High-speed rail trains have a very complex system. Because the signals used by high-speed rails in the sections are mobile blocking systems, this can ensure the safety of the trains in the process of running. However,...High-speed rail trains have a very complex system. Because the signals used by high-speed rails in the sections are mobile blocking systems, this can ensure the safety of the trains in the process of running. However, in the actual operation of high-speed rail, trains cannot directly obtain the information and location of nearby trains. In this way, once the ground control system or signal equipment fails, the trains that are close to each other cannot obtain the information of each other in time and may collide. Therefore, a system has been developed to enable the train to track the nearest train in real time during the course of the train, and to accurately determine the speed and position of the train, which is very necessary for the safety of the train. Based on the Beidou satellite positioning technology, this paper designs a real-time tracking and early warning system suitable for high-speed rail through the analysis of its working principle and workflow, and realizes the real-time tracking of the high-speed rail train position and the collision distance between two high-speed rail trains. Early warning plays a role in improving the precise positioning of high-speed trains.展开更多
On December 27,2011,Ran Chengqi,director of the China Satellite Navigation Office announced that,the BeiDou Navigation Satellite System (BeiDou system) had that day begun to provide initial operational service.
BeiDou 3 preliminary system is completed to provide global services.China Satellite Navigation Office announced at a press conference held at the State Council Information Office on December 27 that the BeiDou 3 preli...BeiDou 3 preliminary system is completed to provide global services.China Satellite Navigation Office announced at a press conference held at the State Council Information Office on December 27 that the BeiDou 3 preliminary system was completed to provide global services,signifying that the coverage of the BeiDou system now extends to global coverage from regional.展开更多
The satellite-based augmentation system(SBAS)provides differential and integrity augmentation services for life safety fields of aviation and navigation.However,the signal structure of SBAS is public,which incurs a ri...The satellite-based augmentation system(SBAS)provides differential and integrity augmentation services for life safety fields of aviation and navigation.However,the signal structure of SBAS is public,which incurs a risk of spoofing attacks.To improve the anti-spoofing capability of the SBAS,European Union and the United States conduct research on navigation message authentication,and promote the standardization of SBAS message authentication.For the development of Beidou satellite-based augmentation system(BDSBAS),this paper proposes navigation message authentication based on the Chinese commercial cryptographic standards.Firstly,this paper expounds the architecture and principles of the SBAS message authentication,and then carries out the design of timed efficient streaming losstolerant authentication scheme(TESLA)and elliptic curve digital signature algorithm(ECDSA)authentication schemes based on Chinese commercial cryptographic standards,message arrangement and the design of over-the-air rekeying(OTAR)message.Finally,this paper conducts a theoretical analysis of the time between authentications(TBA)and maximum authentication latency(MAL)for L5 TESLA-I and L5 ECDSA-Q,and further simulates the reception time of OTAR message,TBA and MAL from the aspects of OTAR message weight and demodulation error rate.The simulation results can provide theoretical supports for the standardization of BDSBAS message authentication.展开更多
Inter-satellite link(ISL)scheduling is required by the BeiDou Navigation Satellite System(BDS)to guarantee the system ranging and communication performance.In the BDS,a great number of ISL scheduling instances must be...Inter-satellite link(ISL)scheduling is required by the BeiDou Navigation Satellite System(BDS)to guarantee the system ranging and communication performance.In the BDS,a great number of ISL scheduling instances must be addressed every day,which will certainly spend a lot of time via normal metaheuristics and hardly meet the quick-response requirements that often occur in real-world applications.To address the dual requirements of normal and quick-response ISL schedulings,a data-driven heuristic assisted memetic algorithm(DHMA)is proposed in this paper,which includes a high-performance memetic algorithm(MA)and a data-driven heuristic.In normal situations,the high-performance MA that hybridizes