Research And Implementation Of Signal Acquisition Technology In Bei Dou Navigation Receiver

Beidou II Navigation Satellite System which developed independently by China has been successfully put into operation.The development of Beidou navigation receiver is also booming and the signal acquisition is the crucial step.The research on signal acquisition technology mainly concentrates to improve on the performance of acquisition speed of the GPS satellite signal,but the characteristic of frequent bit polarity reversal in Beidou II B1 I signal leads to the acquisition algorithm of GPS satellite signal being unsuited to Beidou navigation receiver.Therefore,the study of the signal acquisition technology applying in Beidou II B1 I signal has an important significance for the development of navigation receiver.The overall structure and the modulation technology of Beidou II Navigation Satellite System are studied in this dissertation.After analyzing and simulating the signal characteristics of this system,the problem of acquisition is shown which is caused by NH code.To avoid the influence of NH code,a method is designed by reducing the relevant accumulation time.The acquisition theory and the traditional acquisition algorithm based on time domain serial are studied.Then,a faster acquisition algorithm based on time domain parallel is designed which applies to Beidou II Satellite Navigation System's signal.The experimental results and the performance analysis of the average acquisition time are both 1.31 s which is significantly shorter than traditional algorithm's.A time domain signal could be converted to frequency domain by DFT.After DFT of a signal,it's easy to estimate the carrier Doppler frequency value through analyzing the signal spectrum characteristics.An acquisition algorithm combined with hardware resource consumption and FFT which is based on Frequency domain parallel and code phase segment correlation is designed.The algorithm is implemented,meanwhile,its correctness and rapidity are verified by using a software receiver.In this dissertation,the time domain parallel acquisition algorithm is implemented on a navigation receiver development platform composed by FPGA and DSP.Acquisition system is tested by using the signal produced by "Beidou II" satellite signal simulator.The experimental results verify the correctness of the hardware design which also means a faster acquisition algorithm for Beidou II B1 I signal is achieved.