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he BeiDou Navigation System (simplified Chinese: 北斗导航系统; traditional Chinese: 北斗導航系統; pinyin: Běidǒu dǎoháng xìtǒng) or BeiDou (Compass) Navigation Satellite System (simplified Chinese: 北斗卫星导航系统; traditional Chinese: 北斗衛星導航系統; pinyin: Běidǒu wèixīng dǎoháng xìtǒng) is a project by China to develop an independent satellite navigation system. It may refer to either one or both generations of the Chinese navigation system.
The first BeiDou system, officially called BeiDou Satellite Navigation Experimental System, or known as BeiDou-1, consists of 3 satellites and has limited coverage and applications. It has been offering navigation services mainly for customers in China and from neighboring regions since 2000.
The second generation of the system, known as Compass or BeiDou-2, which will be a global satellite navigation system consisting of 35 satellites, is still under construction. It is planned to offer services to customers in Asia-Pacific region by 2012 and the global system should be finished by 2020.
The chief designer of BeiDou navigation system is Sun Jiadong.
Nomenclature
The BeiDou Navigation System is named after the Big Dipper constellation, which is known in Chinese as Běidǒu. The name literally means "Northern Dipper", the name given by Chinese astronomers to the seven brightest stars of Ursa Major or 'the Great Bear' constellation.[1] Historically, this set of stars was used in navigation to locate the North Star Polaris. As such, BeiDou also serves as a metaphor for the purpose of the satellite navigation system.
[edit]History
[edit]BeiDou system
According to the China National Space Administration, the development of the Chinese global navigation system should be carried out in three steps:[2]
2000 - 2003: experimental BeiDou navigation system consisting of 3 satellites
by 2012: regional BeiDou navigation system covering China and neighboring regions
by 2020: global BeiDou navigation system
The first two satellites, BeiDou-1A was launched on 30 October 2000, BeiDou-1B followed on 20 December 2000. The third satellite BeiDou-1C (as backup satellite), was put into orbit on 25 May 2003.[3][4] The successful launch of BeiDou-1C also meant the establishment of the BeiDou-1 navigation system.
On November 2, 2006, China announced that from 2008 BeiDou would offer an open service with an accuracy of 10 meters, timing of 0.2 nanoseconds, speed of 0.2 meter/second.[5][citation needed]
It followed that in February 2007, the fourth and also the last satellite of BeiDou-1 system, the BeiDou-1D (sometimes called BeiDou-2A, serving as a backup satellite), was sent up into space.[6] It was reported that the satellite had suffered from a control system malfunction but was then fully restored.[7][8]
In April 2007, the first satellite of BeiDou-2, namely Compass-M1 (to validate frequencies for the BeiDou-2 constellation) was successfully put into its working orbit. The second BeiDou-2 constellation satellite Compass-G2 was launched on 15 April 2009.[9] The third satellite (Compass-G1) was carried into its orbit by LM-3C on January 17, 2010.[10] On the 2nd of June 2010, the fourth satellite was launched successfully into orbit.[11] The fifth orbiter was launched into space by LM-3I carrier rocket from Xichang Satellite Launch Center on August 1, 2010.[12] Three months later, on November 1, 2010, the sixth satellite was sent into orbit by LM-3C.[13] It is reported that another satellite (BeiDou-2 IGSO) will be launched by the end of the year.[14]
On January 15, 2010 the official website of BeiDou Navigation Satellite System went online.[10]
[edit]Involvement in Galileo
In September 2003, China intended to join the European Galileo positioning system project and was to invest €230 million (USD296 million, GBP160 million) in Galileo over the next few years.[15] It's believed that China's "BeiDou" navigation system would then only be used by its armed forces.[5] In October 2004, China officially joined the Galileo project by signing the Agreement on the Cooperation in the Galileo Program between the "Galileo Joint Undertaking" (GJU) and the "National Remote Sensing Centre of China" (NRSCC).[16] Based on the Sino-European Cooperation Agreement on Galileo program, China Galileo Industries (CGI), the prime contractor of the China’s involvement in Galileo programs was founded in December 2004.[17] By April 2006, eleven cooperation projects within the Galileo framework had been signed between China and EU.[18]
The Hongkong based South China Morning Post reported in January 2008[19] that China was unsatisfied with its role in the Galileo project and was to compete with Galileo in Asian market.