parallelism,competition,and evolution strategies is performed for high-quality ISL scheduling solutions over time.When in quick-response situations,the data-driven heuristic is performed to quickly schedule high-probability ISLs according to a prediction model,which is trained from the high-quality MA solutions.The main idea of the DHMA is to address normal and quick-response schedulings separately,while high-quality normal scheduling data are trained for quick-response use.In addition,this paper also presents an easy-to-understand ISL scheduling model and its NP-completeness.A seven-day experimental study with 10080 one-minute ISL scheduling instances shows the efficient performance of the DHMA in addressing the ISL scheduling in normal(in 84 hours)and quick-response(in 0.62 hour)situations,which can well meet the dual scheduling requirements in real-world BDS applications.展开更多
This paper presents a novel approach for assessing the precision of the wet refractivity field using BDS （BeiDou navigation satellite system） simulations only,GPS,and BDS＋GPS for the Shenzhen and Hongkong GNSS netw...This paper presents a novel approach for assessing the precision of the wet refractivity field using BDS （BeiDou navigation satellite system） simulations only,GPS,and BDS＋GPS for the Shenzhen and Hongkong GNSS network.The simulations are carried out by adding artificial noise to a real observation dataset.Instead of using the δ and σ parameters computed from slant wet delay,as in previous studies,we employ the Bias and RMS parameters,computed from the tomography results of total voxels,in order to obtain a more direct and comprehensive evaluation of the precision of the refractivity field determination.The results show that：（1） the precision of tropospheric wet refractivity estimated using BDS alone （only 9 satellites used） is basically comparable to that of GPS; （2） BDS＋GPS （as of current operation） may not be able to significantly improve the data＇s spatial density for the application of refractivity tomography; and （3） any slight increase in the precision of refractivity tomography,particularly in the lower atmosphere,bears great significance for any applications dependent on the Chinese operational meteorological service.展开更多
In recent years,geological and mineral resources exploration in China has expanded to deep hinterland of the Qinghai−Tibet Plateau and other regions with complex geological conditions.The special natural conditions of...In recent years,geological and mineral resources exploration in China has expanded to deep hinterland of the Qinghai−Tibet Plateau and other regions with complex geological conditions.The special natural conditions of Qinghai−Tibet Plateau determine the characteristics of“life-forbidden zone”that is characterized by alpine hypoxia,changeable weather,complex road conditions,and beast attack.In particular,the work in wild depopulated zones with severe environment and poor communications imposes serious threats to the life safety of geological personnel.Therefore,how to guarantee the safety of geological personnel working on the Qinghai−Tibet Plateau and how to reduce or even avoid casualty of geological personnel have currently become the urgent challenge.In this study,an emergency rescue information system for field geological survey is constructed based on BeiDou Navigation Satellite System.A case study of emergency rescue has been conducted in the depopulated zone of the Qinghai−Tibet Plateau and good effects have been achieved,providing security assurance for personnel engaged in field geological survey on the Qinghai−Tibet Plateau and technical support for the emergency rescue in case of natural hazards on the Qinghai−Tibet Plateau.The BeiDou Navigation Satellite System(BDS)can be effectively used to locate and communicate in the emergency rescue for rigorous Geological survey task where there is no network signal for the mobile phone,and the emergency rescue guarantee system is independent,reliable,and relatively cheap.The application value of BDS is demonstrated in the geological field.展开更多
The completion of the BeiDou global navigation satellite system has made China becoming the third country owning a global navigation satellite system independently.It has embarked on a development path with Chinese ch...The completion of the BeiDou global navigation satellite system has made China becoming the third country owning a global navigation satellite system independently.It has embarked on a development path with Chinese characteristics,enriched the development route of the world navigation satellite system,and enhanced China’s core competitiveness.The article describes the development and construction of Beidou Navigation Satellite System(BDS)and summaries the main achievements of BDS-1,BDS-2 and BDS-3 systems from the three aspects of independent innovation,system research and technological breakthrough.The article also analyzes the technical innovation characteristics of the BDS satellites comprehensively,providing a reference for subsequent research and planning of the next generation of the BDS satellites that are more ubiquitous,more integrated,and more intelligent.展开更多
