TABLE 3-1 Remote Sensing and Geophysical Requirementsa


Numerical Weather Predictionb

Space Weather



Receiver Sample Rate

30 seconds (ground)

30 seconds

30 seconds

30 seconds

Predicted Orbit Accuracy

<25 cm

30 cm

10 cm

50 cm (real time) 10 cm (long term)

Orbit Access/Delivery Time

Available at 00:00 universal coordinated time (UTC) each day

0.5 hours

Not defined

Real-time continuous delivery (real time) 1 week (long term)

Required Data Product

Total signal delay (ground-based) Bending angle (space-based)

Total electron content

Precipitable water vapor solution (30 minute intervals)

Position differences, covariance, and variance over baselines <500 km

Data Access/Delivery Time

0.5 hours for local models <5.0 hours for global models

0.5 to 1.0 hours

6 months

30 seconds (real time) Not defined (long term)


<1 cm

2 to 5 total electron content units

1 to 2 mm

5 mm (real time) 1 mm (long term)

Spatial Distribution of Reference Stations

500 km globally <200 km locally (ground) <500 km (space)

Global network with emphasis on low latitude sites

Not defined

3 to 50 km

a The quantitative and qualitative requirements listed in this table were determined by the remote sensing working group. They do not represent requirements defined by an internationally recognized standardization committee or a government agency.

b Where they have been defined, requirements are listed for both ground-based and space-based GPS sensing systems.

c Requirements for both real-time and long-term geophysical applications are provided. If only one entry is present, the requirements are the same for both.

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