[edit]System Description
[edit]Experimental System (BeiDou-1)
[edit]Description
BeiDou-1 is an experimental regional navigation system, which consists of four satellites (three working satellites and one backup satellite). The satellites themselves were based on the Chinese DFH-3 geostationary communications satellite and had a launch weight of 1,000 kilograms (2,200 pounds) each.[20]
Unlike the American GPS, Russian GLONASS, and European Galileo systems, which use medium Earth orbit(MEO) satellites, BeiDou-1 uses satellites in geostationary orbit(GEO). This means that the system does not require a large constellation of satellites, but it also limits the coverage to areas on Earth where the satellites are visible.[3] The area that can be serviced is from Logitude 70°E to 140°E, and from Latitude 5°N to 55°N.[7]
[edit]Completion
The first satellite, BeiDou-1A was sent into its orbit on October 31, 2000. The second satellite, BeiDou-1B was successfully launched on December 21, 2000. The last satellite of the constellation, BeiDou-1C was carried into its orbit position on May 25, 2003, this launch also completed the construction of the experimental system.[3]
[edit]Position calculation
To calculate a position, the following procedure is used:[3]
A signal is transmitted skyward by a remote terminal.
Each of the geostationary satellites receive the signal.
Each satellite sends the accurate time of when each received the signal to a ground station.
The ground station calculates the longitude and latitude of the remote terminal, and determines the altitude from a relief map.
The ground station sends the remote terminal's 3D position to the satellites.
The satellites broadcast the calculated position to the remote terminal.
In 2007, the official Xinhua News Agency reported that the resolution of the BeiDou system was as high as 0.5 metres, considerably better than unaided GPS.[21] With the existing user terminals appears that the calibrated accuracy is 20m (100m, uncalibrated).[22]
[edit]Terminal
The terminal can communicate with the ground station by sending and receiving short messages.
As of 2008, one BeiDou-1 terminal costs about 20,000RMB (US$2,929), almost 10 times the price of GPS counterpart.[23] It's said that the reason why is the terminal so expensive is due to "using expensive imported Chips",but China seemed to have found replacement and the price could lower to less than 1,000RMB.[24] By the China High-Tech Fair ELEXCON 2009(November 16–21, 2009) in Shenzhen, China, a terminal solution costing no more than 3,000RMB was presented.[25]
[edit]Applications
Over 1000 BeiDou-1 terminals were used in the 2008 Sichuan earthquake, providing informations from the earthquake area.[26]
As of October 2009, all Chinese border guards in Yunnan are equipped with BeiDou-1 devices.[27]
According to Sun Jiadong, chief designer of the navigation system, "Many organizations have been using our system for a while, and they like it very much."[28]
[edit]Advantages and drawbacks
[edit]Global System (BeiDou-2 or Compass)
Main article: Compass navigation system
[edit]Description
BeiDou-2 is not an extension to the existing BeiDou-1. The new system will be a constellation of 35 satellites, which include 5 geostationary orbit (GEO) satellites, for backward compatibility with BeiDou-1, and 30 non-GSO satellites (27 in Medium Earth Orbit (MEO) and 3 in Inclined GSO (IGSO)),[29] that will offer complete coverage of the globe. There will be two levels of service provided; free service to civilians and licensed service to Chinese government and military users:[11][30]
The free service will have a 10 meter location-tracking accuracy, will synchronize clocks with an accuracy of 10 ns, and measure speeds within 0.2 m/s.
The licensed service will be more accurate than the free service, can be used for communication, and will supply information about the system status to the users.
