GPS Accuracy Improvements

China’s BeiDou global navigation system was completed in June 2020 provides positioning accuracy of 1.5 to two meters to anyone in the world.

GPS World provides details.
From March to June 2020, two BDS-3 GEO satellites were launched, while the in-orbit tests of two IGSO satellites, two GEO satellites, and two MEO satellites were completed. As the result, the global system constellation was successfully deployed.

By the end of October 2020, 45 in-orbit operational BDS satellites provide services to global users, including 15 BDS-2 satellites and 30 BDS-3 satellites.

The accuracy of the BDS signal-in-space is better than 0.5 m, BDS global positioning accuracy is better than 10 m, BDS velocity measurement accuracy is better than 0.2 m/s, and BDS timing accuracy is better than 20 ns. In the Asia-Pacific region, BDS positioning accuracy is better than 5 meters, the velocity measurement accuracy is better than 0.1m/s, and timing accuracy is better than 10 ns.

In the key service area, there are 30 BDS-3 satellites and 15 BDS-2 satellites that jointly provide the services using B1I and B3I signals. The actual average measured positioning accuracies are about 1.48 m horizontally and 2.99 m vertically (95% confidence), which are improvements of about 30% and 5% respectively as opposed to solely relying on the BDS-2 system.

Globally, with the B1I, B3I, B1C and B2a signals, BDS-3 offers service availability of 100% (PDOP ≤6,). The actual measured positioning accuracies are about 1.54 m horizontally and 2.65 m vertically (95% confidence).

In June 2021, the fifth GPS III satellite was launched.

GPS III signals are three times more accurate than the current GPS Block II models. The navigation payload has more than three times reduction in range error and up to eight times increase in power — its signals should be much easier to pick up under tree canopy, within urban canyons and inside buildings.

GPS III has four civilian signals. The L1C signal is interoperable with international GNSS, meaning users can receive signals from any country’s satellites. Also, using two civilian signals means GPS III can directly detect and correct ionospheric errors.

The GPS III constellation is projected to be fully capable in June 2023, when 10 Block IIIA satellites are expected to be in orbit. Ten follow-on satellites are planned to be placed into orbit from 2026 to 2034.

Civilian 5 to 10-meter accuracy you see now with existing GPS technology go to 1 to 3 meters.

Ground based systems can locally improve GPS accuracy to millimeter levels. This is used by construction companies and other businesses.

SOURCES- GPS World, Wikipedia
Written By Brian Wang,