Location Based Navigation System (LBNS) is a specific Location Based Service (LBS) purely for navigational purpose. These systems resolve position of a user by using GNSS/GPS positioning technologies, to which supplem...Location Based Navigation System (LBNS) is a specific Location Based Service (LBS) purely for navigational purpose. These systems resolve position of a user by using GNSS/GPS positioning technologies, to which supplementary information on goods and services are tagged. The navigation services have become popular and can be installed on mobile phones to provide route information, location of points of interest and user’s current location. LBS has continued to face challenges which include “communication” process towards user reference. Location Based Service System conveys suitable information through a mobile device for effective decision making and reaction within a given time span. This research was geared at understanding the state of LBS technology acceptance and adoption by users in Nairobi Kenya. To do this a quantitative study was carried out through a questionnaire, to investigate mobile phone users’ response on awareness and use of LBS technology. Testing the growth of this technology in this region compared to predictions in previous studies using Technology Acceptance Model (TAM), it is evident that many users may be aware of GPS functionality in mobile phones but are certainly yet to fully embrace the technology as they rarely use it. This points to some underlying challenges towards this technology within this part of the World, thereby recommending for deliberate monitoring and evaluation of LBS technology for sustenance growth based on user satisfaction and acceptance for improved usability.展开更多
User response or reaction to navigation applications is influenced by relevance in geographic information, in terms of cartographic context and content delivered within a definite time, providing a direct impact to ou...User response or reaction to navigation applications is influenced by relevance in geographic information, in terms of cartographic context and content delivered within a definite time, providing a direct impact to outcome or consequence based on decision making and hence user reaction. Location Based Navigation Services (LBNS) have continuously advanced in cartographic visualization, making maps interpretation easy and ubiquitous to any user, as compared to pre-historic times when maps were a preserve of a few. Despite rapid growth in LBNS, there exist challenges that may be characterized as technical and non-technical challenges, among them being process of conveying geospatial information to user. LBNS system deliver appropriate information to a user through smartphone (mobile device) for effective decision making and response within a given time span. This research focuses on optimization of cartographic content for contextual information in LBNS to users, based on prevailing circumstances of various components that constitute it. The research looks into Geographic Information Retrieval (GIR), as a technical challenge centered on a non-technical issue of social being of user satisfaction, leading to decision making in LBNS, hence response and outcome. Though advanced technologically, current LBNS on information sourcing depends on user manual web pages navigation and maneuver, this can be painstaking and time consuming that it may cause unnecessary delay in information delivery, resulting to delayed information response time (DIRT). This in turn may lead to unappropriate decision making with erroneous reaction or response being taken, resulting in loss of opportunity, resources, time and even life. Optimization in LBNS is achieved by a mathematical relationship developed between user status, mobile device variables against cartographic content. The relationship is in turn applied in LBNS android application to fulfill optimization solution for user consumption.展开更多
