[time-nuts] Re: GPSDO replacement recommendation

[Jürgen Appel]

Hi, 

That was also the behavior of my Bodnar Precision GPS reference clock (well, it’s actually not an error as the frequency was within specs, but the phase is not locked, as you would expect from a device marketed as a clock). I wrote them an email and only few days later received a firmware giving me a version with worse phase noise but phase tracking to GPS instead.

Cheers, Jürgen

— 
Sent from my mobile device, please excuse my brevity.

On 16 Apr 2024, at 08.55, Jeremy Elson via time-nuts <time-nuts at lists.febo.com> wrote:

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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