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Global Differential GPS System
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System Description
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Orbit & Clock Corrections

The GDGPS System provides 1 Hz corrections to the GPS spacecraft position (X, Y, Z coordinates), and clock state in the GPS broadcast ephemerides. 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, 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 all GPS satellites are available as a low bandwidth (44 Bytes/sec) binary data stream from our Operations Centers through a variety of communications channels.

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.

< 20 cm 3D RMS
< 20 cm RMS (after de-biasing and de-trending)
< 10 cm RMS
Latency 4-6 seconds
Format Proprietary binary
Time span Complete information in 32 seconds
30 seconds
1 second
Access mode UDP (recommended) or TCP

Real-time GNSS
Products & Services
Precise, Global, Reliable
- Embedded Autonomous Ephemeris Prediction (AEP) software
- Orbit & Clock Corrections
- Orbit & Clock States
- Broadcast Ephemeris & Almanac
- Complete 50 bps Navigation Message
- Global Ionospheric (TEC) Maps
- Raw Measurements
- Predicted Orbit & Clock States
- Integrity & Performance Monitoring
- Global Virtual Reference Network
- Assisted GPS Data
- Assisted GLONASS Data
- GLONASS corrections, orbit and clocks

- Automatic Precise Positioning Service
- Consulting
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