CHINA launched the last satellite of the BeiDou Navigation Satellite System(BDS),the 55th in the BeiDou family,on June 23 in Xichang Satellite Launch Center in Sichuan Province.It marks the completion of the deploymen...CHINA launched the last satellite of the BeiDou Navigation Satellite System(BDS),the 55th in the BeiDou family,on June 23 in Xichang Satellite Launch Center in Sichuan Province.It marks the completion of the deployment of China’s own global navigation system.On its journey to explore a path of developing a navigation satellite system suitable for its national conditions since the late 20th century,China formulated a three-step strategy of development for BDS:to complete the construction of BDS-1 and provide services to the whole country by the end of 2000;to complete the construction of BDS-2 and provide services to the Asia-Pacific region by the end of 2012;and to complete the construction of BDS and provide services worldwide around 2020.展开更多
BeiDou navigation satellite system(the BeiDou system) is the only PNT(Positioning, Navigation and Tim-ing) resource in China that has coverage of the globe and near-Earth space and provides continuous high-precision,l...BeiDou navigation satellite system(the BeiDou system) is the only PNT(Positioning, Navigation and Tim-ing) resource in China that has coverage of the globe and near-Earth space and provides continuous high-precision,low-cost positioning, navigation and timing solutions for users in a unified spatio-temporal benchmark. As an importantspatio-temporal benchmark transmission system, the BeiDou system is the most important resource for the nationalPNT system to provide a PNT capability under a unified spatial-temporal benchmark. This paper proposes the con-cept, composition and development model of the space-based PNT system design based on the BeiDou system withall its space characteristics, as well as the advantages of the system. It opens up a new direction for the construction ofChina's PNT system and expands a new horizon in the research of a PNT system in China.展开更多
For scale cotton-picker operation, combination of production resources including field, machine, and drivers, should be organized reasonably both in temporal and spatial dimensions. Xinjian Agri. is such a scale cotto...For scale cotton-picker operation, combination of production resources including field, machine, and drivers, should be organized reasonably both in temporal and spatial dimensions. Xinjian Agri. is such a scale cotton picking service company, which owns more than 400 cotton-pickers, hires nearly 1000 personnel, and works for more than ten big farms each season. The total operation area is about 90,000 ha. In this paper, a Cotton-picker Operation Scheduling & Monitoring System (CPOSMS) was developed for Xinjian Agri. CPOSMS is a WebGIS and BeiDou based management software, which includes four main function modules. Overall scheduling module aims to help the company to create machine fleets for the farms based on operation demands and operation capacity. A real-time evaluation model was studied to adjust the rationality. Local scheduling module is to dispatch machines and personnel to form machine unit. Central navigating module is to guide staff to specific field. Operation monitoring module is to monitor and analyze operation process. Experiments in 2015 showed that the CPOSMS is the necessary tool for the company, and the evaluation model and BeiDou based system can improve management efficiency.展开更多
As the 16th BeiDou navigation satellite was successfully launched into space at 23:33 Beijing Time from the Xichang Satellite Launch Center (XSLC) on October 25, 2012, China completed the construction of the BeiDou Re...As the 16th BeiDou navigation satellite was successfully launched into space at 23:33 Beijing Time from the Xichang Satellite Launch Center (XSLC) on October 25, 2012, China completed the construction of the BeiDou Regional Navigation Satellite System that starts to officially provide services for most parts of the Asia-Pacific region from December 27. The 16th BeiDou navigation satellite, the last one for the regional BeiDou system, was developed by China Academy of Space Technology under CASC.展开更多
