Study On Pn Code Tracking Loop Caused By Multi-user Interference In BOC Modulated Signal Of Satellite Navigation System

Under the exist for pseudo satellite and satellite power enhancement technology the received power imbalance make MAI issue that can not be ignored and become one of the prominent influence on receivers code tracking loop performance,the main work of this paper is to analyze the code tracking performance effected by MAI on BOC modulation techniques.The main work and innovation of this paper are:1.When the cross-correlation function of the magnitude increase it will leading to a serious distortion of the autocorrelation function,qualitatively explain how MAI affect code tracking loop performance.Then get a more accurately model,considering the characteristics of the spread code cycle power spectral density of BOC modulated signal,periodic discrete spreading code signal spectral power density spectrum has a series of spikes separated by 1kHz,the peak changes in existence for nearly 25 dB compared to ideal spreading code signal power spectral density.2.First,deduce the analytical expression of pseudo-code tracking error from making the discriminator output functions to zero,then comprehensive analyze the impact of the law of the pseudo code phase modulation order,the user power difference and the associated spacing indicators for crosscorrelation to autocorrelation extremum ratio and pseudo-code tracking error,come in the conclusion that,when multiple access signal is 20 dB higher than the desired signal,the pseudo-code tracking error can be up to 0.12 chip.3.First,derivepseudo-code tracking standard deviation of expression considering the classic code tracking accuracy formula.From the power spectral density of multiple access signal and desired signal,then systematically analyze the doppler frequency difference,correlator spacing,modulation order,power and users power difference effect law on evaluation index for code tracking spectral sensitivity and incoherent loss spectrum isolation and pseudo-code tracking standard deviation,the equivalent CNR biggest loses reach 9dB draw when the desired user is 10 dB higher than the desired signal.