The Experts below are selected from a list of 31662 Experts worldwide ranked by ideXlab platform

Shaojun Feng - One of the best experts on this subject based on the ideXlab platform.

  • New methods for dual constellation single receiver positioning and Integrity Monitoring
    Geo-spatial Information Science, 2013
    Co-Authors: Shaojun Feng, Altti Jokinen, Carl Milner, Washington Y. Ochieng
    Abstract:

    Navigation system Integrity Monitoring is crucial for mission (e.g. safety) critical applications. Receiver autonomous Integrity Monitoring (RAIM) based on consistency checking of redundant measurements is widely used for many applications. However, there are many challenges to the use of RAIM associated with multiple constellations and applications with very stringent requirements. This paper discusses two positioning techniques and corresponding Integrity Monitoring methods. The first is the use of single frequency pseudorange-based dual constellations. It employs a new cross constellation single difference scheme to benefit from the similarities while addressing the differences between the constellations. The second technique uses dual frequency carrier phase measurements from GLONASS and the global positioning system for precise point positioning. The results show significant improvements both in positioning accuracy and Integrity Monitoring as a result of the use of two constellations. The dual const...

  • Integrity Monitoring algorithms for airport surface movement
    GPS Solutions, 2012
    Co-Authors: Wolfgang Schuster, Shaojun Feng, Jie Bai, Washington Ochieng
    Abstract:

    Navigation algorithms are proposed for carrier phase ambiguity Integrity Monitoring to support aircraft surface movement. The enhanced Integrity Monitoring algorithm addresses the very stringent Integrity requirements for surface movement by the use of multiple test statistics and a group separation concept for single and multiple failure detection and exclusion. The algorithms are subject to a detailed performance characterization for precision approaches and airport surface movement, using simulations as well as static and dynamic field trials, taking into account operational specificities, such as multipath and potential decorrelations between the reference station and aircraft due to ionospheric anomalies. Results show that the proposed algorithms have the potential to satisfy airport surface movement requirements if the ionospheric anomalies are monitored using a special ground-based network.

  • Carrier phase-based Integrity Monitoring for high-accuracy positioning
    GPS Solutions, 2009
    Co-Authors: Shaojun Feng, Washington Ochieng, Terry Moore, Chris Hill, Chris Hide
    Abstract:

    Pseudorange-based Integrity Monitoring, for example receiver autonomous Integrity Monitoring (RAIM), has been investigated for many years and is used in various applications such as non-precision approach phase of flight. However, for high-accuracy applications, carrier phase-based RAIM (CRAIM), an extension of pseudorange-based RAIM (PRAIM) must be used. Existing CRAIM algorithms are a direct extension of PRAIM in which the carrier phase ambiguities are estimated together with the estimation of the position solution. The main issues with the existing algorithms are reliability and robustness, which are dominated by the correctness of the ambiguity resolution, ambiguity validation and error sources such as multipath, cycle slips and noise correlation. This paper proposes a new carrier phase-based Integrity Monitoring algorithm for high-accuracy positioning, using a Kalman filter. The ambiguities are estimated together with other states in the Kalman filter. The double differenced pseudorange, widelane and carrier phase observations are used as measurements in the Kalman filter. This configuration makes the positioning solution both robust and reliable. The Integrity Monitoring is based on a number of test statistics and error propagation for the determination of the protection levels. The measurement noise and covariance matrices in the Kalman filter are used to account for the correlation due to differencing of measurements and in the construction of the test statistics. The coefficient used to project the test statistic to the position domain is derived and the synthesis of correlated noise errors is used to determine the protection level. Results from four cases based on limited real data injected with simulated cycle slips show that residual cycle slips have a negative impact on positioning accuracy and that the Integrity Monitoring algorithm proposed can be effective in detecting and isolating such occurrences if their effects violate the Integrity requirements. The CRAIM algorithm proposed is suitable for use within Kalman filter-based integrated navigation systems.

  • User Level Integrity Monitoring and Quality Control for High Accuracy Positioning Using GPS/INS Measurements
    Journal of Global Positioning Systems, 2008
    Co-Authors: Washington Y. Ochieng, Shaojun Feng
    Abstract:

    This paper presents research undertaken to develop sensor level autonomous Integrity Monitoring and quality control to support centimetre level positioning in all conditions and environments as conceived under the SPACE (Seamless Positioning in All Conditions and Environments) project. The basic philosophy for Integrity Monitoring and quality control is early detection of anomalies which requires Monitoring of the entire processing chain. A number of novel concepts and algorithms are developed including algorithms to deal with special issues associated with carrier phase based Integrity Monitoring (including integration with INS), a new “difference test” Integrity Monitoring algorithm for detection of slowly growing errors, and a new group separation concept for simultaneous multiple failure exclusion. Both real and simulated data are used to test the new algorithms. The results show that the new algorithms, when used together with selected existing ones, provide effective Integrity Monitoring and quality control for centimetre level seamless positioning in all conditions and environments.

  • User Level Autonomous Integrity Monitoring for Seamless Positioning in All Conditions and Environments
    2006
    Co-Authors: Shaojun Feng, Washington Y. Ochieng
    Abstract:

    This paper proposes a new GNSS user level Integrity Monitoring scheme for the detection and exclusion of simultaneous multiple failures. It addresses the weakness of the current methods that assume a single failure a time. The new approach, referred to as the “group separation method”, can be used either in the receiver autonomous Integrity Monitoring (RAIM) mode or its extension the user autonomous Integrity Monitoring (UAIM) when other sensors are used together with GNSS. The group separation method is based on multiple -effect analysis and identification of a common failure mode using prior-knowledge of GNSS and the user receiver measurements. The measurements are then grouped by potential common failure mode. The group most likely to fail has the highest priority for separation (exclusion). Simulation results using pseudorange measurements show that the group separation method is accurate and highly efficient.

