what elevation datum does my garmin gps use
First, what it is not. It is not a singular form of the word data which some of you may have heard. Data is a collective noun and the plural of datum is datums when used in a geophysical sense. For GPS, navigation, and geophysical use a datum represents a reference point from which you can measure things.ime is used in your gps to calculate position. The time used by your gps is a special gps time that is transmitted as part of the satellite message. In addition the satellite transmits information in the form of leap seconds adjustments to permit your unit to adjust the clock display to agree with standard UTC time.