Garmin GPSMAP 175 - Manual (Page 38)

A. To calibrate map,
highlight ‘Calibrate
the Map?’ option and
press EDIT/ENTER.
B. A satellite icon will
remain on the map
to indicate the GPS
position, while the
boat marker will
reflect calibration
changes.
Caution : The map calibration function should never be used
to attempt corrections to Selective Availability errors.
MAP PAGE
Map Configuration & Map Colors
The map configuration options page also features a map calibration
function that allows you to calibrate the map display with your exact physical
surroundings or correct data from older charts. Before using the map
calibration function, check to make sure that your map datum selected on the
GPS matches the datum on the chart you are using (see page 84-88). To
calibrate the map display, you must know exactly where you are, and
understand that the correction is generally valid only in a limited range from
the point of correction.
Map calibration should only be performed while your vessel is not moving,
and should never be used to attempt SA corrections, which can degrade
accuracy up to 330’ (100 meters). The maximum correction is 16,400 feet (5000m).
To calibrate the map:
1. Select the ‘Calibrate the Map?’ option and press T.
2. Use the R keypad to move the arrow cursor from the satellite position
(indicated by the satellite icon) to your exact position. The bearing,
distance and position will be indicated in the data window.
3. Press T to confirm the calibration offset.
The next option available from the map configuration page is the set map
colors option, which allows you to define the fill color (grayscale) of the land
and water used on the map display. Three options are available: no color (no
fills for land or water), gray land/white water (the default setting), and white
land/gray water.
To select a map colors option:
1. Select the ‘Set Map Colors?’ option and press T.
2. Highlight the desired map color option and press T.
The map configuration options page also features a ‘restore defaults’
function that can be used to quickly restore all map configuration options to
the factory settings.
To restore the map configuration options to the factory defaults:
1. Highlight the ‘Restore Defaults?’ settings and press T.
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175 Manual 7/31/98 3:56 PM Page 34