Hi Attila,
In my unit, which is a frequency standard, I chose to tell the receiver to stop
sending 1PPS pulses when it loses sync to the sats. And since the 1PPS is no
longer coming, the PLL does nothing and the DAC doesn't change. (Let's avoid
the question of aging correction for now.) So, I'm wondering where to go and
what to do if I want to get time from my unit. Clearly I could just tell the
receiver to continue to send 1PPS pulses and sync to those - marking the time
as unreliable. When the receiver synced back up, then it would warp the time
output, the 1PPS would warp in phase, and the PLL would correct the phase
error.
So, that's one way, but probably not a desirable way. My interest was in the
option of using the OCXO to create the time, which clearly gives a better
option when the receiver syncs back up to the sats. Is there a published
standard for this, or is this something that everyone (except the newbie) knows
so well that it's not worth discussing?
Bob
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From: Attila Kinali <[email protected]>
To: Bob Stewart <[email protected]>; Discussion of precise time and frequency
measurement <[email protected]>
Sent: Tuesday, August 16, 2016 3:46 PM
Subject: Re: [time-nuts] Holdover
On Tue, 16 Aug 2016 04:35:40 +0000 (UTC)
Bob Stewart <[email protected]> wrote:
> It's been pointed out to me that I didn't understand the function of
> the 1PPS of a time standard. I confess that somehow I had confused the
> term to be timing standard; which would be an entirely different thing.
> But, this is time-nuts, so I should have realized...
> Anyway, is there a standard, or at least an accepted practice, for how
> holdover is handled in a time standard?
There are many ways how to do that and which one you choose depends
on the application and its requirements. You can find everything between
"jump imediatly" and "just keep the frequency stable and don't care about
alignment".
Attila Kinali
--
Malek's Law:
Any simple idea will be worded in the most complicated way.
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