Fast Acquisition Algorithm Based On Fft Correlator Gps Receiver Design

GPS plays a leading role in every field of civil life based on its advantage of high accuracy, all weather and strong real time, and it also possesses unlimited development future in military field. Correlator is the core part of the GPS and it determines the performance of GPS reciever. For our country starts relatively late on this kind of research and USA's export restriction on the correlator, available correlator fails to be applied in more fields. Then, self-research on correlator of high performance becomes a subject of breakthrough.High dynamic motion leads to large Doppler frequency shift to GPS signal and easy lose lock to tracking loop for carrier wave or pseudo random code. And it is difficult to maintain the carrier and code synchronization. So rapid acquisition of satellite signals and improvement of code tracking loop are both key parts to solve the problem caused by high dynamic motion. The article is all about rapid acquisition of satellite signals. First, it shows principle of correlator, and comparation of several common rapid acquisition algorithm. Secondly, it presents a new rapid acquisition algorithm, which is based on the capture in frequency domain algorithm. The new algorithm lead short fourier transform due to difference frequency. At the same time, the article show a method for shorten first positioning time with multi-channel.First, we plan the components and design the parameters of the multi-channel correlator in this thesis. Second, we use hardware description language(Verilog HDL) to program sub module and to realize systematic entirety; in fact, we carry out the function simulation and timing simulation for sub module and correlator entirety at Modelsim and then we can get the theoretical capture result of s.At last, we choose Field Programmable Logic Array(FPGA) as the realizing carrier; through the plate debugging on the GPS receiver based on the correlator, we prove that the correlator of multi-channel and high accuracy designed in this thesis can work well. And we also carry out flight test through live shell and realize first positioning time within 10s.