[time-nuts] Re: GPSDO replacement recommendation

[Ole Petter Ronningen]

Yes, the OCXO dominates on short tau, so to get 2e-13 you need a good one.
I used an Oscilloquartz 8601. But it is nicely scalable - if you have an
OCXO "only" capable of 1e-12, tune the steering loop so that is what you
get until the ADEV "turns downwards".

BR
Ole

On Sat, Apr 20, 2024 at 2:24 AM Matt Huszagh via time-nuts <
time-nuts at lists.febo.com> wrote:

> On Fri, Apr 19, 2024 at 9:21 AM Ole Petter Ronningen via time-nuts
> <time-nuts at lists.febo.com> wrote:
> >
> > The trick to getting good adev based on a Mosaic-T GPSDO is to simply
> > bypass the whole sawtooth problem. Dont compare the PPS from the Mosaic-T
> > with a PPS derived from your steered oscillator, rather run the Mosaic-T
> > with the steered 10MHz directly, and use the relevant messages from the
> > Mosaic-T to run the control loop. No external phase-detector necessary,
> no
> > PPS sawtooth to struggle with. It is described in the hardware manual for
> > the mosaic, appendix D.
> >
> > ADEV of 2e-13 at 1s on the steered clock (OCXO) has been demonstrated this
> > way, although with Atomichron real time PPP - but the architecture should
> > work either way. YMMV.
>
> 2e-13 at 1s was intentional, right? Do you have any further details on
> this? The PPS ADEV of GNSS receivers such as the ZED-F9T is almost 5
> orders of magnitude worse than 2e-13 at 1s. So, normally, you'd need this
> stability to come from the OCXO. As far as I know, it takes a really
> good OCXO to get 2e-13 at 1s.
>
> Matt
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe send an email to time-nuts-leave at lists.febo.com