BeiDou Navigation Satellite System Performance Assessment Theory And Experimental Verification

The assessment of the satellite system performance is not only one of the main basis for the satellite system initial design, research and development, deployment and system upgrade extensions, but an important guarantee for the satellite system continuous operation. In China, BeiDou Navigation Satellite System (BDS) adopts the three-step strategy of "first test, then the area, and last the world". The design of satellite constellation, the performance index, the scope of services of the various stages have the function of connecting the past and future and smoothing transition, which also have its own characteristics. So researching on the theory and method for the evaluation of the BeiDou system performance has an important practical significance for the development of the regional system at the present stage and the future global coverage of the BeiDou satellite system.With the goal of establishing the BDS performance evaluation system, this paper systematically studies the basic theory, model and method of the satellite navigation system, and also designs and develops a software system mainly on the evaluation of the BeiDou system performance, which also contains the evaluation of the Galileo and GPS performance, achieving a relatively perfect performance evaluation system from the spatial signal aspects to the service aspects On this basis, this paper analyzes and processes the BeiDou system massive measured real data since the trial operation, compares and analyzes the basic properties of the ascension process of the BeiDou regional system according to the change of the system constellation structure, which further verified the theory, method and software system of the BeiDou system performance evaluation. Finally, starting with the impact of the data quality of the high-precision positioning carrier observation, this paper comparatively analyzes the carrier to noise ratio, multipath and noise levels of the BeiDou system and GPS under the same environment; and then carried out a short baseline relative positioning and precise point positioning testing to analyze the precision positioning performance levels of BDS. The main research work and contributions in this paper are as follows:1. The research status is analyzed and summarized about the performance evaluation of GPS, GLONASS and Galileo navigation satellite system. The necessity of the theory research and software development of the BeiDou satellite system performance evaluation is stated to improve the existing navigation system assessment theories and methods as well as the BeiDou satellite system development needs and expounds.2. Starting from the definition of performance, the basic theory and method are studied about the evaluation of GNSS satellite system performance with GPS as the representative. The essential performance index of GNSS satellite navigation is focused on, including availability, accuracy, integrity and the definition of indicators of continuity and related calculations. 3. Using the theory and method of the performance evaluation in this research, a software system of the satellite navigation system performance evaluation is designed mainly to evaluate the BDS performance, also containing GPS and Galileo system, including the main research contents:general framework of the software, function module, algorithm flow etc..4. The calculation method is proposed suitable for the accuracy of the BeiDou System spatial signal. The obvious characteristic of the BeiDou system is a constellation of satellites mainly consisted of GEO and IGSO geosynchronous orbit. The different height orbit results in the failure of the existing calculation method of spatial signal error of URE precision. This paper deduces the statistical formula on the URE precision in detail, and demonstrates the calculating method of BeiDou user range rate error (URRE) and user range acceleration error (URAE). After the assessment of the measured data, results show that URE is better than1.5meter; URRE is superior to3.00mm/s; URAE is superior to2.00mm/s2.5. The clock frequency stability of the on-board BeiDou navigation satellite is assessed for the first time using the precise clock offset data from the BeiDou precise orbit determination. Satellite clocks as the time basis of navigation system onboard is a core part of the satellite navigation system, whose performance will directly affect the accuracy of the system services. This paper firstly uses the limited data and the precision clock difference data comprehensive assessment the frequency accuracy, frequency and frequency stability of the BeiDou clock, getting the stability of1-2×10-12per60s,1-2×10-13per10000s,and1-2×10-14per day, which is considerable with GPS Block IIA atomic clock performance levels.6. The statistical properties of the BeiDou spatial signal error are full analyzed for the first time. Using the coefficients Kurtosis and Q-Q plot in statistics test the normality assumption of the BeiDou spatial signal error, while testing correlation of the error between different satellites with hypothesis testing.7. The Positioning and Navigation and Timing(PNT) performance is statistically analyzed since2011the BeiDou system trial operation. In this paper, based on the "BeiDou network", the PNT performance of the typical monitoring station on the distribution in the Asia Pacific region is analyzed (January in2012-June in2013). The assessment results show that the accuracy of the BeiDou system single-frequency pseudo range point positioning near these monitoring stations has been met the BeiDou provided services index within the service level10meters in horizontal and10meters in elevation.8. The PNT performance in the service area is predicted using the method proposed in this paper on the current regional BeiDou system, checked using measured data at the monitoring stations. The calculated results show that most of the PDOP value is3to5and three-dimensional positioning accuracy is better than10meters on the current BeiDou system in China; while the scope expands to the entire Asia Pacific region, the longitude in the east longitude80°and140°most areas, the positioning level is not up to10meters. Then this paper simply predicts the DOP values and the PNT performance in view of the future BeiDou global navigation system (3G+3I+27M) constellation.9. The high-precision positioning performance of BDS is analyzed. In this paper, the observation data quality of BDS and GPS are analyzed under the same environment; and the performance of the short baseline positioning and precise point positioning are tested. Results show that the PPP positioning level of BDS can achieve cm level, which is close to the GPS performance level.10. It is the first time to achieve BDS absolute outdoor phase center variation technology. Phase center variation must be considered for high precision application. This article studies the theory and methods for the absolute robot-based phase center variation, and analyzes the measured data compared with the known GPS antenna phase center, which shows consistency better than1mm. This result indicates that China has initially mastered the key technology of outdoor absolute antenna phase center variation for high-precision BeiDou applications.