China’s Beidou Navigation Satellite System (BDS) provides global coverage with millimeter level accuracy

Rajesh Uppal March 11, 2023 AI & IT, Space Comments Off on China’s Beidou Navigation Satellite System (BDS) provides global coverage with millimeter level accuracy 2,489 Views

The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radio navigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite systems (GNSS) that provides geolocation and time information to a GPS receiver anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites.

BeiDou Navigation Satellite System (BDS) has been developed as an alternative to U.S. GPS. In July 2020, the BDS was officially completed and started providing full-scale global services, after the final satellite to complete BeiDou’s third-generation network was put into a geostationary orbit about 36,000 kilometers above the Earth in late June of that year. It was a new milestone in China’s space industry and a major achievement in the country’s efforts to boost science, technology and innovation. BeiDou is the country’s largest space-based system and one of the four global navigation networks, along with the US’ GPS, Russia’s GLONASS and the EU’s Galileo. The completed Beidou Navigation Satellite System is expected to provide global coverage, with millimeter-level accuracy.

Construction of the BeiDou Navigation Satellite System (BDS-3) has been completed. The system was formally commissioned on July 31, 2020. In 2021, BDS continued to improve performance, expand applications and deepen cooperation, and has achieved sustained, stable and rapid development

There are 45 BDS satellites in orbit. There are now 120 Beidou ground stations around the globe. A few US allies, including Canada, Australia and Japan, host some of the facilities. The ground facilities are intended to track the Chinese satellites when they fly over the region and report their flight status to Beijing. GPS has 11 command and control antennas and 16 monitoring sites around the world, according to the US government. The data is used to help increase the accuracy of the positioning service with a margin of error of 3cm, according to information from the China North Industries Group Corporation Limited (NORINCO).

“The observation stations have covered the operational orbits of all Beidou satellites,” said the representative in Nov 2022. “An observation station does not undertake the role of data transfer [to or from the satellites], and only provides data for calibrating the calculation model.”

The space and ground infrastructure systems have formed a more complete service capacity, and overseas markets have expanded significantly. According to authorities, the scale of China’s satellite navigation industry exceeded 400 billion yuan ($43 billion) by the end of the 13th Five-Year Plan (2016-2020).

The output value of China’s BeiDou Navigation Satellite System (BDS) reached a new high of 469 billion yuan ($69 billion) in 2021, up 16.29 percent year on year, according to a white paper released on Wednesday, noting that China has basically formed its BeiDou industrial system. The white paper, issued by the Global Navigation Satellite System (GNSS) and Location Based Service (LBS) Association of China, together known as GLAC, attributed the rapid growth to the global service of BDS-3 system started on July 31, 2020, which further stimulated demand for and attracted more investments in BDS technological applications.

Yu Xiancheng, president of GLAC, told China Media Group (CMG) that “China’s satellite navigation and positioning service industry is moving towards a new stage of comprehensive space-time system construction in an all-round way. In this context, the BeiDou system is playing a significantly enhanced role in stimulating and leading economic and social development.”In addition, the white paper said that China remained the top source of international satellite navigation patent applications last year, totaling 98,000.

On the business side, more than 70 percent of Chinese smartphones already use the system, according to a BeiDou spokesperson. Smartphone manufacturers such as Xiaomi, Huawei, Apple and Samsung already support BDS. In the first three quarters of 2021, among all types of smartphones applying for online access in China, 72.3% supported positioning function based on BDS, accounting for 93.5% of the total sales volume. The BDS ground-based augmentation function has been introduced into smartphones to achieve high-precision positioning at the 1-meter level; lane-level navigation is being piloted in several cities in China.

In terms of industrial applications, BDS has fully served multiple industries including transportation, public security, disaster relief, agriculture, forestry, animal husbandry and fishing. It has accelerated the integration into electricity, finance, communications and other infrastructure. In particular, in the fight against COVID-19 through scientific and technological approaches, BDS-based precise positioning has facilitated the efficient supply and circulation of anti-epidemic materials.