The transportation industry is one of the largest users of the BeiDou Navigation Satellite System(BDS),characterized by multiple locations,long lines,wide range,and extensive mobility.The application of BDS in the tra...The transportation industry is one of the largest users of the BeiDou Navigation Satellite System(BDS),characterized by multiple locations,long lines,wide range,and extensive mobility.The application of BDS in the transportation industry improves the development level of intelligent,safe,green and shared transportation.Based on the introduction of the application requirements and characteristics of BDS in the transportation industry,this paper systematically introduces the overall status of BDS in the transportation industry,covering highways,waterways,railways,civil aviation,and the postal service.Finally,the paper forecasts future applications of BDS in the field of transportation.It identifies within the transportation industry rich application scenarios for the cultivation of advanced technologies represented by BDS,enhancing transportation safety services and guaranteeing emergency communication,while improving the operation efficiency and management level of an integrated transportation system.展开更多
A LM-3B launched the BeiDou 3 GEO-2 sallite into space at 19:55 Bei-jing time on March 9,2020,from the Xichang Satellite Launch Center.The satellite entered its predetermined orbit later,marking the success of the lau...A LM-3B launched the BeiDou 3 GEO-2 sallite into space at 19:55 Bei-jing time on March 9,2020,from the Xichang Satellite Launch Center.The satellite entered its predetermined orbit later,marking the success of the launch mission.As the 54th satellite in the BeiDou navigation satellite system and also the 29th BeiDou 3 stallite,the BeiDou 3 GEO 2 stlie,developed by the China Academy of Space Technology,is called the“lucky stllite”with the largest size,the longest designed service life and the most funcions.展开更多
At 4:50 on April 30, China's LM-3B/I rocket, an improved type based on LM-3B, made its debut at the Xichang Satellite Launch Center and successfully sending the 12th and 13th BeiDou Navigation Satellite System sat...At 4:50 on April 30, China's LM-3B/I rocket, an improved type based on LM-3B, made its debut at the Xichang Satellite Launch Center and successfully sending the 12th and 13th BeiDou Navigation Satellite System satellites into the planned transfer orbit in space. It was the first time that China launched two BeiDou satellites with one rocket. It was展开更多
China launched the 11th BeiDou navigation satellite in their BeiDou Navigation Satellite System.The satellite was launched from the Xichang Satellite Launch Center in Sichuan Province on a LM-3C rocket at 0:12 on Febr...China launched the 11th BeiDou navigation satellite in their BeiDou Navigation Satellite System.The satellite was launched from the Xichang Satellite Launch Center in Sichuan Province on a LM-3C rocket at 0:12 on February 25 (Beijing time) and was put into the predetermined transfer orbit successfully.The geostationary satellite is the first BeiDou navigation satellite launched in 2012 for the展开更多
Based on the China Meteorological Administration’s Tropical Regional Atmosphere Model for the South China Sea(CMA-TRAMS),the authors conducted a collaborative assimilation forecasting experiment utilizing both Beidou...Based on the China Meteorological Administration’s Tropical Regional Atmosphere Model for the South China Sea(CMA-TRAMS),the authors conducted a collaborative assimilation forecasting experiment utilizing both Beidou radiosonde and drone-dropped(HAIYAN-I)radiosonde data in September 2023.Three assimilation experimental groups were designed as follows:Beidou radiosonde assimilation,drone-dropped radiosonde assimilation,and collaborative assimilation of Beidou and drone-dropped radiosonde data(hereinafter referred to as“Beidoudrop”).Additionally,a control group of operational forecasts without these data assimilations was set up.The results indicate that the operational forecast path in the control group deviated northward from the actual path.Besides,the Beidou-drop group showed the most significant improvement in terms of forecasting the typhoon path at 60 to 90 h lead times.Specifically,the 72 h and 90 h path errors were reduced by 66.8 and 82.4 km,respectively,resulting in a much more accurate forecast of Typhoon Haikui’s landing point,at the coastal junction of Fujian and Guangdong.Furthermore,the collaborative assimilation revealed a notable impact on improving the forecast of wind and rain associated with Haikui’s landfall,aligning more closely with the real case.A marked rise was also seen in the precipitation score of the Beidou-drop group,where the 50 mm TS(threat score)of the 72 h lead time increased from 0.33 in the control experiment to 0.75,and the 100 mm TS rose from 0.18 to 0.39.展开更多
