Research And Realization Of Anomaly Recognition Technology Of GNSS Signal

With the continuous and rapid development of major GNSS(Global Navigation Satellite System)systems in the world,people have become more and more inseparable from satellite navigation.Whether it is traditional navigation and positioning or the emerging unmanned field,GNSS plays an irreplaceable role.In this way,the reliability,security,and integrity of GNSS signals are particularly important.Only normal GNSS signals can provide safe and reliable services for civilian and military use.However,due to the aging of satellite equipment,complex and changeable space environment,external electromagnetic interference and other factors,GNSS signals will inevitably have some degree of abnormality.The consequences of adding GNSS signals to normal applications will be unimaginable,so both domestic and foreign countries attach great importance to the anomaly recognition and detection of GNSS signals.This article focuses on the research of anomaly recognition and detection algorithms for GNSS signals.The work carried out includes the following aspects:1.The basic principles of GNSS signals and the conventional binary phase shift keying(BPSK)modulation and the new binary offset carrier modulation(BOC)modulation principles are analyzed,and the two modulation methods are in the time domain,The correlation and frequency domain characteristics are compared and simulated,which lays a theoretical foundation for GNSS signal anomaly recognition.2.The GNSS anomaly recognition technology studied in this paper is divided into five major areas and eight major indicators,such as time domain,frequency domain,correlation domain,modulation domain,and measurement domain.Gives the simulation results of all indicators under theoretical conditions.Aiming at the most important threshold problem in the above indicators,a threshold selection method based on maximum likelihood estimation is proposed,and the population mean and standard deviation are calculated through sample points to improve the reliability of the threshold.3.The hardware and software design of the multimode multi-frequency point GNSS signal detection receiver is explained.The hardware part analyzes the power management module,the down conversion module and the baseband signal processing module;the software part captures and tracks the signal and the synthesis algorithm of the raw data required for power detection,code carrier deviation detection(CCD)and correlation peak detection is deduced and analyzed.4.Combined with the GNSS anomaly detection receiver and signal acquisition equipment designed in this article,all anomaly indicators are divided into two parts: online detection and offline detection.After receiving the real-time converted raw data,the online detection part adopts corresponding algorithms for real-time detection of different indicators;The offline detection part collects the digital intermediate frequency signal through the collector,and then uses the corresponding algorithm to detect different indicators through software receiving and processing.Finally,all indicators are tested with actual signals,and analyzed and discussed.