The GDGPS System provides 1 Hz corrections to the GNSS
spacecraft position (X, Y, Z coordinates), and clock state
in the broadcast ephemerides. Differential corrections are available for the following constellations:
GPS, GLONASS, BeiDou, Galileo, and QZSS. They
are globally and uniformly valid - just like the broadcast ephemerides.
Adding the corrections to the broadcast ephemerides gives the precise
orbit and clock state of the spacecraft, typically accurate to better than 20 cm 3D RMS. In
fact, we derive the orbit and clock corrections by subtracting the broadcast
ephemeris from our precise real-time orbit and clock solution product.
The corrections for the GNSS satellites are available as in a variety of streaming data formats,
including a compact JPL format, and the RTCM Space State Representation (SSR) format.
The correction message includes velocities of the orbital corrections, enabling the user to propagate
the corrections into the future, and be resilient to short data outages.
Look at our live performance monitor to see real-time point-positioning
carried out, utilizing our correction data stream.
The following table summarizes the key attributes of this product. It applies to all medium Earth altitude GNSS satellites.
Geosynchronous, and inclined geosynchronous satellites (in the BeiDou and QZSS Systems) are somehwat worse.
< 20 cm 3D RMS
< 20 cm RMS (after de-biasing and de-trending)
< 10 cm RMS
||Proprietary binary or RTCM SSR
||UDP (recommended) or TCP