Lowrance AirMap, Installation And Operation Instructions Manual

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36
ing the satellite, or a "S" if the receiver is
searching for it. ELV is the elevation of the sat-
ellite above the horizon; AZM is the azimuth,
or direction of the satellite from your location.
SNR is the signal-to-noise ratio. The higher the
SNR, the better.
If you look at row one in the satellite info screen
at right, channel 1 is tracking satellite number
28. The satellite's elevation is 25 degrees above
the horizon and it's azimuth is 44 degrees. It's SNR is 44, which is good.
The FIX numbers in the lower left corner of the screen show the quality of
fix. If the FIX is 9, then it's the best you can get. A FIX of 1 is the worst. The
DOPS display beneath the fix quality show you the "Dilution of Precision"
for the horizontal (HDOP), geometric (GDOP), position (PDOP), time
(TDOP), and vertical (VDOP). The GDOP is a combination of HDOP, VDOP,
and TDOP. The smaller the DOP's value, the better. The receiver selects
satellites based on the GDOP value, therefore, it always tries to use sat-
ellites that have good DOP values. These depend on the azimuth and
elevation of the satellite, and any ground based obstructions.
The circular plot in the lower right corner of the screen shows a graphical
view of the satellites that are in view. Each satellite is shown on the circu-
lar chart relative to your position. The point in the center of the chart is
directly overhead. The small inner ring represents 45° above the horizon
and the large ring represents the horizon. North is at the top of the screen.
You can use this to see which satellites are obstructed by obstacles in
your immediate area if you hold the unit facing north.
The GPS receiver is tracking satellites that are surrounded by a black
box. If the satellite number is not surrounded by a box, then the receiver
hasn’t locked onto that satellite and it isn’t being used to solve the posi-
tion.