[time-nuts] Does GPS time reception work everywhere all of the time?

[Attila Kinali]

On Mon, 30 Aug 2010 21:42:33 -0500
"Bill Hawkins" <bill at iaxs.net> wrote:

> This is not a challenging application for time accuracy, unless a human
> (like the CIO) wants to have better accuracy than his (it's a testosterone
> thing) competition. Process valves have a 1 second time constant, for the
> most part. Programmable logic controllers and their actuators can't react
> faster than 1/2 of a power line cycle. Millisecond precision is adequate.

[...]
 
> I had hoped for a line frequency clock like the PDP-11, but hardware gave
> me a crystal. Yes, the line frequency is within +/- 0.1% of true time, but
> that was enough in 1985. And it was always back in sync with WWV at 7 AM.
> 
> My concern is with the facilities that don't have Internet connections
> and have to use satellite links. Do facilities that are far apart need to
> have one millisecond resolution? That's a testosterone question.
> 
> How much am I willing to pay? I dunno, how much are you willing to offer?

There are GPS referenced NTP time servers with a hold over of a day for
the OCXO based ones or weeks for the ones based on Rb. From what you
write, these should be enough for your needs. The prices for these are
usually not that high and IMHO the cheapest ones with OCXOs are good
enough for you. As manufactureres, Meinberg and Symmetricon come to mind, 
but there are many others too. Especially Meinberg has Clocks in various
form factors, from 19" rackmount over DIN rails to PCI-e cards.

				Attila Kinali
-- 
If you want to walk fast, walk alone.
If you want to walk far, walk together.
		-- African proverb