Research On The Countermeasures Of GPS Navigation

Global Positioning System(GPS)is becoming more and more important in modern war and it can influence the process and result of the war. The jamming and the anti-jamming to GPS will become important parts in future war, and are getting more and more attentions. There are many methods that can make GPS useless, including destroying the GPS's ground control center and GPS satellites, but the interference to GPS positioning signal is an important part. This paper is focused on how to interfere GPS positioning signal in order to make the signal unusable.First, the paper introduces the structure of GPS, analyses the GPS positioning signal. Then the paper gives detailed analysis how GPS receiver can achieve anti-jamming as a theoretical preparation for following work.From the bandwidth of in terference, interference can be classified into two parts:narrowband interference and broadband interference. GPS has a good anti-jamming capability to interference, especially to narrowband interference. So, in order to efectively interfere GPS signal, broadband interferences have to be used. The broadband interferences that the paper concerned first are broadband noise and pulse interference, which are better than continuous wave (CW). Further more, according to the GPS's signal character, another two kinds of broadband interferences named "on-off" interference and m sequence interference paper are also studied. Analyses show that m sequence interference is the most harmful interferenceto GPS if special m sequence is adopted.The following part is simulation, in cluding simulation of GPS positioning signal, GPS transmiting and receiving system,and interference to GPS waveform. As the power of interference increases, the signals are more and more deteriorated. Bit error probability is an important parameter in communication system, so it is used to evaluate the performance of the interference. The interferences will also influence the error acquisition probability. From simulation results, it can be seen that different interferences have different interference effects, CW interference is bad, broadband noise, pulse interference and "on-off" interference are better, proper m sequence interference is the most harmful interference to GPS.