[edit]Completion
It is planned that BeiDou-2 system will have more than 10 satellites by 2012 and may offer services for the Asia-Pacific region; The global navigation system should be finished by 2020.[31]
As of April 2011, eight satellites for BeiDou-2 have been launched. According to an official report [32], "the eighth Beidou satellite marks the completion of basic function of Beidou (Compass) Navigation Satellite System...collaborate with five navigation satellites...will be able to provide services to most regions in China after a period of orbiting running tests and system integration."
The first BeiDou system, officially called BeiDou Satellite Navigation Experimental System, or known as BeiDou-1, consists of 3 satellites and has limited coverage and applications. It has been offering navigation services mainly for customers in China and from neighboring regions since 2000.
The second generation of the system, known as Compass or BeiDou-2, which will be a global satellite navigation system consisting of 35 satellites, is still under construction. It is planned to offer services to customers in Asia-Pacific region by 2012 and the global system should be finished by 2020.
The chief designer of BeiDou navigation system is Sun Jiadong.
Nomenclature
The BeiDou Navigation System is named after the Big Dipper constellation, which is known in Chinese as Běidǒu. The name literally means "Northern Dipper", the name given by Chinese astronomers to the seven brightest stars of Ursa Major or 'the Great Bear' constellation.[1] Historically, this set of stars was used in navigation to locate the North Star Polaris. As such, BeiDou also serves as a metaphor for the purpose of the satellite navigation system.
[edit]History
[edit]BeiDou system
According to the China National Space Administration, the development of the Chinese global navigation system should be carried out in three steps:[2]
2000 - 2003: experimental BeiDou navigation system consisting of 3 satellites
by 2012: regional BeiDou navigation system covering China and neighboring regions
by 2020: global BeiDou navigation system
The first two satellites, BeiDou-1A was launched on 30 October 2000, BeiDou-1B followed on 20 December 2000. The third satellite BeiDou-1C (as backup satellite), was put into orbit on 25 May 2003.[3][4] The successful launch of BeiDou-1C also meant the establishment of the BeiDou-1 navigation system.
On November 2, 2006, China announced that from 2008 BeiDou would offer an open service with an accuracy of 10 meters, timing of 0.2 nanoseconds, speed of 0.2 meter/second.[5][citation needed]
It followed that in February 2007, the fourth and also the last satellite of BeiDou-1 system, the BeiDou-1D (sometimes called BeiDou-2A, serving as a backup satellite), was sent up into space.[6] It was reported that the satellite had suffered from a control system malfunction but was then fully restored.[7][8]
In April 2007, the first satellite of BeiDou-2, namely Compass-M1 (to validate frequencies for the BeiDou-2 constellation) was successfully put into its working orbit. The second BeiDou-2 constellation satellite Compass-G2 was launched on 15 April 2009.[9] The third satellite (Compass-G1) was carried into its orbit by LM-3C on January 17, 2010.[10] On the 2nd of June 2010, the fourth satellite was launched successfully into orbit.[11] The fifth orbiter was launched into space by LM-3I carrier rocket from Xichang Satellite Launch Center on August 1, 2010.[12] Three months later, on November 1, 2010, the sixth satellite was sent into orbit by LM-3C.[13] It is reported that another satellite (BeiDou-2 IGSO) will be launched by the end of the year.[14]
On January 15, 2010 the official website of BeiDou Navigation Satellite System went online.[10]
[edit]Involvement in Galileo
In September 2003, China intended to join the European Galileo positioning system project and was to invest €230 million (USD296 million, GBP160 million) in Galileo over the next few years.[15] It's believed that China's "BeiDou" navigation system would then only be used by its armed forces.[5] In October 2004, China officially joined the Galileo project by signing the Agreement on the Cooperation in the Galileo Program between the "Galileo Joint Undertaking" (GJU) and the "National Remote Sensing Centre of China" (NRSCC).[16] Based on the Sino-European Cooperation Agreement on Galileo program, China Galileo Industries (CGI), the prime contractor of the China’s involvement in Galileo programs was founded in December 2004.[17] By April 2006, eleven cooperation projects within the Galileo framework had been signed between China and EU.[18]
The Hongkong based South China Morning Post reported in January 2008[19] that China was unsatisfied with its role in the Galileo project and was to compete with Galileo in Asian market.
