If the GPS machine is new, it needs positioning. There are a number of settings, such as coordinate system, the base map, the reference position, metric / English, and the data interface format, etc.

Coordinate system: it is commonly used LAT / LON and UTM. LAT / LON is latitude and longitude.

Base map: generally use WGS84.

Reference position: that is where the North. In fact there are two norths the CB and ZBY.

Compass refers to the CB, the Plough is ZBY. Both in different parts have different angle, the North in the map is ZBY.

Metric / English: own election.

Data interface format: GPS real-time location data can be exported for other equipment to use, data exchange, now almost all GPS receivers have to follow the the standard specifications prescribed by U.S. National Marine Electronics Association, which set communications standards among all electronic navigation equipment, including transmission data format and data transmission protocol. NMEA agreement has three kinds 0180,0182 and 0183, and 0183 can be considered to be a superset of the first two, are now widely used, the 0183 has V1.5 and V2.1versio. Therefore, if your GPS receiver is linked to GPS navigation procedures in the common laptop, , such as OZIEXPLORER and GPSRECEIVER, you should choose NEMA V2.0 above agreement. NMEA communication speed is 4800 b / S. At present, some receivers will be able to provide higher speed, 4800 is sufficient.

As GARMIN, has a mapsource software, in order to not allow other brands to use the GPS software, it designs a private agreement GARMIN, only GARMIN machine can output data and only MAPSOURCE can receive GARMIN agreement, so MAPSOURCE only allow GARMIN machine to use.

Latitude and longitude
Generally the data from GPS is the latitude and longitude. There are many ways.
1. ddd.ddddd
2. Ddd.mm.mmm
3. Ddd.mm.ss

In the LAT / LON coordinates, the latitude is the average distribution from the Antarctic to the Arctic, a total of 180 latitudes. Earth's diameter is 12756KM, the perimeter 12756 * PI, a latitude 12756 * PI / 360 = 111.133 KM (inaccurate).

It is not the case on the longitude, only latitude in zero, just on the equator, a longitude distance is 111.319KM, as the increase of latitude, longitude is getting closer, and at last intersect in north and south poles. Therefore, the longitude's unit distance is closely related to where the latitude is, the simple formula: 1longitude length = 111.413cos, in latitude.