Sony NV-U50T [93/96] Glossary

User's manual Sony Personal Navigation System

Glossary - 91 -

Glossary

COM-port A COM port is a connector to a communications interface, usually

the serial port. The ports are numbered by a number behind

"COM". A communications interface is designed to connect

hardware like a mouse or a GPS receiver.

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orbit, GMT has been replaced by UTC (Universal Time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

that 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 elevation 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 is

possible. The smaller the value is, the more accurate is the

position determination (value 0 = no deviation from the actual

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

POI Point of Interest (POI). See ÎSpecial destination.

RDS Radio Data Signal (RDS) is a service offered by broadcasting

stations. TMC information is broadcasted via RDS.

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.

TMC Traffic Message Channel (TMC) supplies your navigation system

with the latest traffic information. A TMC module which is

available as accessory receives the signals which are broadcasted

by radio stations.