Research On Technologies Fo GPS Receiver Anti-jamming

Along with the increasing quantity and extension of application in the military and civil field, the scholars inside and outside have been paid more and more attentions to the anti-jamming problem of GPS receiver, simultaneously, the GPS anti-jamming technology based on array signal processing gradually becomes a research focus now. The blanket jamming is the supreme menace among the interferences for GPS, while the suppression of GPS multipath signal ensures the high-accuracy positioning availably. The thesis makes an in-depth research on the GPS anti-jamming technologies used in two different application conditions based on array signal processing and the GPS multipath rejection.A GPS research platform is designed by adopting software simulator to generate IF GPS signals, the GPS C/A code spectral characteristic is utilized to discuss the affection on the performance of acquisition by CW interference, and the effects to the noise power in acquisition of the parameters of FM-AM, wideband noise signal and the coherent integration time, non-coherent integration time are analysed in detail, and the Monte Carlo model is adopted for the research on the effects to the output bit error rate of these interferences.The computational complexity of the conventional beamforming is O(n3), and the estimation error of the interference DOA effects the performance deeply, although the rank-reduced STAP of Multistage Wiener Filter(MWF) reduces the computational complexity to O(n2), it needs the reference signal, while the GPS anti-jamming based on the subspace tracking technique only requires the DOA of the signal of interest(SOI). It is discovered that the FAPI algorithm has better subspace estimation performace and convergence performace, by discussing the effect of the interference number to this kind of GPS anti-jamming methods. An estimation method of the effective interference number that is suitable for the methods and a novel anti-jamming scheme are proposed. By comparing it with the conventional beamforming and MWF, the advantage of the novel one is obtained. Aiming at the property of the GPS C/A code, the technique of blind GPS anti-jamming receiver based on constant modulusalgorithm (CMA) is analysed in detail, and the problems which are about digital code, computational complexity and convergence time are solved. A modified blind GPS anti-jamming receiver is proposed, and the computer simulations validate it. In the modified scheme,10ms' data is adopted for despread, and the convergence time is reduced to 0.2ms. This method is very suitable for the receiver which is in the tracking condition.The code phase error and the carrier phase error performances caused by the GPS multiputh signal in-depth are discussed. By analysing the GPS multiputh suppression based on narrow correlator, MEDLL, Strobe correlator, enhanced Strobe correlator and E1/E2 correlator, it is known that all of them have a weak capability when short multiputh signals exist. Sometimes the code phase error is positive, and sometimes it is negative. the adaptive multipath estimation and elimination technique are analysed, and a modified scheme is proposed. The time between the two taps determine its performance straightly. The modified adaptive multipath estimation and elimination technique is better than the classical methods, and it can give a better suppression performance for short multiputh signals.