[time-nuts] Timing Distribution in Mountainous Terrain

[Stanley Reynolds]

Does the GPS backup include other sats ? As long as all sites could see the same 
sat then using it as a standard they would drift together.

Stanley


----- Original Message ----
From: Ralph Smith <ralph at ralphsmith.org>
To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
Sent: Thu, September 9, 2010 11:45:04 AM
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain

The requirement is 30 nanoseconds, so individual rubidium holdover over
six days won't cut it.

Ralph

On Thu, September 9, 2010 11:58 am, Robert Darlington wrote:
> Symmetricom makes GPS based NTP time servers with excellent holdover
> capability.  I think our "SyncServer" with an OXCO is good for +/- 0.5
> second holdover over something like 60 days.  They have options for Rb
> oscillators installed that will make that much much better and it might
> fall
> inside of your requirements.  Give them a look.  You're welcome to mail me
> directly with questions about mine if you like.
>
> -Bob
>
> On Thu, Sep 9, 2010 at 9:37 AM, Ralph Smith <ralph at ralphsmith.org> wrote:
>
>> 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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