• China’s BeiDou Navigation Satellite System (BDS), touted as a rival to the widely-used American GPS, has started providing global services.
• The positioning accuracy of the system has reached 10 metres globally and five metres in the Asia-Pacific region. Its velocity accuracy is 0.2 metres per second, while its timing accuracy stands at 20 nanoseconds.
• Pakistan has become the first country to use the BeiDou system ending its reliance on the Global Positioning System (GPS).
• It will be the fourth global satellite navigation system after the US GPS, Russia’s GLONASS and the European Union’s Galileo.

About BeiDou Satellite System:

• Named after the Chinese word for the Big Dipper or Plough constellation [Ursa Major], Beidou has been in the works for over two decades but only became operational within China in 2000 and the Asia-Pacific region in 2012.
• When complete in 2020, it will have a constellation of 35 satellites to provide global coverage. This year alone, there have been more than 10 Beidou satellite launches - two more were launched this week. More are planned in what state media describe as a "period with unprecedentedly intensive launches".
• This system will have a positioning accuracy of 2.5m (8.2ft), which will further be improved to centimetre-level accuracy with additional ground stations.
• But despite its technological sophistication, Beidou has a supposed flaw - a two-way transmission process that involves satellites sending signals to earth and devices transmitting signals back. This can compromise accuracy and takes up more spectrum bandwidth. In contrast, GPS devices do not have to transmit signals back to the satellites.

Other navigation satellites:

• Currently, there are three other satellite navigation systems - Russia's Glonass, Europe's Galileo, and GPS - which is the most-widely used.
• The UK is also considering building its own satellite navigation system as it may not be able to access Galileo post-Brexit.