Report on the Development of BeiDou（COMPASS）Navigation Satellite System（V1.0）China Satellite Navigation OfficeFebruary2012ContentsPreface 1 I. System Description 3 II. System Development 51. System Planning 52. System Progress 7 III. System Applications 8 IV. International Exchange and Cooperation 10 Conclusion 13 Annex 14PrefaceNavigation satellite systems can provide all time, all weather and high accuracy positioning, navigation and timing services to users on the earth surface or in the near-earth space. It is an important space infrastructure, which extends people’s range of activities and promotes social development. Satellite navigation is bringing up revolutionary changes to the world politics, economy, military, technology and culture.With a long history and a splendid culture, China is one of the important cradles of early human civilization. In ancient times, Chinese people used the Big Dipper (Beidou) for identifying directions, and invented the world’s first navigation device, the ancient compass (Sinan), which was a great contribution to the development of world civilization. In modern society, the Chinese-built BeiDou（COMPASS）system will become another contribution to the mankind.In early 1980s, China began to actively study the navigation satellite systems in line with China’s conditions. In 2000, BeiDou Navigation Demonstration System is basically established, which made China the third nation in possession of an independent navigation satellite system following the United States and Russia. At present, China is steadily accelerating the construction of the BeiDou Navigation Satellite System, and has already successfully launched 10satellites so far.Many governmental departments of our country have been involved in the construction, operation and application management of BeiDou system. As a joint office established by related national departments, China Satellite Navigation Office is in charge of management on the construction, application promotion and industrialization of BeiDou system. Meanwhile, an Experts1Committee and an Experts Team were also established to bring into full p lay of the experts’ experience, and make scientific and democratic decisions.The BeiDou system will meet the demands of China’s national security, economic development, technological advances and social progress, safeguard national interests and enhance the comprehensive national strength. The BeiDou system will commit to providing stable, reliable and quality satellite navigation services for global users. Along with other GNSS providers, the BeiDou system will jointly promote the development of satellite navigation industry, make contributions to human civilization and social development, serve the world and benefit the mankind.2I. System DescriptionAs a Global Navigation Satellite System compatible with other navigation satellite systems worldwide, BeiDou system is independently established and operated by China.The BeiDou system is comprised of three major components: space constellation, ground control segment and user terminals. The space constellation consists of five GEO satellites and 30 non-GEO satellites. The GEO satellites are positioned at 58.75°E, 80°E, 110.5°E, 140°E and 160°E respectively. The non-GEO satellites include 27 MEO satellites and three IGSO satellites. The MEO satellites are operating in an orbit with an altitude of 21,500 km and an inclination of 55°, which are evenly distributed in three orbital planes. The IGSO satellites are operating in an orbit with an altitude of 36,000 km and an inclination of 55°, which are evenly distributed in three inclined geo-synchronous orbital planes. The subsatellite track for the three IGSO satellites are coincided while the longitude of the intersection point is at 118°E, with a phase difference of 120°.Ground control segment consists of several Master Control Stations (MCS), Upload Stations (US) and a network of globally distributed Monitor Stations (MS). The main tasks of MCS are to collect observing data from each MS, to process data, to generate satellite navigation messages, wide area differential data and integrity information, to perform mission planning and scheduling, and to conduct system operation and control. The main tasks of Upload Stations include completing the upload of satellite navigation messages, wide area differential data and integrity information, controlling and managing the payload. The tasks of Monitor Stations include continuous tracking and monitoring of navigation satellites, receiving navigation signals, sending3observational data to the Master Control Station for the satellites orbit determination and time synchronization.The user terminals include various BeiDou user terminals, and terminals compatible with other navigation satellite systems, to meet different application requirements from different fields and industries.The time reference for the BeiDou Navigation Satellite System uses BeiDou Time (BDT), which is a continuous timekeeping system. BDT’s length of second is a SI second. BDT zero time-point started at 00:00 UTC on January 1st, 2006. BDT is synchronized with UTC in 100 nanoseconds (modulo one second).The coordinate framework of BeiDou system adopts China Geodetic Coordinate System 2000 (CGCS2000).Upon the full system completion, the BeiDou Navigation Satellite System can provide positioning, navigation and timing services to worldwide users. It can also provide wide area differential services with the accuracy of 1m and short messages services with the capacity of 120 Chinese characters each time.