Research On Receiving Channel Equalization Methods Of GNSS Signals Quality Assessment

GNSS Quality Assessment System is an evaluation system focusing on themonitoring and analysis of navigation signals. In practice, in view of the complexstructure of this system, many factors will affect the performance of the channelresulting in the signal distortion in the receiving end. Therefore, researches andanalysis will be conducted from the characteristics of the channel and the causes forthe distortion and then the corresponding solutions will be tried to developed. Basedon this, the results of signal quality assessment may accurately reflect thecharacteristics of the signal, which will help further promote the progress in spacesignal quality assessment.This thesis focuses on the characteristic parameters, imitating and analyzing theinfluences of the characteristics of the channel on the signal quality, exploring andtestify the feasibility of the adaptive channel equalization method.The thesis will cover the following parts:1. The mechanisms of receiving antennas, RF cables, low noise amplifier (LNA)and other facilities are studied and the influences of various devices on the signal areanalyzed.2. The principle of equalization algorithm is discussed from the perspectives ofthe time domain and frequency domain by imitating and analyzing the influences ofthe channel equalization method on the signal quality and the performances of thetwo equalization algorithms are compared.3. The classic adaptive equalization method of time domain is studied and theleast mean square (LMS) algorithm and recursive least squares (RLS) algorithm arefurther deduced. Meanwhile, the convergence speed and steady-state error of the twoalgorithms are compared.4. By taking the BPSK（10）and BOC（10,5）as examples, the power spectrum,time-domain waveform, constellation diagram and other properties before and afterequalization are imitated and analyzed, during which process the equalizationmethod is testified.5. Four kinds of channels are established including the ideal channel,amplitude-frequency and phase-frequency distortion channel, amplitude-frequency distortion channel and phase-frequency distortion channel. Taking the BPSK（10）as input which is generated from capturing the signal source, characteristics likepower spectrum and time-domain waveform before and after equalization arecompared and analyzed in terms of software simulation.