Due to the lack of authentication mechanism in BeiDou navigation satellite system(BDS),BD-Ⅱ civil navigation message(BDⅡ-CNAV) are vulnerable to spoofing attack and replay attack.To solve this problem,we present a s...Due to the lack of authentication mechanism in BeiDou navigation satellite system(BDS),BD-Ⅱ civil navigation message(BDⅡ-CNAV) are vulnerable to spoofing attack and replay attack.To solve this problem,we present a security authentication protocol,called as BDSec,which is designed by using China’s cryptography Shangyong Mima(SM) series algorithms,such as SM2/4/9 and Zu Chongzhi(ZUC)algorithm.In BDSec protocol,both of BDⅡ-CNAV and signature information are encrypted using the SM4 algorithm(Symmetric encryption mechanism).The encrypted result is used as the subject authentication information.BDSec protocol applies SM9 algorithm(Identity-based cryptography mechanism) to protect the integrity of the BDⅡ-CNAV,adopts the SM2 algorithm(Public key cryptosystem) to guarantee the confidentiality of the important session information,and uses the ZUC algorithm(Encryption and integrity algorithm) to verify the integrity of the message authentication serial number and initial information and the information in authentication initialization sub-protocol respectively.The results of the SVO logic reasoning and performance analysis show that BDSec protocol meets security requirements for the dual user identity authentication in BDS and can realize the security authentication of BDⅡ-CNAV.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
Due to the civil BeiDou navigation system is open,unauthenticated,and non-encrypted,civilian BeiDou navigation signals may have great security loopholes during transmission or reception.The main security loophole here...Due to the civil BeiDou navigation system is open,unauthenticated,and non-encrypted,civilian BeiDou navigation signals may have great security loopholes during transmission or reception.The main security loophole here is spoofing attacks.Spoofing attacks make the positioning or timing results of BeiDou civilian receivers wrong.Such errors may cause a series of security problems,which lays a serious hidden danger for Bei-Dou satellite information security.This article proposes an anti-spoofing method for BeiDou navigation system based on the combination of SM commercial cryptographic algorithm and Timed Efficient Stream Loss-tolerant Authentication(TESLA)for spoofing attacks.In this solution,we use the SM3 algorithm to generate a TESLA key chain with time information,and then use the key in the key chain to generate the message authentication code for the BeiDou D2 navigation message.The message authentication code is inserted into a reserved bit of the D2 navigation message.In addition,this solution uses the SM2 algorithm to protect and encrypt time information in the TESLA key chain to prevent key replay attacks in TESLA.The experimental results tested on the experimental platform built in this paper show that this scheme reduces the possibility of the BeiDou navigation system being deceived and enhances the safety of the BeiDou navigation system.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
Initial alignment is the precondition for strapdown inertial navigation system(SINS)to navigate.Its two important indexes are accuracy and rapidity,the accuracy of the initial alignment is directly related to the work...Initial alignment is the precondition for strapdown inertial navigation system(SINS)to navigate.Its two important indexes are accuracy and rapidity,the accuracy of the initial alignment is directly related to the working accuracy of SINS,but in self-alignment,the two indexes are often contradictory.In view of the limitations of conventional data processing algorithms,a novel method of compass alignment based on stored data and repeated navigation calculation for SINS is proposed.By means of data storage,the same data is used in different stages of the initial alignment,which is beneficial to shorten the initial alignment time and improve the alignment accuracy.In order to verify the correctness of the compass algorithm based on stored data and repeated navigation calculation,the simulation experiment was done.In summary,when the computer performance is sufficiently high,the compass alignment method based on the stored data and the forward and reverse navigation calculation can effectively improve the alignment speed and improve the alignment accuracy.展开更多
Aiming at the issue of influence of blanket jamming on performances of Beidou navigation signals, through studying Beidou signals based on the BOC modulation technology, establishing a blanket jamming mathematical mod...Aiming at the issue of influence of blanket jamming on performances of Beidou navigation signals, through studying Beidou signals based on the BOC modulation technology, establishing a blanket jamming mathematical model, and performing modeling and simulation on multiple jamming technologies, to attain the jamming curves of time domains and frequency domains of Beidou signals, and the correlation curve of the signal-to-jamming rate and the bit error rate under blanket jamming, and thus realizing evaluation on the jamming performance.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
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
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
