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

Chris Albertson albertson.chris at gmail.com
Sun May 22 22:24:40 UTC 2016


How do you measure "simple"?   Do you count the chips and the passive
components or do you count lines of code?  Or maybe you draw a block
diagram and count the blocks and the number of interconnections?

If you count chips the design with the micro controller wins by a long shot
But if you count lines of code, even a one foot square PCB loaded with
op amps and precision passive parts wins.

I think the design presented here by Lars Walenious is about as simple
as it gets.  I build a GPS disciplined XO using only part of Lars'
design so it was even more simple but I don't know if I got to 1E-10.
(my goal was to experiment to find the simplest design that could
still work, so  removed everything I could.)  Lars used a regular
Arduino for the micro controller.  These are by far the easiest to
program micro you will find.  Ease of use was their primary design
goal.  I used a "mini" version of the Arduino, same thing but smaller
and 8x cheaper.

An advantage of using a micro controller is that it is easy to make
changes but I find most important is that it can log internal data so
you can collect performance statistics and make informed design
changes until you like the logged statistics



On Sun, May 22, 2016 at 10:41 AM, 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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-- 

Chris Albertson
Redondo Beach, California



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