摘要 :
Modernized GPS and GLONASS, together with new GNSS systems, BeiDou and Galileo, offer code and phase ranging signals in three or more carriers. Traditionally, dual-frequency code and/or phase GPS measurements are linearly combined...
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Modernized GPS and GLONASS, together with new GNSS systems, BeiDou and Galileo, offer code and phase ranging signals in three or more carriers. Traditionally, dual-frequency code and/or phase GPS measurements are linearly combined to eliminate effects of ionosphere delays in various positioning and analysis. This typical treatment method has imitations in processing signals at three or more frequencies from more than one system and can be hardly adapted itself to cope with the booming of various receivers with a broad variety of singles. In this contribution, a generalized-positioning model that the navigation system independent and the carrier number unrelated is promoted, which is suitable for both single- and multi-sites data processing. For the synchronization of different signals, uncalibrated signal delays (USD) are more generally defined to compensate the signal specific offsets in code and phase signals respectively. In addition, the ionospheric delays are included in the parameterization with an elaborate consideration. Based on the analysis of the algebraic structures, this generalized-positioning model is further refined with a set of proper constrains to regularize the datum deficiency of the observation equation system. With this new model, uncalibrated signal delays (USD) and ionospheric delays are derived for both GPS and BeiDou with a large dada set. Numerical results demonstrate that, with a limited number of stations, the uncalibrated code delays (UCD) are determinate to a precision of about 0.1 ns for GPS and 0.4 ns for BeiDou signals, while the uncalibrated phase delays (UPD) for L1 and L2 are generated with 37 stations evenly distributed in China for GPS with a consistency of about 0.3 cycle. Extra experiments concerning the performance of this novel model in point positioning with mixed-frequencies of mixed-constellations is analyzed, in which the USD parameters are fixed with our generated values. The results are evaluated in terms of both positioning accuracy and convergence time.
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摘要 :
Modernized GPS and GLONASS, together with new GNSS systems, BeiDou and Galileo, offer code and phase ranging signals in three or more carriers. Traditionally, dual-frequency code and/or phase GPS measurements are linearly combined...
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Modernized GPS and GLONASS, together with new GNSS systems, BeiDou and Galileo, offer code and phase ranging signals in three or more carriers. Traditionally, dual-frequency code and/or phase GPS measurements are linearly combined to eliminate effects of ionosphere delays in various positioning and analysis. This typical treatment method has imitations in processing signals at three or more frequencies from more than one system and can be hardly adapted itself to cope with the booming of various receivers with a broad variety of singles. In this contribution, a generalized-positioning model that the navigation system independent and the carrier number unrelated is promoted, which is suitable for both single- and multi-sites data processing. For the synchronization of different signals, uncalibrated signal delays (USD) are more generally defined to compensate the signal specific offsets in code and phase signals respectively. In addition, the ionospheric delays are included in the parameterization with an elaborate consideration. Based on the analysis of the algebraic structures, this generalized-positioning model is further refined with a set of proper constrains to regularize the datum deficiency of the observation equation system. With this new model, uncalibrated signal delays (USD) and ionospheric delays are derived for both GPS and BeiDou with a large dada set. Numerical results demonstrate that, with a limited number of stations, the uncalibrated code delays (UCD) are determinate to a precision of about 0.1 ns for GPS and 0.4 ns for BeiDou signals, while the uncalibrated phase delays (UPD) for L1 and L2 are generated with 37 stations evenly distributed in China for GPS with a consistency of about 0.3 cycle. Extra experiments concerning the performance of this novel model in point positioning with mixed-frequencies of mixed-constellations is analyzed, in which the USD parameters are fixed with our generated values. The results are evaluated in terms of both positioning accuracy and convergence time.
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摘要 :
In this paper, the theory of satellite navigation independent compound receiving and transmitting array is proposed. Analyze the feasibility of satellite navigation receiving array, microwave energy transmitting array, RF rectific...
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In this paper, the theory of satellite navigation independent compound receiving and transmitting array is proposed. Analyze the feasibility of satellite navigation receiving array, microwave energy transmitting array, RF rectification array and energy independent network. Explore the possibility framework of MEMS multifunction skin array. The concept of possibility application mode of array system in outer space, heaven and ground is proposed based on the simulation, analysis and experiment results. The elementary ideas in this paper have some reference value in development of BD system.
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摘要 :
In this paper, the theory of satellite navigation independent compound receiving and transmitting array is proposed. Analyze the feasibility of satellite navigation receiving array, microwave energy transmitting array, RF rectific...