·Main functions: positioning, velocity measurement, one-way and two-way timing, short messages·Service area: global·Positioning accuracy: better than 10m·Velocity accuracy: better than 0.2m/s·Timing accuracy: 20ns4II. System Development1. System PlanningAccording to the general guideline of ‘quality, safety, application and benefits’, adhering to the development principle of ‘independency, openness, compatibility and gradualness’and following the development concept of starting with regional services first and expanding to global services later, BeiDou system is steadily accelerating the construction based on a ‘three-step’development strategy, with specifics as follows:Phase I: BeiDou Navigation Satellite Demonstration System. In 1994, China started the construction of BeiDou Navigation Satellite Demonstration System. In 2000, two BeiDou navigation experiment satellites were launched, and the BeiDou Navigation Satellite Demonstration System was basically established, which made China the third nation in the world in possession of an independent navigation satellite system. In 2003, the third BeiDou navigation experiment satellite was launched, further enhancing the performance of the BeiDou Navigation Satellite Demonstration System.BeiDou Navigation Satellite Demonstration System consists of three major components: space constellation, ground control segment and user terminals. The space constellation includes three geostationary orbit (GEO) satellites, positioned at longitude of 80 degrees East, 110.5 degrees East and 140 degrees East respectively above the equator. Ground control segment consists of the ground control center and a number of calibration stations. The ground control center is to complete satellite orbit determination, ionospheric correction, user location determination and user short message information exchange and processing. The calibration5ground control stations are mainly to provide the distance measurement and correction parameters to the ground control center.The user terminals include the hand-held type, vehicle type, command type and other types of terminals, capable of position service application, location coordinates information receiving and other functions.The main functions and performance specifications of the BeiDou Navigation Satellite Demonstration System are as follows: ·Main functions: positioning, one-way and two-way timing, short message communications;·Service Area: China and the surrounding areas;·Positioning Accuracy: better than 20 meters;·Timing Accuracy: 100 ns one-way, two-way 20 ns;·Short message communications: 120 Chinese characters per time.Phase II: BeiDou Navigation Satellite (regional) System. In 2004, China started construction of BeiDou Navigation Satellite System. In 2007, the first satellite, a round medium earth orbit satellite (COMPASS-M1) was launched. By 2012, the BeiDou system will consist of 14 satellites, including five GEO satellites, five IGSO satellites (two in-orbit spares), and four MEO satellites.The functions and performance parameters of BeiDou Navigation Satellite (regional) System are as follows:·Main functions: positioning, velocity measurement, one-way and two-way timing, short message communications;·Service Area: China and part of Asia- Pacific region ;·Positioning Accuracy: better than 10 meters;·Velocity Accuracy: better than 0.2 m/s;·Timing Accuracy: 50 ns;·Short message communications: 120 Chinese characters per message.Phase III: BeiDou Navigation Satellite System with global coverage will completely be established by 2020.62. System ProgressSo far, 10 BeiDou satellites have been launched and already formed the basic system. It retains the active positioning and short message services from BeiDou Navigation Satellite Demonstration System, and will provide Initial Operational Services to China and its surrounding areas from December 27th, 2011, including continuous passive positioning, navigation and timing services.Through previous testing upon the system, the main service performances of BeiDou system during the Initial Operational Service period are as follows:·Coverage Area: from 84°E to 160°E, from 55°S to 55°N;·Positioning Accuracy: Horizontally, 25 m, Vertically, 30 m;·Velocity Accuracy: 0.4 m/s;·Timing Accuracy: 50 ns.Based on the launching plan of BeiDou system, 6 more BeiDou satellites will be launched in 2012 to further expand service area, improve performances and provide services for most parts of Asia-Pacific region.Meanwhile, in order to encourage domestic and foreign enterprises to participate in the R&D of BeiDou system application terminals and promote its application, China Satellite Navigation Office announce the test version of ICD concerning BeiDou System signal-in-space. Both Chinese and English versions have been published on BeiDou governmental website（）. This document defines the B1 carrier signal interface relationship between the space segment and the user segment of the BeiDou Navigation Satellite (regional) System, specifies the signal structure, basic characteristics and signal radio frequency characteristics including carrier frequency, signal bandwidth and out-band suppression, spurious, carrier phase noise, user-received signal level and signal coherence, presents the specification related to B1 ranging code. It is a necessary technical document for manufacturing and development of receivers and chips.7III. System ApplicationsSince it was officially brought into service in 2003, the BeiDou Navigation Satellite Demonstration System has been widely used in transportation, marine fisheries, hydrological monitoring, weather forecasting, forest fire prevention, timing for communication systems, power distribution, disaster mitigation, national security, and many other fields, which has been resulting in significant social and economic benefits. Particularly, the system has played an important role in the South China frozen disaster, earthquake relief in Wenchuan, Sichuan Province and Yushu, Qinghai Province, the Beijing Olympic Games, and the Shanghai World Expo.