Normal Point Data

Normal Point Content Criteria

Normal Point (NP) data are consolidated from full-rate (FR) data into time intervals from 5 sec to 5 minutes depending the altitude of the satellite. Normal points are generated at the stations very shortly after the satellite pass, and transmitted rapidly (within an hour or so) to the data centers, where they are available to the users.

In recent years the network has evolved into its modernized form with the majority of the stations operating in kHz rates. Nevertheless, a significant number of important stations are still operating legacy systems at 10 Hz or below. To strengthen data quality and reliability, the ILRS urges its legacy stations, to operate with a minimum requirement of:

  • Daytime normal points: a minimum of 6 full-rate data points
  • Night-time normal points: a minimum of 3 full-rate data points

Data users should recognize that some of the legacy stations may submit normal points that fall below this minimum threshold, thereby introducing biased data NPs. Users may want to do some selective filtering (as above) to avoid these lower quality data that may degrade the quality of solutions depending upon the application.

Stations should include their adopted minimum NP data policy as a note in their Site Logs, however, normal points themselves include the number of full rate data points used in generating them.

The CRD format allows a 6-digit number in the FRPs/NP field, so we can accommodate up to 999999 full-rate points per normal point for the kHz systems.

Normal point data are available from the ILRS Data Centers at:

Related information: