The threshold value used in receiver autonomous integrity monitoring algorithms to identify faults has a significant impact on positioning integrity and GPS/GNSS availability. The value is usually selected empirically...
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The threshold value used in receiver autonomous integrity monitoring algorithms to identify faults has a significant impact on positioning integrity and GPS/GNSS availability. The value is usually selected empirically or under certain distribution assumptions;its calculation for a non-Gaussian test statistic has not been solved. For fault detection methods using a particle filter, a new heuristic method is proposed to select an appropriate fault detection threshold value using an optimization model. In this method, a non-Gaussian cumulative log likelihood ratio (LLR) value is used as the test statistic. Its threshold is determined using an integrity risk minimization problem with an availability constraint. Since there is no closed form for this optimization model, a genetic algorithm with a local search strategy is adopted to find a near-optimal solution. Experimental results show that this method can be used to compute the non-Gaussian fault detection threshold value subject to different availability constraints. Comparisons with empirical and distribution-based methods indicate that while meeting the same probability for false-alert constraint, the probability of missed detection in the optimized approach is much lower than for other methods, especially for small numbers of errors. Since the cumulative LLR value does not exhibit obvious statistical features for any distribution, the performance of our optimized approach is stable for different test cases and satellite data sets.
The basic principle of attitude determination by multi-antenna GPS technology is discussed and the algorithm model is established. According to the problems in the applications, the raim algorithm is used in the GPS a...
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ISBN:
(纸本)9781424426928
The basic principle of attitude determination by multi-antenna GPS technology is discussed and the algorithm model is established. According to the problems in the applications, the raim algorithm is used in the GPS attitude determination. The performance of this system is improved in this paper. The test result and the accuracy analysis have demonstrated that the new method used in attitude determination is effective.
The traditional Gauss-Newton iterative method is highly dependent on the initial value when locating the multimode GNSS receiver. If the difference between the initial value and the true value is higher, the algorithm...
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The traditional Gauss-Newton iterative method is highly dependent on the initial value when locating the multimode GNSS receiver. If the difference between the initial value and the true value is higher, the algorithm has the problem of increasing number of iterations, and the algorithm lacks the self main monitoring process of the GNSS receiver, which leads to a great reduction in the positioning accuracy. A high precision multi-mode GNSS positioning algorithm is proposed. It is based on the composition and working principle of multimode GNSS multimode receiver, and the pseudo distance positioning distance is obtained by using GNSS multi constellation combined location algorithm. It uses a direct algorithm without initial value and iteration through the new algorithm of high precision positioning. After linearizing the pseudo range location distance equation, the user's general position is calculated. After the pseudo range location distance equation is carried out in the general position of the user, the user's position correction is calculated by weighted least squares, and the exact location of the user is obtained. The receiver autonomous integrity monitoring (raim) algorithm based on the least square residual method of GNSS receiver is used to realize the self-improvement monitoring of GNSS, and to further improve the precision of the multi-mode GNSS positioning algorithm. Experimental results show that the proposed location algorithm has high location accuracy and stability.
In the global positioning system (GPS), code division multiple access (CDMA) signals are used. Because of the known spectral characteristics of the CDMA signal, continuous wave (CW) interference has a predictable effe...
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In the global positioning system (GPS), code division multiple access (CDMA) signals are used. Because of the known spectral characteristics of the CDMA signal, continuous wave (CW) interference has a predictable effect on the different pseudo random noise (PRN) spreading codes (unique to each satellite) depending on the Doppler frequency of the signal. The Doppler frequency for each signal is also predictable once the receiver position is known. As different satellite signals have different Doppler frequencies, the effect on the signal quality is also different. In this paper first the effect is studied analytically. The concept of an "exclusion zone" is defined and analyzed for each satellite. This exclusion zone, where that satellite should not be used due to interference degradation, is shown to be predictable for each satellite as a function of time. Using this prediction, the CW interference effect on the positioning quality of the receiver can be mitigated by ignoring the affected satellites within exclusion zones when performing position evaluation. The threshold beyond which a satellite should be excluded is then derived by studying the mutual effects of the geometry and the signal quality of that satellite on the positioning quality. Receiver autonomous integrity monitoring (raim) uses redundancy in measurements to perform an internal consistency check to see if all of the measurements are satisfactory. In this paper this technique is also used to mitigate the effect of CW interference on the positioning accuracy. Finally it is shown that the prediction of the exclusion zone for each satellite outperforms the raim algorithm in mitigation the effect of the interference when 5 satellites are visible.
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