—In the field of transportation, built on the Beidou Navigation Satellite Demonstration System, applications such as Xinjiang Satellite Navigation Monitoring System of Public Transport, the Highway Infrastructure Safety Monitoring System, and the Port Scheduling High-precision Real-time Position Monitoring System, have promoted the BeiDou system and achieved a good demonstration effect.—In marine fisheries, built on the BeiDou Navigation Satellite Demonstration System, the marine fisheries integrated information service platform has provided vessel position monitoring, emergency rescue, information distribution, fishing boats in and out of port management and other services to the fishery administration departments.—The hydrological monitoring system, based on the BeiDou Navigation Satellite Demonstration System, has realized the real-time transmission of hydrological forecast information in mountainous regions, which has improved the accuracy of the disaster forecasting and has helped the planning and scheduling programs for the flood and drought control.8—In the field of weather forecasting, a series of BeiDou terminal equipment have been developed for weather forecast, and various practical and feasible system solutions have been worked out to address the automatic data transmission issues for the China Meteorological Administration and a number of local weather centers and stations.—In the field of forest fire prevention, the BeiDou Navigation Satellite Demonstration System has been successfully used in forest fire prevention system. Its positioning and short message communication services have achieved good results.—In the field of time synchronization for communication systems, the successful implementation of BeiDou two-way timing demonstration program has achieved breakthroughs in some key technical areas such as long distant fiber technology, and an integrated satellite-based timing system has been developed.—In the field of power distribution, built on the BeiDou Navigation Satellite Demonstration System, the successful implementation of power system time synchronization demonstration program has created basis for the high precision applications such as the electric accident analysis, the electricity early warning and protection systems.—In the field of disaster mitigation, the navigation, positioning, short message communications and position reporting capabilities of the BeiDou Navigation Satellite Demonstration System have provided services for the nationwide real-time disaster relief commanding and dispatching, emergency communications, rapid reporting and sharing of disaster information, which has significantly improved the rapid response of the disaster emergency relief and decision-making capability.Upon the full completion, the BeiDou Navigation Satellite System will provide more high-performance positioning, navigation, timing and short-message communication services for civil aviation, shipping, railways, finance, postal and other industries.9IV. International Exchange and Cooperation The international exchange and cooperation for the BeiDou Navigation Satellite System will be carried out in an active and pragmatic way, which is in line with China’s foreign policies, focusing on China's basic tasks and strategic objectives for the construction of navigation satellite systems, using the domestic and international markets and resources in a coordinated way. The international exchange and cooperation will be proceeded in a phased, focus-centered, non-discriminatory and selective approach in accordance with the overall development plan of China's navigation satellite system. It will be built upon the basis of equality, mutual benefit, mutual complementarity, peaceful utilization and mutual development and the generally accepted principles of the international laws.The BeiDou Navigation Satellite System adheres to the open and friendly attitude, and has already carried out extensive exchanges and consultation with the countries that have navigation satellite systems, to promote navigation satellite system compatibility and interoperability globally. Through the exchange and cooperation with countries that do not have a navigation satellite system, we also support their use of the existing resources globally and share the benefits of the satellite navigation development.China's international exchange and cooperation in the field of satellite navigation started in the 1990s. In nearly 20 years, various forms of activities have been carried out with extensive results.In 1994, under the framework of International Telecommunication Union (ITU), China started the BeiDou Navigation Satellite System frequency coordination activities. Satellite network information was submitted in accordance with the BeiDou system construction plan and progress. International 10frequency coordination has been carried out in a phased, step by step, focus-centered approach. China has actively participated bilateral frequency coordination activities with Europe, the United States and Russia, and has actively taken