Design And Realization Of Tracking Loop In GPS Receiver

Global Navigation Satellite System is the radio-navigation system established by all of the global navigation satellite, and we can use GPS system, European Galileo system and Russia's GLONASS and China's Compass for navigation and positioning. Due to the advantages of GNSS, GNSS receiver has become a hotspot. As is known to all, Tracking algorithm is very important in GPS receiver. This thesis mainly studies the design and realize of tracking loop and algorithm.Firstly, the thesis takes GPS as the study object, it describes the function modules of GPS receiver. and the process from GPS satellite signal to decoding the data in GPS receiver is introduced. Besides, mainly analyzes the design of tracking loop. Including carrier track loop, code track loop and Loopfilter of FLL, PLL, DLL, and tne appropriate algorithms of them is determined for GPS receiver. Then introduced the relationship between the measurement error and the tracking threshold, they are very important when setting the loop parameters. In the loop design, in order to improve the tracking loop performance, this algorithm has been improved int the thesis.the technique of FLL assisted PLL used to improve the performance of the carrier tracking loop, and the technique of carrier tracking loop assisted code tracking loop used to overcome the code Doppler. the techniques have been realized in tracking loop, The test results show that the improved algorithms are fully able to meet the the requirements of tracking and positioning in the statiic environment. INS(Inertial Navigation System) are put forward for high dynamic environment, INS-aided techniques have also been realized in tracking loop, but need to be tested infutre. Finally, the thesis gives a large number of test results to assess performance of tracking loop, according to the test results, Satellite signal is tracked stably in the conditions of user's speed up to 900m/s, the performance of the tracking loop run stably in this systemand meet the system design requirements.