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

Rob Kimberley rk at timing-consultants.com
Tue Jun 29 13:44:58 UTC 2010

I don't necessarily agree with that last statement. It would depend on the
receiver type and the number of SVs being tracked. 


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of bg at lysator.liu.se
Sent: 29 June 2010 9:33 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Motion effects on accuracy of GPS pps

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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