Garmin 190-00683-00 Manuale Utente

A datum is a mathematical model of the Earth that approximates 

the shape of the Earth and enables calculations to be carried out in a 

consistent and accurate manner. The datum is physically represented 

by a framework of ground monuments whose positions have been 

accurately measured and calculated on this reference surface. Lines 

of latitude and longitude on a map or chart are referenced to a 

specific map datum. Every chart has a map datum reference, and you 

can set the GPSMAP 378/478 to match most of those commonly 

used.

If you are navigating and comparing the GPS coordinates to a map, 

chart, or other reference, set the map datum in the GPS unit to the 

same datum as the map to ensure the most accurate navigation.

Your current location can be viewed on the GPS in the form of 

coordinates. Because different maps and charts use different 

location formats, Garmin GPS units allow you to choose the correct 

coordinate system for the type of map you are using. The most 

common format is latitude and longitude, which is used by all 

Garmin units. 
You can choose to change the location format to use with other 

coordinate systems in the Location field of the Setup tab—Location 

sub tab. UTM/UPS (Universal Transverse Mercator/Universal Polar 

Stereographic) are easy-to-use metric grids that are found on most 

USGS topographic quadrangle maps. You can also select one of 

several other grids, including a user-definable grid (for the advanced 

user). 
For more information about using paper maps with your 

Garmin unit, refer to Using a Garmin GPS with Paper Land 

Maps, available for download at 

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