The composition of GPS system
GPS consists of three segment parts:
Space part: 21 working satellite, 3 spare satellite
The ground support system:1 main control station, 3 injection station, 5 monitoring station
User equipment part: receive GPS satellite transmitting signals to obtain necessary navigation and positioning information, through the data processing to complete navigation and positioning work.GPS hardware typically consists of host, antenna, power supplier.
The general principle of GPS positioning is based on moment place of satellite high-velocity motion is taken as known initial data. Use the method of space distance resection is used to confirm the location of the point to be measured
DGPS principle:
Currently the positional accuracy provided by GPS system is superior to 10m. and in order to obtain the higher positional accuracy, we usually adopt the differential GPS technology:one GPS receive is placed on standard station for observation, according to the known coordinates of standard station to calculate the distance between the standard station and the satellite, and the data is transmitted by the standard station in real time.When the user receives the GPS observation, it also receives the correction from the standard station and correct the location result,thus improving the positioning accuracy.