Research On GNSS Reflection Signal Processing Method Based On The Principle Of Bistatic Radar

Global Navigation Satellite System-Reflection(GNSS-R)provides a new type of technical means for the detection of moving targets.It is an important research branch in the field of remote sensing.Its technical feature is a navigation satellite that uses target reflection.The pseudo-random code signal or carrier signal extracts the parameter characteristics of the target.In practical applications,due to the special modulation method of the navigation satellite signal,the echo of the moving target is affected by the Doppler frequency shift,which causes the target to be unable to be detected on the time delay-Doppler image,so it needs to be processed accordingly.In this thesis,the global positioning system(Global Positioning System,GPS)satellite reflected signal as an example,through the establishment of the target reflection model,carried out the research on the processing method of the GNSS reflected signal of different targets,the main work of the thesis is as follows:1.Analyze the composition and working principle of the GPS satellite system,focusing on the waveform properties,correlation characteristics,ambiguity performance of GPS satellite signals,the power of the target reflected signal,the signal-to-noise ratio and the maximum detection distance of the signal,in order to explore the bistatic radar The principle GPS reflected signal target detection system provides theoretical support.2.Carried out the research of signal processing method based on GPS satellite weak reflection signal,mainly for the signal processing in the receiver reference channel and echo channel.According to the characteristics of GPS signal pseudo-random code,this thesis proposes a signal purification algorithm for separating multiple time-frequency aliasing satellite signals.This method can extract the required reference signal from multiple satellite signals.Then several time-domain adaptive filtering algorithms are studied,and the Extensive Cancellation Algorithm(ECA-B)is used to suppress the direct wave,multipath clutter and other components in the echo signal,and finally the reference signal,echo The signal undergoes time Delay-Doppler coherent detection.3.Carried out the research of moving target detection based on GPS satellite reflection signal.By establishing a moving target echo model,analyzing the influence of the Doppler frequency shift effect of the moving target echo on the output of the matched filter correlation and the time Delay-Doppler image peak value,the Doppler distance optimization based on phase correction is proposed.Compensation algorithm.The simulation experiment proves that the algorithm can eliminate the Doppler frequency shift effect of the echo and restore the peak value of the target in the Delay-Doppler image to normal.4.In view of the low signal-to-noise ratio of the reflected signal,which is not conducive to target detection,this thesis improves the traditional signal accumulation algorithm,using the navigation data of the reconstructed reference signal and the local pseudo-random code for modulation,so that the reflected signal is in progress.During correlation processing,avoid the loss of signal integral gain due to data jumps,so as to obtain higher signal integral gain.Finally,simulation experiments prove the effectiveness of this improved algorithm for improving the signal-to-noise ratio of the reflected signal.