[time-nuts] Motion effects on accuracy of GPS pps

bg at lysator.liu.se bg at lysator.liu.se
Tue Jun 29 08:32:42 UTC 2010

Hi Daniel,

> Hi,
> I've recently completed a GPSDO using the pps output of a uBlox Antaris
> TIM4 GPS module to discipline a 10MHz OCXO. I'm now investigating the
> motion effects (acceleration/uniform velocity) on the accuracy of the
> time-pulse and hence on my frequency output.

Are you moving around in areas with little obstruction for the GPS antenna
towards the sky? Then I would first look at the dynamics inpact on your

> I've been unable to find any detailed information on the relationship
> between the accuracy of the pps output and the effects of having the
> receiver in motion (i.e. in a car/boat, at velocities far below the
> modules operating limit of 515m/s) - I'd appreciate some input on this
> matter. Does motion cause increased jitter?

Tilting/accelerating your GPS oscillator might possibly yield an effect.
Other than that there is no theoretical advantage keeping your receiver
stationary. All its measurements are done against satellites moving at ca



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