part in the World Radiocommunication Conference and the meetings of ITU study groups and working groups.China, as an important member of the International Committee on Global Navigation Satellite Systems (ICG), has participated in every ICG General Assembly Meeting and the ICG Providers Forum. In 2007, China became one of the four core providers designated by the organization. In 2011, China co-organized and co-chaired an ICG Enhancement of GNSS Services Performance Working Group (WG-B) meeting in Shanghai. The proposal initiated by China to establish subgroups on International GNSS Monitoring and Assessment Service and Applications was endorsed during the ICG-6 meeting, while China is the co-chair of these two subgroups.Focusing on compatibility and interoperability, China has carried out the extensive exchange and cooperation with the other navigation satellite systems in the world. The Technical Working Group (TWG) on compatibility and interoperability between BeiDou and Galileo was established. Until now, seven TWG meetings have been held.China actively participates, organizes and hosts international academic exchanges on satellite navigation, which include the American Institute of Navigation (ION) Conferences, the International Symposium on GPS/GNSS (ISGNSS), Munich Satellite Navigation Summit and other international conferences and forums. The China academic conference on satellite navigation is held annually, together with many other forums and seminars.China encourages and supports domestic research institutions, industrial enterprises, universities and social organizations, under the guidance of the government policy, to carry out international exchanges, coordination and cooperation activities with other countries and international organizations in the fields of the compatibility and interoperability, satellite navigation standards,11coordinates frame, time reference, application development and scientific research. China has been actively engaged in international activities in terms of monitoring and assessment of open service for GNSS to promote the BeiDou Navigation Satellite System better serving the global users, and to promote the development of satellite navigation technology.12ConclusionThe rapid development of the BeiDou Navigation Satellite System is attributed to China's reform and opening-up policy as well as the sustainable development of economy. As always, China will continue to promote the Global Navigation Satellite System construction and industrial development, to encourage the use of new satellite navigation technologies to provide new services, meeting the growing diversified needs of the people. By actively propelling international exchanges and cooperation, China will realize the compatibility and interoperability between the BeiDou Navigation Satellite System and other navigation satellite systems in the world. China will provide global customers with high performance and highly reliable positioning, navigation and timing services.13AnnexThe Launch Record of BeiDouNavigation Satellites·October 31, 2000, launch of 1st BeiDou navigation experiment satellite.·December 21, 2000, launch of 2nd BeiDou navigation experiment satellite.·May 25, 2003, launch of the 3rd BeiDou navigation experiment satellite.·February 3, 2007, launch of the 4th BeiDou navigation experiment satellite.·April 14, 2007, launch of the 1st BeiDou navigation satellite.·April 15, 2009, launch of the 2nd Beidou navigation satellite.·January 17, 2010, launch of the 3rd BeiDou navigation satellite.·June 2, 2010, launch of the 4th BeiDou navigation satellite.·August 1, 2010, launch of the 5th BeiDou navigation satellite.·November 1, 2010, launch of the 6th BeiDou navigation satellite.·December 18, 2010, launch of the 7th BeiDou navigation satellite.·April 10, 2011, launch of the 8th BeiDou navigation satellite.·July 27, 2011, launch of the 9th BeiDou navigation satellite.·December 2, 2011, launch of the 10th BeiDou navigation satellite.14。
Beidou (Compass) Navigation Satellite System With the long history and its splendid culture. China is one of the important creatures of early human civilization. Chinese people have used the big dipper for identifying direction ever since ancient times. They invented the world's first navigation device 'Compass', which was a great contribution for the development of the world. And become a bridge of friendship between China and foreign countries. The ancient Compass has become the glory of our history. While Beidou system will become a new contribution of China to mankind.Beidou (Compass) Navigation Satellite System is a global navigation satellite system,which is being independently developed and operated by China. It will provide all weather-position velocity and timing services with high accuracy and reliability with users anywhere anytime. It has advantages of quick-positioning, location-reporting and information exchange.The development of Beidou system can be divided into three phases.Phase 1. In the early 1980s China began to study Beidou Navigation Demonstration System based on dual satellite active positioning. The construction of the Demonstration System started in 1994. The system began to provide services in 2000. Which made China the third nation in position of an independent navigation satellite system following the U.S and Russia. The Demonstration System consists of three GE satellites and corresponding ground systems. The cost efficient system was quickly put into use. It has been providing positioning, short message telecommunication and timing