The visibility for low earth orbit（LEO） satellites provided by the BeiDou-2 system is analyzed and compared with the global positioning system（GPS）. In addition, the spaceborne receivers＇ observations are simulat...The visibility for low earth orbit（LEO） satellites provided by the BeiDou-2 system is analyzed and compared with the global positioning system（GPS）. In addition, the spaceborne receivers＇ observations are simulated by the BeiDou satellites broadcast ephemeris and LEO satellites orbits. The precise orbit determination（POD） results show that the along-track component accuracy is much better over the service area than the non-service area, while the accuracy of the other two directions keeps at the same level over different areas. However, the 3-dimensional（3D） accuracy over the two areas shows almost no difference. Only taking into consideration the observation noise and navigation satellite ephemeris errors, the 3D accuracy of the POD is about30 cm. As for the precise relative orbit determination（PROD）, the 3D accuracy is much better over the eastern hemisphere than that of the western hemisphere. The baseline length accuracy is 3.4 mm over the service area, and it is still better than 1 cm over the non-service area. This paper demonstrates that the BeiDou regional constellation could provide global service to LEO satellites for the POD and the PROD. Finally, the benefit of geostationary earth orbit（GEO） satellites is illustrated for POD.展开更多
文摘High-speed rail trains have a very complex system. Because the signals used by high-speed rails in the sections are mobile blocking systems, this can ensure the safety of the trains in the process of running. However, in the actual operation of high-speed rail, trains cannot directly obtain the information and location of nearby trains. In this way, once the ground control system or signal equipment fails, the trains that are close to each other cannot obtain the information of each other in time and may collide. Therefore, a system has been developed to enable the train to track the nearest train in real time during the course of the train, and to accurately determine the speed and position of the train, which is very necessary for the safety of the train. Based on the Beidou satellite positioning technology, this paper designs a real-time tracking and early warning system suitable for high-speed rail through the analysis of its working principle and workflow, and realizes the real-time tracking of the high-speed rail train position and the collision distance between two high-speed rail trains. Early warning plays a role in improving the precise positioning of high-speed trains.
文摘On December 27,2011,Ran Chengqi,director of the China Satellite Navigation Office announced that,the BeiDou Navigation Satellite System (BeiDou system) had that day begun to provide initial operational service.
文摘BeiDou 3 preliminary system is completed to provide global services.China Satellite Navigation Office announced at a press conference held at the State Council Information Office on December 27 that the BeiDou 3 preliminary system was completed to provide global services,signifying that the coverage of the BeiDou system now extends to global coverage from regional.
基金supported by National Natural Science Foundation of China:Space-based occultation detection with ground-based GNSS atmospheric horizontal gradient model(41904033).
文摘The satellite-based augmentation system(SBAS)provides differential and integrity augmentation services for life safety fields of aviation and navigation.However,the signal structure of SBAS is public,which incurs a risk of spoofing attacks.To improve the anti-spoofing capability of the SBAS,European Union and the United States conduct research on navigation message authentication,and promote the standardization of SBAS message authentication.For the development of Beidou satellite-based augmentation system(BDSBAS),this paper proposes navigation message authentication based on the Chinese commercial cryptographic standards.Firstly,this paper expounds the architecture and principles of the SBAS message authentication,and then carries out the design of timed efficient streaming losstolerant authentication scheme(TESLA)and elliptic curve digital signature algorithm(ECDSA)authentication schemes based on Chinese commercial cryptographic standards,message arrangement and the design of over-the-air rekeying(OTAR)message.Finally,this paper conducts a theoretical analysis of the time between authentications(TBA)and maximum authentication latency(MAL)for L5 TESLA-I and L5 ECDSA-Q,and further simulates the reception time of OTAR message,TBA and MAL from the aspects of OTAR message weight and demodulation error rate.The simulation results can provide theoretical supports for the standardization of BDSBAS message authentication.
