TH-D72A/E - N3UJJ

4 GPS4.1.2 Datum (Geodetic Survey System)The latitude and longitude information required by the GPS receiver does not allow for accuraterepresentation of the unevenness of the Earth’s surface. For use with GPS, the current standard thatdefines the precise shape of the Earth is called WGS-84. By using this standard in conjunction withmapping standards for each country, accurate position plotting on a map can be done.4.1.2.1 GPS and APRS Position FormatAlthough position can be described in many different formats, such as degrees, degrees andminutes, and degrees, minutes and seconds, the GPS system and APRS have standardized on thedegrees and decimal minutes format. Just like it is important to use proper international phoneticswhen spelling on the air, it is important in APRS as in any communications system to have a defaultstandard for position. All operators should be trained to use the DDD MM.mm format by default invoice communications just like in the data formats. Using these standards on the air will preventcommunications errors, confusion, repeats, and conversions.APRS Standard:GeographicCoordinatesLatitudeLongitudeFormatDD MM.mm(degrees and minutes)DDD MM.mm(degrees and minutes)39 49.31N+39 49.31Example84 15.39W-84 15.39TH-D72A/E CONTENTS 25From The N3UJJ.COM Document Library