LM launch vehicles established a new record by successfully performing the 16th successful flight this year.A LM-3A launched the 10th BeiDou 2 satellite into its predetermined transfer orbit on December 2 from the XSL...LM launch vehicles established a new record by successfully performing the 16th successful flight this year.A LM-3A launched the 10th BeiDou 2 satellite into its predetermined transfer orbit on December 2 from the XSLC in Sichuan Province.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
The fiber strapdown inertial navigation system （FSINS）/dead reckoning （DR）/Beidou double-star integrated navigation scheme is proposed aiming at the need of land fighting-vehicle independence positioning. The meas...The fiber strapdown inertial navigation system （FSINS）/dead reckoning （DR）/Beidou double-star integrated navigation scheme is proposed aiming at the need of land fighting-vehicle independence positioning. The measurement information fusion technology is studied by introducing the FSINS/DR/Beidou double-star integrated scheme. Several specific methods for the information fusion are discussed, and a Kalman filter is designed for the information fusion. Experimental results show that the design of the integrated scheme can improve the positioning accuracy of the navigation system.展开更多
This paper presents a learning-based control policy design for point-to-point vehicle positioning in the urban environment via BeiDou navigation.While navigating in urban canyons,the multipath effect is a kind of inte...This paper presents a learning-based control policy design for point-to-point vehicle positioning in the urban environment via BeiDou navigation.While navigating in urban canyons,the multipath effect is a kind of interference that causes the navigation signal to drift and thus imposes severe impacts on vehicle localization due to the reflection and diffraction of the BeiDou signal.Here,the authors formulated the navigation control system with unknown vehicle dynamics into an optimal control-seeking problem through a linear discrete-time system,and the point-to-point localization control is modeled and handled by leveraging off-policy reinforcement learning for feedback control.The proposed learning-based design guarantees optimality with prescribed performance and also stabilizes the closed-loop navigation system,without the full knowledge of the vehicle dynamics.It is seen that the proposed method can withstand the impact of the multipath effect while satisfying the prescribed convergence rate.A case study demonstrates that the proposed algorithms effectively drive the vehicle to a desired setpoint under the multipath effect introduced by actual experiments of BeiDou navigation in the urban environment.展开更多
To better improve the emergency communication and location-based services of disaster information reporting network for serious natural response and relieL disaster emergency the national natural disaster reduction ap...To better improve the emergency communication and location-based services of disaster information reporting network for serious natural response and relieL disaster emergency the national natural disaster reduction application platform based on BeiDou navigation satellite system is constructed. The administrative distributed platform is integrated with BeiDou positioning and multiple communication ways so as to achieve main disaster reduction application services, including disaster information acquisition and monitoring, emergency relief for trapped people, on-site emergency relief command service, relief supplies＇ transportation monitoring, and disaster information publishing service. By the platform, serious disaster information reporting time may be reduced to one hour and the emergency decision-making information service for serious natural disasters can be effectively improved, and it will be helpful to provide technical references for the industrial application and promotion of BeiDou inte- grated disaster reduction.展开更多
The BeiDou-2 satellite navigation system broadcasts triple frequency data. In this paper, the pseudorange multipath is extracted by using the geometry-free and ionosphere-free combination of one pseudorange and two ph...The BeiDou-2 satellite navigation system broadcasts triple frequency data. In this paper, the pseudorange multipath is extracted by using the geometry-free and ionosphere-free combination of one pseudorange and two phase measurements, and the phase multipath is extracted by using triple frequency phase measurements, respectively. By using several days’ static observation data, we exact the noisy pseudorange and phase multipath of three types of satellites, GEO, IGSO and MEO satellites. Because of the low frequency characteristics of the multipath, the low frequency wavelet filter is further used to recover the high-precision low frequency multipath signals that are specified by their amplitudes, periods and phases. The results show that the multipath periods are about 86160s, 86158s and 46391s for GEO, IGSO and MEO satellites, respectively, which coincide with that of the corresponding satellite orbits. Then we use the extracted multipath signals to correct the pseudorange measurements in order to improve the accuracy of point positioning. The positioning accuracy in East-West direction can be significantly improved by using the multipath corrected pseudorange measurements, and in the other two directions the positioning accuracy can also be improved to some extent.展开更多
基金supported in part by the National Key R&D Program of China(No.2022YFB3904503)National Natural Science Foundation of China(No.62172418)the joint funds of National Natural Science Foundation of China and Civil Aviation Administration of China(No.U2133203).