基金supported by the National Natural Science Foundation of China(61773120)the National Natural Science Fund for Distinguished Young Scholars of China(61525304)+2 种基金the Foundation for the Author of National Excellent Doctoral Dissertation of China(2014-92)the Hunan Postgraduate Research Innovation Project(CX2018B022)the China Scholarship Council-Leiden University Scholarship。
文摘Inter-satellite link(ISL)scheduling is required by the BeiDou Navigation Satellite System(BDS)to guarantee the system ranging and communication performance.In the BDS,a great number of ISL scheduling instances must be addressed every day,which will certainly spend a lot of time via normal metaheuristics and hardly meet the quick-response requirements that often occur in real-world applications.To address the dual requirements of normal and quick-response ISL schedulings,a data-driven heuristic assisted memetic algorithm(DHMA)is proposed in this paper,which includes a high-performance memetic algorithm(MA)and a data-driven heuristic.In normal situations,the high-performance MA that hybridizes parallelism,competition,and evolution strategies is performed for high-quality ISL scheduling solutions over time.When in quick-response situations,the data-driven heuristic is performed to quickly schedule high-probability ISLs according to a prediction model,which is trained from the high-quality MA solutions.The main idea of the DHMA is to address normal and quick-response schedulings separately,while high-quality normal scheduling data are trained for quick-response use.In addition,this paper also presents an easy-to-understand ISL scheduling model and its NP-completeness.A seven-day experimental study with 10080 one-minute ISL scheduling instances shows the efficient performance of the DHMA in addressing the ISL scheduling in normal(in 84 hours)and quick-response(in 0.62 hour)situations,which can well meet the dual scheduling requirements in real-world BDS applications.
基金supported by the National Basic ResearchDevelopment (973) Program of China (Grant No. 2012CB955903)+1 种基金the National Natural Science Foundation of China (Grant No. 20907047 and Grant No. 71373131)National Industry-specific Topics (Grant No.GYHY 201406078)
文摘This paper presents a novel approach for assessing the precision of the wet refractivity field using BDS （BeiDou navigation satellite system） simulations only,GPS,and BDS＋GPS for the Shenzhen and Hongkong GNSS network.The simulations are carried out by adding artificial noise to a real observation dataset.Instead of using the δ and σ parameters computed from slant wet delay,as in previous studies,we employ the Bias and RMS parameters,computed from the tomography results of total voxels,in order to obtain a more direct and comprehensive evaluation of the precision of the refractivity field determination.The results show that：（1） the precision of tropospheric wet refractivity estimated using BDS alone （only 9 satellites used） is basically comparable to that of GPS; （2） BDS＋GPS （as of current operation） may not be able to significantly improve the data＇s spatial density for the application of refractivity tomography; and （3） any slight increase in the precision of refractivity tomography,particularly in the lower atmosphere,bears great significance for any applications dependent on the Chinese operational meteorological service.
基金This study was supported by the Public Beneficial Industrial Funds by the Ministry of Land and Resources of China[grant number 201011010].
文摘In recent years,geological and mineral resources exploration in China has expanded to deep hinterland of the Qinghai−Tibet Plateau and other regions with complex geological conditions.The special natural conditions of Qinghai−Tibet Plateau determine the characteristics of“life-forbidden zone”that is characterized by alpine hypoxia,changeable weather,complex road conditions,and beast attack.In particular,the work in wild depopulated zones with severe environment and poor communications imposes serious threats to the life safety of geological personnel.Therefore,how to guarantee the safety of geological personnel working on the Qinghai−Tibet Plateau and how to reduce or even avoid casualty of geological personnel have currently become the urgent challenge.In this study,an emergency rescue information system for field geological survey is constructed based on BeiDou Navigation Satellite System.A case study of emergency rescue has been conducted in the depopulated zone of the Qinghai−Tibet Plateau and good effects have been achieved,providing security assurance for personnel engaged in field geological survey on the Qinghai−Tibet Plateau and technical support for the emergency rescue in case of natural hazards on the Qinghai−Tibet Plateau.The BeiDou Navigation Satellite System(BDS)can be effectively used to locate and communicate in the emergency rescue for rigorous Geological survey task where there is no network signal for the mobile phone,and the emergency rescue guarantee system is independent,reliable,and relatively cheap.The application value of BDS is demonstrated in the geological field.
