Beidou Navigation Satellite System The BeiDou Navigation Satellite System ( BDS , ) is a Chinese satellite navigation system . It consists of two separate satellite constellations – a limited test system that has been operating since 2000 , and a full - scale global navigation system that is currently under construction . The first BeiDou system , officially called the BeiDou Satellite Navigation Experimental System ( ) and also known as BeiDou - 1 , consists of three satellites and offers limited coverage and applications . It has been offering navigation services , mainly for customers in China and neighboring regions , since 2000 . The second generation of the system , officially called the BeiDou Satellite Navigation System ( BDS ) and also known as COMPASS or BeiDou - 2 , will be a global satellite navigation system consisting of 35 satellites , and is under construction as of January 2013 . It became operational in China in December 2011 , with 10 satellites in use , and began offering services to customers in the Asia - Pacific region in December 2012 . It is planned to begin serving global customers upon its completion in 2020 . 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 ancient Chinese astronomers to the seven brightest stars of the Ursa Major constellation . Historically , this set of stars was used in navigation to locate the North Star Polaris . As such , the name BeiDou also serves as a metaphor for the purpose of the satellite navigation system . History . Conception and initial development . The original idea of a Chinese satellite navigation system was conceived by Chen Fangyun and his colleagues in the 1980s . According to the China National Space Administration , the development of the system would be carried out in three steps : The first satellite , " BeiDou - 1A " , was launched on 30 October 2000 , followed by " BeiDou - 1B " on 20 December 2000 . The third satellite , " BeiDou - 1C " ( a backup satellite ) , was put into orbit on 25 May 2003 . The successful launch of " BeiDou - 1C " also meant the establishment of the BeiDou - 1 navigation system . On 2 November 2006 , China announced that from 2008 BeiDou would offer an open service with an accuracy of 10 meters , timing of 0 . 2 microseconds , and speed of 0 . 2 meters / second . In February 2007 , the fourth and last satellite of the BeiDou - 1 system , " BeiDou - 1D " ( sometimes called " BeiDou - 2A " , serving as a backup satellite ) , was sent up into space . It was reported that the satellite had suffered from a control system malfunction but was then fully restored . 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 . On 15 January 2010 , the official website of the BeiDou Navigation Satellite System went online , and the system ' s third satellite ( " Compass - G1 " ) was carried into its orbit by a Long March 3C rocket on 17 January 2010 . On 2 June 2010 , the fourth satellite was launched successfully into orbit . The fifth orbiter was launched into space from Xichang Satellite Launch Center by an LM - 3I carrier rocket on 1 August 2010 . Three months later , on 1 November 2010 , the sixth satellite was sent into orbit by LM - 3C . Another satellite , the Beidou - 2 / Compass IGSO - 5 ( fifth inclined geosynchonous orbit ) satellite , was launched from the Xichang Satellite Launch Center by a Long March - 3A on 1 December 2011 ( UTC ) . Chinese involvement in Galileo system . In September 2003 , China intended to join the European Galileo positioning system project and was to invest €230 million ( US $ 296 million , GBP160 million ) in Galileo over the next few years . At the time , it was believed that China ' s " BeiDou " navigation system would then only be used by its armed forces . 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 ) " . 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 . By April 2006 , eleven cooperation projects within the Galileo framework had been signed between China and EU . However , the Hong Kong - based " South China Morning Post " reported in January 2008 that China was unsatisfied with its role in the Galileo project and was to compete with Galileo in Asian market . Experimental system ( BeiDou - 1 ) . 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 . Unlike the American GPS , Russian GLONASS , and European Galileo systems , which use medium Earth orbit satellites , BeiDou - 1 uses satellites in geostationary orbit . 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 . The area that can be serviced is from longitude 70°E to 140°E and from latitude 5°N to 55°N . A frequency of the system is 2491 . 75 MHz . Completion . The first satellite , BeiDou - 1A , was launched on October 31 , 2000 . The second satellite , BeiDou - 1B , was successfully launched on December 21 , 2000 . The last operational satellite of the constellation , BeiDou - 1C , was launched on May 25 , 2003 . Position calculation . To calculate a position , the following procedure is used : 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 . With the existing user terminals it appears that the calibrated accuracy is 20m ( 100m , uncalibrated ) . Terminals . In 2008 , a BeiDou - 1 ground terminal cost around RMB ( ) , almost 10 times the price of a contemporary GPS terminal . The price of the terminals was explained as being due to the cost of imported microchips . At the China High - Tech Fair ELEXCON of November 2009 in Shenzhen , a BeiDou terminal priced at RMB was presented . Applications . According to Sun Jiadong , the chief designer of the navigation system , " Many organizations have been using our system for a while , and they like it very much . " Global system ( BeiDou Navigation Satellite System or BeiDou - 2 ) . Description . BeiDou - 2 ( formerly known as COMPASS ) is not an extension to the older BeiDou - 1 , but rather supersedes it outright . The new system will be a constellation of 35 satellites , which include 5 geostationary orbit satellites for backward compatibility with BeiDou - 1 , and 30 non - geostationary satellites ( 27 in medium earth orbit and 3 in inclined geosynchronous orbit ) , that will offer complete coverage of the globe . Accuracy . There are two levels of service provided ; a free service to civilians and licensed service to the Chinese government and military . The free civilian service has a 10 - meter location - tracking accuracy , synchronizes clocks with an accuracy of 10 nanoseconds , and measures speeds to within 0 . 