Compass (Beidou in Chinese) is the name of the Chinese Global Navigation Satellite System. China has indicated it intends to expand the current local geostationary system (Compass phase 1) into a fully global medium-earth-orbit GNSS constellation (Compass phase 3), via an interim step of a regional system using both geosynchronous (Geo) and inclined Geo (IGSO) satellites. Satellites for this phase of the project are already broadcasting signals.

The first phase of Compass, known as Beidou 1 or Compass 1, is an experimental system comprising three payloads on geosynchronous satellites. Beidou provides wide area precise positioning and is substantially a China-only system in terms of access and users.

The second phase, Compass 2 (CP2) or Beidou 2 is not a development of Beidou 1 but is an entirely new regional system which when fully deployed will consist of 5 GEO, 5 IGSO and 4 MEO satellites broadcasting on 3 frequencies. This phase lays the foundation for final stage (CP3) which is a global system based around 5GEO, 3IGSO and 27MEO satellites which orbiting the earth every 12 hours or so will provide true global coverage.

The constellation structure will be similar to the European Galileo network and the ranging signals are based on the CDMA principle, like GPS and Galileo. In line with other GNSS, there will be two levels of positioning service: open and restricted.

The Chinese government has stated that their aim is “provision of Compass to provide free use all over the world”. The world is watching with interest for more information, and an ICD is expected to be placed in to the public domain imminently.

Spirent’s Compass simulators are based on public domain information and our assumptions of the likely content of the ICD. They will be updated to ICD compliance once the ICD is made available. If you have an interest in testing Compass please contact us.