On-The-Fly Ambiguity Resolution Based on Double-Differential Square Observation
Global navigation systems provide worldwide positioning, navigation and navigation services. However, in some challenging environments, especially when the satellite is blocked, the performance of GNSS is seriously degraded or even unavailable. Ground based positioning systems, including pseudolites...
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| Format: | Article |
| Language: | English |
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MDPI AG
2018-08-01
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| Series: | Sensors |
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| Online Access: | http://www.mdpi.com/1424-8220/18/8/2495 |
| _version_ | 1798039167152685056 |
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| author | Tengfei Wang Zheng Yao Mingquan Lu |
| author_facet | Tengfei Wang Zheng Yao Mingquan Lu |
| author_sort | Tengfei Wang |
| collection | DOAJ |
| description | Global navigation systems provide worldwide positioning, navigation and navigation services. However, in some challenging environments, especially when the satellite is blocked, the performance of GNSS is seriously degraded or even unavailable. Ground based positioning systems, including pseudolites and Locata, have shown their potentials in centimeter-level positioning accuracy using carrier phase measurements. Ambiguity resolution (AR) is a key issue for such high precision positioning. Current methods for the ground based systems need code measurements for initialization and/or approximating linearization. If the code measurements show relatively large errors, current methods might suffer from convergence difficulties in ground based positioning. In this paper, the concept of double-differential square observation (DDS) is proposed, and an on-the-fly ambiguity resolution (OTF-AR) method is developed for ground based navigation systems using two-way measurements. An important advantage of the proposed method is that only the carrier phase measurements are used, and code measurements are not necessary. The clock error is canceled out by two-way measurements between the rover and the base stations. The squared observations are then differenced between different rover positions and different base stations, and a linear model is then obtained. The floating integer values are easy to compute via this model, and there is no need to do approximate linearization. In this procedure, the rover’s approximate coordinates are also directly obtained from the carrier measurements, therefore code measurements are not necessary. As an OTF-AR method, the proposed method relies on geometric changes caused by the rover’s motion. As shown by the simulations, the geometric diversity of observations is the key factor for the AR success rate. Moreover, the fine floating solutions given by our method also have a fairly good accuracy, which is valuable when fixed solutions are not reliable. A real experiment is conducted to validate the proposed method. The results show that the fixed solution could achieve centimeter-level accuracy. |
| first_indexed | 2024-04-11T21:50:10Z |
| format | Article |
| id | doaj.art-1e9cd12719044fba80baad0cee6596cc |
| institution | Directory Open Access Journal |
| issn | 1424-8220 |
| language | English |
| last_indexed | 2024-04-11T21:50:10Z |
| publishDate | 2018-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj.art-1e9cd12719044fba80baad0cee6596cc2022-12-22T04:01:15ZengMDPI AGSensors1424-82202018-08-01188249510.3390/s18082495s18082495On-The-Fly Ambiguity Resolution Based on Double-Differential Square ObservationTengfei Wang0Zheng Yao1Mingquan Lu2Department of Electronic Engineering, Tsinghua University, Beijing 100084, ChinaDepartment of Electronic Engineering, Tsinghua University, Beijing 100084, ChinaDepartment of Electronic Engineering, Tsinghua University, Beijing 100084, ChinaGlobal navigation systems provide worldwide positioning, navigation and navigation services. However, in some challenging environments, especially when the satellite is blocked, the performance of GNSS is seriously degraded or even unavailable. Ground based positioning systems, including pseudolites and Locata, have shown their potentials in centimeter-level positioning accuracy using carrier phase measurements. Ambiguity resolution (AR) is a key issue for such high precision positioning. Current methods for the ground based systems need code measurements for initialization and/or approximating linearization. If the code measurements show relatively large errors, current methods might suffer from convergence difficulties in ground based positioning. In this paper, the concept of double-differential square observation (DDS) is proposed, and an on-the-fly ambiguity resolution (OTF-AR) method is developed for ground based navigation systems using two-way measurements. An important advantage of the proposed method is that only the carrier phase measurements are used, and code measurements are not necessary. The clock error is canceled out by two-way measurements between the rover and the base stations. The squared observations are then differenced between different rover positions and different base stations, and a linear model is then obtained. The floating integer values are easy to compute via this model, and there is no need to do approximate linearization. In this procedure, the rover’s approximate coordinates are also directly obtained from the carrier measurements, therefore code measurements are not necessary. As an OTF-AR method, the proposed method relies on geometric changes caused by the rover’s motion. As shown by the simulations, the geometric diversity of observations is the key factor for the AR success rate. Moreover, the fine floating solutions given by our method also have a fairly good accuracy, which is valuable when fixed solutions are not reliable. A real experiment is conducted to validate the proposed method. The results show that the fixed solution could achieve centimeter-level accuracy.http://www.mdpi.com/1424-8220/18/8/2495ambiguity resolutionground based positioningcarrier phase measurement |
| spellingShingle | Tengfei Wang Zheng Yao Mingquan Lu On-The-Fly Ambiguity Resolution Based on Double-Differential Square Observation Sensors ambiguity resolution ground based positioning carrier phase measurement |
| title | On-The-Fly Ambiguity Resolution Based on Double-Differential Square Observation |
| title_full | On-The-Fly Ambiguity Resolution Based on Double-Differential Square Observation |
| title_fullStr | On-The-Fly Ambiguity Resolution Based on Double-Differential Square Observation |
| title_full_unstemmed | On-The-Fly Ambiguity Resolution Based on Double-Differential Square Observation |
| title_short | On-The-Fly Ambiguity Resolution Based on Double-Differential Square Observation |
| title_sort | on the fly ambiguity resolution based on double differential square observation |
| topic | ambiguity resolution ground based positioning carrier phase measurement |
| url | http://www.mdpi.com/1424-8220/18/8/2495 |
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