Bin Wu - One of the best experts on this subject based on the ideXlab platform.

  • initial analysis of the bds satellite autonomous Integrity Monitoring capability
    Gps Solutions, 2019
    Co-Authors: Xiaogong Hu, Jinping Chen, Lang Bian, Wei Wang, Rui Li, Xue Wang, Xin Meng, Bin Wu
    Abstract:

    The Integrity of Global Navigation Satellite System (GNSS) has the capability of sending a timely alarm to users when the GNSS is out of use, and it is one of the significant parameters of GNSS. Compared with ground-based Integrity Monitoring, Integrity Monitoring within the satellite constellation itself could lessen the effects of possible failures in the signal propagation path and ground systems and shorten the alarm time, which would quickly alert users of the system failure. Developing satellite autonomous Integrity Monitoring (SAIM) has been one of the main objectives of the upgrade plan for future GNSS such as GPS III, Galileo and the third generation of Beidou satellite navigation system (BDS3). To test the new technology, BDS3 experimental satellites are equipped with SAIM payload which is independently developed by China and it is the first satellite navigation system that applies SAIM method to monitor the navigation signals Integrity. SAIM monitors signal quality and clock and frequency stability. We briefly introduce the payload design of SAIM on BDS3 experimental satellites, and evaluate in detail the Monitoring measurements stability for two new civil signals of BDS3 open service, B1C_pilot signal, and B2a_pilot signal. By artificially setting signal faults, we analyze the time-to-alert performance of SAIM under its two kinds of alarming modes. The results show that the onboard observation stabilities of signal power, pseudorange, code?carrier bias, and code?carrier divergence are better than 0.12 dB, 0.1?ns, 0.14?ns, and 3.5?mm/s, respectively, which were reliable at 1-year interval. The onboard satellite clock step Monitoring precision is approximately 0.5?ns. Once the abnormal signal is detected, the BDS SAIM may provide a warning within 6?s. With the characteristics of overcoming the ground Monitoring network limitation and fast alarming ability, SAIM is expected to be an effective method to enhance the BDS3 system Integrity Monitoring capability.

Chen Xiuwan - One of the best experts on this subject based on the ideXlab platform.

  • Algorithm for Global Navigation Satellite System Receiver Autonomous Integrity Monitoring
    Computer Engineering, 2009
    Co-Authors: Chen Xiuwan
    Abstract:

    This paper presents a new Receiver Autonomous Integrity Monitoring(RAIM) algorithm based on Probability of Hazardously Misleading Information(PHMI) dynamically allocated strategy.This algorithm is feasible to fuse multi-constellation measurements for Integrity Monitoring.It also dynamically allocates PHMI among all satellites used to get a solution,which improves the availability of traditional RAIM algorithms at 2% to 3%.With the algorithm,it analyzes the Integrity Monitoring performance of GPS and GPS/Galileo.Results show that with the new method,unaided GNSS RAIM allows LPV-200 approaches in the future.

Li Yu-lin - One of the best experts on this subject based on the ideXlab platform.

Xiaogong Hu - One of the best experts on this subject based on the ideXlab platform.

  • initial analysis of the bds satellite autonomous Integrity Monitoring capability
    Gps Solutions, 2019
    Co-Authors: Xiaogong Hu, Jinping Chen, Lang Bian, Wei Wang, Rui Li, Xue Wang, Xin Meng, Bin Wu
    Abstract:

    The Integrity of Global Navigation Satellite System (GNSS) has the capability of sending a timely alarm to users when the GNSS is out of use, and it is one of the significant parameters of GNSS. Compared with ground-based Integrity Monitoring, Integrity Monitoring within the satellite constellation itself could lessen the effects of possible failures in the signal propagation path and ground systems and shorten the alarm time, which would quickly alert users of the system failure. Developing satellite autonomous Integrity Monitoring (SAIM) has been one of the main objectives of the upgrade plan for future GNSS such as GPS III, Galileo and the third generation of Beidou satellite navigation system (BDS3). To test the new technology, BDS3 experimental satellites are equipped with SAIM payload which is independently developed by China and it is the first satellite navigation system that applies SAIM method to monitor the navigation signals Integrity. SAIM monitors signal quality and clock and frequency stability. We briefly introduce the payload design of SAIM on BDS3 experimental satellites, and evaluate in detail the Monitoring measurements stability for two new civil signals of BDS3 open service, B1C_pilot signal, and B2a_pilot signal. By artificially setting signal faults, we analyze the time-to-alert performance of SAIM under its two kinds of alarming modes. The results show that the onboard observation stabilities of signal power, pseudorange, code?carrier bias, and code?carrier divergence are better than 0.12 dB, 0.1?ns, 0.14?ns, and 3.5?mm/s, respectively, which were reliable at 1-year interval. The onboard satellite clock step Monitoring precision is approximately 0.5?ns. Once the abnormal signal is detected, the BDS SAIM may provide a warning within 6?s. With the characteristics of overcoming the ground Monitoring network limitation and fast alarming ability, SAIM is expected to be an effective method to enhance the BDS3 system Integrity Monitoring capability.