Design Of The Network Dgps Receiver

GPS system was fully completed in the early1990s. It has been wisely used which ranged from the early military, nautical, surveying, geology and other fields, and gradually to the location-based services (LBS), traffic control management, land resources survey, logistics, especially in precision agriculture.As the GPS standard positioning service accuracy is not high, so people often use differential methods to improve positioning accuracy.While the conventional difference method can eliminate most errors though interference, but there are also a fatal drawback that the positioning accuracy is getting lower as the distance between the mobile user receiver and the base station increased.The emergence and development of the CORS system (Continuously Operating Reference System) has become possible to eliminate such shortcomings.The purpose of this study is to design the network differential GPS receiver in the embedded platform which used the correction data from the JSCORS (Jiangsu Continuously Operating Reference Station). This GPS receiver hardware part is mainly composed by the GPS OEM board, ARM development board, GPRS Modem. The software application program which can run on the Windows CE5.0operating system easily was developed by EVC4.0. The main purpose of the design of the receiver is to replace the expensive GPS navigation equipment which is currently used on Autonomous Agricultural Mobile Robot. Firstly, the CORS development history is reviewed. After the several mainstream network RTK technology introduced according to CORS, the one of other main function of CORS, which is named RTD, was discussed. Secondly, the network RTD software of mobile users which can run in the Windows CE5.0operating system is completed based on the analysis of the RTCM data format, NTRIP communication protocol, GPRS communication technology as well as Internet communication foundation of Windows CE5.0. The application software mainly involves the serial port communication and the network communication technology and so on in the Windows CE5.0operating system. Finally, the reliability and positioning precision of this equipment were analyzed with the data collected from experiment which was done on the laboratory building roof and the parking of Enginering College of Nanjing Agricultural University.