Questions about the hourly file latency graphs

Where do the numbers plotted come from?

The time of file availability is determined by checking the timestamp of each hourly file at the following Data Centers: CDDIS, IGN, SIO, and BKG. If found at multiple DC's, the earliest timestamp is chosen. The difference between this timestamp and the final epoch of this hourly file gives the displayed latency.

What are the error bars in the 3-day average plots?

Standard deviations of the previous 3 days of data as plotted in the "Latency of each hourly file" plots.

What are "good" numbers?

The IGS recommends hourly data files be available within 10 minutes past the last epoch in the file. This benefits certain applications such as tropospheric investigations. If this cannot be met due to shortcomings of infrastructure at a given site, it can still benefit other applications which tolerate somewhat higher latencies. Each site should strive to the lowest latency feasible within operating constraints.

This page last updated: 13 May 2010
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