Research On Gnss Channel Optimization And Signal Quality Evaluation Method For High-Precision Ranging Technology

With the construction and development of the new generation satellite navigation system,especially the mature application of modern navigation signals,the increase of bandwidth and the change of multiplexing mode,the quality of signal transceiver channel and navigation signal become more and more important factors affecting the service performance of the system.Channel optimization and signal quality assessment must be considered during the development of system equipment and terminal equipment.This paper focuses on pseudorange bias suppression and receiver parameter optimizationunder non-ideal channel,and has achieved the following innovative results:(1)In the traditional multi-level channel data processing,the linear superposition sum of the ranging errors of all levels of channels is usually taken as the estimation of the ranging errors of multi-level channel.However,under the condiction of non-ideal channel transmission,there is a big error between the estimated value and the actual result,and there is a lack of real and effective channel ranging bias analysis model.In this paper,an analysis model of satellite-ground multistage channel ranging bias based on global channel transmission characteristics is established.The analysis shows that for the double-channel cascade with polynomial groupdelay characteristics,if the delay fluctuation of the two partial channel superposition groups is less than 100 ns,the above estimated error can be controlled within 0.1m.When the group delay in-band is further increased to 200 ns,the estimated error will be more than 1m.The aboved research results can provide support for the development and testing of satellite-ground system equipment.(2)For receivers with different technical parameters,different pseudorange bias will be generated for the same non-ideal navigation signal,and then additional positioning errors will be introduced.A user receiving parameter optimization algorithm for Beidou satellite pseudorange bias suppression is proposed.Based on the Beidou satellite signal data in orbit,the Beidou satellite navigation signal distortion model is established.Typical receiver technical parameters are optimized based on the maximum pseudorange bias suppression of Beidou navigation users,such as receiver front-end filter bandwidth,correlator interval and signal tracking algorithm.The optimization is performed to minimize the ranging error and the positioning error caused by the pseudorange bias.Among them,for the B1 I signal with the most serious pseudorange bias,the current maximum pseudorange bias can be controlled within 1ns from several ns by reasonably setting the user receiver correlator interval and the filter bandwidth.In addition,pseudorange bias for special types of receiver can be estimatited,and the pseudorange bias would be corrected by the same type of receivers,with a position precision improvement of 1m.The research can provide optimization parameters for receiver design.(3)Channel adaptive equalization algorithm is an effective means to solve the channel non-ideal problem.Convational adaptive equalization algorithm is based on the minimum criterion of output mean square error,which cannot fundamentally solve the influence of channel non-ideal on pseudorange bias.For the time domain equalization algorithm,a channel adaptive equalization algorithm based on the ideal navigation signal tracking bias minimization is proposed.The analysis of a collection device B3 channel in this paper shows that,compared with the traditional equalization algorithm,the maximum pseudorange bias after equalization which used the algorithm proposed in this paper decreases from 0.7ns to 0.04 ns.For the frequency domain equalization algorithm,under the criterion of minimum fluction channel groupdelay,two kinds of frequency domain equalization based on FFT full bandwidth and bandwidth partition are proposed.The equalization target is to optimize the frequency domaineuqlization filter coefficients.Analysis of a B2 channel showed that the maximum pseudorange bias before and after equalization decreased from 0.13 ns to 0.05 ns.(4)In the context of modern navigation signal quality monitoring,the traditional quadrature demodulation method can't separate the authorized signal component in the multiplexed signal.A navigation component restoration algorithm based on the constellation template is proposed.According to the mapping relationship between the navigation baseband complex signal and the modulation domain constellation,the algorithm uses the constellation phase lookup table in reverse to analyze the military-civilian signals under the modern multiplex modulation.The traditional orthogonal separation method for the multiplexed navigation signal analysis will introduce higher system BER.The algorithm can recover the authorized signal component under the multiplex condition with very low error rate.Therefore,the on-orbit satellite payload signal quality problem is checked,and the quality of the authorized signal can be refined and evaluated.Finally,the main research results of this paper can provide reference for navigation signal quality monitoring and evaluation,high-precision receiver parameter optimization design,etc.Some of the results in this paper have been applied in the development of BDS-3 ground system equipment.