BeiDou Performances

COMPASS
Title	BeiDou Performances
Author(s)	GMV.
Level	Basic
Year of Publication	2011

The Compass Navigation Satellite System (CNSS), also named BeiDou-2, is China’s second-generation satellite navigation system that will be capable of providing positioning, navigation, and timing services to users on a continuous worldwide basis.

On November 2, 2006, China announced the 2nd generation Chinese navigation system, COMPASS. The system is currently under development evolving from a regional system called BeiDou-1, and in the first phase will provide high-accuracy positioning services for users in China and its neighbouring regions. As of April 2011, eight satellites for Compass have been launched. According to an official report, " the eighth Beidou/Compass satellite marks the completion of basic function of Beidou (Compass) Navigation Satellite System " .

The long-term goal is to develop an independent global navigation satellite system similar to the GPS and GLONASS.

COMPASS Performances

In May 2003, the successful launch of BeiDou-1C also meant the establishment of the BeiDou-1 navigation system, providing navigation, communication and timing services for the greater China area. The system services and performance characteristics at this time (2003) were:

• Positioning: 100m (1σ); 20m (1σ, with reference stations).
• Regional Service short message service (SMS): up to 120 Chinese characters.
• Timing: 20 ns.

On November 2, 2006, China announced the second generation Chinese navigation system, COMPASS, that in the completion of its first phase by 2012 would offer an open service with an accuracy of 10 meters, timing of 0.2 nanoseconds, speed of 0.2 meter/second. As of April 2011, eight satellites for Compass have been launched, and another 3 more satellites will be put in orbit in 2011, expecting by 2012 to complete the first phase of the system and then, the open service performances reached the levels described before , The global COMPASS system will be built by 2020.

The performances for the two global services of Compass would be:

• Open service: a free service for civilian users with positioning accuracy of within 10 metres, velocity accuracy of within 0.2 m/s and timing accuracy of within 20 nanoseconds;

• Authorized service:a licensed service with higher accuracy even in complex situations for authorised and military users only.

The performances for the two kinds of regional services (over China and neighboring areas):

• Wide area differential positioning service: with positioning accuracy of 1 m.
• Short message service (SMS): up to 120 Chinese characters.

Initially the COMPASS system provides initially the regional services covering China and its neighbouring countries in 2012, and it will eventually extend into a global navigation satellite system, providing the corresponding global services by 2020.