[time-nuts] Time source for indoor standalone PC

[Keenan Tims]

If a phone line is available and you can stomach the small cost of a
long distance phone call now and then, it seems like ACTS would be the
simplest route. Several countries still maintain ACTS services;
Australia's NMI lists a number that they say is not functional, but it
does pick up with a modem tone (I dialed it), so they might've just
forgotten to update the web page. All you'd need to do is find an old
serial modem and connect it to whatever computer is handy (or a
Raspberry Pi etc.) and configure NTP. Even across a transoceanic phone
circuit I think you'll synchronize well better than 1s, and if you
precalibrate your server's nominal drift a call every few days should be
enough to keep you within a couple of seconds.

Keenan

On 2013-05-16 9:45 PM, Grant Waldram wrote:
> Hi folks. I wouldn't call myself a time nut, so this is really an effort to
> ask for advice from some people who know the field. My first contact with
> time synchronisation was looking at the instrumentation clocks for the
> Woomera rocket test facility when I went out there for a few (large!) hobby
> rocket launches. I can't even remember the system's name but it used a
> series of pulses of various lengths to give a unique time code. But, I
> digress...
>
>  
>
> I've not had much need for time synchronisation over the years, but in
> recent years NTP has been able to get me by. Unfortunately I'm now faced
> with a network that needs a moderately correct clock (I'm scared of using
> the word 'acurate' around you folks!) to the order of a few seconds or so,
> but with no possibility of an external internet connection (for a number of
> reasons). At present I'm using one PC running Windows Server as an SNTP
> server to synchronise all of the devices, as it is the only device in a
> physically secure location. This is inside a security-fob protected room. I
> can't get GPS signals in there, and the Australian radio clock network was
> shut down about ten years ago. Our CDMA network was turned off in 2008.
> Right now all I can think of is GSM, and while i know it's not terribly
> accurate it seems like it might be the easiest. It also might be that I've
> got tunnel vision and there's a simpler solution out there.
>
> I would be quite happy with some sort of dedicated GSM/NTP-server box, and
> there are Arduino/Raspberry Pi/Linux homebuilts for that out there, but I
> have been wondering if one of the fairly common GSM USB sticks could somehow
> be a time source to set the server clock?
>
>  
>
> Regards,
>
>  
>
> Grant
>
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