The analysis centers of the Multi-GNSS Pilot Project of the International GNSS Service provide orbit and clock products for the global navigation satellite systems(GNSSs)Global Positioning System(GPS),GLONASS,Galileo,...The analysis centers of the Multi-GNSS Pilot Project of the International GNSS Service provide orbit and clock products for the global navigation satellite systems(GNSSs)Global Positioning System(GPS),GLONASS,Galileo,and BeiDou,as well as for the Japanese regional Quasi-Zenith Satellite System(QZSS).Due to improved solar radiation pressure modeling and other more sophisticated models,the consistency of these products has improved in recent years.The current orbit consistency between different analysis centers is on the level of a few centimeters for GPS,around one decimeter for GLONASS and Galileo,a few decimeters for BeiDou-2,and several decimeters for QZSS.The clock consistency is about 2 cm for GPS,5 cm for GLONASS and Galileo,and 10 cm for BeiDou-2.In terms of carrier phase modeling error for precise point positioning,the various products exhibit consistencies of 2–3 cm for GPS,6–14 cm for GLONASS,3–10 cm for Galileo,and 10–17 cm for BeiDou-2.展开更多
BeiDou regional navigation satellite system(BDS)also called BeiDou-2 has been in full operation since December 27,2012.It consists of 14 satellites,including 5 satellites in Geostationary Orbit(GEO),5 satellites in In...BeiDou regional navigation satellite system(BDS)also called BeiDou-2 has been in full operation since December 27,2012.It consists of 14 satellites,including 5 satellites in Geostationary Orbit(GEO),5 satellites in Inclined Geosynchronous Orbit(IGSO),and 4 satellites in Medium Earth Orbit(MEO).In this paper,its basic navigation and positioning performance are evaluated preliminarily by the real data collected in Beijing,including satellite visibility,Position Dilution of Precision(PDOP)value,the precision of code and carrier phase measurements,the accuracy of single point positioning and differential positioning and ambiguity resolution(AR)performance,which are also compared with those of GPS.It is shown that the precision of BDS code and carrier phase measurements are about 33 cm and 2 mm,respectively,which are comparable to those of GPS,and the accuracy of BDS single point positioning has satisfied the design requirement.The real-time kinematic positioning is also feasible by BDS alone in the opening condition,since its fixed rate and reliability of single-epoch dual-frequency AR is comparable to those of GPS.The accuracy of BDS carrier phase differential positioning is better than 1 cm for a very short baseline of 4.2 m and 3 cm for a short baseline of 8.2 km,which is on the same level with that of GPS.For the combined BDS and GPS,the fixed rate and reliability of single-epoch AR and the positioning accuracy are improved significantly.The accuracy of BDS/GPS carrier phase differential positioning is about 35 and 20%better than that of GPS for two short baseline tests in this study.The accuracy of BDS code differential positioning is better than 2.5 m.However it is worse than that of GPS,which may result from large code multipath errors of BDS GEO satellite measurements.展开更多
针对野外通信线缆所经地形复杂、环境恶劣、铺设方式多样、探查维护困难的问题,设计并开发了一款可用于线缆巡查的高精度数字地图系统(High precision digital map,HPDM)。该系统采用Qt构建窗口界面,使用OSG earth(Open Scene Graph,OSG...针对野外通信线缆所经地形复杂、环境恶劣、铺设方式多样、探查维护困难的问题,设计并开发了一款可用于线缆巡查的高精度数字地图系统(High precision digital map,HPDM)。该系统采用Qt构建窗口界面,使用OSG earth(Open Scene Graph,OSG)三维渲染引擎利用高精度的卫星影像数据构建数字地球,通过北斗全球卫星导航系统实时定位人员位置,地下线缆定位精度小于1米,可实现地下管线的快速定位。系统可视化程度高、结构轻便、操作简单、扩展性强,极大地方便了线缆巡查工作。展开更多
文摘Location Based Navigation System (LBNS) is a specific Location Based Service (LBS) purely for navigational purpose. These systems resolve position of a user by using GNSS/GPS positioning technologies, to which supplementary information on goods and services are tagged. The navigation services have become popular and can be installed on mobile phones to provide route information, location of points of interest and user’s current location. LBS has continued to face challenges which include “communication” process towards user reference. Location Based Service System conveys suitable information through a mobile device for effective decision making and reaction within a given time span. This research was geared at understanding the state of LBS technology acceptance and adoption by users in Nairobi Kenya. To do this a quantitative study was carried out through a questionnaire, to investigate mobile phone users’ response on awareness and use of LBS technology. Testing the growth of this technology in this region compared to predictions in previous studies using Technology Acceptance Model (TAM), it is evident that many users may be aware of GPS functionality in mobile phones but are certainly yet to fully embrace the technology as they rarely use it. This points to some underlying challenges towards this technology within this part of the World, thereby recommending for deliberate monitoring and evaluation of LBS technology for sustenance growth based on user satisfaction and acceptance for improved usability.