Other reports indicate that BeiDou receivers have been integrated into millions of taxis, buses, and trucks. And as of 2019, it had more than 400 million users worldwide.

In September 2022 , Chinese tech giant Huawei Technologies Co launched the Mate 50 smartphone, a device that uses the Beidou system to offer greater signal range in remote areas. Registered users can send free messages to high-altitude Beidou satellites that orbit more than 30,000km above Earth.

According to NORINCO, the Beidou data centre can handle 18 million messages per hour, with each message containing about 1,000 Chinese characters for non-military users. The service is currently limited to Chinese consumers, but some governments have expressed concerns that the technology could be used as a spy tool.

International Cooperation

BDS has always adhered to the development concepts of openness, cooperation and resource sharing; actively carried out practical international exchanges and cooperation; and contributed to China’s peaceful use of outer space

Over 30 countries, largely in the Middle East, Africa and Asia, use the system, including for various projects in Indonesia, Kuwait, Uganda, Myanmar, the Maldives, Cambodia, Thailand, and Russia. With an advanced satellite-based augmentation system, the BDS can also provide low-cost and reliable navigation services to civil aviation clients at home and abroad.

China’s home-grown BeiDou Navigation Satellite System (BDS) will expand its cooperation to Thailand and Sri Lanka, and then to the entire Southeast Asia, in a bid to go global, the system’s operator has said. Du Li, general manager of Wuhan Optics Valley BeiDou Holding Group Co., told Xinhua recently that his company will continue to explore models for international scientific and technical cooperation on BDS, including the joint construction of base stations, joint technical development and research, personnel training and exchanges, and others. China has registered it as standard and become part of Global radio Navigation system.

China is also providing services for countries participating in the Belt and Road Initiative (BRI). In the future, the Chinese government sees BeiDou and related services as a major industry, particularly for countries along the “Belt and Road” initiative, the swath of countries from Central Asia to Europe with whom Beijing has established trade, infrastructure, and debt deals to enhance its influence. This growing user base for BeiDou outside of China adds to its geopolitical and economic heft.

The space-based Silk Road initiative was proposed in 2014 by the International Alliance of Satellite Application Service (ASAS), a China-based organization of aerospace companies, institutions and scholars that promotes Chinese satellite services around the world. The space-based Silk Road will use dozens of these satellites to meet the communication and remote-sensing application demand for the “One Belt, One Road” initiative, according to Wang Zhongguo, executive vice-president of the ASAS.

Russia and China have signed an agreement for navigation cooperation to increase the compatibility and interoperation between BDS and GLONASS. This will provide a more robust satellite navigation system with each architecture filling in the gaps of the other and jointly reaching further regions of the Globe.”In addition to developing Beidou, China is also looking for a chance to cooperate with Russia”, the paper said. Russian deputy prime minister Dmitry Rogozin told the Moscow-based RIA Novosti that Russia’s GLONASS satellite system is capable of cover up the weaknesses of the Beidou Navigation Satellite System in future operations.” Russia and China signed a memorandum of understanding on cooperation between Russia’s GLONASS navigation system and China’s Beidou, each is considering placing three ground stations in the other’s country.

BeiDou Navigation Satellite System (BDS) technical details

China stated goal is to build a world-class navigation satellite system to meet the needs of the country’s national security as well as economic and social development, and providing continuous, stable and reliable services for global users; developing BDS-related industries to support China’s economic and social development, as well as improvement of people’s living standards; and enhancing international cooperation to share the fruits of development in the field of satellite navigation, increasing the comprehensive application benefits of Global Navigation Satellite System (GNSS).

