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 Xingqun ZHAN, Professor of Guidance, Navigation and Control at School of Aeronautics and Astronautics, Shanghai, China discusses the benefi ts, services and future plans of the BeiDou system
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What is the origin and meaning of BeiDou?
BeiDou is the Chinese pronunciation of the Big Dipper, which consists of seven stars located exactly at the north sky. Chinese people used BeiDou for identifying directions as long back as the ancient times. They also invented the world’s first navigation device based on terrestrial magnetism, the ancient compass, whose Chinese pronunciation is Sinan. Today, BeiDou will continue serving people from China and all over the world not only on navigation, but also on positioning and timing. The BeiDou system will meet the demands of China’s national security, economic development, technological advances and social progress, safeguard national interests and will enhance the comprehensive national strength. Meanwhile, it will provide stable, reliable and quality satellite navigation services for global users along with other Global Navigation Satellite Systems.
How has been the performance of the system so far?
BeiDou Initial Operational period provides services to China and most parts of its surrounding areas covering from 84E to 160E, from 55S to 55N. A number of field tests have been carried out, showing that, the user receiver positioning accuracy is 25m horizontally and 30m vertically. Its velocity accuracy is 0.4m/s and timing accuracy is 50ns. Besides, BeiDou Initial Operational period retains the active positioning and short message services from BeiDou Demonstration System.
What are the major application areas of BeiDou?
The BeiDou 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. Upon the full operation, BeiDou will provide more high-performance services for civil aviation, maritime, rail, finance, postal, land resources, agriculture, tourism and other industries.
How many satellites have been launched and how many are planned for this year?
By the end of April 2012, 13 BeiDou satellites have been launched and formed a basic system. The launch of two MEO and one GEO BeiDou satellite have been planned for this year. By then, the BeiDou regional service will be formally provided.
How is rest of the world going to be benefitted from BeiDou?
From December 27, 2011, the BeiDou Initial Operation Service and the following BeiDou Regional Service have been covering most of the surrounding areas of China. Chinese government promotes international cooperation on BeiDou regional and global applications. Multi- GNSS applications based on a BeiDou user terminal compatible and interoperable with other satellite navigation systems are also encouraged. China is actively promoting BeiDou Application Demonstration & Experience Campaign program (BADEC) in Asia and Pacific areas. The main purpose of BADEC is to spread awareness about BeiDou’s real performance for local communities and promote multi-GNSS applications. This program invites a wide participation from countries the world over.
What is your opinion about interoperability ?
Interoperability is the ability of open services of multiple satellite navigation system to be used together to provide better capabilities at the user level than would be achieved by relying solely on one service, without significantly increasing the complexity of receivers. From my understanding, interoperability is to coordinate a common signal architecture and time/space reference frame that simplifies the multi- GNSS receiver as much as possible.
How do you look at the issue of jamming?
Jamming is normally an intentional interference with on GNSS signal in space. It is because the signal is too weak, which results in serious influences especially for applications relying on GNSS. Much work shall be done simultaneously. One is investigation of related laws and regulations, such as FCC on LightSquared issues in USA. Another is anti-jamming technology development not only on receivers but also on the system architecture. Some novel technologies are being developed on the frame of Interference Detection & Mitigation (IDM) and Vulnerability Monitoring which focus on th e Environment Segment.
“BeiDou system will focus on compatibility and interoperability with other GNSS”
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 YANG Dongkai, Dr Professor, School of Electronic and Information Engineering, Beihang University, China explains the applications and the advantages of BeiDou system
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What are the main application areas for BeiDou System?
Since the BeiDou Navigation Satellite Demonstration System was officially brought into service in 2003, China has achieved remarkable progress in the field of theoretical study, technology R&D, receiver production, application and service development. Along with the construction of the BeiDou Navigation Satellite System and the development of RNSS services, China has made breakthrough in multi-mode chips, antenna and receiver boards, which are compatible with other navigation satellite systems. This led to advances of independent intellectual property rights and product industrialization.
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.
Upon the full completion, the BeiDou Navigation Satellite System will provide a better high-performance positioning, navigation, timing and short-message communication services for civil aviation, shipping, railways, finance, postal, land resources, agriculture, tourism and other industries. In addition, the BeiDou signal (including reflections) would be useful in the fields of atmosphere detection, meteorology prediction, crust distortion monitoring, mud avalanche monitoring, etc.
Is the BeiDou system competing with other existing GNSS?
As a global navigation satellite system compatible with other navigation satellite systems worldwide, i.e., American GPS, Russian GLONASS and European GALILEO system, the BeiDou system is independently established and operated by China. The BeiDou system could be used for users across the globe and its open service is free of charge. Generally, GNSS providers are encouraged to make full use of positioning, navigation and timing service in the lives of people and for industries. At the same time, the customers usually consider multiple GNSS to promote its performance when they select the systems.
What are the co-operation areas for the BeiDou system with other GNSS?
In the multi – GNSS age, the BeiDou Navigation Satellite System will carry out active and pragmatic international exchange and cooperation. This will be in line with China’s foreign policies, focusing on China’s basic tasks and strategic objectives for the construction of navigation satellite systems, utilizing domestic and international markets and resources in a coordinated way.
Under the framework of International Telecommunication Union (ITU), China started the BeiDou Navigation Satellite System frequency coordination activities with other GNSS. And as the core provider and member of International Committee on Global Navigation Satellite Systems (ICG), the BeiDou system has carried out extensive exchange and cooperation with other GNSS, focusing on compatibility and interoperability.
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, coordinates frame, time reference, application development and scientific research. China actively promotes BeiDou Application Demonstration & Experience Campaign (BADEC), International GNSS Monitoring & Assessment Service for OS (iGMAS) and other projects, develops navigation satellite technology and enhances system service performance.
What are the advantages of the BeiDou system?
The BeiDou system comprises 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 non-GEO satellites include 27 MEO satellites and three IGSO satellites.
The BeiDou system will meet the demands of China’s national security, economic development, technological advances and social progress, safeguard national interests and will enhance the comprehensive national strength. Along with other GNSS providers, the BeiDou system will jointly promote the development of satellite navigation industry, contribute to human civilization and social development, serve the world and benefit mankind. The BeiDou system can provide positioning, velocity measurement and one-way and two-way timing services to worldwide users. It can also provide wide area differential services with the accuracy better than 1m and short messages services with the capacity of 120 Chinese characters each time.
How do you see the future of satellite navigation market?
The satellite navigation market volume is larger as its service performance is better. As multi-GNSS could provide higher accuracy, availability and more stable signal source, many new application areas and application modes help to increase the satellite navigation market.
On the other hand, the requirements from humanss such as traveling, transportation, indoor positioning, search and rescue are becoming an essential in improving the working efficiency, decrease the traveling cost and improving the life environment, etc. In addition, the combination of satellite navigation and mobile communication will enlarge and promote further the application market.
How to evaluate the problem of interference and jamming?
Satellite navigation system is basically a radio system and based on wireless transmission link so it has congenital vulnerability from the interference on the navigation radio signal. The cancellation of interference could not be done 100% theoretically as the interference problem coexists with the satellite navigation system itself. However, the interference mitigation could be done through the integration of multi-GNSS to some extent. In recent years, the GNSS providers proposed the interference detection and mitigation (IDM) based on the joint effort to improve the user service performance and discussed as an important topic in ICG meeting.
With the technology progress, the satellite signal will become more and more stable and the detection capability for the interference will become stronger and stronger. The influence on GNSS from interference would be controlled to the acceptable range for users.
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(5 votes, average: 1.60 out of 5)
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