services for users in China and nearby areas.Phase 2. To provide better services for national economic development and to meet in creasing demand for satellite navigation. China started to build Beidou Navigation SatelliteSystem besed on passive positioning in 2004. Around 2012, they system will cover the Asia-Pacific region with more than 10 satellites. Currently several satellites have been successfully launched, and the project is advancing on schedule.Phase 3. Around 2020, Beidou System will be completed and provide global coverage with 35 satellites, offering state-of-the-art services. Worldwide users will enjoy two kinds of high quality, including Open and Authorized services. The Open services will be free of direct charge with an accuracy of 10m for positioning 0.2m/s for velocity and 20ns for timing. The Authorized service will have higher accuracy and better reliability and will be available to authorized users.From the snow cover of Plateau to the Gobi Desert, from the Northern border to the Southern territorial seas. Since 2000, Beidou Navigation Demonstration System has been widely used in many fields. Such as Mapping, Telecommunications, Water conservancy, Fishery, Transportation, Forest fire prevention, Disaster relief and Public safety. Especially in the Beijing Olympic Games, the Frozen, Disaster Wenchuan Earthquake relief and Shanghai World Expo. The Demonstration System has played an important role and produce significant economic and social benefits.Beidou System has been widely used in the field of China maritime fishery. It can provide services for fishery management devolvement. Such as Vessel position monitoring, Emergency rescue, Policy issue and Vessel in and out management. It can also provide services for fishing vessels. Such as Navigation and position, Distress signals, Maritime notice and Value attitude information, providing vessel-vessel and vessel-shore message telecommunications.Beidou System has also played an important role in disaster rescue. In 2008, Wenchuan suffered a catastrophic earthquake, in which the ground cables and communication facilities were damaged seriously. Under the emergency of interruption of regular communications and impossible roads, Beidou System provided an important assurance for command of relief teams and notice of disaster's situation. And it was an advantage for positioning and short message telecommunications.As an important member of IGE, China has participated in all previous assemblies and private forums. Widely communicated with authorities of relevant countries. China will always actively cooperate with foreign countries. And promote cooperation in Frequency coordination, Compatibility and interoperability, International standard, Time and coordinate reference, Scientific research and Applicative development between Beidou System and other satellite navigation systems. China will promote worldwide application of satellite navigation and make contributions to scientific development, and technological progress of this field.Our own ancestors used the big dipper for identifying direction. Today we use Beidou system for global positioning. As one of the cooperators of global navigation satellite systems. Beidou system will be committed to providing satellite positioning. Navigation and timing services with high performance high quality and high reliability for global users, and make important contributions to human society.Serve the world. Benefit the mankind. This is Beidou Navigation Satellite System.北斗导航系统在漫长的充满文化底蕴的历史长河中，中国是早期人类文明发展的重要一环。
北斗卫星导航系统（Beidou satellite navigation system）Beidou satellite navigation systemPublished: 2011-9-19 21:27:01 Views: 99 []: small fontsBeidou satellite navigation system is developed by Chinese regional active 3D satellite positioning and communication system (CNSS), in addition to America's global positioning system (GPS), after the Russian GLONASS third sophisticated satellite navigation system. Beidou satellite navigation system is committed to the global users to provide high quality positioning, navigation and timing service, its construction and development will follow the openness, autonomy, compatibility and gradual progress of the 4 principles.brief introductionBeidou satellite navigation system, BeiDou (COMPASS) Navigation Satellite System, is a global satellite navigation system, independent research and development, Chinese is implementing the independent operation of the.Schematic diagram of the Beidou satellite navigation systemBeidou satellite navigation system by the end of the space, the ground end and user end is composed of three parts, including 5 end space satellites in geostationary orbit and non geostationary orbit 30 satellites, the ground terminal comprises a main control station, into the station and monitoring station several ground stations, the user terminal composed by Beidou user terminal and compatible with the UnitedStates GPS, Russia GLONASS, GALILEO and other European satellite navigation system.China had been successfully launched four Beidou navigation satellite test and three Beidou navigation satellite system, will be in the network and on the basis of experiment, and gradually extended to the global satellite navigation system.targetBeidou satellite navigation system aims to build a global coverage of the Beidou satellite navigation system independent, open and compatible, built with advanced technology, stable and reliable, promote the satellite navigation industry chain formation, the formation of a sound national satellite navigation industry