[time-nuts] Re: GPSDO replacement recommendation

[Jeremy Elson]

Does the BG7TBL unit still have a frequency error? Last time I tested one
of his units the frequency was wrong by about 1e-11 due to a software bug.
(Other people on the Internet have observed the same, e.g.
https://blog.febo.com/?p=636) I was briefly in contact with the designer
via email a couple years ago and he promised a fix but then stopped
replying to my emails.

On Mon, Apr 15, 2024 at 8:29 AM Zen via time-nuts <time-nuts at lists.febo.com>
wrote:

> I have been doing an analysis of GPSDO's from the usual auction site.
> These are usually coupled with a crystal I have done the $99.99 TM4313 one
> and the BG7TBL (2019 version) $150.00. I have started to keep a spread
> sheet of the Allen variance as well as the Pk-Pk deviation. The analysis
> has been 100 Samples averaged with gate times of 0.01, .1, 1, 10, and 100
> seconds. I have found them to wobble around 20uHz range and up in to the
> low mHz (>9mHz) If there is a place I can post the Excel document I am
> happy to do so.
>
> Testing was done on a HP 53230A with an SRS FS725 as its time base. This
> is backed up by a GPSDO 1pps -> FS725.
> Warm up and settling times are as follows
>
> FS725 - more than a month
> HP 53230A - More than 1 Hour (Internal clock not used)
> GPSDO under test - 24 Hours or more for stability
>
> I will have videos about this testing on YouTube in a few weeks.
>
> Eric
>
>
> -----Original Message-----
> From: Wilko Bulte via time-nuts <time-nuts at lists.febo.com>
> Sent: Sunday, April 14, 2024 4:06 PM
> To: Discussion of precise time and frequency measurement <
> time-nuts at lists.febo.com>
> Cc: Attila Kinali <attila at kinali.ch>; Wilko Bulte <wkb at xs4all.nl>
> Subject: [time-nuts] Re: GPSDO replacement recommendation
>
> hi Atilla,
>
> Assuming you can find one: the Samsung UCCM is form/fit compatible but
> sports a much more sensitive GPS module. Fast satellite lock with signal
> levels that made Trimble and Symm. UCCM modules very slow to acquire lock.
>
>  I happen to own 2 of these Samsungs. Previously also had both a Trimble
> and a Symm UCCM. The Samsungs were to stay.
>
> hth,
> Wilko
>
> > On 14 Apr 2024, at 15:17, Attila Kinali via time-nuts <
> time-nuts at lists.febo.com> wrote:
> >
> > Moin,
> >
> > My house GPSDO (a Trimble UCCM) died recently and I am now looking for
> > a replacement. As I have been a bit out of touch with the current
> > state of affairs regarding GPSDOs, I'd like to ask what the current
> > recommendation for getting a GPSDO is, these days.
> >
> > Thanks in advance
> >
> >            Attila Kinali
> >
> > --
> > Science is made up of so many things that appear obvious after they
> > are explained. -- Pardot Kynes
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