BeiDou System Started Trial Operation at the End of 2011

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 System Begins to Serve the World

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.

Data-Driven Heuristic Assisted Memetic Algorithm for Efficient Inter-Satellite Link Scheduling in the BeiDou Navigation Satellite System

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.

Tropospheric Wet Refractivity Tomography Based on the BeiDou Satellite System

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.

Development and Innovation of BeiDou Navigation Satellite System

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.

The Compatible and Interoperable BeiDou Satellite Navigation System

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.

Design of Space-based PNT System Based on BeiDou Navigation Satellite System

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.

Evaluating Model and BeiDou Based Management System for Scale Operation of Cotton-Pickers

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.

Beidou receiver based on anti-jamming antenna arrays with self-calibration for precise relative positioning

Unmanned aerial vehicles(UAVs)may be subjected to unintentional radio frequency interference(RFI)or hostile jamming attack which will lead to fail to track global navigation satellite system(GNSS)signals.Therefore,the simultaneous realization of anti-jamming and high-precision carrier phase difference positioning becomes a dilemmatic problem.In this paper,a distortionless phase digital beamforming(DBF)algorithm with self-calibration antenna arrays is proposed,which enables to obtain distortionless carrier phase while suppressing jamming.Additionally,architecture of high precision Beidou receiver based on anti-jamming antenna arrays is proposed.Finally,the performance of the algorithm is evaluated,including antenna calibration accuracy,carrier phase distortionless accuracy,and carrier phase measurement accuracy without jamming.Meanwhile,the maximal jamming to signal ratio(JSR)and real time kinematic(RTK)positioning accuracy under wideband jamming are also investigated.The experimental results based on the real-life Beidou signals show that the proposed method has an excellent performance for precise relative positioning under jamming when compared with other anti-jamming methods.

BeiDou Regional Navigation Satellite System Completed

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.

LM-3B Launched the Penultimate BeiDou-3 Navigation System Satellite Successfully

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.

Application and Prospect of BeiDou Navigation Satellite System in the Transportation Industry

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.

BDSec:Security Authentication Protocol for BeiDou-Ⅱ Civil Navigation Message

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.

Construction of BDS Spatiotemporal Information Agricultural Product Digital Credit System

Spatiotemporal information,positioning and navigation services have become important elements of new type infrastructure.The rapid development of global digital trade provides a large-scale application scenario for the use of Beidou Navigation Satellite System(BDS)spatiotemporal information to support the certification of origin of agricultural products.The BDS spatiotemporal information agricultural product digital credit system uses such modules as BDS,spatiotemporal information collection,spatiotemporal coding,and spatiotemporal blockchain.It incorporates multi-level joint supervision mechanisms such as government,associations,and users.Starting from the initial production link of agricultural products,it realizes the correspondence and locking of online and offline products,effectively improves the integrity and credibility of information in the production process,finished product quality and circulation process of products,effectively manages the green production and anti-channel conflicts of producers,and provides credible information for consumers,thus realizing the digital credit certification of products.The successful practice of characteristic agricultural products in Yunnan Province has verified the application ability of the BDS spatiotemporal information agricultural product digital credit system.This system has played a significant role in promoting the online and offline locking,credible information,effective supervision and high quality and high price of characteristic agricultural products from the field.The BDS provides services for global digital trade and contributes to the further enhancement of the global application scale of GNSS.

Networking of BeiDou Navigation Satellite System Accelerated with Two New Members

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

China Launches the 11th BeiDou Satellite in Navigation Satellite System

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

基于FFT的北斗信号快速并行捕获算法研究

为研究如何捕获北斗卫星信号,对捕获信号的整个过程进行仿真。通过逆快速傅里叶变换(IFFT)对传统快速傅里叶变换(FFT)信号捕获算法进行改进,利用傅里叶变换系数X_(k)与C_(k)^(*)相乘再作IFFT,在时域内对信号x_(n)进行频率补偿,再做FFT就等效于循环移位完成。通过在MATLAB仿真环境中对北斗信号各阶段的频谱进行分析,比较改进FFT算法与传统FFT算法的信号捕获误码率。结果表明,改进后的FFT算法的北斗信号频谱变化稳定,与传统FFT算法相比信号捕获精度和灵敏度更高。在90%捕获概率下,改进FFT算法可使接收机的灵敏度提高2 dB。

BeiDou、Galileo、GLONASS、GPS多系统融合精密单点

随着中国BeiDou系统与欧盟Galileo系统的出现以及俄罗斯GLONASS系统的恢复完善,过去单一的GPS导航卫星系统时代已经逐步过渡为多系统并存且相互兼容的全球性卫星导航系统（multi-constellation global navigation satellite systems,multi-GNSS）时代,多系统GNSS融合精密定位将成为未来GNSS精密定位技术的发展趋势。本文采用GPS、GLONASS、BeiDou、Galileo 4大卫星导航定位系统融合的精密单点定位（precise point positioning,PPP）实测数据,初步研究并分析了4系统融合PPP的定位性能。试验结果表明：在单系统观测几何构型不理想的区域,多系统融合能显著提高PPP的定位精度和收敛速度。4大系统融合的PPP收敛速度相对于单GNSS可提高30%~50%,定位精度可提高10%~30%,特别是对高程方向的贡献更为明显。此外,在卫星截止高度角大于30°的观测环境下,单系统由于可见卫星数不足导致无法连续定位,而多系统融合仍然可以获得PPP定位结果,尤其是水平方向具有较高的定位精度。这对于山区、城市以及遮挡严重的区域具有非常重要的应用价值。

GPS/BeiDou组合单点定位的定权与结果分析

利用Helmert方差分量估计方法为GPS/BeiDou组合单点定位不同系统观测值定权,获得了合理的权值。分析了开阔环境和遮挡环境两种情况下的动态GPS/BeiDou组合单点定位的精度。结果表明:在静态观测和动态观测中,组合单点定位与单独GPS单点定位相比精度有显著提高。

基于北斗测速的电驱式小麦播种机监控系统设计与试验

针对当前小麦播种机智能化程度低、播种作业时种子漏播肥料堵塞导致缺苗断垄现象产生的问题,设计了一款基于北斗测速的电驱式小麦播种机监控系统。通过电容检测可以实时监测小麦种子漏播情况,通过光电检测可以实时监控排肥管内肥料堵塞情况;北斗卫星实时定位并计算出播种机的前进速度,控制器根据播种机前进速度实时调节播种施肥电机转速,实现种子漏播、肥料堵塞报警和精量播种施肥的目的。在田间试验中,装载监控系统的播种机各项性能表现良好,漏播检测准确率91%以上,肥料堵塞检测准确率95%以上,播种合格率平均值大于94.6%,漏播指数小于2.8%,重播指数小于3%,均匀度变异系数小于3.5%,能够满足小麦精量播种的要求。