support, promotion and support, promote the applications of satellite navigation in the national economic and social sectors.Schematic diagram of the Beidou satellite navigation systemThere are 4 sets of satellite navigation systems in the world at present: Chinese compass, American GPS, the Russian GLONASS, the European Galileo satellite navigation system is an important infrastructure space, has brought great economic and social benefits for human beings. Chinese as a developing country, has a vast territory and sea area, attaches great importance to the construction of satellite navigation system, exploring and developing with satellite navigation and positioning system with independent intellectual property rights.Since 2000, Chinese has successfully launched 4 Beidou navigation satellite test, built Beidou navigation experiment system (first generation system). This system has the localization, in the range of China and its surrounding areas in the timing, message and GPS wide area differential function, and has been in the mapping, telecommunications, water conservancy, transportation, fishery, exploration, forest fire prevention and national security and other areas to gradually play an important role.Chinese composition is the construction of the Beidou satellite navigation system, the space segment consists of 5 satellites in geostationary orbit and non geostationary orbit 30 satellites, provides two kinds of services, namely open service and authorization service (which belongs to the second generation system). Open service is free in the service area to provide positioning, velocity and timing services, positioning accuracy of 10 meters, the timing accuracy of 50 ns, measurement accuracy of 0.2 meters per second. The authorization service is to provide positioning, more secure to authorized users speed, timing and communication service and integrity information system.Chinese plans around 2012, the Beidou system will cover the Asia Pacific region, around 2020 global coverage. Our country is carrying out the construction of the Beidou satellite navigation system, has successfully launched four Beidou navigation satellite. According to the overall planning, system construction about 2012, the system will first have to cover the Asia Pacific region of positioning, navigation andtiming and short message communication service capability; built around 2020, global coverage Beidou satellite navigation system.courseSchematic diagram of the Beidou satellite navigation systemSatellite navigation system is an important spatial information infrastructure. Chinese attaches great importance to the construction of satellite navigation system, satellite navigation system has independent intellectual property rights in the exploration and development efforts. In 2000, the first built Beidou navigation test system,China has become the United States and Russia after the world's third country with autonomous navigation satellite system. The system has been successfully applied in surveying and mapping, telecommunications, water conservancy, fishery, transportation, forest fire prevention, disaster relief and public security and other fields, has significant economic and social benefits. Especially in the 2008 Beijing Olympic Games, Wenchuan has played an important role in earthquake relief. In order to better serve the national construction and development, to meet the global application demand, our country started to implement the construction of the Beidou satellite navigation system.navigation satellite[first]In April 14, 2007, Chinese successfully launched first Beidou navigation satellite.Schematic diagram of the Beidou satellite navigation system[Second]In April 15, 2009 16, China with a "Long March three rocket from the Xichang satellite launch center, the success of the second Beidou navigation satellite into orbit. Chinese satellite navigation engineering center responsible person, the Beidou navigation satellite launch (COMPASSG2), is China Beidou satellite navigation system (COMPASS, BeiDou, Chinese name) second satellite network construction plan, the geosynchronous orbit satellite. The successful launch of the satellite has a very important significance for the construction of the Beidou satellite navigation system.Satellite navigation system is an important space infrastructure that can provide high precision positioning, velocity measurement and time service, can bring enormous social and economic benefits. China attaches great importance to the construction of satellite navigation system, has been working to explore and develop satellite navigation system with independent intellectual property rights. Beidou navigation test system has been built China, plays an important role in surveying and mapping, telecommunications, water conservancy, transportation, fishery, exploration, forest fire prevention and national security etc.. At present, is carrying out the construction of the Beidou satellite navigation system.The launch of the satellite and rocket are developed by China Aerospace Science and Technology Corporation owned Chinese Research Institute of space technology and China rocket technology research institute. This is the long march rocket flight 116th.