To Be More Precise: The Beidou Satellite Navigation and Positioning System

China’s launch of its fifth navigation and positioning satellite in April 2007 reaffirms its commitment to establishing an increasingly capable satellite navigation and positioning system able to compete with the U.S. Global Positioning System (GPS). Called Beidou, but sometimes referred to as the Compass Navigation Satellite System, China’s current system consists of five satellites that provide regional coverage of China and surrounding areas. China began researching satellite navigation and positioning technologies in the 1960s, and after a hiatus brought on by the Cultural Revolution, research was restarted in the late 1970s. In 1983, a plan for a satellite navigation and positioning system under the name “Double Star Rapid Positioning System” was developed (www.china-spacenews.com, January 7, 2006). Chen Fangyun, an 863 Project founder, later proposed a two-satellite Radio Determination Satellite Service (RDSS) system that was formally approved for development in 1994 [1]. The first Beidou satellite was launched in 2000 with two more satellites launched in 2003, which formed the first generation of a constellation all in geosynchronous orbit. Two additional satellites have been launched in 2007.

Technology

The Beidou system is based on the now defunct U.S. Geostar system, which is dissimilar to GPS. Beidou is a RDSS providing regional coverage that requires two satellites, a centralized earth station, mobile terminals and a subscriber station where transmitted data is delivered. In contrast, GPS is a constellation of 24 satellites, which provides global coverage and does not require a centralized earth station. The biggest difference in performance is in accuracies and communications. While GPS can provide accurate positions of within a few meters, the accuracy of Beidou is 20 meters with the use of calibration points and 100 meters without calibration.

In addition, unlike GPS, Beidou can also provide two-way communication between a client’s mobile terminals and headquarters. Customers can transmit up to 120 characters at a time using Beidou. The primary application for Beidou is in the transportation industry. Using a RDSS system, a trucking company can obtain a nationwide inventory of its trucks and past records of truck routes. RDSS systems can also be used to monitor a vehicle’s performance or to monitor changes in the vehicle, such as door locks or acceptable temperature ranges of a refrigerated truck, which can be used to warn of vehicle theft or malfunction. An emergency function can also be used to alert clients of an accident or a crime in progress. In areas with poor coverage, the Beidou signal can be supplemented with GPS.

Applications

China has developed the Beidou system for both military and civilian uses. In this regard, China is following the lead of the United States in developing a system that is at its core a military system, but will also serve a variety of civil and commercial applications. The main concern for China is that GPS can be turned off or degraded by the United States in the event of conflict. Consequently, China’s national interests require access to a satellite navigation and positioning system that is independent of foreign operation. Ultimately, China wants to develop Beidou such that it is on par with GPS in both operation and capabilities.

The importance of satellite navigation and positioning for military and civilian applications has not been lost on the People’s Liberation Army (PLA) or Chinese commercial interests. The use of GPS for navigation and precision guided bombing by the U.S. military has been demonstrated by its indispensability in fighting “informationized” warfare. Precision guided bombing is especially important in the case of a conflict with Taiwan in which China would want to avoid indiscriminate bombing so as not to alienate the Taiwanese public. The PLA also uses the two-way communication function of Beidou to communicate with units and to monitor their positions (Jiefangjun Bao, June 4, 2006). Satellite navigation and positioning can also be used by China’s increasingly capable submarine force that can receive the signal without surfacing. The PLA Navy’s next generation of ballistic missile submarines could use Beidou for more precise positioning data that could be entered into the guidance system of the missiles before launch. In fact, the first satellite navigation and positioning system, Transit, was developed for the U.S. Navy for this purpose. Chinese authors have also explored the use of satellite navigation and positioning for use in the guidance systems of ballistic missiles [2].

The growing market for GPS applications has also drawn interest in developing Beidou for commercial use. It has been estimated that the global GPS market will increase to $22 billion by 2008 (Directions Magazine, October 2, 2003). Obvious applications include those used in the transportation industry and individual automobiles, but applications are also being used by commercial entities for its precision timing. GPS is used for the synchronization of wireless and telecommunications networks and in the measurement and monitoring of power transmission systems.