文摘The completion of the BeiDou global navigation satellite system has made China becoming the third country owning a global navigation satellite system independently.It has embarked on a development path with Chinese characteristics,enriched the development route of the world navigation satellite system,and enhanced China’s core competitiveness.The article describes the development and construction of Beidou Navigation Satellite System(BDS)and summaries the main achievements of BDS-1,BDS-2 and BDS-3 systems from the three aspects of independent innovation,system research and technological breakthrough.The article also analyzes the technical innovation characteristics of the BDS satellites comprehensively,providing a reference for subsequent research and planning of the next generation of the BDS satellites that are more ubiquitous,more integrated,and more intelligent.
文摘CHINA launched the last satellite of the BeiDou Navigation Satellite System(BDS),the 55th in the BeiDou family,on June 23 in Xichang Satellite Launch Center in Sichuan Province.It marks the completion of the deployment of China’s own global navigation system.On its journey to explore a path of developing a navigation satellite system suitable for its national conditions since the late 20th century,China formulated a three-step strategy of development for BDS:to complete the construction of BDS-1 and provide services to the whole country by the end of 2000;to complete the construction of BDS-2 and provide services to the Asia-Pacific region by the end of 2012;and to complete the construction of BDS and provide services worldwide around 2020.
文摘BeiDou navigation satellite system(the BeiDou system) is the only PNT(Positioning, Navigation and Tim-ing) resource in China that has coverage of the globe and near-Earth space and provides continuous high-precision,low-cost positioning, navigation and timing solutions for users in a unified spatio-temporal benchmark. As an importantspatio-temporal benchmark transmission system, the BeiDou system is the most important resource for the nationalPNT system to provide a PNT capability under a unified spatial-temporal benchmark. This paper proposes the con-cept, composition and development model of the space-based PNT system design based on the BeiDou system withall its space characteristics, as well as the advantages of the system. It opens up a new direction for the construction ofChina's PNT system and expands a new horizon in the research of a PNT system in China.
文摘For scale cotton-picker operation, combination of production resources including field, machine, and drivers, should be organized reasonably both in temporal and spatial dimensions. Xinjian Agri. is such a scale cotton picking service company, which owns more than 400 cotton-pickers, hires nearly 1000 personnel, and works for more than ten big farms each season. The total operation area is about 90,000 ha. In this paper, a Cotton-picker Operation Scheduling & Monitoring System (CPOSMS) was developed for Xinjian Agri. CPOSMS is a WebGIS and BeiDou based management software, which includes four main function modules. Overall scheduling module aims to help the company to create machine fleets for the farms based on operation demands and operation capacity. A real-time evaluation model was studied to adjust the rationality. Local scheduling module is to dispatch machines and personnel to form machine unit. Central navigating module is to guide staff to specific field. Operation monitoring module is to monitor and analyze operation process. Experiments in 2015 showed that the CPOSMS is the necessary tool for the company, and the evaluation model and BeiDou based system can improve management efficiency.
文摘As the 16th BeiDou navigation satellite was successfully launched into space at 23:33 Beijing Time from the Xichang Satellite Launch Center (XSLC) on October 25, 2012, China completed the construction of the BeiDou Regional Navigation Satellite System that starts to officially provide services for most parts of the Asia-Pacific region from December 27. The 16th BeiDou navigation satellite, the last one for the regional BeiDou system, was developed by China Academy of Space Technology under CASC.
文摘The transportation industry is one of the largest users of the BeiDou Navigation Satellite System(BDS),characterized by multiple locations,long lines,wide range,and extensive mobility.The application of BDS in the transportation industry improves the development level of intelligent,safe,green and shared transportation.Based on the introduction of the application requirements and characteristics of BDS in the transportation industry,this paper systematically introduces the overall status of BDS in the transportation industry,covering highways,waterways,railways,civil aviation,and the postal service.Finally,the paper forecasts future applications of BDS in the field of transportation.It identifies within the transportation industry rich application scenarios for the cultivation of advanced technologies represented by BDS,enhancing transportation safety services and guaranteeing emergency communication,while improving the operation efficiency and management level of an integrated transportation system.
