NASA Home Page JPL Home Page Caltech Home Page
NASA - Jet Propulstion Laboratory vertical separator + View the NASA Portal
JPL Home JPL - Earth JPL - Solar System JPL - Stars and Galaxies JPL - Technology
Global Differential GPS System
Home
About Us
System Description
- Overview
- Network
- Software
- References
Applications
Live Performance Monitoring
Customer Portal
Live Performance Monitoring

The ultimate quality metric of a differential positioning system is, of course, positioning. To demonstarte the key attributes of the GDGPS System, namely, global coverage, outstanding accuracy, and high real-time reliability we present in this page the live, real-time positioning performance at three, widely separated locations.

At each location a dual-frequency GPS receiver is streaming its measurements to a GDGPS Operations Center (GOC). At the GOC we also calculate the real-time orbit and clock states of the GPS satellites based on such data streams from nearly 100 receivers spread all over the world. In a separate point positioning process we use the precise real-time orbit and clock states to position the three receivers in real-time.

These three receivers may or may not have contributed their data to the GPS orbit determinationn process. But with so many receivers contributing their data, any one receiver has neglible impact, and it does not skew the point-positioning results.

Below you can see the accuracy of the real-time positioning measured against the surveyed location of the antenna. The point-positioning is done kinematically at 1 Hz, that is, at each second we estimate a new location with no assumptions on the velocity (which is zero, of course).

GoldStone,CA Position

Madrid Position

Tidbinbilla Position

link to First Gov NASA logo