[time-nuts] Time source for indoor standalone PC

[Grant Waldram]

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