文摘User response or reaction to navigation applications is influenced by relevance in geographic information, in terms of cartographic context and content delivered within a definite time, providing a direct impact to outcome or consequence based on decision making and hence user reaction. Location Based Navigation Services (LBNS) have continuously advanced in cartographic visualization, making maps interpretation easy and ubiquitous to any user, as compared to pre-historic times when maps were a preserve of a few. Despite rapid growth in LBNS, there exist challenges that may be characterized as technical and non-technical challenges, among them being process of conveying geospatial information to user. LBNS system deliver appropriate information to a user through smartphone (mobile device) for effective decision making and response within a given time span. This research focuses on optimization of cartographic content for contextual information in LBNS to users, based on prevailing circumstances of various components that constitute it. The research looks into Geographic Information Retrieval (GIR), as a technical challenge centered on a non-technical issue of social being of user satisfaction, leading to decision making in LBNS, hence response and outcome. Though advanced technologically, current LBNS on information sourcing depends on user manual web pages navigation and maneuver, this can be painstaking and time consuming that it may cause unnecessary delay in information delivery, resulting to delayed information response time (DIRT). This in turn may lead to unappropriate decision making with erroneous reaction or response being taken, resulting in loss of opportunity, resources, time and even life. Optimization in LBNS is achieved by a mathematical relationship developed between user status, mobile device variables against cartographic content. The relationship is in turn applied in LBNS android application to fulfill optimization solution for user consumption.
基金We would like to acknowledge the efforts of the MGEX station operators,data,and analysis centers,as well as the ILRS for providing SLR normal points.
文摘The analysis centers of the Multi-GNSS Pilot Project of the International GNSS Service provide orbit and clock products for the global navigation satellite systems(GNSSs)Global Positioning System(GPS),GLONASS,Galileo,and BeiDou,as well as for the Japanese regional Quasi-Zenith Satellite System(QZSS).Due to improved solar radiation pressure modeling and other more sophisticated models,the consistency of these products has improved in recent years.The current orbit consistency between different analysis centers is on the level of a few centimeters for GPS,around one decimeter for GLONASS and Galileo,a few decimeters for BeiDou-2,and several decimeters for QZSS.The clock consistency is about 2 cm for GPS,5 cm for GLONASS and Galileo,and 10 cm for BeiDou-2.In terms of carrier phase modeling error for precise point positioning,the various products exhibit consistencies of 2–3 cm for GPS,6–14 cm for GLONASS,3–10 cm for Galileo,and 10–17 cm for BeiDou-2.
基金sponsored by the National Natural Science Foundation of China(Grant Nos.41020144004,41374019,41104022)the National High Technology Research and Development Program of China(Grant No.2013AA122501)
文摘BeiDou regional navigation satellite system(BDS)also called BeiDou-2 has been in full operation since December 27,2012.It consists of 14 satellites,including 5 satellites in Geostationary Orbit(GEO),5 satellites in Inclined Geosynchronous Orbit(IGSO),and 4 satellites in Medium Earth Orbit(MEO).In this paper,its basic navigation and positioning performance are evaluated preliminarily by the real data collected in Beijing,including satellite visibility,Position Dilution of Precision(PDOP)value,the precision of code and carrier phase measurements,the accuracy of single point positioning and differential positioning and ambiguity resolution(AR)performance,which are also compared with those of GPS.It is shown that the precision of BDS code and carrier phase measurements are about 33 cm and 2 mm,respectively,which are comparable to those of GPS,and the accuracy of BDS single point positioning has satisfied the design requirement.The real-time kinematic positioning is also feasible by BDS alone in the opening condition,since its fixed rate and reliability of single-epoch dual-frequency AR is comparable to those of GPS.The accuracy of BDS carrier phase differential positioning is better than 1 cm for a very short baseline of 4.2 m and 3 cm for a short baseline of 8.2 km,which is on the same level with that of GPS.For the combined BDS and GPS,the fixed rate and reliability of single-epoch AR and the positioning accuracy are improved significantly.The accuracy of BDS/GPS carrier phase differential positioning is about 35 and 20%better than that of GPS for two short baseline tests in this study.The accuracy of BDS code differential positioning is better than 2.5 m.However it is worse than that of GPS,which may result from large code multipath errors of BDS GEO satellite measurements.
文摘针对野外通信线缆所经地形复杂、环境恶劣、铺设方式多样、探查维护困难的问题,设计并开发了一款可用于线缆巡查的高精度数字地图系统(High precision digital map,HPDM)。该系统采用Qt构建窗口界面,使用OSG earth(Open Scene Graph,OSG)三维渲染引擎利用高精度的卫星影像数据构建数字地球,通过北斗全球卫星导航系统实时定位人员位置,地下线缆定位精度小于1米,可实现地下管线的快速定位。系统可视化程度高、结构轻便、操作简单、扩展性强,极大地方便了线缆巡查工作。
