Compiled by Bo Ning Translated by Liu Jie

China’s BeiDou Navigation System Is Benefiting the World

Compiled by Bo Ning Translated by Liu Jie

“雙星定位”建設(shè)方案：把地心視為一顆虛擬衛(wèi)星、再發(fā)射兩顆地球同步衛(wèi)星構(gòu)成星座，經(jīng)地面控制中心計(jì)算處理，實(shí)現(xiàn)對(duì)地面目標(biāo)的快速定位。（制圖/萬璇）“Duel-satellite positioning” plan:Take the earth’s core as a virtual satellite,which forms a constellation with the other two geosynchronous satellites launched into the orbit, thus realizing rapid positioning of a ground target through the computing process of the ground control center.(Photo edited by Wan Xuan)

On the drilling grounds, the army was embattling; the war flags, soldiers,fighter planes, and war vehicles just finishing their drilling were inspected by the supreme commander with no error at all. On the rough South China Sea,the fishermen roving over the sea,generation after generation, to make their living had to pray to Goddess Matsu for their safety on the sea. But nowadays, they no longer need to rely on Matsu for their safety, for no matter what waters or island they get to,the mother land will be overlooking them from above.

All these are due to China’s BeiDou Navigation Satellite System hovering in the starry sky.

On November 5, China successfully launched two BeiDou-3 satellites via a single carrier rocket to support its global navigation and positioning network from the Xichang Satellite Launch Center in Sichuan Province. The launching of the fi rst two BeiDou-3 satellites symbolizes the beginning of a new era of global networking for the BeiDou system.

沙場(chǎng)，三軍列陣。剛下演兵場(chǎng)的戰(zhàn)旗、戰(zhàn)士、戰(zhàn)鷹、戰(zhàn)車，接受最高統(tǒng)帥檢閱，米秒不差；南海，驚濤駭浪。世代漂泊在這里求媽祖、討生活的漁民，如今無論到哪塊海域、哪個(gè)島礁，都在祖國俯瞰之中。這些，都緣自翱翔星空的中國“北斗”。

11月5日，中國在西昌成功發(fā)射兩顆北斗三號(hào)全球組網(wǎng)衛(wèi)星。這是北斗三號(hào)衛(wèi)星的首次發(fā)射，標(biāo)志著北斗衛(wèi)星導(dǎo)航系統(tǒng)步入全球組網(wǎng)新時(shí)代。

打造大國重器

中國是繼美國、俄羅斯之后世界上第三個(gè)擁有自主衛(wèi)星導(dǎo)航系統(tǒng)的國家。衛(wèi)星導(dǎo)航系統(tǒng)是重要的空間信息基礎(chǔ)設(shè)施，從上世紀(jì)后期開始探索，中國逐步形成從北斗一號(hào)服務(wù)國內(nèi)，到北斗二號(hào)提供區(qū)域服務(wù)，再到北斗三號(hào)全球組網(wǎng)的發(fā)展戰(zhàn)略，服務(wù)擴(kuò)大到全球。建設(shè)過程中，困難從不鮮見。

2005年，正在建設(shè)的北斗二號(hào)系統(tǒng)的“原子鐘”突遇問題。原子鐘就如同一塊“手表”，為衛(wèi)星導(dǎo)航用戶提供精確的時(shí)間信息服務(wù)。

它直接決定系統(tǒng)導(dǎo)航定位精度，其重要性如同人的心臟。國外的技術(shù)封鎖，成為制約北斗衛(wèi)星導(dǎo)航系統(tǒng)工程建設(shè)的瓶頸。

Following the U.S. and Russia, China is the third country in the world to launch their self-developed satellite navigation system. Satellite navigation systems are an important infrastructural asset for space information. Starting from the end of last century,China’s BeiDou Navigation System has developed from BeiDou-1 which is mainly intended to serve the inland needs, to BeiDou-2, which is a provider of regional services,and finally to BeiDou-3—a global networking satellite system.

In the process of the construction, it was never uncommon to run into various diff i culties.

I n 2005, t h e “a t o m i c clock” under construction for BeiDou-2 system encountered a problem unexpectedly. An atomic clock is just like a“watch”—it provides accurate time information for the users of the satellite navigation system. As it decides the navigation and positioning accuracy of the system, it is the heart of the system. The technological blockade on the part of the other countries became a bottleneck constraint for the development of the BeiDou system.

However, BeiDou people set up a goal for themselves,they aimed to develop a highaccuracy atomic clock which loses only one second in 100,000 years. They organized three teams to carry out research in basic theories,materials, and engineering simultaneously.

