Indeed.  I state the limits.  I have a number of packaged Samsungs from
amoj1010 (apparently no longer available) that the internal regulator
was set at around 6V.  The module was working but had the Power Fail
light on.  Sweeping their limits, the Power Fail light will be set below
5.0V and above 5.5V.  I changed the resistors on the supplying regulator
to give 5.25V.

Ours use a RPi3 host running Lady Heather for monitoring.  See
https://hamsci.org/publications/traveling-ionospheric-disturbances-observed-using-doppler-measurements-clear%E2%80%90channel-am,
PDF of the presentation at the bottom.

73,

David N1HAC

On 4/15/24 12:04 PM, Wilko Bulte wrote:

On 14/04/2024 13:24, Attila Kinali via time-nuts wrote:

Leo Bodnar has a 1 Hz to 1.6 GHz unit:

https://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=107&products_id=393

The unit now has firmware allowing operation up to 1.6 GHz, even though the
data sheet says 1.1 GHz.

Not an expensive unit, and very versatile.

Cheers,
David

SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: davidtaylor@writeme.com
Twitter: @gm8arv

How about the Jackson Labs offerings - Fury and Firefly ? I believe
they've recently been respun.

I've used those.

On 14/04/2024 11:53 pm, Bob Camp via time-nuts wrote:

Moin,

Thanks everyone who answered. All your suggestions have been noted!

I'd like to pick a few points out and comment on them, partially to explain
a bit what I'm doing and partially to give feedback to the group in general.

On Sun, 14 Apr 2024 09:53:33 -0400
Bob Camp via time-nuts time-nuts@lists.febo.com wrote:

If cost was no object, I'd go for a PolaRx5TR. But alas, I do not have
the small change to afford one of these. But I would definitely not say
no if someone at Septentrio would let me "borrow" one :-)

Yes, this is only a home lab (ok, a little bit more as I'm using it
for my scientific work as well, as my curent employer is very
very stingy when it comes to spending money on their scientists),
which means that I'm not going to spend thousands of euros on a nice
clock from Septentrio, Meinberg or SRS, even though I would like to.

On Sun, 14 Apr 2024 09:51:05 -0400
"David G. McGaw via time-nuts" time-nuts@lists.febo.com wrote:

It's my second Trimble UCCM that died. And I guess it's the same failure
again: A dead reference in the OCXO. I could probably sit down and
get it working again. But I saw this as an opportunity to see whether
I can get something more up-to-date than an UCCM.

On Mon, 15 Apr 2024 19:07:03 +0100
David Taylor via time-nuts time-nuts@lists.febo.com wrote:

I looked at Leo's original design many years ago. I was not thrilled at what
I saw. While the design per se is ok for what it is intended: a cheap, kind
of accurate frequency source for the hobbyist who needs to calibrate his
3-digit counter or to set his kitchen clock. But it is no good for what
a time-nut needs. We have had many DIY designs coming through this list
that were much better fits for time-nuts. I'm quite fond of the very simple,
yet astonishingly performant design of Nick Sayer a couple of years ago.
And one cannot beat Lars Valenius' design for simplicity.

Overall, what I found on ebay & co doesn't look very enticing at the moment.
The prices are astonishingly high. Most GPSDO go for higher prices than
rubidium clocks would go for just 5 years ago. I'm not sure I want to pay
that much for a GPSDO of questionable origin.

		Attila Kinali

--
In science if you know what you are doing you should not be doing it.
In engineering if you do not know what you are doing you should not be doing it.
-- Richard W. Hamming, The Art of Doing Science and Engineering

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@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.

time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com

Hi

I think that there are a lot of us looking for a “really good deal” on a PolaRx5TR :) :) :)

Bob

Hi,

P,erformance wise I imagine a SRs PRS10 rubidium clock connected with its 1pps input to the 1pps output of a ublox zf9t will be hard to beat for approx 2. 2kEur with respect to many requirement profiles.
Has anyone here tried that out?

Cheers,
Jürgen

On 14 April 2024 15:53:33 CEST, Bob Camp via time-nuts time-nuts@lists.febo.com wrote:

I have FS725 so effectively PRS10 and use it with ZED-F9T. It works well,
but I cannot say more as I dont have any other reference and my GNSS
antenna and location is not ideal.

Mete

On Thu, Apr 18, 2024 at 12:16 PM Jürgen Appel via time-nuts <
time-nuts@lists.febo.com> wrote:

Hi

Yup, various folks have indeed done that sort of thing. Some have done it on multiple Rb’s.

The “filter” in these Rb’s (many of them have that option) is not ideal for a GPSDO. It does not handle the “corner cases” very well. Unfortunately > 90% of the “smarts” in a good GPSDO involves those corner cases. Yes, that makes the term corner case a bit suspect …. still, it’s the term that gets commonly used. The “why?” is simply that the feature is primarily intended for “quick calibration" against a Cs or something similar.

The PRS10 has a bit of a bump in its ADEV curve around 10 seconds. It is a result of their fancy mag field management approach. That also (at least to me) makes it a less than perfect choice for this sort of thing. A 10 second gate time on a frequency counter is a pretty common thing …..

On the plus side, you can hook up something like a Mosaic-T and have a pretty fancy drive into the device. To get the best performance, you would need to come up with a way to apply the sawtooth correction data to the pps before it goes over to the Rb. That certainly can be done, it just adds another layer of excitement to the setup.

Fun !!

Bob

Hi,

it is very difficult to tame Mosaic-T's sawtooth (clock quantisation error) as the correction data for the sawtooth are reported from Mosaic-T only after the pulse is out (as oppose to, for example u-blox’s ZED-F9T/NEO-F10T, or Furuno’s GT-100). Also note that simply cleaning up sawtooth with a PLL is also not that easy, as the sawtooth is not uniformly, or normally distributed at times, that means it introduces a significant bias which needs to be cleaned up by PLL. Therefore you would need a PLL with 5mHz bandwidth or lower to clean up the sawtooth (and bias) properly. OCXO’s won’t do, but then a good Rb may be enough to keep PLL stable at those low bandwidths.

In general I would go with a good low cost receiver (my recommendation is NEO-F10T, which you can buy cheap here: https://gnss.store/54-neo-f10t-timing-gnss-modules) and a reasonably good PLL to clean up the sawtooth. The sawtooth is reported from ubx receivers before the pulse, so you can correct it directly in the PLL, if it supports it (supported by Si5383 or AD9545, for example). For some of those PLLs a reasonably cheap (300$) evaluation boards exist, so you don’t have to design your own PCB.

Cheers
Zdenek