The engineers use various softwares for observation processing and GPS networks, generally everyone who uses a device, he uses softwares with the same brand for the processing of it GPS processing networks by defined ...The engineers use various softwares for observation processing and GPS networks, generally everyone who uses a device, he uses softwares with the same brand for the processing of it GPS processing networks by defined default parameters and models. The most outstanding issue is that, it should be understood, the application of which kinds of softwares will help us to gain the desirable accuracy and whether the accuracy of coordinate estimation is acceptable in all commercial softwares or not. In this article, we compared a series of softwares which engineers use for their data processing with powerful scientific software that meanwhile it is too hard and time consuming to learn it. We have considered accuracy and validity of scientific software, which gives acceptable results, as a baseline to see how much errors and difference is between this software and the commercial softwares, so we selected Bernese as a scientific software and LGO, Ashtech Solutions, CGO softwares as commercial softwares and we analyzed them and compared the applied models of the softwares with each other. To do so, we choose a GPS network from Tehran city and discussed it, in order to evaluate the measured accuracy for baselines and also coordinate system that after data processing, it was understood that if the polygon of a network is small, commercial softwares can be utilized with very high acceptable accuracies and even by Ephemerides Precise data, their accuracy will increase more, but if our network is more extended and bigger, there is no other choice except using scientific softwares to calculate coordinate that performs a processing by many parameters.展开更多
越来越多的LEO卫星装载了高精度的星载GPS接收机,星载GPS定轨已成为LEO卫星精密定轨的重要手段之一。星载GPS精密定轨精度依赖于GPS星历及钟差精度,采用CODE(Center for Orbit Determination in Europe)官方网站提供的GPS精密星历及钟...越来越多的LEO卫星装载了高精度的星载GPS接收机,星载GPS定轨已成为LEO卫星精密定轨的重要手段之一。星载GPS精密定轨精度依赖于GPS星历及钟差精度,采用CODE(Center for Orbit Determination in Europe)官方网站提供的GPS精密星历及钟差数据,基于瑞士伯尼尔大学开发的Bernese 5.0软件,采用非差减缩动力学定轨方法,解算了60天的CHAMP卫星和SAC-C卫星轨道,并将所得轨道与JPL和GFZ事后科学轨道比较,得出的轨道位置三维精度优于20 cm量级,速度三维精度约为0.20 mm/s。展开更多
A magnitude M;7.8 earthquake occurred on 25 April 2015(referred as Gorkha earthquake).We have analyzed the spatial variation of b-value and two-dimensional strain within Nepal Himalaya before and after the Gorkha eart...A magnitude M;7.8 earthquake occurred on 25 April 2015(referred as Gorkha earthquake).We have analyzed the spatial variation of b-value and two-dimensional strain within Nepal Himalaya before and after the Gorkha earthquake.We have used continuous Global Navigation Satellite System(GNSS)data from 30 stations in the Nepal region for geodetic strain estimation and earthquake data for b-value estimation.The GNSS data were processed using double differencing technique for the accurate position of each station.The precise velocity vectors show a general azimuth of north east for all the stations and have been used to derive two-dimensional strain.Between epicenters of Gorkha(25 April 2015)and Dolakha earthquakes(12 May 2015),we observed high co-seismic horizontal displacements(0.2 m to 2 m).In the Pre-seismic deformation study,maximum strain accumulation(56.40×10;)and low bvalue(0.79-0.89)was observed in and around the Western Nepal region,which may be responsible for the 2015 Gorkha earthquake.The potential seismic zones were identified by GIS based integration of geodetic strain and b-value map and superimposition using weighted overlay method.The Maximum strain and low b-value are now observed in the eastern part of Nepal.Hence,the spatial disposition of elastic energy has changed after the two major earthquakes and continuous seismic hazard assessment is required in the eastern Nepal.展开更多
文摘The engineers use various softwares for observation processing and GPS networks, generally everyone who uses a device, he uses softwares with the same brand for the processing of it GPS processing networks by defined default parameters and models. The most outstanding issue is that, it should be understood, the application of which kinds of softwares will help us to gain the desirable accuracy and whether the accuracy of coordinate estimation is acceptable in all commercial softwares or not. In this article, we compared a series of softwares which engineers use for their data processing with powerful scientific software that meanwhile it is too hard and time consuming to learn it. We have considered accuracy and validity of scientific software, which gives acceptable results, as a baseline to see how much errors and difference is between this software and the commercial softwares, so we selected Bernese as a scientific software and LGO, Ashtech Solutions, CGO softwares as commercial softwares and we analyzed them and compared the applied models of the softwares with each other. To do so, we choose a GPS network from Tehran city and discussed it, in order to evaluate the measured accuracy for baselines and also coordinate system that after data processing, it was understood that if the polygon of a network is small, commercial softwares can be utilized with very high acceptable accuracies and even by Ephemerides Precise data, their accuracy will increase more, but if our network is more extended and bigger, there is no other choice except using scientific softwares to calculate coordinate that performs a processing by many parameters.
文摘越来越多的LEO卫星装载了高精度的星载GPS接收机,星载GPS定轨已成为LEO卫星精密定轨的重要手段之一。星载GPS精密定轨精度依赖于GPS星历及钟差精度,采用CODE(Center for Orbit Determination in Europe)官方网站提供的GPS精密星历及钟差数据,基于瑞士伯尼尔大学开发的Bernese 5.0软件,采用非差减缩动力学定轨方法,解算了60天的CHAMP卫星和SAC-C卫星轨道,并将所得轨道与JPL和GFZ事后科学轨道比较,得出的轨道位置三维精度优于20 cm量级,速度三维精度约为0.20 mm/s。
文摘A magnitude M;7.8 earthquake occurred on 25 April 2015(referred as Gorkha earthquake).We have analyzed the spatial variation of b-value and two-dimensional strain within Nepal Himalaya before and after the Gorkha earthquake.We have used continuous Global Navigation Satellite System(GNSS)data from 30 stations in the Nepal region for geodetic strain estimation and earthquake data for b-value estimation.The GNSS data were processed using double differencing technique for the accurate position of each station.The precise velocity vectors show a general azimuth of north east for all the stations and have been used to derive two-dimensional strain.Between epicenters of Gorkha(25 April 2015)and Dolakha earthquakes(12 May 2015),we observed high co-seismic horizontal displacements(0.2 m to 2 m).In the Pre-seismic deformation study,maximum strain accumulation(56.40×10;)and low bvalue(0.79-0.89)was observed in and around the Western Nepal region,which may be responsible for the 2015 Gorkha earthquake.The potential seismic zones were identified by GIS based integration of geodetic strain and b-value map and superimposition using weighted overlay method.The Maximum strain and low b-value are now observed in the eastern part of Nepal.Hence,the spatial disposition of elastic energy has changed after the two major earthquakes and continuous seismic hazard assessment is required in the eastern Nepal.