The team of Mei Ganghua from Wuhan Institute of Physics and Mathematics o f C h i n e s e A c a d e m y o f Sciences was one of the abovementioned teams. Over the past 20 years, they have put all their time into the work and never enjoyed a normal long holiday.In 2008, they successfully developed a rubidium atomic clock with full proprietary intellectual property rights,which was used in BeiDou-2 satellites, and thus breaking the technological blockade and monopoly of the West on satellite positioning.

The atomic clock now used in BeiDou-3 has been improved with an even higher accuracy,which loses only one second in three million years. Upon completion, BeiDou’s global satellite navigation system will be able to provide positioning services with an accuracy of 10 meters and velocity measurement of 0.2 meter per second for civilian users for free.

On November 5, China successfully launched two BeiDou-3 satellites via a single carrier rocket from the Xichang Satellite Launch Center in Sichuan Province.11月5日，兩顆北斗三號(hào)衛(wèi)星在西昌衛(wèi)星發(fā)射中心成功發(fā)射。

北斗人給自己確定目標(biāo)，要研制誤差僅有10的-12次方的原子鐘，通俗地講，就是它每十萬年只會(huì)出現(xiàn)一秒的誤差。他們組織三支隊(duì)伍同時(shí)開展研發(fā)，在基礎(chǔ)理論、材料、工程等領(lǐng)域同步進(jìn)行推進(jìn)。

中國科學(xué)院武漢物理與數(shù)學(xué)研究所梅剛?cè)A團(tuán)隊(duì)，便是其中一支團(tuán)隊(duì)。20年來，他們沒有正常休過一次長假。2008年前后，他們研制出具有完整自主知識(shí)產(chǎn)權(quán)的銣原子鐘，打破西方技術(shù)壟斷和封鎖，用在“北斗二號(hào)”衛(wèi)星上。

而現(xiàn)在用在北斗三號(hào)上的原子鐘，提升到每300萬年才會(huì)出現(xiàn)1秒誤差的精度。建成后的北斗全球?qū)Ш较到y(tǒng)，能為民用用戶免費(fèi)提供約10米精度的定位服務(wù)、0.2米/秒的測(cè)速服務(wù)。

中國不可能像美國GPS那樣，在全球建立地面站，于是，北斗三號(hào)采取星間、星地傳輸功能一體化設(shè)計(jì)，實(shí)現(xiàn)衛(wèi)星與衛(wèi)星、衛(wèi)星與地面站的鏈路互通。整個(gè)導(dǎo)航系統(tǒng)的精度可以提升到兩倍左右。

2017年，1400多個(gè)北斗基站遍布全國，上萬臺(tái)套設(shè)備組成星地“一張網(wǎng)”，國內(nèi)定位精度全部達(dá)到亞米級(jí)，部分地區(qū)達(dá)到分米級(jí)，最高精度甚至可到厘米或毫米級(jí)。

后發(fā)自主創(chuàng)新

北斗人一步一個(gè)腳印，開創(chuàng)了很多只有北斗衛(wèi)星才有的新技術(shù)和獨(dú)特方案。

按照空間定位原理，對(duì)地球上一個(gè)目標(biāo)點(diǎn)進(jìn)行定位，至少需要3顆衛(wèi)星；考慮到時(shí)間誤差，精確定位至少需要4顆衛(wèi)星。這就是GPS和格洛納斯的工作原理和全球組網(wǎng)方案。

中國陳芳允院士，創(chuàng)造性提出“雙星定位”建設(shè)方案。把地心視為一顆虛擬衛(wèi)星、再發(fā)射兩顆地球同步衛(wèi)星構(gòu)成星座，經(jīng)地面控制中心計(jì)算處理，實(shí)現(xiàn)對(duì)地面目標(biāo)的快速定位。中國能以最少的投入、最短的周期，投入衛(wèi)星導(dǎo)航系統(tǒng)建設(shè)。

北斗造福世界

北斗系統(tǒng)已成功應(yīng)用于測(cè)繪、電信、水利、漁業(yè)、交通運(yùn)輸、森林防火、減災(zāi)救災(zāi)和公共安全等領(lǐng)域。

交通部使用北斗系統(tǒng)，建立全國的交通監(jiān)管系統(tǒng)，對(duì)危險(xiǎn)品的運(yùn)輸車、旅游客車、長途客車實(shí)時(shí)監(jiān)控。目前規(guī)模已達(dá)480多萬輛。據(jù)2016年統(tǒng)計(jì)，事故率跟原來的同期相比，已經(jīng)減少50%，人員的傷亡率也下降50%。

