Research On The GPS And Pseudo Satellite Receiver With Frequency Division Multi-Channel And An Anti-Jamming Technique

With the development of science and technology,people's demand for high-precision navigation and positioning is increasing.Compared with other navigation and positioning systems,GPS satellite positioning system is still one of the most widely used navigation technologies.However,in some scenarios where high accuracy is required and signals are easily blocked,the GPS satellite positioning system still has application limitations in which positioning accuracy and reliability cannot be fully guaranteed.Pseudo-satellites can be an effective complement to GPS operations,which can improve navigation performance and geometric accuracy.At the same time,pseudo-satellites can also be independently networked.However,there are problems of multipath effect and near-far effect in the combination of pseudo-satellite and GPS satellite systems or independent networking.The multipath effect will seriously affect the positioning accuracy,and the near-far effect will affect the normal operation of the receiver.Pseudo satellites can use TDMA technology to suppress the near-far effect,but the clock synchronization requirements are very high.In the context of the combined application of GPS satellites and pseudolites,this paper proposes a technical solution for GPS and pseudolite frequency division multi-channel receivers.The receiver can simultaneously receive GPS signals and pseudolite signals without interfering with each other.Complete the design and implementation of the receiver on the basis.At the same time,the anti-multipath technology in the pseudo-satellite indoor dense multi-path application environment is studied,and a dual-antenna pseudo-satellite anti-multipath technical solution is designed,which has a better effect on improving the anti-multipath performance of the pseudo-satellite system.The main contents include:(1)Aiming at the problem of multipath effect in indoor pseudo-satellite positioning system,a multi-path fading scheme based on STBC(Space Time Block Coding)dual-transmit antenna single-receive antenna diversity is designed.At the receiving end,two independent received signals are obtained by frequency domain channel estimation and maximum likelihood decoding,and the two signals are combined by the EGC(Equal Gain Combining)algorithm.It is verified by MATLAB simulation that the scheme can effectively suppress the multipath effect in the indoor environment and significantly improve the signal-to-noise ratio of the signal.(2)Aiming at the problem of near-far effect in the application of GPS and pseudo-satellite hybrid positioning system,according to the GPS signal structure and system,the overall technical scheme of the GPS and pseudo-satellite frequency division multi-channel receiver is completed.(3)Using software radio design ideas and architecture,using LMS6002 D as a broadband radio frequency front-end module,and FPGA + DSP architecture as a baseband signal processing module,completed the design of the hardware solution.(4)According to the overall technical scheme and the design idea of frequency division multiple access,in response to the technical requirements of resisting near and far effects,a frequency division multi-channel digital front-end signal processing scheme design and verification was completed,which realized the division and distribution of frequency and spectrum And interference suppression.(5)Based on the analysis of the existing signal acquisition algorithm and tracking algorithm,the PMF-FFT acquisition algorithm is improved.The differential coherent accumulation algorithm,triangular polynomial interpolation algorithm and windowed PMF-FFT acquisition algorithm are combined to improve the system acquisition probability and Puler frequency estimation accuracy.(6)According to the requirements of the overall technical plan,the design,debugging and verification of GPS satellite and pseudo-satellite frequency division multi-channel receiver software have been completed.(7)Experiments were conducted on the GPS and pseudo-satellite frequency division multi-channel receiver.The test results verified the correctness and feasibility of the GPS and pseudo-satellite frequency division multi-channel receiver design.