Research On Channel Characteristics And Receiving Technology Of New Satellite Navigation System

At present,the signals' carrier frequencies of Global Navigation Satellite System are mainly concentrated in the L-band,so the frequency band is very crowded.In order to make better use of the limited frequency band resources,satellite signals modulated by Binary Offset Carrier(BOC)are widely used as new satellite navigation system signals.This thesis mainly studies the channel characteristics and receiving technology of the new system satellite navigation signal.The main work includes:The characteristics of satellite navigation channel are studied.The satellite navigation channel model is constructed by combining the multi-state satellite statistical channel model based on Markov chain with the tapped delay line(TDL)model,in which the relevant measurement statistics of ITU and DLR are extracted as a reference.It takes into account the characteristics of signal fading and delay in navigation application scenarios,which lays a foundation for the research of signal receiving technology.The unambiguous acquisition and tracking technology of BOC modulated signal is studied,and its practicability is verified by the constructed navigation channel.Firstly,taking B1 C signal as an example,the time-frequency domain characteristics of BOC modulation signal are analyzed.Its split spectrum characteristics can not only alleviate the congestion of frequency band,but also provide narrower correlation main peak and improve some performance when receiving and processing satellite signals.However,this modulation type of signal also brings the fuzziness of acquisition and tracking because of the multi-modal characteristics of the correlation function.Traditional unambiguous acquisition algorithms always face problems such as weak universality or reduced acquisition probability.In this thesis,an unambiguous acquisition algorithm for BOC signals named assignment weights to cross correlation function(AWCCF)which is suitable for positive integer modulation order is proposed.Through the simulation in white Gaussian noise channel and the constructed navigation channel,it is proved that this method has better capability of unambiguous acquisition than several classical unambiguous acquisition algorithms,and the effectiveness and practicability of the algorithm are verified.Because this method extracts the characteristics of some chips of signal for combination,the reconstructed correlation function will be sensitive to short-time multipath signal when applied to the tracking module.Therefore,a multi-layer perceptron based on extended Kalman filter is proposed for further processing.Through simulation analysis,the processed results effectively eliminate the sensitivity of tracking,and the capability of anti multipath is better than the traditional unambiguous tracking algorithm.