2016年，北斗系統(tǒng)已實(shí)現(xiàn)產(chǎn)值2000億。以這次北斗三號(hào)的首次發(fā)射任務(wù)為起點(diǎn)，中國將迎來北斗三號(hào)衛(wèi)星高密度發(fā)射。到2018年年底，將有18顆北斗衛(wèi)星發(fā)射升空，到2020年，將完成30多顆北斗三號(hào)衛(wèi)星的全球組網(wǎng)，實(shí)現(xiàn)全球服務(wù)。

如今，緬甸的農(nóng)業(yè)、林業(yè)、土地規(guī)劃，老撾的精細(xì)農(nóng)業(yè)和病蟲災(zāi)害監(jiān)測(cè)管理，文萊的智慧旅游……北斗系統(tǒng)已覆蓋巴基斯坦、沙特、緬甸等近30個(gè)“一帶一路”沿線國家。?

一名觀眾在“砥礪奮進(jìn)的五年”大型成就展上體驗(yàn)北斗高精度導(dǎo)航駕駛A visitor experiencing BeiDou-navigated driving in an exhibition featuring “China’s outstanding achievements over the past fi ve years” in Beijing

The people at BeiDou have created many new techniques and unique solutions for BeiDou satellites by working steadily over the years.

According to the law of spatial orientation, when positioning a target point on the earth, it requires at least three satellites.In view of time error, accurate positioning requires at least four satellites. This has been the working principle and global networking solution for GPS and GLONASS (Russia’s global navigation satellite system).

Chinese expert Chen Fangyun creatively put forward the development scheme of “duelsatellite positioning.” According to this plan, the earth’s core is viewed as a virtual satellite,which forms a constellation with the other two geosynchronous satellites launched into the orbit. Then rapid positioning of a ground target can be realized after the computing process of the ground control center. As a result,China could start its construction of a satellite navigation system with minimum investment in the shortest time possible.

Since it was impossible for China to build ground stations around the world as what the US had done for GPS, BeiDou-3 adopts an integrated design for the transmission function between the satellites and the satellite-earth transmission function. This realizes the interflow between the links of satellite to satellite, and satellite to the ground station, with double the precision of older orientations.

By 2017, more than 1,400 BeiDou base stations have settled all over the country, whose tens of thousands of pieces of equipment compose a network between the satellites and the earth,realizing the level of sub-meter positioning accuracy nationwide,and decimeter accuracy in some places. The highest positioning accuracy may even reach the level of centimeter or millimeter.

BeiDou system has now been successfully employed in various fields including s u r v e y i n g a n d m a p p i n g,telecommunications, hydraulic engineering, the fi shing industry,transportation, forest fire prevention, disaster mitigation and relief, and public security.

The Ministry of Transport has set up traffic control systems across the country by means of the BeiDou system, so that they can have real-time monitoring on the carrier vehicles for hazardous materials, sightseeing buses, and inter-city buses. The number of the above vehicles has reached more than 4.8 million. However,according to the statistics in 2016,the accident rate, compared to the corresponding period of previous years, was reduced by 50%, and the casualty rate also dropped by 50%.

In 2016, BeiDou’s output value amounted to 200 billion yuan.Starting from the first launch of BeiDou-3, China has stepped into a period when more BeiDou satellites will be launched into the orbit. By the end of 2018,18 BeiDou-3 satellites will have been launched, and by 2020, a global network of more than 30 BeiDou-3 satellites will have been accomplished, realizing the aim of global services.

At present, the BeiDou system covers nearly 30 countries along the Belt and Road, benefiting,for instance, the agriculture,forestry, and land planning in Myanmar (Burma), the precision agriculture, and monitoring and management for diseases and pests in Laos, and the smart tourism in Brunei.?

支持新一代北斗三號(hào)信號(hào)體制的高精度導(dǎo)航定位芯片與1角硬幣的對(duì)比照片High-precision navigation and positioning chip supporting BeiDou-3 signal system in comparison with a one-jiao coin

通過北斗衛(wèi)星定位系統(tǒng)獲得的經(jīng)緯度實(shí)時(shí)繪制的飛機(jī)飛行軌跡圖Real-time fl ight path of an aircraft drawn with the latitude and longitude obtained via the BeiDou Navigation Satellite System

中國北斗惠全球

編/柏寧 譯/劉潔