文摘Due to the lack of authentication mechanism in BeiDou navigation satellite system(BDS),BD-Ⅱ civil navigation message(BDⅡ-CNAV) are vulnerable to spoofing attack and replay attack.To solve this problem,we present a security authentication protocol,called as BDSec,which is designed by using China’s cryptography Shangyong Mima(SM) series algorithms,such as SM2/4/9 and Zu Chongzhi(ZUC)algorithm.In BDSec protocol,both of BDⅡ-CNAV and signature information are encrypted using the SM4 algorithm(Symmetric encryption mechanism).The encrypted result is used as the subject authentication information.BDSec protocol applies SM9 algorithm(Identity-based cryptography mechanism) to protect the integrity of the BDⅡ-CNAV,adopts the SM2 algorithm(Public key cryptosystem) to guarantee the confidentiality of the important session information,and uses the ZUC algorithm(Encryption and integrity algorithm) to verify the integrity of the message authentication serial number and initial information and the information in authentication initialization sub-protocol respectively.The results of the SVO logic reasoning and performance analysis show that BDSec protocol meets security requirements for the dual user identity authentication in BDS and can realize the security authentication of BDⅡ-CNAV.
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 in part by the Joint Foundation of National Natural Science Committee of China and Civil Aviation Administration of China under Grant U1933108in part by the Scientific Research Project of Tianjin Municipal Education Commission under Grant 2019KJ117.
文摘Due to the civil BeiDou navigation system is open,unauthenticated,and non-encrypted,civilian BeiDou navigation signals may have great security loopholes during transmission or reception.The main security loophole here is spoofing attacks.Spoofing attacks make the positioning or timing results of BeiDou civilian receivers wrong.Such errors may cause a series of security problems,which lays a serious hidden danger for Bei-Dou satellite information security.This article proposes an anti-spoofing method for BeiDou navigation system based on the combination of SM commercial cryptographic algorithm and Timed Efficient Stream Loss-tolerant Authentication(TESLA)for spoofing attacks.In this solution,we use the SM3 algorithm to generate a TESLA key chain with time information,and then use the key in the key chain to generate the message authentication code for the BeiDou D2 navigation message.The message authentication code is inserted into a reserved bit of the D2 navigation message.In addition,this solution uses the SM2 algorithm to protect and encrypt time information in the TESLA key chain to prevent key replay attacks in TESLA.The experimental results tested on the experimental platform built in this paper show that this scheme reduces the possibility of the BeiDou navigation system being deceived and enhances the safety of the BeiDou navigation system.
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.
基金This work was supported by the National Nature Science Foundation of China(Grant No.5200110367)Natural Science Foundation of Jiangsu Province(Grant No.SBK2020043219)+1 种基金Scientific Research Foundation of the Higher Education Institutions of Jiangsu Province(Grant No.19KJB510052)NUPTSF(Grant No.NY219023).
文摘Initial alignment is the precondition for strapdown inertial navigation system(SINS)to navigate.Its two important indexes are accuracy and rapidity,the accuracy of the initial alignment is directly related to the working accuracy of SINS,but in self-alignment,the two indexes are often contradictory.In view of the limitations of conventional data processing algorithms,a novel method of compass alignment based on stored data and repeated navigation calculation for SINS is proposed.By means of data storage,the same data is used in different stages of the initial alignment,which is beneficial to shorten the initial alignment time and improve the alignment accuracy.In order to verify the correctness of the compass algorithm based on stored data and repeated navigation calculation,the simulation experiment was done.In summary,when the computer performance is sufficiently high,the compass alignment method based on the stored data and the forward and reverse navigation calculation can effectively improve the alignment speed and improve the alignment accuracy.
