Real-time Processing Model Of BDS/GPS Data At Sub-meter Level

BDS, GPS, GLONASS and GALILEO together compose the Global NavigationSatellite System (GNSS). BDS has formed the regional network in the end of2012.Subjected to the software and hardware, the system is still in the stage of rapiddevelopment.GPS occupies the most civil market of navigation and positioning. The projectsabout intelligent transportation and precision agriculture are mostly based on GPS, butrarely on BDS. Meanwhile, the required precision of these areas is improving, whichmakes the low-cost receivers fail to meet the standard. Since RTK always costs much,it is inappropriate to purchase more devices. As a result, improving the precision oflow-cost receiver will meet the demand of associated areas without increasing the cost.It makes sense and gains a promising expectation.The thesis relies on the key project of CAS knowledge innovation projects andpartnership project in science and technology of Ministry. The research is made onthe real-time processing model of BDS, GPS and combined BDS/GPS at sub-meterlevel using the low-cost receiver. The main contents and innovation lies in:1. The differencesin time and coordinate datum between BDS and GPSwereanalyzed, the way to unify the datum was given out, and the data fusion method wasstudied.2. The message type, structure, data check-up algorithm and decoding methodof RTCM was introduced, and was implement with python. In order to break throughthe distance limitation of radio, an approach of transmitting the GNSS data based onmodern mobile communications technology and NTRIP was discussed.3. Considering the data feature and movement characteristic, the real-timeprocessing model of single system at sub-meter level was proposed, and the exceptionduring the data acquisition, including the satellite lost, addition, pivot change andcycle slip, was worked.4. The real-time data transmission in a long baseline was researched based onthe cases of huaibei and Laos. The data acquisition platform was set up to verify its’validity and reliability.5. The method of combined BDS/GPS system was modeled, and the techniqueof the differential positioning with ambiguity resolution was research. The validityand reliability was verified according to the actual measured data.