1.2m望远镜卫星跟踪定位精度的实测与分析

用 1 .2m地平式望远镜加装的视频CCD、计算机图象数据采集卡及其运用数据处理软件 ,对 2 0 0 0年 4月 1 7日观测视角速度比较快的激光卫星Topex进行了实测及结果分析。每组资料数据为 1 0帧图象 ,在当天晚上的跟踪观测过程中取得 3 2组数据 ,用一个二次多项式进行拟合处理后的结果 ,再把计时误差引起的定位误差分离出来 ,余下为 1 .4″误差视为望远镜的跟踪定位精度。为了提高跟踪定位精度 ,我们认为主要解决CCD计时误差即可。

GPS全球卫星定位静态测量数据处理探讨

以广西建设职业技术学院→农院路→明秀路→大学路→鲁班路→桂林工学院南宁分院→外环路→秀灵路→秀灵路西一里的GPS卫星定位控制网的测量数据处理为例,探讨通过不同的数据处理手段提高GPS卫星定位控制网观观测精度的方法。

Modified algorithm of combined GPS/GLONASS precise point positioning for applications in open-pit mines

A modified algorithm of combined GPS/GLONASS precise point positioning （GG-PPP） was developed by decreasing the number of unknowns to be estimated so that accurate position solutions can be achieved in the case of less number of visible satellites. The system time difference between GPS and GLONASS （STDGG） and zenith tropospheric delay （ZTD） values were firstly estimated in an open sky condition using the traditional GG-PPP algorithm. Then, they were used as a priori known values in the modified algorithm instead of estimating them as unknowns. The proposed algorithm was tested using observations collected at BJFS station in a simulated open-pit mine environment. The results show that the position filter converges much faster to a stable value in all three coordinate components using the modified algorithm than using the traditional algorithm. The modified algorithm achieves higher positioning accuracy as well. The accuracy improvement in the horizontal direction and vertical direction reaches 69% and 95% at a satellite elevation mask angle of 50°, respectively.

“伽利略”叫板GPS

国家科技部组织有关专家对欧洲“伽利略”的卫星定位精度提高系统(英文简称为EGNOS)于2004年月1月10日在长江武汉段首次进行了动态测试。结果表明。该系统能使美国GPS定位精度至少提高10倍。这是我国2003年受邀加盟“伽利略计划”以来，第一次对其部分系统进行的实地动态测试。

High Precision Orbit Determination of CHAMP Satellite

The precision orbit determination of challenging minisatellite payload(CHAMP) satellite was done based on position and navigation data analyst(PANDA) software which is developed in Wuhan University, using the onboard GPS data of year 2002 from day 126 to 131. The orbit accuracy was assessed by analyzing the difference from GFZ post-processed science orbits (PSO), the GPS carrier and pseudo-range data residuals and the satellite laser ranging (SLR) residuals.

USING TLS ALGORITHM TO IMPROVE GPS POSITIONING PRECISION WITH ALTITUDE HOLD MODE

This paper presents a new method of improving Global Positioning System(GPS)positioning precision. Based on the altitude hold mode, the method does not need any other equipment. Under this constraint condition, the Total Least Squares(TLS) algorithm is used to prove that the method is effective. Theoretical analysis shows that the algorithm can significantly improve the GPS positioning precision.

The wide-area difference system for the regional satellite navigation system of COMPASS

The regional satellite navigation system of COMPASS (Phase I) provides both open services and authorized services. Authorized services offer differential corrections and integrity information to users to support higher positioning, navigation and timing precision. Experimenting with real data, positioning accuracy is estimated with a 3GEO/4IGSO COMPASS constellation. The results show that with dual-frequency and single-frequency pseudo-range measurements, the positioning errors are respectively 8 and 10 m (RMS) for open service users, while for authorized users, the errors are 4 and 5 m (RMS), respectively. The COMPASS constellation geometry may cause large error to occur in the height component by 7-9 m for dualor single-frequency users, which can be effectively reduced with the differential corrections supplied by the authorized services. Multipath errors are identified and corrected for COMPASS, resulting in 25% positioning accuracy improvement for dual-frequency users and 10% improvement for single-frequency users.

Analysis of RDSS positioning accuracy based on RNSS wide area differential technique

The BeiDou Navigation Satellite System(BDS) provides Radio Navigation Service System(RNSS) as well as Radio Determination Service System(RDSS).RDSS users can obtain positioning by responding the Master Control Center(MCC) inquiries to signal transmitted via GEO satellite transponder.The positioning result can be calculated with elevation constraint by MCC.The primary error sources affecting the RDSS positioning accuracy are the RDSS signal transceiver delay,atmospheric trans-mission delay and GEO satellite position error.During GEO orbit maneuver,poor orbit forecast accuracy significantly impacts RDSS services.A real-time 3-D orbital correction method based on wide-area differential technique is raised to correct the orbital error.Results from the observation shows that the method can successfully improve positioning precision during orbital maneuver,independent from the RDSS reference station.This improvement can reach 50% in maximum.Accurate calibration of the RDSS signal transceiver delay precision and digital elevation map may have a critical role in high precise RDSS positioning services.

Research on positioning enhancement scheme of CAPS via UWB pseudolite

The positioning precision of the transmitting Chinese Area Positioning System(CAPS) is reduced due to the non-ideal distribution of the satellite constellation.Positioning and navigation enhancement methods are able to improve the reliability and accuracy of the positioning system,especially for users in special regions and special applications.In this paper,a positioning enhanced scheme based on ultra-wide band(UWB) pseudolite is proposed for CAPS.It is demonstrated that the link budget of UWB pseudolite satisfies the FCC's emission mask requirements.The localization algorithm of the enhanced CAPS is presented.The simulations indicate that the positioning precision of the proposed enhanced scheme is improved greatly,and the feasibility of the enhanced scheme is thus proved.