GPS World, December 2017

DIRECTIONS 2018 BeiDou Builds Diversifies Expands A s one of the four major GNSS providers the establishment of BeiDou Navigation Satellite System BDS has been steadily developed following a three step strategy By around 2020 BDS will form a nominal space constellation consisting of 30 satellites including three satellites in geostationary Earth orbit GEO three satellites in inclined geosynchronous satellite orbit IGSO and 24 satellites in medium Earth orbit MEO It will provide global users with open and high quality services free of charge including navigation positioning timing short message communication search and rescue and so on BDS is aimed at developing into a world class global navigation satellite system with innovative and advanced technologies extraordinary user experience international development and worldwide presence which can provide fundamental time and space reference for national defense and economic social development and advance the progress of high tech and IT industries BDS has initiated several innovative attempts in the fields of both international satellite navigation and domestic aerospace for the first time and paved a unique development path of a satellite navigation system with an eye on the state conditions and distinctive features On Jan 9 2017 the BD 2 Project won the top National Scientific and Technological Progress Award In 2017 BDS achieved fruitful results in the aspects of system construction integrated applications and international development System Construction Through upgrading and reconstructing the ground system the service performance stability and availability of the BD 2 constellation have been improved To achieve useroriented services the updated Interface Control Document ICD for B1C and B2a open service signals Version 21 was released in accordance with the constellation change The international GNSS Monitoring and Assessment System iGMAS has been built consisting of eight domestic monitoring stations and 16 overseas stations to monitor and assess the service performances of BDS GPS GLONASS and Galileo at real time worldwide It has taken all factors into consideration including constellation status signalin space navigation message service performance and high precision products and so on According to its analysis results the nominal positioning accuracy of the BD 2 system in the coverage area has been optimized from 10 meters to 8 meters 16 GPS WORLD WWW GPSWORLD COM DECEMBER 2017 Development of the BD 3 System On Nov 5 the first pair of the 24 BD 3 MEO satellites were successfully launched while another pair is planned to be launched by the end of the year The BD 3 satellites are equipped with B1C and B2a signals with optimized performance which are compatible and interoperable with other GNSS signals The interface control document of B1C and B2a signals beta version was released in September The BD 3 satellites also adopt the higher performance rubidium atomic clock with stability of E 14 and hydrogen atomic clock with stability of E 15 By utilizing new technologies the signal in space SIS accuracy will be superior to 05 m the position accuracy will be doubled or quadrupled and reach 25 m to 5 m The BD 3 system will retain the short message communication service of its predecessors and further enhance basic positioning navigation and timing PNT service capabilities Satellite based augmentation system SBAS and search and rescue SAR services will be added and developed according to international standards After in orbit tests and networking validation the BD 3 satellites will be able to provide operational services and accelerate the global coverage of BDS Ground Based Augmentation The Phase I construction of the BDS GNSS ground based augmentation system has been completed consisting of 150 framework reference stations 1200 reference stations of higher density network national data processing center six industrial dataprocessing centers and manufacturing of user terminals This system has achieved basic service capabilities and its service performance standard version 10 has been BY Changfeng Yang CHI EF ARCHITECT O F B EIDOU NAVIGATION SATEL L ITE SYSTEM