[time-nuts] Mentorship needed in learning about Allan Deviation and variation.

[Joe & Gisela Noci]

Hi Bob,
Yes, I am - I use a Dallus digital delay line in series with the GPS 1pps
and program the delay line each second with the GPS delay estimate in the
GPS NAV message.
It works really well, jitter on the 1pps pulse is hugely reduced, but one
side effect is that those 'hanging bridges' can become severely extended in
time.
I can by pushbutton selection bypass the delay line, ie, no sawtooth
correction - since I do not have a reference frequency source, I cannot say
if it is better or worse.
However, the logged values output from the time-digital convertor still
shows the spikes either way- I still suspect the spikes are conversion
artifacts from digital noise in the box..
Being green on the science of this I packed to much 'stuff' into the
enclosure and there are DC-DC converters for power, Nucleo processor
running at 140MHz, a NEXTION touch screen LCD, which
I am discovering is very noisy, etc....It is difficult to target any
solution at the moment as I believe there are too many areas that are
marginal - I need to clean it up!
Joe

On Tue, Nov 10, 2020 at 6:24 PM Bob kb8tq <kb8tq at n1k.org> wrote:

> Hi
>
> Are you using sawtooth correction?
>
> Bob
>
> > On Nov 10, 2020, at 8:55 AM, Joe & Gisela Noci <jgnoci at gmail.com> wrote:
> >
> > Hi everyone,
> > Still playing with my GPSDO..The Rubidium source I was hoping to have the
> > loan off did not work out, so still in the dark. I have sort of convinced
> > myself to procure a reasonable 'proven' source, Rubidium or whatever, but
> > that
> > seems to be more easily decided than done..Or at least so if the money
> > available is not astronomical... Also complicated by the difficulties
> > getting the goods here to Namibia!
> >
> > Anyway, I am still unhappy with my analogue time-to-digital conversion -
> I
> > do see the odd spike in the logged data and have been unable to find why
> -
> > have applied lots of filtering of supplies, used a separate A/D
> convertor (
> > as opposed to the convertor internal to the STM Processor) with own dc
> > regulated supply, own clean A/D Reference voltage ( 1ppm device). etc...
> >
> > Does not mean implementing a digital method will get rid of the spikes,
> so
> > I am still chasing that till I understand, but to that end:
> > I found this device and am keen to get the dev kit and try it out :
> >
> https://www.sciosense.com/products/time-to-digital-converters/development-kit-for-as6500/
> >
> > Has anyone perhaps played with it? Would be interested to know more about
> > it if so..
> > Regards
> > Joe
> > V51JN / ZS6JGN
> >
> > On Wed, Oct 28, 2020 at 7:08 PM Alberto di Bene <dibene at usa.net> wrote:
> >
> >> On 2020-10-28 2:29, jimlux wrote:
> >>> I'm still agitating for alien deviation - Microsoft offers it as a
> >>> suggestion, but not Allan, so it must be true.
> >>
> >> :-):-):-)
> >>
> >> Thanks Tom and Jim for the explanations. All clear now.
> >>
> >> 73  Alberto  I2PHD
> >>
> >>
> >>
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