Or use 1ns per foot of antenna cable.  That will get you closer.

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> On Dec 8, 2014, at 8:16 AM, David J Taylor <[email protected]> 
> wrote:
> 
> Hi
> 
> On *most* GPSDO’s, the simple answer is “there is a cable delay adjustment to 
> align it”. Without some sort of reliable representation of UTC (at the ns 
> level) it’s tough to measure. If you happen to live at USNO or NIST, you can 
> access that sort of timing. For the rest of us - not so easy. The NIST two 
> way GPS “modem” setup is about the only practical method that I know of.
> 
> The PPS out of any GPSDO will be much lower jitter than the pps from a normal 
> GPS module.
> 
> Bob
> ======================================
> 
> Bob,
> 
> Thanks for your comments.  The antenna location and cable lengths are very 
> similar (either 0, 5m or 10m) so I was expecting somewhat less than 50 ns 
> difference.  200+ ns is rather more than I expected for the LTE-Lite, so I 
> did wonder whether anyone else had measured it.
> 
> Although I've not checked it rigorously, most of the GPS/PPS units here of 
> various brands are within under 100 ns of each other, hence my expectation.
> 
> Cheers,
> David
> -- 
> SatSignal Software - Quality software written to your requirements
> Web: http://www.satsignal.eu
> Email: [email protected] 
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