Research For Enhancement Technology Of Satellite Navigation In Complex Environments

Satellite navigation system is playing a more and more important role in civil and military. Butbecause of the interference easily of the satellite navigation, the positioning accuracy of satellitenavigation will be reduced or even completely unavailable, so it is imperative to enhance thenavigation signals in some special cases. This paper presents two enhancement methods of satellitenavigation. The first method is the differential enhanced positioning without interference. We use theobservations got by two CC50-BG satellite navigation modules of double system for the differentialdata processing of the pseudorange, and realize the short-baseline difference positioning. The othermethod is the research of launching the navigation enhanced signal aheap in the satellite broadcastsignal with interference. Transmit the differential correction data after spectrum spreading. Let thesignal spectrum and the satellite broadcast signal spectrum overlap, and retransmit them by thesatellite.First, analyse the principles of data acquisition and the format of data collected by CC50-BGsatellite navigation module, and generate the user file and the ephemeris file. Then use the ephemerisfile to solve the satellite position in the signal transmission time. Use the observations and the satelliteposition for the differential positioning. Design the interface in Matlab and give the differentialpositioning accuracy. Data showed that: at a specific close distance experimental measurement point,the GPS satellite smoothing differential enhanced positioning improves the accuracy in the height byabout60%.Second, analyse the principle of spectral overlap, and choose the WorldSpace satellite signals tocover the differential enhanced signal. Give the mathematical models of the two signals, and designthe overlapping spectrum transmission system of the two signals. Design the differential receiver, andthe differential receiver can get the differential enhanced signal from the mixed signal by thesuccessive interference cancellation. Use the software receiver to test the extracted signal, and we willknow that the differential enhanced signal has little effect on the reception and the demodulation ofthe broadcast signal. The differential receiver can despread and secondarily measure distance by usingthe differential enhanced signal. When the mixed power ratio is26dB, the acquisition probability is99.99%, and the ranging accuracy is10.67m, which prove the feasibility of the method.