Future Systems

To capitalize on most of these applications, Beidou will have to be improved upon. Its relatively imprecise positioning and timing data are insufficient for true precision bombing and accurate navigation and timing. Chinese authors recognize this and admit that Beidou is unable to satisfy China’s future satellite navigation needs, but defend it as a system built with little investment that is performing to specification. Chinese authors write that if China is to meet the technical challenges of the twenty-first century, it must field a more capable satellite navigation and positioning system by following the United States’ lead and develop a system that primarily serves military purposes but also remains fully useable by civilian sectors [3].

To this end, six academics from the China Aerospace Science and Technology Corporation argued in early 2005 in a document entitled “Suggestions for Improving Beidou Satellite Navigation Applications,” that satellite navigation and positioning systems required full government support and that no single organization could overcome insufficient funding no matter how hard they worked. The document came to the attention of the State Council and in September 2005, the National Development and Reform Commission and COSTIND issued the document “A Notice Concerning Increasing the Promotion of the Relevant Work of Beidou Navigation Applications” which stipulated that Beidou would be classified as a part of the national basic construction plan and receive sufficient funding. This document also stated that in order to promote Beidou applications, the government should begin demonstration applications of Beidou, support the industrialization of ground terminals, establish and support stable long-term mechanisms for civilian users, set up standards for the timing signal of Beidou, conduct overall planning for the development of component parts and localize the production of receivers [4].

There are conflicting reports about the exact nature of future Beidou constellations. China’s present configuration of five satellites appears to have been put in place to guarantee service for the Olympics since the first three satellites may be near the end of their service life (www.spacechina.com, February 3). Beyond that, Chinese press reports have stated that the second generation of Beidou will consist of four geostationary satellites, 12 medium earth orbiting satellites and nine high earth orbiting satellites and will achieve global coverage by 2010 [5]. More recent reports have stated that the system will consist of five geostationary satellites and 30 medium earth orbiting satellites, but do not give a timetable (Xinhua, November 13, 2006). Another press report states that China has registered 36 satellite slots with the International Telecommunications Union for Beidou, of which fourteen will be in geosynchronous orbits and 22 in medium earth orbits (SatNews Daily, April 16). Regardless of the number of satellites, the second generation Beidou will only be capable of achieving accuracies of 10 meters, still much less accurate than GPS.

Conflicting accounts also exist over the exact nature of services to be offered. According to many press reports, China will offer the Beidou navigation and positioning services free of charge. Another article, however, states that China will offer an “open” level of service as well as a second level of service that will offer “authorized” positioning, velocity and timing communications service (Xinhua, November 13, 2006). The biggest difference of the second generation of Beidou satellites will be its similarity to GPS. China plans to eliminate the centralized earth station, which could serve as a target for U.S. military operations, and have it function much like the GPS system with the use of satellites and client terminals [6]. Eventually China hopes to achieve GPS-like accuracies with Beidou [7].

China boasts that the Beidou system does have its own advantages. These include the ability to facilitate communications between subscriber headquarters and mobile terminals and that it is indigenously made. Beidou supporters also argue that the potential for the U.S. military to turn off or degrade the GPS signal means that Chinese customers must depend on a more reliable form of navigation and positioning services.

Market Potential

Despite these advantages, use of the Beidou system has lagged behind GPS usage. The Chinese navigation and positioning services market has been expanding in recent years. In 2002, it was estimated at 3.95 billion yuan ($514 million) and in 2003, it was estimated at 7 billion yuan ($900 million) [8]. These numbers are expected to increase. Less than two percent of the country’s automobiles, for example, are equipped with a satellite navigation and positioning system, indicating that the market remains largely untapped. Chinese market analysts are hopeful for Beidou’s prospects and estimate that there will be 300,000 Beidou users in 2008 with a market value of 3.5 billion yuan ($455 million) constituting about 20 percent of the total Chinese market for satellite navigation and positioning services [9].

It is uncertain if Beidou service providers will be able to meet this projection, however. GPS receivers in China cost 3,000-6,000 ($390-780) yuan, while Beidou receivers are a whopping 20,000-30,000 yuan ($2,600-3,900) [10]. The discrepancy in prices is attributed to a low customer base and the necessity of receivers to provide both location data and two-way communications [11]. Moreover, considering the eventual demise of Geostar and the advent of similar systems using GPS and cellular communications to provide many of the same features as Beidou, it is uncertain if providing satellite-based two-way communications will be viable.

