A multi-antenna-based GNSS receiver is capable of providing high-precision and drift-free attitude solution. Carrier phase measurements need be utilized to achieve high-precision attitude. The traditional attitude determination methods in the measurement domain and the position domain resolve the attitude and the ambiguity sequentially. The redundant measurements from multiple baselines have not been fully utilized to enhance the reliability of attitude determination. A multi-baseline-based attitude determination method in the measurement domain is proposed to estimate the attitude parameters and the ambiguity simultaneously. Meanwhile, the redundancy of attitude resolution has also been increased so that the reliability of ambiguity resolution and attitude determination can be enhanced. Moreover, in order to further improve the reliability of attitude determination, we propose a partial ambiguity resolution method based on the proposed attitude determination model. The static and kinematic experiments were conducted to verify the performance of the proposed method. When compared with the traditional attitude determination methods, the static experimental results show that the proposed method can improve the accuracy by at least 0.03° and enhance the continuity by 18%, at most. The kinematic result has shown that the proposed method can obtain an optimal balance between accuracy and reliability performance.

International GNSS Service (IGS) launched an open-access Real Time Service (RTS) for Real Time Precise Point Positioning (RT-PPP). At present, RTS mainly includes the real-time precision orbit and clock products. Although User Range Accuracy (URA) is reserved according to Radio Technical Commission for Maritime services-State Space Representation (RTCM-SSR) protocol, none of the real-time products broadcast URA. As an indication of quality of orbit and clock products, the value of URA is of great importance for the quality controlling and integrity monitoring. In this paper, we mainly analyze the real time precision orbit and clock product from Centre National d'Études Spatiales (CNES). The accuracy and error distribution characteristics of real-time products can be obtained firstly. And then, we analyzed the correlation among the radial, along, cross errors of orbit and clock errors. Finally, We studied the computational strategy of URE and URA. URE is mainly affected by satellite clock errors, and do not satisfy Gaussian distribution. URA value is about 0.03-0.35 m getting from Root Mean Square (RMS) estimation of URE. URA has no obvious correlation with satellite type, but it is different with different satellites, which need to be accounted for high precision and high integrity navigational applications.

Traditional generalized likelihood test method can detect faults while can not isolate multiple faults in redundant strapdown inertial navigation system. In this paper, a multi-faults detection and isolation method based on generalized likelihood test and linear prediction approach is proposed. A generalized likelihood test method is used to detect the fault of the system, and the linear prediction method is used to estimate the values of inertial sensors. The faulty inertial sensors can be isolated through comparing the estimated values with measurements of inertial sensors, and the faulty information is recorded for system reconstruction. Through simulation and experiment, it is proved that new method can accurately detect and isolate multiple faults and thus guarantee the reliability of strapdown inertial navigation system.

Signal In Space (SIS) anomalies in satellite navigation systems can degrade satellite-based navigation and positioning performance. The occurrence of SIS anomalies from the BeiDou navigation satellite System (BDS) may be more frequent than for the Global Positioning System (GPS). In order to guarantee the integrity of BDS users, detecting and excluding SIS anomalies is indispensable. The traditional method through the comparison between the final precision ephemeris and the broadcast ephemeris is limited by the issue of long latency of precision ephemeris release. Through the statistical characteristics analysis of Signal In Space User Range Error (SISURE), we propose a real-time Instantaneous SISURE (IURE) estimation method by using the Kalman filtering-based carrier-smoothed-code to detect and exclude BDS SIS anomalies, in which the threshold for BDS IURE anomaly detection are obtained from the integrity requirement. The experimental results based on 1 Hz data from ground observations show that the proposed method has an estimation accuracy of 1.1 m for BDS IURE. The test results show that the proposed method can effectively detect the SIS anomalies caused by either orbit faults or clock faults.