[time-nuts] Timing Distribution in Mountainous Terrain

[Rob Kimberley]

30ns for six days? 

You will probably will have to install Cesiums or Hydrogen Masers, a good
Rubidium can drift 1.1us per day.
Even with GPS it is hard to achieve, try to find a GPSDO that specifies
+/-30ns to UTC .... some specify 30ns RMS, i.e. being < 30ns in ~70% of
the time.

Rob Kimberley

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Ralph Smith
Sent: 09 September 2010 5:49 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain

The network is spread over about 250-300 US miles.

Ralph

On Thu, September 9, 2010 12:01 pm, Didier Juges wrote:
> How widely spread is your network?
>
> ------------------------
> Sent from my BlackBerry Wireless thingy while I do other things...
>
> -----Original Message-----
> From: "Ralph Smith" <ralph at ralphsmith.org>
> Sender: time-nuts-bounces at febo.com
> Date: Thu, 9 Sep 2010 11:37:46
> To: <time-nuts at febo.com>
> Reply-To: Discussion of precise time and frequency measurement
> 	<time-nuts at febo.com>
> Subject: [time-nuts] Timing Distribution in Mountainous Terrain
>
> We have a requirement for approximately ten radio sites to be 
> synchronized to within 30 ns of each other. Ordinarily you could throw 
> in an appropriate GPSDO and be done with it. However, we also have the 
> reqirement to be able to operate independent of GPS for up to six 
> days. If we were able to have each site within line of sight of 
> another, and could form a network including all sites, we could do 
> differential time measurement between the mutually visible sites and
correct in that way.
> Unfortunately, that is not the case. Absolute time accuracy is not 
> critical, but relative time accuracy is. Does anyone out there have 
> any ideas?
>
> Thanks,
> Ralph
> AB4RS
>
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