The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
Randolph Ware - One of the best experts on this subject based on the ideXlab platform.
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gps meteorology direct estimation of the absolute value of precipitable water
Journal of Applied Meteorology, 1996Co-Authors: Jingping Duan, Michael Bevis, Peng Fang, Yehuda Bock, Steven R Chiswell, Steven Businger, Christian Rocken, Frederick Stuart Solheim, Terasa Van Hove, Randolph WareAbstract:Abstract A simple approach to estimating vertically integrated atmospheric water vapor, or precipitable water, from Global Positioning System (GPS) radio signals collected by a regional network of ground-based geodetic GPS receiver is illustrated and validated. Standard space geodetic methods are used to estimate the zenith delay caused by the neutral atmosphere, and surface pressure measurements are used to compute the hydrostatic (or “dry”) component of this delay. The zenith hydrostatic delay is subtracted from the zenith neutral delay to determine the zenith wet delay, which is then transformed into an estimate of precipitable water. By incorporating a few remote global Tracking Stations (and thus long baselines) into the geodetic analysis of a regional GPS network, it is possible to resolve the absolute (not merely the relative) value of the zenith neutral delay at each station in the augmented network. This approach eliminates any need for external comparisons with water vapor radiometer observation...
Kefei Zhang - One of the best experts on this subject based on the ideXlab platform.
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a method for identification of optimal minimum number of multi gnss Tracking Stations for ultra rapid orbit and erp determination
Advances in Space Research, 2017Co-Authors: Qianxin Wang, Kefei Zhang, Suqin Wu, Chao HuAbstract:Abstract With the rapid increase in the numbers of new generation Global Navigation Satellite Systems (GNSS) satellites, signal frequencies and ground Tracking Stations, the burden on data processing increases significantly, especially for those real-time or near real-time applications, e.g. generating ultra-rapid satellite orbit and Earth rotation parameters (ERP) products. In order to reduce the number of observations used to estimate the orbit and ERP unknown parameters for better computational efficiency, this study first introduced a parameter called orbit and ERP dilution of precision (OEDOP) factor and a method in “optimally” selecting multi-GNSS Tracking Stations based on the OEDOP factor is investigated to minimize the data processing burden without significantly sacrificing the accuracy and precision of the satellite orbit and ERP determination. The trade-off between computational efficiency and quality of results is primary focus of this research. The contribution of each Tracking station to the precision of the parameter estimates is investigated first, according to the location and multi-GNSS data measurement capacity of the station as well as the length of observations, then those Stations that contribute least will be identified and excluded in the estimation system. It aims to use as a fewer number of Tracking Stations as possible but the degradation in the precision of the solution is still under a desired level. The method was tested using GNSS observations from 409 International GNSS service (IGS) Stations over a one-month period. Results showed that when the “degradation” factor of the precision of satellite orbit and ERPs solutions is 5%, 10%, 15% and 20% the accuracy of the satellites orbit and polar motion parameters estimated from an optimal minimum number of Stations (in comparison with the results from all Stations) reduced about 0.33–9.92 cm and 5.77–41.53 μas respectively, and the accuracy of UT1–UTC reduced 10.63–15.50 μs; while their computational speed was improved by 196%, 332%, 527% and 617% respectively. This suggests that our method is a good trade-off method and an ideal option in cases that rapid solutions are required, e.g. ultra-rapid determination of orbit and ERP using multi-GNSS measurements from global ground Tracking Stations.
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identifying the relationship between gps data quality and positioning precision case study on igs Tracking Stations
Journal of Surveying Engineering-asce, 2012Co-Authors: Yida Chung, Kefei Zhang, Chienting Wu, Chuansheng Wang, Chiehhung ChenAbstract:AbstractThe number of global positioning system (GPS) Tracking Stations is increasing, primarily because the Stations are multifunctional. In civil engineering, they can be used for precision positioning; in the earth sciences, they can be used to monitor faults and earthquakes; and in the atmospheric sciences, they can be applied to predict perceptible water vapor. Currently, there are more than 400 GPS Stations in Taiwan; however, the data obtained through such Stations are not being assessed carefully. Experienced scientists and engineers examine the data in advance to see if they qualify for research purposes, but inexperienced users can adopt poor quality data that eventually lead to inaccurate research results. Of the observation Stations with receivers that were renewed between 2006 and 2008 in the International GNSS Service Network, four Stations (ZIMM, BOR1, NRC1, and NICO) were selected to be the subjects of this research. Six indexes of data quality were observed to calculate the quality of dat...
Jingping Duan - One of the best experts on this subject based on the ideXlab platform.