On April 14, 2007, China successfully launched the first BeiDou-2 navigation satellite, officially kicking off the nation’s independent building of a satellite navigation system. In December 2012, the system became operational providing positioning, navigation, timing, and short message services to users in China and parts of the Asia-Pacific region. It will provide operational coverage for all countries concerned by the “Belt and Road” initiative by 2018, and global coverage with 35 operational satellites by 2020. The 35 satellites global system include five in geostationary earth orbit, 27 in medium earth orbit at around 22,000 kms and three in inclined geostationary orbits at 35,786 km.

China launched a pair of Beidou navigation satellites on 19th Sep 18 by long March 3B rocket. This mission saw the 37th and the 38th satellites of the Beidou system put into orbit, following the launch of the first in 2000. Three incremental loads for international search and rescue, global short messaging, plasma and surface charge wind monitoring are installed in these two satellites. The rescue load makes China a space equipment provider of COSPAS-SARSAT, atreaty based satellite-aided search and rescue (SAR) initiative.

Specifically, for the entire planet, the system provides three services:

Positioning, navigation and timing (PNT).
Global short-message communication.
International search-and-rescue (SAR) services.

For the Asia-Pacific region, the system provides four additional services:

Satellite-based augmentation.
Ground-based augmentation.
Precise point positioning.
Regional short-message communication services.

The network will be dual use: a free service for civilians, and a licensed service for the Chinese government and military. The civilian service will provide an accuracy of about 33 feet (10 meters) in the user position, 0.45 mph (0.2 m/s) on the user velocity, and 50 nanoseconds in time accuracy. The restricted military and authorized users’ service will provide higher tracking accuracies of 0.33 feet (0.1 meters).

The deputy designer of the BeiDou Navigation Satellite Chang Xinuo said, ” The self-developed BDS-3 satellites are more stable and have higher accuracy than the previous BDS-2 satellites. They are equipped with higher-performance rubidium atomic clocks with stability of E-14 and as well as hydrogen atomic clocks with stability of E-15. The signal-in-space (SIS) accuracy will be superior to 0.5 meters, the position accuracy will reach 2.5 meters to 5 meters. And the overall performance will be dramatically improved.

At the technical level, Beidou offers a short messaging service through which messages of up to 120 characters can be sent to other Beidou receivers, unlike GPS. Via this service, Chinese fishing vessels are reportedly able to sound “instant alarms” to fishing departments when emergencies arise, while a supplementary “vessel management system” allows them to request assistance from nearby vessels. This feature is particularly relevant to the ongoing disputes in the South China Sea, where fishing rights are at stake and where China’s maritime militia—a quasimilitary force of fishermen that are tasked by and report to the PLA—plays a key role in advancing Beijing’s claims, according to U.S.-China Economic and Security Review Commission report.

Huawei releases world’s first smartphone to support satellite communication, reported in Sep 2022

Chinese tech giant Huawei has released a high-end smartphone series that supports satellite communication. The Mate 50 series can be linked to China’s Beidou Navigation Satellite System and allows users to enjoy emergency short-message services. Huawei is now the first company to bring satellite communication technology to mass markets.

YU CHENGDONG Executive Director, CEO of the Consumer BG, Huawei “In the past 70 years, satellite communications have been mainly used in professional fields and terminals. It was difficult for ordinary users to obtain satellite communications services. We now have the world’s first smartphone that supports Beidou satellite messaging. Our new smartphone is capable of sending location and trajectory map, when users are in the desert, on the sea or in the mountains, where there’s no ground or wireless network.”

Fear of Security Risk

The concern has also been raised that Beidou could pose a security risk by allowing China’s government to track users of the system by deploying malware transmitted through either its navigation signal or messaging function (via a satellite communication channel), once the technology is in widespread use, according to U.S.-China Economic and Security Review Commission report. “Our priority is to expand BDS from China to the frontline of the Belt and Road Initiative, and Optics Valley BeiDou is a pioneer,” Li said. China-made smartphones, such as Huawei smartphones, will be good platforms for BDS to go overseas as they carry Chinese chips, Li said.

