[time-nuts] Weird GPSDO behavior - update

Azelio Boriani azelio.boriani at gmail.com
Wed Oct 4 06:04:03 EDT 2017


Very interesting: can you flash the firmware? I'm aware (until now)
that there is no firmware around and no firmware flashing tool for
these GPSes. Maybe the flashing tool(s) is(are) suitable for the
Thunderbolt too.

On Wed, Oct 4, 2017 at 10:58 AM, robkimberley
<robkimberley at btinternet.com> wrote:
> Is there any way you can run it on batteries? The 8AM glitch still makes me think it is power line problem.Rob
>
>
> Sent from my Samsung Galaxy smartphone.
> -------- Original message --------From: Skip Withrow <skip.withrow at gmail.com> Date: 03/10/2017  19:15  (GMT+00:00) To: time-nuts <time-nuts at febo.com> Subject: [time-nuts] Weird GPSDO behavior - update
> Hello Time-Nuts,
>
> Well, I think I know a little more about my GPSDO problem, but
> probably have more questions now than before.  Thanks for all the
> replies to the first post with thoughts and suggestions.
>
> I first tried restarting Lady Heather and doing a cold boot on the
> NTGS50AA (then entering the same disciplining values). Same behavior.
>
> I let it run over the weekend and the same behavior happened on
> Saturday and Sunday morning.
>
> So, yesterday (Monday morning) I changed the gain to the gain of the
> oscillator (.0072Hz/V), damping to 1.2, and time constant to 900s.  On
> the attached PRS10-2 plot you can see that it quickly settled.  This
> morning, it looks like all is well from the plot (about an hour before
> the furnace kicks in at the right of the plot).  HOWEVER, when the
> plot is expanded there is still funny business going on with the DAC
> control voltage at the same time of day.  I just think the changed
> parameters limit the disturbance.  The expanded plot is the attached
> PRS10-1.
>
> At this point I'm beginning to think that the NTGS50AA is the issue,
> but there are lots of questions left.
>
> 1. There are various version of the NTBW50AA/NTGS50AA GPS/operating
> firmware.  Mine is 10.3 and I notice that it has the LH 'ro'
> designation (as does the 10.4 version).  The 10.5 version does not
> give the LH ro notice.  Maybe it behaves better with the disciplining?
>  I will have to give a 10.5 a try.
>
> 2. Why does the glitch occur at 8am in the morning?  Will have to try
> powering the NTGS50AA up at different times and see it the glitch
> moves around.
>
> 3. Which disciplining parameters are affected by this glitch and which are not?
>
> 4. Have other people seen this same behavior?  Does it happen on
> Thunderbolts too?
>
> I'll update again when I have more data.
>
> Regards,
> Skip Withrow
>
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