com Transmission - Garmin G1000 Reference Manual

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.
Garmin G1000 Cockpit Reference Guide for Cessna Nav III
SECTION 4 – AUDIO PANEL
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.
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.
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