文摘Aiming at the issue of influence of blanket jamming on performances of Beidou navigation signals, through studying Beidou signals based on the BOC modulation technology, establishing a blanket jamming mathematical model, and performing modeling and simulation on multiple jamming technologies, to attain the jamming curves of time domains and frequency domains of Beidou signals, and the correlation curve of the signal-to-jamming rate and the bit error rate under blanket jamming, and thus realizing evaluation on the jamming performance.
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LM launch vehicles established a new record by successfully performing the 16th successful flight this year.A LM-3A launched the 10th BeiDou 2 satellite into its predetermined transfer orbit on December 2 from the XSLC in Sichuan Province.
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The fiber strapdown inertial navigation system （FSINS）/dead reckoning （DR）/Beidou double-star integrated navigation scheme is proposed aiming at the need of land fighting-vehicle independence positioning. The measurement information fusion technology is studied by introducing the FSINS/DR/Beidou double-star integrated scheme. Several specific methods for the information fusion are discussed, and a Kalman filter is designed for the information fusion. Experimental results show that the design of the integrated scheme can improve the positioning accuracy of the navigation system.
基金supported in part by the National Natural Science Foundation of China under Grant Nos.62320106008 and 62373114in part by the Collaborative Innovation Center for Transportation Science and Technology of Guangzhou under Grant No.202206010056.
文摘This paper presents a learning-based control policy design for point-to-point vehicle positioning in the urban environment via BeiDou navigation.While navigating in urban canyons,the multipath effect is a kind of interference that causes the navigation signal to drift and thus imposes severe impacts on vehicle localization due to the reflection and diffraction of the BeiDou signal.Here,the authors formulated the navigation control system with unknown vehicle dynamics into an optimal control-seeking problem through a linear discrete-time system,and the point-to-point localization control is modeled and handled by leveraging off-policy reinforcement learning for feedback control.The proposed learning-based design guarantees optimality with prescribed performance and also stabilizes the closed-loop navigation system,without the full knowledge of the vehicle dynamics.It is seen that the proposed method can withstand the impact of the multipath effect while satisfying the prescribed convergence rate.A case study demonstrates that the proposed algorithms effectively drive the vehicle to a desired setpoint under the multipath effect introduced by actual experiments of BeiDou navigation in the urban environment.
基金supported by National Bei Dou Special Project and National Science & Technology planning project of China (Grant No. 2014BAK12B04)
文摘To better improve the emergency communication and location-based services of disaster information reporting network for serious natural response and relieL disaster emergency the national natural disaster reduction application platform based on BeiDou navigation satellite system is constructed. The administrative distributed platform is integrated with BeiDou positioning and multiple communication ways so as to achieve main disaster reduction application services, including disaster information acquisition and monitoring, emergency relief for trapped people, on-site emergency relief command service, relief supplies＇ transportation monitoring, and disaster information publishing service. By the platform, serious disaster information reporting time may be reduced to one hour and the emergency decision-making information service for serious natural disasters can be effectively improved, and it will be helpful to provide technical references for the industrial application and promotion of BeiDou inte- grated disaster reduction.
文摘The BeiDou-2 satellite navigation system broadcasts triple frequency data. In this paper, the pseudorange multipath is extracted by using the geometry-free and ionosphere-free combination of one pseudorange and two phase measurements, and the phase multipath is extracted by using triple frequency phase measurements, respectively. By using several days’ static observation data, we exact the noisy pseudorange and phase multipath of three types of satellites, GEO, IGSO and MEO satellites. Because of the low frequency characteristics of the multipath, the low frequency wavelet filter is further used to recover the high-precision low frequency multipath signals that are specified by their amplitudes, periods and phases. The results show that the multipath periods are about 86160s, 86158s and 46391s for GEO, IGSO and MEO satellites, respectively, which coincide with that of the corresponding satellite orbits. Then we use the extracted multipath signals to correct the pseudorange measurements in order to improve the accuracy of point positioning. The positioning accuracy in East-West direction can be significantly improved by using the multipath corrected pseudorange measurements, and in the other two directions the positioning accuracy can also be improved to some extent.
