[time-nuts] Motion effects on accuracy of GPS pps
hmurray at megapathdsl.net
Tue Jun 29 19:44:06 UTC 2010
> Thanks for the response Björn. Also thanks to Didier Juges for pointing out
> that this has been covered on a previous thread. I'll go and find it in the
Somebody setup a good oscillator on a pendulum. They could measure the
frequency shift as G changed slightly.
There have been several mentions of the change in frequency when you turn an
oscillator over. That's a 2G shift.
> Unfortunately the device will be used in urban areas so some multipath &
> obstruction of skyview is expected. I've just done some testing on my OCXO
> and it has a maximum sensitivity of about 5 ppb / *g*, which is notable,
> but shouldn't present a problem. I've yet to explore the vibration effects
> - thanks for pointing my attention to the motion effects on the OCXO
> itself, its an aspect I'd otherwise have overlooked.
Somebody provided the URL for a good article on vibration, a PDF from a
The problem they were working on was radar in helicopters. The return signal
is smeared by the noise bandwidth in the source signal. That determines the
minimal velocity that you can see if you filter out the ground clutter. They
were measuring acceleration and correcting via EFC. It was a fun read.
Sorry, I don't have any URLs or subjects to search on, but the ideas might
help if you are scanning the archives.
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