[edit]System Description
[edit]Experimental System (BeiDou-1)
[edit]Description
BeiDou-1 is an experimental regional navigation system, which consists of four satellites (three working satellites and one backup satellite). The satellites themselves were based on the Chinese DFH-3 geostationary communications satellite and had a launch weight of 1,000 kilograms (2,200 pounds) each.[20]
Unlike the American GPS, Russian GLONASS, and European Galileo systems, which use medium Earth orbit(MEO) satellites, BeiDou-1 uses satellites in geostationary orbit(GEO). This means that the system does not require a large constellation of satellites, but it also limits the coverage to areas on Earth where the satellites are visible.[3] The area that can be serviced is from Logitude 70°E to 140°E, and from Latitude 5°N to 55°N.[7]
[edit]Completion
The first satellite, BeiDou-1A was sent into its orbit on October 31, 2000. The second satellite, BeiDou-1B was successfully launched on December 21, 2000. The last satellite of the constellation, BeiDou-1C was carried into its orbit position on May 25, 2003, this launch also completed the construction of the experimental system.[3]
[edit]Position calculation
To calculate a position, the following procedure is used:[3]
A signal is transmitted skyward by a remote terminal.
Each of the geostationary satellites receive the signal.
Each satellite sends the accurate time of when each received the signal to a ground station.
The ground station calculates the longitude and latitude of the remote terminal, and determines the altitude from a relief map.
The ground station sends the remote terminal's 3D position to the satellites.
The satellites broadcast the calculated position to the remote terminal.
In 2007, the official Xinhua News Agency reported that the resolution of the BeiDou system was as high as 0.5 metres, considerably better than unaided GPS.[21] With the existing user terminals appears that the calibrated accuracy is 20m (100m, uncalibrated).[22]
[edit]Terminal
The terminal can communicate with the ground station by sending and receiving short messages.
As of 2008, one BeiDou-1 terminal costs about 20,000RMB (US$2,929), almost 10 times the price of GPS counterpart.[23] It's said that the reason why is the terminal so expensive is due to "using expensive imported Chips",but China seemed to have found replacement and the price could lower to less than 1,000RMB.[24] By the China High-Tech Fair ELEXCON 2009(November 16–21, 2009) in Shenzhen, China, a terminal solution costing no more than 3,000RMB was presented.[25]
[edit]Applications
Over 1000 BeiDou-1 terminals were used in the 2008 Sichuan earthquake, providing informations from the earthquake area.[26]
As of October 2009, all Chinese border guards in Yunnan are equipped with BeiDou-1 devices.[27]
According to Sun Jiadong, chief designer of the navigation system, "Many organizations have been using our system for a while, and they like it very much."[28]
[edit]Advantages and drawbacks
[edit]Global System (BeiDou-2 or Compass)
Main article: Compass navigation system
[edit]Description
BeiDou-2 is not an extension to the existing BeiDou-1. The new system will be a constellation of 35 satellites, which include 5 geostationary orbit (GEO) satellites, for backward compatibility with BeiDou-1, and 30 non-GSO satellites (27 in Medium Earth Orbit (MEO) and 3 in Inclined GSO (IGSO)),[29] that will offer complete coverage of the globe. There will be two levels of service provided; free service to civilians and licensed service to Chinese government and military users:[11][30]
The free service will have a 10 meter location-tracking accuracy, will synchronize clocks with an accuracy of 10 ns, and measure speeds within 0.2 m/s.
The licensed service will be more accurate than the free service, can be used for communication, and will supply information about the system status to the users.
[edit]Completion
It is planned that BeiDou-2 system will have more than 10 satellites by 2012 and may offer services for the Asia-Pacific region; The global navigation system should be finished by 2020.[31]
As of April 2011, eight satellites for BeiDou-2 have been launched. According to an official report [32], "the eighth Beidou satellite marks the completion of basic function of Beidou (Compass) Navigation Satellite System...collaborate with five navigation satellites...will be able to provide services to most regions in China after a period of orbiting running tests and system integration."