Modeling And Research On Radio Frequency Channel And Receiving Scene Of Satellite Navigation Signal

The Beidou global system B1 frequency adopts Binary Offset Carrier(BOC)modulation,pilot and data separation and multiplexing technology,which have characteristics such as occupying a large bandwidth,multiple correlation peaks and complex modulation constellation.Higher requirements are imposed on the characteristics of the navigation signal transmission channel.During the orbit test,the navigation signal distortion caused by the channel characteristics has occurred many times.Therefore,the optimization of navigation signal quality needs to research the influence of channel characteristics on signal quality.Based on the realization of the signal simulation software,this paper also conducted in-depth research on the characteristics of the spatial environment and the influence of the receiver motion status on signal ranging performance.The main research contents in this paper are as follows:(1)Global Navigation Satellite System(GNSS)signal simulation software was proposed based on Matlab platform.It can realize the generation of multiple high-precision GNSS signals with flexible and adjustable parameters.Signal segmentation generation technique was adopted in this paper to solve the problem of occupying too much memory for generating GNSS signal data.Moreover,high-precision continuous sampling technique was adopted to ensure the continuity of the GNSS signal sampling in this paper.The GNSS signal simulation software provides a verification platform for navigation signal system verification and quality assessment research.Furthermore,the software defined receiver was adopted to verify the correctness of the navigation signals generated by simulation.(2)The equivalent baseband analysis models were proposed in this paper,which based on the nonlinear distortion characteristics of the components for the RF channel on the satellite payload.This models can be thought of researching the influence of the characteristics for the RF channel on the satellite payload on the navigation signal.The results show that the phase noise of the direct quadrature up-converter method,the phase distortion characteristic of the filter and the high power amplifier memory polynomial model have a great influence on the change of the navigation signal S curve,which affects navigation signal ranging performance.(3)The navigation signal generation models under multipath environment with specular reflection and near-surface reflection were proposed in this paper.This models can be thought of researching the influence of the multipath interference on the navigation signal.Moreover,the research on the combined receiving algorithms for Quadrature Multiplexed Binary Offset Carrier(QMBOC)signal under multipath environment was carried out in this paper.The results show that the Double Estimator Technology(DET)and High Resolution Correlator(HRC)combined receiving algorithm solved the problem of ambiguous tracking of QMBOC signal,improved the performance of multipath mitigation,and possessed better tracking stability.(4)The navigation signal generation model under high dynamic environment was proposed in this paper.This model can be thought of researching the influence of the high dynamic environment on the navigation signal.Moreover,the research on the combined receiving algorithms for BOC signal under high dynamic environment was carried out in this paper.The results show that the second-order Frequency Locked Loop(FLL)assisted third-order Phase Locked Loop(PLL)and DET combined receiving algorithm obtained a small mean difference for the consistency between the ranging code and the carrier.Therefore,it provided better tracking loop performance.