[Third]0:12 on January 17, 2010, China's "Long March three rocket from the Xichang satellite launch center, the success of the third Beidou navigation satellite into orbit, which marks the construction of Beidou satellite navigation system project is an important step, satellite network is steadily according to plan.Schematic diagram of the Beidou satellite navigation systemAccording to the Chinese satellite navigation engineering center responsible person, is the implementation of the Beidou satellite navigation system (COMPASS, Chinese, named BeiDou) construction work, planning launched 5 satellites in geostationary orbit and non geostationary orbit 30 satellites, built Beidou satellite navigation system covering the whole world. Previously, has successfully launched two Beidou navigation satellite, the satellite into geostationary orbit satellite. In 2012, according to the construction plan, the Beidou satellite navigation system will be the first to provide coverage in the Asia Pacific region navigation, timing and short message communication service ability. Around 2020, built global coverage Beidou satellite navigation system.[Fourth]The evening of June 2, 2010 at 23:53, China's "Long March three rocket from the Xichang satellite launch center, the fourth Beidou navigation satellite into space orbit, which marks the network construction of the Beidou satellite navigation system is an important step, China satellite navigation system project management office responsible person said, at present, Chinese Beidou navigation satellite launch network has entered the intensive stage.Beidou satellite navigation system is a global satellite navigation system of autonomous development, China is implemented independently, its construction goal: to build a global coverage of the Beidou satellite navigation system independent, open and compatible, advanced technology, stable and reliable, promote the satellite navigation industry chain formation, the formation of a sound national satellite navigation industry support and promotion and security system, promote the wide application of satellite navigation in the national economic and social sectors.Working principleThe working process of the Beidou satellite navigation system is: first to the satellite I and satellite II and sends the interrogation signal from the central control system via satellite transponder to users in radio service area. One of the satellites, the user response to the interrogation signal, and also to the two satellite transmits a response signal viasatellite transmitted to the central control system. The central control system to receive and demodulate the user's signal, the corresponding data processing according to the application user and service content. The location for the central control system, measure two time delay: from the center of the control system sends out the interrogation signal by a satellite forwarded to users, the user sends positioning response signal delayed by the same satellite transmitted to the central control system; and a request signal from the central control, the same satellite arrived the user, user sends a response signal, the delay of another satellite transmitted to the central control system. Because of the central control system and two satellite locations are known, so from the above two delay amount can be calculated by the user to the first satellite distance, and users to two satellites and distance, so as to know the user in a first satellite for a sphere surface, and to two. As the intersection between satellite focus on ellipsoid. In addition to the central control system from the storage in the computer digital topographic map to search the user can know the user elevation value in a parallel and ellipsoidal earth reference ellipsoid surface. To the central control system can finally calculate the 3D coordinates of the point where the user, the coordinate encrypted by outbound signal sent to the user.Schematic diagram of the Beidou satellite navigation systemShort message communication: one can transmit up to 120 messages Chinese characters.Precision timing accuracy: up to 10 ns.Positioning accuracy: the level of accuracy of 100 meters (1 sigma), after the establishment of the calibration station is 20 meters (similar to differential state). Working frequency: 2491.75MHz.System capacity: 540000 households per hour.Construction principleThe construction and development of the Beidou satellite navigation system, in order to promote the application and development of industry as the basic goal, not only to build the system, but also to use the system, emphasis on quality, safety, efficiency, application, follow the following principles of construction:1, open. The construction of the Beidou satellite navigation system development and application will be open to the world, to provide high quality services for free users worldwide, and actively carry out exchanges and cooperation with other countries in the world widely and deeply, promoting the compatible satellite navigation systems and interoperability, promote the development of satellite navigation technology and industry.2, autonomy. Chinese self construction and operation of the Beidou satellite navigation system, Beidou satellite navigation system can provide services for independent users worldwide.3, compatibility. The International Committee on global navigation satellite systems (ICG) and ITU (ITU) under the framework of the Beidou satellite navigation system and the satellite navigation system to achieve compatibility and interoperability, so that all users can enjoy the fruits of the development of satellite navigation.4, progressive. China will actively and steadily push forward the construction and development of the Beidou satellite navigation system, and constantly improve the service quality, and realize the seamless connection of each