[time-nuts] Low cost GPS module for < 100ns timestamping error

nuts nuts at lazygranch.com
Sat May 3 20:25:42 EDT 2014


On Sat, 03 May 2014 02:38:07 +0100
Tony <tnuts at toneh.demon.co.uk> wrote:

> On 03/05/2014 00:59, EWKehren at aol.com wrote:
> > Welcome to the nuts Tony
> 
> Thanks, Bert.
> 
> > You are not specifying exactly how accurate time has to be but in
> > my book and based on tests the most reasonable priced GPS with 1
> > pps is a Ublox 6M
> > that  you can get with antenna for less than $ 22 antenna included
> > from _www.DX.com_  (http://www.DX.com) . They have volume discount. 
> > Shipping is  very
> > slow but included. They seem to be presently out of the 1 pps
> > version but all ublox units have a 1 pps output and I use with and
> > without and all I do is
> >   solder a wire to pin 3.
> > Bert Kehren
> 
> As I said in my first post I'd like to achieve an accuracy of better 
> than 100ns - or 50ns if possible at reasonable cost.
> 
> I had come across the Ublox 6M when I was looking earlier, but I 
> misunderstood the data sheet and thought it was only the expensive 
> ($135) LEA/NEO-6T versions which provided timing. Definitely worth a 
> closer look - the NEO-6M is specced at 30ns RMS which is good enough. 
> The power consumption is a little higher than I would have liked  at 
> 37mA/3V, but still rather less than others.
> 
> Thanks,
>        Tony
> _______________________________________________

I hope I'm not getting to philosophical here, but isn't the time stamp 
accuracy measured between receivers? That is, if I have two GPSDO, they
are guarenteed to be within X amount of time from each other. 

Or do you consider a time stamp to be absolute?



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