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In this paper, the theory of satellite navigation independent compound receiving and transmitting array is proposed. Analyze the feasibility of satellite navigation receiving array, microwave energy transmitting array, RF rectification array and energy independent network. Explore the possibility framework of MEMS multifunction skin array. The concept of possibility application mode of array system in outer space, heaven and ground is proposed based on the simulation, analysis and experiment results. The elementary ideas in this paper have some reference value in development of BD system.
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摘要 :
Single-frequency (SF) Precise Point Positioning (PPP) is a promising technique for real-time positioning and navigation at sub-meter (about 0.5 m) accuracy level because of its convenience and low cost. With satellite orbit and cl...
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Single-frequency (SF) Precise Point Positioning (PPP) is a promising technique for real-time positioning and navigation at sub-meter (about 0.5 m) accuracy level because of its convenience and low cost. With satellite orbit and clock error being greatly mitigated by the precise products from the International GNSS Service (IGS), ionospheric delay becomes the bottleneck of SF PPP users. There are five commonly used approaches to mitigate ionospheric delay in SF PPP: (1) broadcast ionospheric model in Global Navigation Satellite System (GNSS) navigation message; (2) global ionospheric map released by the IGS; (3) local ionospheric model generated using GNSS data from surrounding reference stations; (4) satellite based ionospheric model; (5) the parameter estimation method. Those approaches are briefly reviewed in our contribution and the performances of some classical ionospheric approaches for SF PPP are validated and compared using GPS data from two networks in China and the Netherlands respectively. Validation results show that a set of reference stations is critical for SF PPP with sub-meter positioning accuracy, especially in China. It is better to model the ionospheric delay in a satellite by satellite mode rather than an integral mode under the assumption of a thin-layer ionosphere. Comparing to GIM, the suggested approach, satellite based ionospheric model (SIM), can improve the horizontal positioning accuracy of SF PPP from 0.40 to 0.10 m in China and from 0.20 to 0.05 m in the Netherlands, while it can improve the vertical accuracy from 0.70 to 0.15 m (China) and from 0.20 to 0.10 m (the Netherlands). Furthermore, the recommended ionospheric model has been applied to GPS/BDS data for SF PPP as well. The experiment in Beijing shows that the positioning of about 0.5 m accuracy can be achieved by single epoch SF PPP based on a reference network of about 40 km inter-station distance. The accuracy of SF PPP based on an accumulation of 10-15 min of observations in dynamic mode is about 0.04 m (horizontal) and 0.04-0.08 m (vertical) using only GPS data, while it is about 0.03 m (horizontal) and 0.03-0.06 m (vertical) by combining GPS and BDS data.
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摘要 :
The prediction accuracy of satellite clock bias (SCB) directly affects the performance of navigation system. According to the spectrum analysis method, the periodic characteristics of satellite clocks are analyzed, and using preci...
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The prediction accuracy of satellite clock bias (SCB) directly affects the performance of navigation system. According to the spectrum analysis method, the periodic characteristics of satellite clocks are analyzed, and using precise SCB data of BDS/GPS satellite the prediction tests are conducted, and then we build the forecast model considering periodic items. Based on this, the influence of the number of periodic items on the result of SCB prediction is analyzed. The effect of SCB prediction between periodic term model and quadratic polynomial model is compared, and the SCB prediction performance of different types of satellites is summarized. Experimental results show that the periodic variation of satellites are significant. The periodic items of BDS are 24, 12 and 8 h, and the periodic items of GPS are 24, 12 and 6 h. The number of periodic items affects the prediction results. The prediction accuracy of BDS using 2-3 main periodic items is the best, and the prediction accuracy of GPS using 3-4 main periodic items is the best. Compared with the quadratic polynomial prediction model, the prediction accuracy of the proposed model with additional periodic items can be improved by 1-6 ns.
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摘要 :
The prediction accuracy of satellite clock bias (SCB) directly affects the performance of navigation system. According to the spectrum analysis method, the periodic characteristics of satellite clocks are analyzed, and using preci...
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The prediction accuracy of satellite clock bias (SCB) directly affects the performance of navigation system. According to the spectrum analysis method, the periodic characteristics of satellite clocks are analyzed, and using precise SCB data of BDS/GPS satellite the prediction tests are conducted, and then we build the forecast model considering periodic items. Based on this, the influence of the number of periodic items on the result of SCB prediction is analyzed. The effect of SCB prediction between periodic term model and quadratic polynomial model is compared, and the SCB prediction performance of different types of satellites is summarized. Experimental results show that the periodic variation of satellites are significant. The periodic items of BDS are 24, 12 and 8 h, and the periodic items of GPS are 24, 12 and 6 h. The number of periodic items affects the prediction results. The prediction accuracy of BDS using 2-3 main periodic items is the best, and the prediction accuracy of GPS using 3-4 main periodic items is the best. Compared with the quadratic polynomial prediction model, the prediction accuracy of the proposed model with additional periodic items can be improved by 1-6 ns.
