Evaluation Technology And Analysis Of BDS Signal Quality

Monitoring and Analysis of navigation signal quality provide the second-generation BDS for favorable signal performance evaluation, the ability to be compatible and interoperability with other systems, system fault diagnosis and signal integrity monitoring. Since 1993, when the U.S. GPS SV19 satellite signal problems occur, satellite navigation signal quality monitoring has attracted wide attention, and soon become an important topic of GNSS. With the major development of the system, a number of theoretical studies of signal quality were all launched by all the GNSS, including the BDS, setting up the satellite navigation signal monitoring center in succession.At present, these systems use real-time observations by reused high-gain antenna to evaluate signal quality, collecting and restoring the high-quality data. In other way, the system receives the traditional navigation antenna signals are analyzed to assess the quality of navigation signals, to complete. However, these two methods cannot guarantee a real-time and efficiency simultaneity. To address this situation, this article will combine these existing methods to design and build a new GNSS signal quality platform, which unites the low-gain omnidirectional antenna for rough detection and large-diameter high-gain antenna for sophisticated detection. The system can simultaneously monitor in orbit satellite signal of BDS, GPS, GLONASS and other navigation system. Moreover, based on this evaluation platform, the paper investigates the assessment methods of signal quality in both the signal layer and data layer. To demonstrate the theory, the in-orbit signal quality analyzing experiment and real-time evaluation is carried out to testify the signal quality evaluation indicators, which can directly guide the engineering practice. The content of paper mainly includes three parts:The first part is focused on the navigation signal quality monitoring analyzing theory and technique. Based on the GNSS signal characteristic under different modulation, the part mainly analyze the correlation and power spectrum, which provide a theoretic basis for signal monitoring.The second part of the study aims at the signal quality evaluation indicators. By drawing on the traditional navigation signal quality assessment techniques based on communication signal quality indicators, covering the time domain, frequency domain, modulation domain, correlation domains and many other related evaluation indicators. In order to solve the actual requirements for GNSS users, this part provides a reasonable and effective series of evaluation indicators, especially the crucial data layer measurement methods, involving pseudorange measurement accuracy, carrier phase measurement accuracy and the performance-related indicators for users. This method makes up the lack of traditional signal quality assessment results, which cannot be directly used by the navigation users. In all, this ways and means provide a theorical guidance for the follow up signal quality measurements and comparative analysis for BDS and GNSS signal.The third part makes a design and implementation platform for BDS signal monitoring, including hardware platform and software analysis. Based on this platform, not only a real-time monitoring of the entire in-orbit satellite constellation network is achieved, but also the monitoring of abnormal satellite and terrestrial test satellite can be accomplished. It is validated that this design platform can achieve the desired results and effectively support BDS signal cable testing on ground and satellite testing in-orbit.At last, the research work of this dissertation and its application are summarized and reviewd; presenting the future research to be carried out. The results have been used to GNSS signal quality analyzing engineering prototype, testing satellite project of BDS-II, and in-orbit navigation signal evaluation.