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GMR 404/406 Owner’s Manual 1
bAsIc oPerAtIon > understAndIng rAdAr
basIc operatIon
This section covers the features and operation of the GMR 404/406.
Understanding Radar
The GMR 404/406 transmits a narrow beam of microwave energy
in a rotating 360° pattern. When the transmitted energy contacts a
target, some of that energy is reected and returned to the scanner.
The scanner collects the returned energy to process and display.
Your GMR 404/406 is operated and adjusted using controls on your
Garmin Marine Network chartplotter. You can view radar data on the
Radar Page or as an overlay on the Map Page. All radar controls are
accessible from both pages.
When you turn on the radar, the status bar shows the message “Radar
Warming Up” with a countdown to Standby Mode. The countdown
also appears in the middle of the Radar Page. When the countdown
reaches 0 (zero), the “Hold FCTN to transmit” message appears.
As a safety feature, the radar enters standby mode after it warms
up. This gives the operator an opportunity to verify that the area
around the scanner is clear before beginning radar transmission. It is
important to remember that the microwave energy transmitted by the
scanner can potentially be dangerous.
CAUTION: The GMR 404/406 transmits microwave energy that
has the potential to be harmful to humans and animals. Before
beginning radar transmission, verify that the area around the radar
is clear. The radar transmits a beam approximately 12° above and
below a line extending horizontally from the center of the scanner.
Avoid looking directly at the scanner, because the eyes are the
most susceptible part of the body.
When the area surrounding the scanner is clear, press and hold
FCTN. The message “Do you want to begin radar transmission?” is
shown. Select Yes, and then press ENTER.