stage.Compared with the GPS systemCoverageBeidou navigation system is China local coverage area navigation system. The coverage of about 70 degrees -140 degrees east longitude, latitude 5 degrees -55. GPS is an all-weather navigation system covering the whole world, to ensure that any place on the earth at any time can also observed 6-9 satellites (in fact, most can be observed in 11).Schematic diagram of the Beidou satellite navigation system advantagesThe number of satellites and orbital characteristicsBeidou navigation system is a set of 2 geostationary satellites in the earth's equatorial plane, satellite equatorial angular distance is about 60 degrees. GPS is a set of 24 satellites in6 orbital planes, equatorial orbit at an angle of 55 degrees, 60 degrees angle equatorial orbit plane. GPS navigation satellite orbit for quasi synchronous orbit around the earth, 11 hours and 58 minutes a week.The positioning principleBeidou navigation system is active two-way rangingtwo-dimensional navigation.The center of the ground control system solution for the user, three-dimensional positioning data. GPS is a passive pseudo code ranging 3D navigation. Is your solution independent of three-dimensional positioning data from the user equipment. The working principle of Beidou "has two aspects, one is the user location and lost radio concealment, the military is adverse, on the other hand, because the equipment must include a transmitter, so in the volume, weight, price and power consumption at a disadvantage.positioning accuracyThe 3D positioning accuracy of the Beidou navigation system about several tens of meters, the timing accuracy of about 100ns. GPS 3D positioning accuracy P code has increased from 16m to 6m, the C/A code has been increased from 25-100m to 12M, the timing accuracy of about 20ns.User capacityBeidou navigation system is the enquiry response system foractive two-way ranging, not only to ask the reception center of the ground signal control system between the user equipment and the geostationary satellite, also requires the user equipment to transmit the response signal, synchronous satellite, the channel frequency response of the user capacity of the system depends on the user to allow the blocking rate of the signal rate and asked, user. Therefore, the user equipment capacity of Beidou navigation system is limited. GPS is a one-way ranging system, ranging positioning device sends users as long as the receiving navigation satellite navigation message, so the user equipment capacity of GPS is infinite.ViabilityAs with all satellite navigation and positioning system, Beidou satellite system and control center based on the work, but the "Beidou" dependence on the central control system is obviously much larger, because the positioning solution in there and not by the user equipment to complete the. In order to compensate for the vulnerability of the system, GPS is the development of star transverse data link technology, the main event after the destruction of the GPS satellite can run independently. "Beidou" system from the principle of ruling out the possibility that once the central control system is damaged, the system will not be able to continue to work.Real time"Beidou" user applications must be sent back to the central control system, after the central control system calculates the user's three-dimensional position data and then sent back tothe user, after go back and forth a geostationary satellite, and satellite transmission, processing center control system, time delay is longer, so for high speed movement body, can increase the positioning error. In addition, Beidou satellite navigation system has its own characteristics, its communication function is not available on the GPS.Service IntroductionBeidou satellite navigation system is committed to the global users to provide high quality positioning, navigation and timing services, including open service and authorization service in two ways. Open service is provided free of charge to the global positioning, velocity and timing services, positioning accuracy of 10 meters, the measurement precision of 0.2 M / s, the timing accuracy of 10 ns. Authorized service for high precision and high reliability of satellite navigation user needs, provide location, speed, timing and communication service and integrity information system.The Beidou satellite navigation system to better serve the global service, strengthen the Beidou satellite navigation system compatible with other satellite navigation systems and interoperability, promote the comprehensive application of satellite positioning, navigation and timing services, China is willing to cooperate with other countries, the common development of the satellite navigation industry.。
编者按：2020年11月23日，第十一届中国卫星导航年会在成都召开。
在年会开幕式上，中国卫星导航系统管理办公室副主任杨军作了《北斗卫星导图1 北斗三号全球卫星导航系统星座组网图优于0.2m/s，授时精度优于20ns；亚太地区定位精度优于5m，测速精度优于0.1m/s，授时精度优于10ns。
交通运输方面，北斗系统广泛应用于重点运输过程监控、公路基础设施安全监控、港口高精度实时定位调度监控等领域，使综合交通管理效率和运输安全水平显著提升。
截至2020年10月底，有近700万辆道路营运车辆已经安装使用北斗系统，占运营车辆的96%；3.14万辆邮政快递车辆安装使用北斗系统，占比88%；约1400艘公务船舶安装使用北斗系统，占比75%；约300架通用飞行器安装使用北斗系统，占比11%。
特别是在运输航空器上成功实现了北斗首次应用。
此外，北斗在中欧班列运输、京张高铁建设运营、浩吉和沪昆等铁路测试监测等方面也得到大量应用，为铁路运输高质量发展赋能赋智。
农业领域，基于北斗的农机自动驾驶系统推广应用近4.5万台套，节约50%的用工成本；基于北斗的农机作业监管平台和物联网平台为近40万余台套农机设备提供服务，极大提高了作业管理效率。
林业领域，北斗定位与短报文通信功能广泛应用于森林防火、天然林保护、森林自然调查、病虫害防治等。
渔业领域，为渔业管理部门和渔船提供船位监控、紧急救援、信息发布、渔船出入港管理等服务。
减灾救灾方面，基于北斗的导航、定位、短报文通信功能，提供实时救灾指挥调度、应急通信、灾情信息快速上报与共享等服务，显著提高了灾害应急救援的快速反应能力和决策能力。
已建成部、省、市 （县）三级平台，实现六级业务应用，推广北斗终端超过4.5万台。
湖南、江苏、贵州、广西、四川等地利用北斗/GNSS高精度技术建立地质灾害监测预警系统，在2020年抗击南方洪灾期间，多次成功预报山体滑坡等灾害事件发生，保障了人民生命财产安全。
