BeiDou Navigation Satellite System
Geomatics and Information Science of Wuhan University,Vol 43,No. 04
【Abstract】 Aiming at the acquisition problem brought by NH code in the signal of BD2 which leads to sensitivity reduction problem by traditional acquisition methods, this paper presents a weak BD2 signal acquisition method based on adaptive stochastic resonance algorithm. By combining the DBZP method with adaptive stochastic resonance algorithm, the method can eliminate the data hopping and NH hopping, and significantly improve the signal-to-noise ratio. The method can be adopted to achieve the fast signal acquisition with high sensitivity characteristic. The simulation and test results verify that, this method provides stronger capacity of acquainting BD2 signal, has more advantages in real-time, high sensitivity and has a higher application value.
Geomatics and Information Science of Wuhan University,Vol 43,No. 06
【Abstract】 Presently, most of the errors caused by the B3 frequency, antenna phase center offset are corrected by the satellite clock a0 parameter. The errors caused by the variance of different frequencies are corrected by timing group delay (Tgd) parameter for BeiDou navigation satellite system (BDS) through navigation messaging. In order to improve the broadcast ephemeris, we put forward a satellite antenna phase center offset correction and fitting broadcast ephemeris methods. The two approaches are compared in two ways, including the influence on user ranging error and precise point positioning. The results show that the two methods can correct most errors caused by antenna phase center offset. The correction accuracy of the new method is improved by 76% compared with the method using satellite clock a0 parameter, and the positioning accuracy is improved by 12.5%. Accuracy is not affected by time-space factor. The positioning accuracy when correcting the satellite position before ephemeris fitting is about 38.1% higher than that when the satellite antenna phase center offset is not corrected. The correction of the variance of different frequencies of the antenna phase center by Tgd residuals is analyzed. The results show that the influence is at the mm order, so we can correct the variance by Tgd parameter.
Geomatics and Information Science of Wuhan University,Vol 43,No. 08
【Abstract】 Currently, there are five test satellites of BeiDou Global Satellite Navigation System broadcasting new signals. Quality analysis of test satellite observations is a significant content for the verification of the new signal system. Based on single station measurement of BeiDou test satellites, the code minus phase combination (CC) and multipath combination (MP) are employed to analyze the pseudorange noises and multipath errors of civil signals and Bs signal of the test satellites. The result shows that the pseudorange measurement accuracy of inclined geosynchronous satellite orbit (IGSO) satellite is better than that of the medium earth orbit (MEO) satellite; B2a + b signal has the highest pseudorange measurement accuracy as well as the best anti-multipath performance, while the B1C signal performs the worst in both aspects; the pseudorange measurement accuracy of Bs signal is relatively poor, yet better than that of the B1C signal and a systematic error related to elevation exists in the pseudorange multipath series of Bs signal with its maximum value up to 0.5 m.