Determined to become a new member of the well-established GNSS family,COMPASS(or BeiDou-2) is developing its capabilities to provide high accuracy positioning services.Two positioning modes are investigated in this st...Determined to become a new member of the well-established GNSS family,COMPASS(or BeiDou-2) is developing its capabilities to provide high accuracy positioning services.Two positioning modes are investigated in this study to assess the positioning accuracy of COMPASS' 4GEO/5IGSO/2MEO constellation.Precise Point Positioning(PPP) for geodetic users and real-time positioning for common navigation users are utilized.To evaluate PPP accuracy,coordinate time series repeatability and discrepancies with GPS' precise positioning are computed.Experiments show that COMPASS PPP repeatability for the east,north and up components of a receiver within China's Mainland is better than 2 cm,2 cm and 5 cm,respectively.Apparent systematic offsets of several centimeters exist between COMPASS precise positioning and GPS precise positioning,indicating errors remaining in the treatments of COMPASS measurement and dynamic models and reference frame differences existing between two systems.For common positioning users,COMPASS provides both open and authorized services with rapid differential corrections and integrity information available to authorized users.Our assessment shows that in open service positioning accuracy of dual-frequency and single-frequency users is about 5 m and 6 m(RMS),respectively,which may be improved to about 3 m and 4 m(RMS) with the addition of differential corrections.Less accurate Signal In Space User Ranging Error(SIS URE) and Geometric Dilution of Precision(GDOP) contribute to the relatively inferior accuracy of COMPASS as compared to GPS.Since the deployment of the remaining 1 GEO and 2 MEO is not able to significantly improve GDOP,the performance gap could only be overcome either by the use of differential corrections or improvement of the SIS URE,or both.展开更多
The positioning precision of the transmitting Chinese Area Positioning System(CAPS) is reduced due to the non-ideal distribution of the satellite constellation.Positioning and navigation enhancement methods are able t...The positioning precision of the transmitting Chinese Area Positioning System(CAPS) is reduced due to the non-ideal distribution of the satellite constellation.Positioning and navigation enhancement methods are able to improve the reliability and accuracy of the positioning system,especially for users in special regions and special applications.In this paper,a positioning enhanced scheme based on ultra-wide band(UWB) pseudolite is proposed for CAPS.It is demonstrated that the link budget of UWB pseudolite satisfies the FCC's emission mask requirements.The localization algorithm of the enhanced CAPS is presented.The simulations indicate that the positioning precision of the proposed enhanced scheme is improved greatly,and the feasibility of the enhanced scheme is thus proved.展开更多
The construction of a navigation system plays an important role in the development of national politics,economy and military affairs.Nowadays,the Beidou navigation system is facing a transition period from the regiona...The construction of a navigation system plays an important role in the development of national politics,economy and military affairs.Nowadays,the Beidou navigation system is facing a transition period from the regional navigation system to the global one.For the global constellation,the system performance will not be seriously degraded when one or two satellites are invalid,but it is out of case for the regional constellation,which usually has fewer satellites and less redundancy.This paper deals with this problem of hybrid constellations and analyzes the influence of the disabled satellites on the system.With hybrid constellations and simulation methods designed,the influence of invalid satellites on the navigation system is fully investigated.展开更多
基金supported by the Shanghai Committee of Science and Technology(Grant No.11ZR1443500)the National Natural Sciences Foundation of China(Grant Nos.11033004 and 11203009)China Satellite Navigation Conference(Grant No.CSNC2011-QY-01)
文摘Determined to become a new member of the well-established GNSS family,COMPASS(or BeiDou-2) is developing its capabilities to provide high accuracy positioning services.Two positioning modes are investigated in this study to assess the positioning accuracy of COMPASS' 4GEO/5IGSO/2MEO constellation.Precise Point Positioning(PPP) for geodetic users and real-time positioning for common navigation users are utilized.To evaluate PPP accuracy,coordinate time series repeatability and discrepancies with GPS' precise positioning are computed.Experiments show that COMPASS PPP repeatability for the east,north and up components of a receiver within China's Mainland is better than 2 cm,2 cm and 5 cm,respectively.Apparent systematic offsets of several centimeters exist between COMPASS precise positioning and GPS precise positioning,indicating errors remaining in the treatments of COMPASS measurement and dynamic models and reference frame differences existing between two systems.For common positioning users,COMPASS provides both open and authorized services with rapid differential corrections and integrity information available to authorized users.Our assessment shows that in open service positioning accuracy of dual-frequency and single-frequency users is about 5 m and 6 m(RMS),respectively,which may be improved to about 3 m and 4 m(RMS) with the addition of differential corrections.Less accurate Signal In Space User Ranging Error(SIS URE) and Geometric Dilution of Precision(GDOP) contribute to the relatively inferior accuracy of COMPASS as compared to GPS.Since the deployment of the remaining 1 GEO and 2 MEO is not able to significantly improve GDOP,the performance gap could only be overcome either by the use of differential corrections or improvement of the SIS URE,or both.
基金supported by the National Natural Science Foundation of China (Grant Nos. 61173012. 61173036)the National Basic Research Program of China (Grant No. 2007CB815500)+2 种基金the National High Technology Research and Development Program of China(Grant No. 2007AA12z343)the State Key Laboratory of Integrated Services Networks Open Project (Grant No. ISN12-05)the Open Fund Project of Key Laboratory in Hunan Universities (Grant No. 11K017)
文摘The positioning precision of the transmitting Chinese Area Positioning System(CAPS) is reduced due to the non-ideal distribution of the satellite constellation.Positioning and navigation enhancement methods are able to improve the reliability and accuracy of the positioning system,especially for users in special regions and special applications.In this paper,a positioning enhanced scheme based on ultra-wide band(UWB) pseudolite is proposed for CAPS.It is demonstrated that the link budget of UWB pseudolite satisfies the FCC's emission mask requirements.The localization algorithm of the enhanced CAPS is presented.The simulations indicate that the positioning precision of the proposed enhanced scheme is improved greatly,and the feasibility of the enhanced scheme is thus proved.
文摘The construction of a navigation system plays an important role in the development of national politics,economy and military affairs.Nowadays,the Beidou navigation system is facing a transition period from the regional navigation system to the global one.For the global constellation,the system performance will not be seriously degraded when one or two satellites are invalid,but it is out of case for the regional constellation,which usually has fewer satellites and less redundancy.This paper deals with this problem of hybrid constellations and analyzes the influence of the disabled satellites on the system.With hybrid constellations and simulation methods designed,the influence of invalid satellites on the navigation system is fully investigated.