The Taiwan Ministry of Science and Technology said government employees should avoid using phones that use Beidou to prevent ‘targeted attacks’. China’s Beidou Satellite System (北斗衛星) poses an information security risk to Taiwan in that the satellite is able to track smartphone users via embedded malware in devices with Chinese-manufactured chips directly tied into the system or phones manufactured in China, according to the latest mobile device security report that the Ministry of Science and Technology submitted to the Legislative Yuan. The ministry also suggested that national defense units should monitor the Beidou Satellite System’s transmitted signals and warn of any anomalies, adding that such monitoring would reduce the risk of hacking attacks from China via satellite-broadcast signals.

China’s BeiDou satellite navigation system breaks underwater barriers

China has succeeded in providing underwater communications from BeiDou to its submarine fleet. A move which will allow it to develop and use underwater drones and more stealthily communicate with subsurface vessels, experts say.

China Shipbuilding Industry Corporation (CSIC) said underwater precision positioning tests conducted by its No 716 Research and Development Institute in waters off Lianyungang in Jiangsu province, proved that it had overcome a number of core technical problems with the BeiDou Navigation Satellite System. CSIC, China’s biggest state-owned naval shipbuilder, said the tests showed that the BeiDou system could not only provide accurate and consistent positioning data to underwater vessels, but could also send tracking and positioning information from underwater devices to shore-based and surface stations.

“The tests were meant to comprehensively test the BeiDou system’s capacity to deal with the complex sea environment,” CSIC said, adding that the system’s positioning accuracy and ranges were better than expected.

Military Impact

The PLA has considered [its] dependence on a foreign PNT system to be a strategic vulnerability since at least the mid-1980s. These fears were exacerbated during the 1995–1996 Taiwan Straits Crisis. According to a retired PLA general, the PLA concluded that an unexpected disruption to GPS caused the PLA to lose track of some of the ballistic missiles it fired into the Taiwan Strait during the crisis. He then said that ‘it was a great shame for the PLA … an unforgettable humiliation. That’s how we made up our mind to develop our own global [satellite] navigation and positioning system, no matter how huge the cost. Beidou is a must for us. We learned it the hard way as reported by U.S.-China Economic and Security Review Commission report.

A cornerstone of the PLA’s modernization has been working toward being able to fight modern wars that require precision-guided weapons and advanced communication networks. Those need positioning, navigation, and timing satellites like BeiDou. The system provides China a distinct advantage in navigation capabilities, targeting for conventional and nuclear missiles, precision weapons, relative strategic independence and immunity from manipulation by other countries.

The People’s Liberation Army (PLA) recently tested application of its independently developed global satellite navigation system in combat in Guangxi Zhuang Autonomous Region. The military used the Beidou Navigation Satellite System for precise positioning and navigating, real-time location reporting and data transmission over long distances, according to a news release from the PLA General Staff Headquarters. Beidou has allowed the armies to be more precise in command, weapon firing and logistics and that the technology has “been integrated into the PLA’s modern command system and weapon platform”.

BeiDou Navigation Satellite System (BDS)

The BDS is mainly comprised of three segments: space segment, ground segment and user segment.

– The space segment. The BDS space segment is a hybrid navigation constellation consisting of GEO, IGSO and MEO satellites.

– The ground segment. The BDS ground segment consists of various ground stations, including master control stations, time synchronization/uplink stations, and monitoring stations.

– The user segment. The BDS user segment consists of various kinds of BDS basic products, including chips, modules and antennae, as well as terminals, application systems and application services, which are compatible with other systems.

The BDS possesses the following characteristics: First, its space segment is a hybrid constellation consisting of satellites in three kinds of orbits. In comparison with other navigation satellite systems, the BDS operates more satellites in high orbits to offer better anti-shielding capabilities, which is particularly observable in terms of performance in the low-latitude areas. Second, the BDS provides navigation signals of multiple frequencies, and is able to improve service accuracy by using combined multi-frequency signals. Third, the BDS integrates navigation and communication capabilities for the first time, and has five major functions – real-time navigation, rapid positioning, precise timing, location reporting and short message communication services.