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gps meteorology direct estimation of the absolute value of precipitable water
Journal of Applied Meteorology, 1996Co-Authors: Jingping Duan, Michael Bevis, Peng Fang, Yehuda Bock, Steven R Chiswell, Steven Businger, Christian Rocken, Frederick Stuart Solheim, Terasa Van Hove, Randolph WareAbstract:Abstract A simple approach to estimating vertically integrated atmospheric water vapor, or precipitable water, from Global Positioning System (GPS) radio signals collected by a regional network of ground-based geodetic GPS receiver is illustrated and validated. Standard space geodetic methods are used to estimate the zenith delay caused by the neutral atmosphere, and surface pressure measurements are used to compute the hydrostatic (or “dry”) component of this delay. The zenith hydrostatic delay is subtracted from the zenith neutral delay to determine the zenith wet delay, which is then transformed into an estimate of precipitable water. By incorporating a few remote global Tracking Stations (and thus long baselines) into the geodetic analysis of a regional GPS network, it is possible to resolve the absolute (not merely the relative) value of the zenith neutral delay at each station in the augmented network. This approach eliminates any need for external comparisons with water vapor radiometer observation...
C S Chen - One of the best experts on this subject based on the ideXlab platform.
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Constructing a System to Monitor the Data Quality of GPS Receivers
Dynamic Planet, 2020Co-Authors: C S ChenAbstract:In Taiwan, there are more than one hundred GPS Tracking Stations maintained by Ministry of the Interior (MOI), Academia Sinica, Central Weather Bureau and Central Geological Survey. In the future, they may take place of the GPS controlling points after given a legal status. Therefore, the data quality of the Tracking Stations has become more and more important. This paper addresses the feasibility of establishing a system for monitoring GPS receivers.
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automatic data quality monitoring for continuous gps Tracking Stations in taiwan
Metrologia, 2007Co-Authors: Chihjen Wang, B F Chao, C S ChenAbstract:Taiwan has more than 300 Global Positioning System (GPS) Tracking Stations maintained by the Ministry of the Interior (MOI), Academia Sinica, the Central Weather Bureau and the Central Geological Survey. In the future, GPS Tracking Stations may replace the GPS control points after being given a legal status. Hence, the data quality of the Tracking Stations is an increasingly significant factor. This study considers the feasibility of establishing a system for monitoring GPS receivers. This investigation employs many data-quality indices and examines the relationship of these indices and the positioning precision. The frequency stability of the GPS receiver is the most important index; the cycle slip is the second index and the multipath is the third index. An auto-analytical system for analysing GPS data quality and monitoring the MOI's Tracking Stations can quickly find and resolve problems, or changes in station environment, to maintain high data quality for the Tracking Stations.
Chao Hu - One of the best experts on this subject based on the ideXlab platform.
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a method for identification of optimal minimum number of multi gnss Tracking Stations for ultra rapid orbit and erp determination
Advances in Space Research, 2017Co-Authors: Qianxin Wang, Kefei Zhang, Suqin Wu, Chao HuAbstract:Abstract With the rapid increase in the numbers of new generation Global Navigation Satellite Systems (GNSS) satellites, signal frequencies and ground Tracking Stations, the burden on data processing increases significantly, especially for those real-time or near real-time applications, e.g. generating ultra-rapid satellite orbit and Earth rotation parameters (ERP) products. In order to reduce the number of observations used to estimate the orbit and ERP unknown parameters for better computational efficiency, this study first introduced a parameter called orbit and ERP dilution of precision (OEDOP) factor and a method in “optimally” selecting multi-GNSS Tracking Stations based on the OEDOP factor is investigated to minimize the data processing burden without significantly sacrificing the accuracy and precision of the satellite orbit and ERP determination. The trade-off between computational efficiency and quality of results is primary focus of this research. The contribution of each Tracking station to the precision of the parameter estimates is investigated first, according to the location and multi-GNSS data measurement capacity of the station as well as the length of observations, then those Stations that contribute least will be identified and excluded in the estimation system. It aims to use as a fewer number of Tracking Stations as possible but the degradation in the precision of the solution is still under a desired level. The method was tested using GNSS observations from 409 International GNSS service (IGS) Stations over a one-month period. Results showed that when the “degradation” factor of the precision of satellite orbit and ERPs solutions is 5%, 10%, 15% and 20% the accuracy of the satellites orbit and polar motion parameters estimated from an optimal minimum number of Stations (in comparison with the results from all Stations) reduced about 0.33–9.92 cm and 5.77–41.53 μas respectively, and the accuracy of UT1–UTC reduced 10.63–15.50 μs; while their computational speed was improved by 196%, 332%, 527% and 617% respectively. This suggests that our method is a good trade-off method and an ideal option in cases that rapid solutions are required, e.g. ultra-rapid determination of orbit and ERP using multi-GNSS measurements from global ground Tracking Stations.
