[time-nuts] Simple solution for disciplining OCXO with 1 PPS

Bob Camp kb8tq at n1k.org
Sun May 22 17:55:54 EDT 2016


Hi

Of course it’s possible, you simply need enough high quality film capacitors to make up the control loop integrator. 
You probably also would use a pile of the same capacitors to slow down the PPS jitter a bit before it went into the loop. 
The setup process would probably involve a bunch of toggle switches or relays to walk the loop into the long time constant 
mode. You would be wise to put the caps all in some sort of oven arrangement. That way odd drafts hating the caps would 
not drive the GPSDO nuts. 

Bob

> On May 22, 2016, at 1:41 PM, Bernd Neubig <BNeubig at t-online.de> wrote:
> 
> Hello Fellow time-nuts,
> I am looking for a simple solution to discipline my 10 MHz reference OCXO in my private lab with an 1 PPS signal from a separate GPS receiver.
> I am curious if there is a solution possible without programming a microcontroller, as I am an old-fashioned "analogue" guy ;)
> I am well aware, that such a solution would have a lot of disadvantages, as it cannot effectively compensate for short-term variations. However I would be happy if such a KISS solution could achieve  a stability (STS) of better 1E-10 over an hour. I know this is a damned long integration time for an analogue integrator...
> If that sounds too weird, I am open to receive advises for a microcontroller based solution.
> 
> Thanks a lot for your comments to come.
> BTW: you need not to teach me about basics of short-term stability. I just want to evaluate the limits of a possible analogue solution. For sure, that's not real disciplining, but more like a long-tau integration PLL
> 
> Best regards
> Bernd DK1AG
> 
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