Technology Gaps

Moreover, China has yet to master most of the technologies needed to indigenously develop a satellite navigation and positioning system and must even concentrate on basic components such as microchips and circuit boards before it can do so [12]. China’s 200 million Euro ($280 million) investment in the Galileo satellite navigation and positioning project, for example, is an implicit recognition on the part of the Chinese government that the independent development of these technologies will be difficult. In February 2006, the China Astronautics Association Satellite Application Work Committee held a “China Beidou Navigation System Application Forum” that advised the government to develop a new generation of navigation and positioning satellites by replacing the “Made in China” concept with the concept of “Innovated in China,” replacing foreign components with domestic components (www.spacechina.com, February 10, 2006).

China appears to have far to go before it can bring this goal to reality. A critical component of navigation and positioning satellites is timing technology. GPS, for example, uses very precise atomic clocks to perform its calculations. China, on the other hand, lacks atomic clock technology that can survive the harsh space environment. To compensate, China has purchased rubidium atomic clocks from the Swiss company Temex. These clocks are three times less accurate than the clocks to be used on the Galileo satellites. According to one source, China has been working on atomic clock technology since 2000 with limited results, but may close the gap in three to four years (Space News, June 19, 2006).

Conclusion

China’s development of the Beidou navigation and positioning satellite system holds the possibility that China will develop a viable competitor to GPS. Yet, when this may occur is uncertain. China’s inability to develop technologies that are precise enough and the proposed 10-meter accuracy of the second generation Beidou indicate that it may be some time before it can match GPS on performance. In addition, because GPS services are so ubiquitous and the signal free of charge it is not apparent what comparative advantage Beidou possesses, besides being made in China and free from U.S. control. Given these hurdles, GPS will likely remain the best satellite navigation and positioning service for many years to come.

Notes

1. The 863 Program is China’s premier high technology research and development funding source. Shan Bian, “China’s Satellite Navigation System – The Beidou Navigation and Positioning System [Zhongguo de weixing daohang xitong – beidou daohang dingwei xitong],” China Surveying and Mapping News [Zhongguo cehui bao], August 17, 2004.

2. See, for example, Kang Guohua, Liu Jianye, Xiong Zhi, and Zhu Yanhua, “GNSS/SST/SINS Integrated Navigation System for Ballistic Missile [DaodandandaoGNSS/SST/SINS zuhe daohang xitong yanjiu],” Geomatics and Information Science of Wuhan University [Wuhan daxue xuebao – xinxi kexueban], February 2006 p. 176-179.

3. Tong Kai, “China’s Progress in Navigation and Positioning Satellite Systems [Zhongguo daohang dingwei weixing xitong de jinzhan], Aerospace China [Zhongguo hangtian], August 2002.

4. “Beidou Navigation Applications Reach a Critical Stage [Beidou daohang yingyong jinru guanjian jieduan],” www.spacechina.com, February 10, 2006.

5. Zheng Di, “‘Beidou System’ Commercial Application Layout: China Satellite Navigation Breakthrough GPS [‘Beidou xi’shang yong buzhen：zhongguo weixing daohang tuwei GPS],” 21st Century Economic Report [21Shiji jingji baodao], April 25, 2005.

6. Tong Kai, “China’s Progress in Navigation and Positioning Satellite Systems.

7. Xie Jinshi, “Several Issues Concerning Our Country’s Satellite Navigation and Positioning System Construction and Development Process [Woguo weixing daohang dingwei xitong jianshe yu fazhan guocheng zhong yingzhuyi de jige wenti], Aerospace China [Zhongguo hangtian], September 2005.

8. Yang Jun and Zhou Ruxin, “Our Country’s Satellite Navigation Application Market Analysis [Wogou weixing daohang yingyong shichang fenxi], GNSS World of China [Quanqiu dingwei xitong], May 2003, p. 46.

9. Shan Bian, “China’s Satellite Navigation System – The Beidou Navigation and Positioning System.

10. Shi Lei and Hu Qunfang, “Beidou Applications Drives On the Expressway Early [Beidou yingyong zao ri shiru kuaichedao],” China Space News [Zhongguo hangtian bao], April 22, 2005.

11. “Beidou Navigation System Faces the Market’s Final Exam [Beidou daohang xitong zhimian shichang dakao],” China Space News [Zhongguo hangtian bao], October 1, 2003, p.1.

12. Tong Kai, “China’s Satellite Navigation and Positioning System [Zhongguode weixing daohang dingwei xitong], Conmilit [Xiandai junshi], October 2003, p. 9-10.