User's Manual MobileNavigator6

8 Glossary

GMT

GMT (Greenwich Mean Time) is the mean solar time at the Royal

 

Greenwich Observatory in Greenwich near London, England,

 

which by convention is at 0 degrees geographic longitude.

 

Theoretically, noon Greenwich Mean Time is the moment when

 

the Sun crosses the Greenwich meridian (and reaches its highest

 

point in the sky in Greenwich). Up to 1972, GMT was the global

 

time standard. Because of the Earth's uneven speed in its elliptic

 

orbit, GMT has been replaced by UTC (Universal Time

 

Coordinated) which is an ultra stable time standard based on

 

atomic clocks.

GPS

The GPS (Global Positioning System) is based on 24 satellites

 

which are in orbit round the earth. They are permanently

 

emitting the time and their current position. The GPS receiver

 

receives this information and calculates the longitude and the

 

latitude of its own current position. The signals of at least three

 

satellites are needed to determine the longitude and the latitude.

 

With the signals of at least four satellites the altitude may be

 

calculated, too. The determination has an accuracy of about 3

 

yards.

HDOP

The Horizontal Dilution of Precision (HDOP) indicates the quality

 

of position determination. Theoretically any value from 0 to 50

 

may occur. The smaller the value, the more accurate is the

 

position determination (value 0 = no deviation from the real

 

position). Values up to 8 are convenient for navigation purposes.

POI

Point of Interest (POI). See: Special destination.

Special destination

Special destinations, also called POI (Points of Interest), are

 

covered by the map and may be displayed on it. Harbours,

 

airports, restaurants, hotels, petrol stations, public buildings, and

 

others belong to the special destinations. You may determine

 

special destinations as itinerary points for navigation purposes.

Glossary

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Navigon MN 6 user manual Glossary