Compared to earlier generation products, the BeiDou-3 is able to cover a wider range and has a longer lifespan of 12 years, according to Bao Weimin, another CPPCC National Committee member and an official with China Aerospace Science and Technology Corporation. “New technology has significantly improved the performance of the BeiDou-3, with the signal accuracy in space higher than half a meter while its positioning accuracy has reached 2.5 to five meters, said Yang Changfeng, chief designer of the BeiDou system.

The Satellite Navigation Center of the PLA National University of Defense Technology (NUDT) has developed a Beidou electromagnetic shield to protect satellites, aircraft, missiles and other user equipment from interference. Beijing UniStrong Science& Technology Co., Ltd has set up a network in Pakistan including five base stations and one processing center, covering Karachi and the second stage of the network will cover the whole of Pakistan. It can provide positioning with a precision of 2 centimeters, while the precision can reach 5 millimeters after post processing.

The company Shanghai Beiga Satellite Technology has developed first 40-nanometer satellite navigation chip called Hangxin-1, which will soon be used in consumer electronics, such as tablet PCs, wearable devices, and vehicle navigation system. Wuhan University, Techtotop Microelectronics and ZTE, launched country’s first mobile phone phone that utilizes Beidou GNSS chip and runs on the Xihe system, a self-developed positioning system which connects to various satellite navigation systems, including Beidou. The Shanghai government has also announced to bolster further R&D of another type of chip which will be used for map drawing, lane positioning and unmanned systems.

The system will also likely have new, jam-proof chips. Allystar Technology has unveiled a computer chip for use in Beidou receivers, providing instant accuracy without the aid of augmentation by ground control stations. This computer chip’s ability to enhance satellite navigation signals could enable military Beidou users to withstand enemy attempts to jam satellite navigation.

Now, scientists in China have successfully demonstrated a cold atom clock in space, an achievement that could lead to more accurate terrestrial timekeeping and better tests of fundamental physics. The device, called Cacs, or Cold Atomic Clock in Space, was launched in Sep 2017 along with other instruments of the Tiangong-2, China’s second orbital lab. China’s Beidou satellite navigation network currently provides less precise guidance than the US GPS system, but Xu said that using Cacs as a time reference in space would give a “significant boost” to Beidou’s performance.

Different from other GNSS, BDS adopts two-way satellite time and frequency transfer (TWSTFT) method to realize both station to station and satellite to ground time synchronization. Precise satellite clock errors are calculated by two-way pseduorange measurements, and then the Beidou Time (BDT) standard kept by ground atomic clock sets is transferred to each BDS satellite.

While the receivers in GPS systems are entirely passive and emits no signals make it immune from interference, the many to and fro transmissions involved in Beidou tesults in higher vulnerability to interference. The second generation IGSO satellites are bigger with and reports also suggest they carry a hydrogen maser based atomic clock and involves transmission signal compatibility with GPS. All second generation GSO and IGSO satellites have in-orbit mass of around 2000 kg.

The Beidou Phase III system includes the migration of its civil Beidou 1 or B1 signal from 1561.098 MHz to a frequency centered at 1575.42 MHz – the same as the GPS L1 and Galileo E1 civil signals — and its transformation from a quadrature phase shift keying (QPSK) modulation to a multiplexed binary offset carrier (MBOC) modulation similar to the future GPS L1C and Galileo’s E1. The current (Phase II) B1 open service signal uses QPSK modulation with 4.092 megahertz bandwidth centered at 1561.098 MHz.

The system has been operating continuously and stably since commissioning, with the average value of satellite availability better than 0.99 and the average value of satellite continuity better than 0.999.

China’s Beidou Navigation Satellite System (BDS) provides global coverage with millimeter level accuracy

Related Articles