Research And Implementation Of GNSS Signal Quality Assessment Method

The Global Navigation Satellite System(GNSS)is an important infrastructure for the development of modern intelligent information technology in a country.In the past 40 years,satellite navigation applications have played an increasingly important role in areas such as national defense security,social and economic development,and people's daily production and life.However,due to the complex space electromagnetic environment,deficiencies in the design of the system,and accidents in the system during the transmission of thousands of kilometers from the user to the launch satellite,the GNSS navigation signals require the satellite to be reliable and safe.Comprehensive evaluation of signal quality.This paper focuses on the research of monitoring and evaluation of GNSS signal quality.The work carried out mainly includes:1.In-depth research on the research status and development of GNSS signal quality monitoring and evaluation technology at home and abroad,introduced the current GNSS signal system and modulation technology,considering the factors affecting GNSS signal quality,the factors affecting GNSS signal quality are divided into systems Correlation,space transmission environment,electromagnetic interference are studied and analyzed at three levels,and the influence of signals is analyzed.2.Study the signal quality evaluation system,compare the evaluation methods and technologies between different systems,and use the evaluation monitoring receiver system for monitoring and evaluation according to the actual needs of the project.This article mainly discusses and analyzes 6 evaluation contents and technologies,such as signal carrier-tonoise ratio and data utilization rate,satellite signal message monitoring,long-term analysis of system signal continuity and availability,GNSS signal observation,signal space environment,and signal integrity.And gives a detailed calculation process.In terms of signal integrity assessment,the traditional threshold-based fault recognition has a problem of low recognition rate for double-star satellite fault judgment.This paper constructs and improves the fault feature plane of the parity vector algorithm,eliminates the misjudgment caused by the superposition of the faulty satellite vectors,and improves the double star fault recognition rate.3.Designed and developed a signal quality monitoring and evaluation receiver based on FPGA + DSP architecture,and introduced hardware circuit and software design.For the monitoring of multi-frequency signals,a new generation of RF front-end circuit modules is developed,while enhancing the performance of front-end RF circuits.In view of the poor signal quality,a scheme to improve the measurement accuracy in a weak signal environment is adopted.When the carrier-to-noise ratio is lower than 28 d B-Hz,the signal signal is accurately reconstructed to ensure stable output observation of the receiver data.In view of the sudden loss of signal quality resulting in signal loss of lock,the traditional signal acquisition method has the problem of slow speed.In this paper,a fast method of folding matched filter is selected,which reduces the consumption of hardware resources and achieves a fast signal.Recapture.4.This paper develops a signal quality software monitoring and evaluation module,and uses the monitoring and evaluation receiver and simulator to form a closed loop and the satellite observation website data to actually test the evaluation method.The test and verification of 8 signal quality monitoring and evaluation software modules show that the GNSS signal quality evaluation test method studied in this paper has perfect signal quality evaluation function,which is conducive to the research of GNSS signal quality evaluation.