China expands navigation system with Beidou-21

China expands navigation system with Beidou-21


China: With Long March-3C rocket, China launched the Beidou-21 navigation satellite into the space on Monday. The launch of BDS M3-S (or Beidou-21) took place from the Xichang Satellite Launch Center at 07:29 UTC. The second satellite launch of the country, this year, the Beidou-21 was apparently the last experimental satellite of BeiDou Phase III.

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 Beidou constellation of geostationary (GEO) – five inclined geosynchronous orbit (IGSO), and four middle Earth orbiting (MEO) – spacecraft are transmitting open and authorized signals at B2 (1207.14 MHz) and an authorized service at B3 (1268.52 MHz).

This phase aimed at deploying a system with passive positioning and timing capability over a regional area. The Phase 3 (starting in 2020), by 2020, the system would reach full operational capability with a constellation of 27 MEOs plus 5 GEOs and the existing 3 IGSOs satellites of the regional system. In this, another Chinese satellite navigation system, that is CNSS (Compass Navigation Satellite System), would provide global navigation services to Phase 3, similarly to the GPS, GLONASS or Galileo systems.

Source: NASA