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摘要 :
BeiDou Navigation Satellite System (BDS) on-orbit satellites contain BDS-2 and BDS-3 satellites. Due to the existence of ISB between BDS-2 and BDS-3 on receiver side, the traditional BDS precise clock estimation (PCE) and precise ...
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BeiDou Navigation Satellite System (BDS) on-orbit satellites contain BDS-2 and BDS-3 satellites. Due to the existence of ISB between BDS-2 and BDS-3 on receiver side, the traditional BDS precise clock estimation (PCE) and precise point positioning (PPP) models for the BDS-2 and BDS-3 combined processing will reduce the accuracy and stability of solutions. To improve the BDS service performance, the ISB between BDS-2 and BDS-3 for both old (B1I/B3I) and new signals (B1C/B2a) and its impact on PCE and PPP are investigated in this contribution. The BDS-2 and BDS-3 integrated PCE and PPP models with and without ISB estimation are presented. The combined processing is comprehensively assessed in terms of the precision of clock offsets and PPP performances. The result demonstrates that the ISB is stable for both old and new signals, and estimating ISB can effectively avoid the confusion of receiver clock datum. The integration of BDS-2 and BDS-3 indeed improves the precision of satellite clock offsets estimations based on the proper PCE models. The average STD for BDS-2 and BDS-3 clock offsets using old signals is improved by 15.8% and 11.1% compared with BDS-2-only and BDS-3-only solutions, respectively. For new signals, the improvement for BDS-3 clock offsets is 14.6% from 0.081 ns to 0.069 ns. The BDS clock offsets estimated by the proposed PCE model with ISB estimation (PCE0) can well support PPP applications. The positioning accuracy for old signals can be improved by 40.4%, 20.0% and 35.4% compared with those of using GFZ rapid products. Similarly, the positioning performance for new signals is slightly better than GFZ PPP. The PCE0 model is the optimal BDS-2 and BDS-3 integrated satellite clock offsets determination model for the server, and the PPP model with ISB estimation (PPP0) is the optimal PPP model for the client. The cooperation between PCE0 and PPP0 can improve the BDS service performance.
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摘要 :
The standard GNSS combined PPP algorithm cannot be used satisfactorily in the real-time and high frequency precise positioning because of its low compute efficiency. A new algorithm based on the parameter equivalent reduction prin...
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The standard GNSS combined PPP algorithm cannot be used satisfactorily in the real-time and high frequency precise positioning because of its low compute efficiency. A new algorithm based on the parameter equivalent reduction principle is proposed. First, the observations equation and the normal equation which belong to the single navigation system can be solved independently. Second, the normal equations of overlapping parameters between the different systems can be obtained by using parameter equivalent reduction principle. At last, the combined PPP resolutions can be computed easily by using the Least Squares method. The proposed algorithm can improve the calculating efficiency immensely. In addition, an adaptively combined method which can automatically adjusts the contributed weight of different GNSS systems is also proposed in this paper. The numerical examples using the data set of three IGS stations, show that the PPP precisions and efficiencies based on the proposed model have been improved significantly compared with those of standard model. This proposed principle can also be applied in the GNSS precise satellite clock determination and the indifference baseline network adjustment plus the GNSS time offset monitoring.
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摘要 :
The standard GNSS combined PPP algorithm cannot be used satisfactorily in the real-time and high frequency precise positioning because of its low compute efficiency. A new algorithm based on the parameter equivalent reduction prin...
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The standard GNSS combined PPP algorithm cannot be used satisfactorily in the real-time and high frequency precise positioning because of its low compute efficiency. A new algorithm based on the parameter equivalent reduction principle is proposed. First, the observations equation and the normal equation which belong to the single navigation system can be solved independently. Second, the normal equations of overlapping parameters between the different systems can be obtained by using parameter equivalent reduction principle. At last, the combined PPP resolutions can be computed easily by using the Least Squares method. The proposed algorithm can improve the calculating efficiency immensely. In addition, an adaptively combined method which can automatically adjusts the contributed weight of different GNSS systems is also proposed in this paper. The numerical examples using the data set of three IGS stations, show that the PPP precisions and efficiencies based on the proposed model have been improved significantly compared with those of standard model. This proposed principle can also be applied in the GNSS precise satellite clock determination and the indifference baseline network adjustment plus the GNSS time offset monitoring.
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