[time-nuts] Using a UBlox NEO-6 GPS module for calibrating a PIC microprocessor based timer.

[Chris Albertson]

> The short term noise arises from the signal-to-noise of the
> "as received" signals, so the 99% accuracy of 60 ns likely means that you
> can assume that all of the pulses are within +/-100 ns.  The time noise is
> "white" for GPS signals.  Note also that this is time accuracy, not
> frequency accuracy.  Frequency accuracy is maintained by GPS Ground Control
> Segment with reference to the US Naval Observatory Time Scale.

This is true, when the GPS signal is being received and processed.
This may not be 100% of the time.  The satellites move about 1/2
degree per minute and if you are indoors can be hidden by heating
ducts and what not.  You can expect short term anomalies. You might
want to monitor this.  At least have an LED that lights when it is
"good data".
-- 

Chris Albertson
Redondo Beach, California