2 m / s . The restricted military service has a location accuracy of 10 centimetres , can be used for communication , and will supply information about the system status to the user . To date , the military service has been granted only to the People ' s Liberation Army and to the Military of Pakistan . Constellation . The new system will be a constellation of 35 satellites , which include 5 geostationary orbit ( GEO ) satellites and 30 medium Earth orbit ( MEO ) satellites , that will offer complete coverage of the globe . The ranging signals are based on the CDMA principle and have complex structure typical of Galileo or modernized GPS . Similar to the other GNSS , there will be two levels of positioning service : open and restricted ( military ) . The public service shall be available globally to general users . When all the currently planned GNSS systems are deployed , the users will benefit from the use of a total constellation of 75 + satellites , which will significantly improve all the aspects of positioning , especially availability of the signals in so - called urban canyons . The general designer of Compass navigation system is Sun Jiadong , who is also the general designer of its predecessor , the original Beidou navigation system . Frequencies . Frequencies for Compass are allocated in four bands : E1 , E2 , E5B , and E6 and overlap with Galileo . The fact of overlapping could be convenient from the point of view of the receiver design , but on the other hand raises the issues of inter - system interference , especially within E1 and E2 bands , which are allocated for Galileo ' s publicly regulated service . However , under International Telecommunication Union ( ITU ) policies , the first nation to start broadcasting in a specific frequency will have priority to that frequency , and any subsequent users will be required to obtain permission prior to using that frequency , and otherwise ensure that their broadcasts do not interfere with the original nation ' s broadcasts . It now appears that Chinese Compass satellites will start transmitting in the E1 , E2 , E5B , and E6 bands before Europe ' s Galileo satellites and thus have primary rights to these frequency ranges . Although little was officially announced by Chinese authorities about the signals of the new system , the launch of the first Compass satellite permitted independent researchers not only to study general characteristics of the signals but even to build a Compass receiver . Compass - M1 . Compass - M1 is an experimental satellite launched for signal testing and validation and for the frequency filing on 14 April 2007 . The role of Compass - M1 for Compass is similar to the role of the GIOVE satellites for the Galileo system . The orbit of Compass - M1 is nearly circular , has an altitude of 21 , 150 km and an inclination of 55 . 5 degrees . Compass - M1 transmits in 3 bands : E2 , E5B , and E6 . In each frequency band two coherent sub - signals have been detected with a phase shift of 90 degrees ( in quadrature ) . These signal components are further referred to as " I " and " Q " . The " I " components have shorter codes and are likely to be intended for the open service . The " Q " components have much longer codes , are more interference resistive , and are probably intended for the restricted service . The investigation of the transmitted signals started immediately after the launch of Compass - M1 on 14 April 2007 . Soon after in June 2007 , engineers at CNES reported the spectrum and structure of the signals . A month later , researchers from Stanford University reported the complete decoding of the “ I ” signals components . The knowledge of the codes allowed a group of engineers at Septentrio to build the COMPASS receiver and report tracking and multipath characteristics of the “ I ” signals on E2 and E5B . Characteristics of the " I " signals on E2 and E5B are generally similar to the civilian codes of GPS ( L1 - CA and L2C ) , but Compass signals have somewhat greater power . The notation of Compass signals used in this page follows the naming of the frequency bands and agrees with the notation used in the American literature on the subject , but the notation used by the Chinese seems to be different and is quoted in the first row of the table . Operation . In December 2011 , the system went into operation on a trial basis . It has started providing navigation , positioning and timing data to China and the neighbouring area for free from 27 December . During this trial run , Compass will offer positioning accuracy to within 25 meters , but the precision will improve as more satellites are launched . Upon the system ' s official launch , it pledged to offer general users positioning information accurate to the nearest 10 m , measure speeds within 0 . 2 m per second , and provide signals for clock synchronisation accurate to 0 . 02 microseconds . The BeiDou - 2 system began offering services for the Asia - Pacific region in December 2012 . At this time , the system could provide positioning data between longitude 55°E to 180°E and from latitude 55°S to 55°N . Completion . In December 2011 , Xinhua stated that " [ t ] he basic structure of the Beidou system has now been established , and engineers are now conducting comprehensive system test and evaluation . The system will provide test - run services of positioning , navigation and time for China and the neighboring areas before the end of this year , according to the authorities . " The system became operational in the China region that same month . The global navigation system should be finished by 2020 . As of December 2012 , 16 satellites for BeiDou - 2 have been launched , 14 of them are in service .