BeiDou Performances

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

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

The system has evolved 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. The long-term goal is to develop an independent global navigation satellite network 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: 20ns

On November 2, 2006, China announced that from 2008 BeiDou would offer an open service with an accuracy of 10 meters, timing of 0.2 nanoseconds, speed of 0.2 meter/second. It followed that in February 2007, the fourth and also the last satellite of BeiDou-1 system, the BeiDou-1D was put into orbit, and after suffering from a control system malfunction, it was fully restored by the end of 2007. Then, the open service performances reached the levels described before.

The global COMPASS system will be built by 2020. The peformances for the two global services 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 has initially provide the regional services covering China and its neighbouring countries in 2008, and it will eventually extend into a global navigation satellite system, providing the corresponding global services by 2020.