文摘A LM-3B launched the BeiDou 3 GEO-2 sallite into space at 19:55 Bei-jing time on March 9,2020,from the Xichang Satellite Launch Center.The satellite entered its predetermined orbit later,marking the success of the launch mission.As the 54th satellite in the BeiDou navigation satellite system and also the 29th BeiDou 3 stallite,the BeiDou 3 GEO 2 stlie,developed by the China Academy of Space Technology,is called the“lucky stllite”with the largest size,the longest designed service life and the most funcions.
文摘At 4:50 on April 30, China's LM-3B/I rocket, an improved type based on LM-3B, made its debut at the Xichang Satellite Launch Center and successfully sending the 12th and 13th BeiDou Navigation Satellite System satellites into the planned transfer orbit in space. It was the first time that China launched two BeiDou satellites with one rocket. It was
文摘China launched the 11th BeiDou navigation satellite in their BeiDou Navigation Satellite System.The satellite was launched from the Xichang Satellite Launch Center in Sichuan Province on a LM-3C rocket at 0:12 on February 25 (Beijing time) and was put into the predetermined transfer orbit successfully.The geostationary satellite is the first BeiDou navigation satellite launched in 2012 for the
文摘Based on the China Meteorological Administration’s Tropical Regional Atmosphere Model for the South China Sea(CMA-TRAMS),the authors conducted a collaborative assimilation forecasting experiment utilizing both Beidou radiosonde and drone-dropped(HAIYAN-I)radiosonde data in September 2023.Three assimilation experimental groups were designed as follows:Beidou radiosonde assimilation,drone-dropped radiosonde assimilation,and collaborative assimilation of Beidou and drone-dropped radiosonde data(hereinafter referred to as“Beidoudrop”).Additionally,a control group of operational forecasts without these data assimilations was set up.The results indicate that the operational forecast path in the control group deviated northward from the actual path.Besides,the Beidou-drop group showed the most significant improvement in terms of forecasting the typhoon path at 60 to 90 h lead times.Specifically,the 72 h and 90 h path errors were reduced by 66.8 and 82.4 km,respectively,resulting in a much more accurate forecast of Typhoon Haikui’s landing point,at the coastal junction of Fujian and Guangdong.Furthermore,the collaborative assimilation revealed a notable impact on improving the forecast of wind and rain associated with Haikui’s landfall,aligning more closely with the real case.A marked rise was also seen in the precipitation score of the Beidou-drop group,where the 50 mm TS(threat score)of the 72 h lead time increased from 0.33 in the control experiment to 0.75,and the 100 mm TS rose from 0.18 to 0.39.
基金co-supported by the National Natural Science Foundation of China (Nos: 61002033, 61370013)the Program for New Century Excellent Talents in University and the Scientific Research Foundation for the Returned Overseas Chinese Scholars of Ministry of Education of China
文摘The visibility for low earth orbit（LEO） satellites provided by the BeiDou-2 system is analyzed and compared with the global positioning system（GPS）. In addition, the spaceborne receivers＇ observations are simulated by the BeiDou satellites broadcast ephemeris and LEO satellites orbits. The precise orbit determination（POD） results show that the along-track component accuracy is much better over the service area than the non-service area, while the accuracy of the other two directions keeps at the same level over different areas. However, the 3-dimensional（3D） accuracy over the two areas shows almost no difference. Only taking into consideration the observation noise and navigation satellite ephemeris errors, the 3D accuracy of the POD is about30 cm. As for the precise relative orbit determination（PROD）, the 3D accuracy is much better over the eastern hemisphere than that of the western hemisphere. The baseline length accuracy is 3.4 mm over the service area, and it is still better than 1 cm over the non-service area. This paper demonstrates that the BeiDou regional constellation could provide global service to LEO satellites for the POD and the PROD. Finally, the benefit of geostationary earth orbit（GEO） satellites is illustrated for POD.
