[time-nuts] Re: of possible interest
On 21/3/20 6:07 am, djl wrote: > > https://www.sv1afn.com/en/products/vhf-uhf-triplexer-1.html > > 10 mhz and uhf/vhf on same cable. I've pondered if IRIG modulated on 10MHz would make enough sense to work, or if the modulation would end up degrading the 10MHz enough to no longer be a good reference. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: About 10 MHz Optical Distro
On 8/28/21 7:13 PM, AC0XU (Jim) wrote: Thanks to all the posters. Especially to Dana - That is exactly what I was looking for - suggestions for parts and/or circuits to do the job. I was originally thinking that I would go with a digital circuit (sine to square to sine), but maybe analog/sinewave would be simpler and perform about as well. Anyway, I have ordered some of the recommended optical transceivers. We'll see how that works out. One or two posters mentioned that phase noise and/or thermal stability may be issues. The referenced research papers don't seem to indicate that phase noise is a problem. I don't think that thermal effects will be a big problem for me - I just need to check the phase calibration from time to time. Certainly there are expensive commerical optical clock distribution systems with excellent properties. Maybe the devil is in the details... My specifical application at the moment is putting several SDRs at diverse antenna locs and feeding the IF via ethernet-converted-to-optical to my computer. I may want to transmit at some point but receiving is all I want to do for now. Still need a way to get a stable ref clock to each radio to provide phase coherence I only need 50-60 meters but an optical solution with single mode fibers can go many km if I ever wanted to scale up. Anyway, my plan is to have only power carried by copper. I don't want to go with coax, twisted pair, or any other copper solution because of high ambient noise levels in my area and a desire to avoid adding to it. Stringing several 100 meters of copper about my yard, carrying 10 MHz clock signals, no matter if the cables are well shielded, doesn't seem like a great idea. This is totally the thing that OVRO LWA dealt with.. Not only is fiber a LOT cheaper than coax, it solves a lot of problems. Ethernet to fiber is really cheap ($20 for an endpoint from TP-link ) $20 from newegg https://www.newegg.com/tp-link-mc100cm/p/N82E16833704015?item=N82E16833704015 ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Subject: Re: Leviton VTP24 Is this Time Accurate enough? - Line Frequency and TXOs
In Southern California Edison's region I know that 60Hz used as a time reference has been unstable in possibly the last 10+ years. I have found that depending on whether in the summer clocks which use this reference tend to run slower, and in the winter they run faster. Have you noticed that in some way it between running fast or slow the gain/loss combination averages out over the course of the year? Don Resor -Original Message- From: Thomas D. Erb Sent: Saturday, August 28, 2021 4:16 AM To: time-nuts@lists.febo.com Subject: [time-nuts] Subject: Re: Leviton VTP24 Is this Time Accurate enough? - Line Frequency and TXOs We have been running long term tests on a TXO chip we use for time keeping vs line frequency vs NIST time. Over 4 years the TXO is within 4 minutes Line Frequency 9 minutes The TXO is well within specification - and the line frequency is off because we lose power in our leafy Boston suburb a lot - and the control fall over to an older time keeping chip. Thomas D. Erb p:508-359-4396 f:508-359-4482 a:97 West Street, Medfield, MA 02052 USA e: t...@electrictime.com w:www.electrictime.com Tower & Street Clocks Since 1928 ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] About 10 MHz Optical Distro
Thanks to all the posters. Especially to Dana - That is exactly what I was looking for - suggestions for parts and/or circuits to do the job. I was originally thinking that I would go with a digital circuit (sine to square to sine), but maybe analog/sinewave would be simpler and perform about as well. Anyway, I have ordered some of the recommended optical transceivers. We'll see how that works out. One or two posters mentioned that phase noise and/or thermal stability may be issues. The referenced research papers don't seem to indicate that phase noise is a problem. I don't think that thermal effects will be a big problem for me - I just need to check the phase calibration from time to time. Certainly there are expensive commerical optical clock distribution systems with excellent properties. Maybe the devil is in the details... My specifical application at the moment is putting several SDRs at diverse antenna locs and feeding the IF via ethernet-converted-to-optical to my computer. I may want to transmit at some point but receiving is all I want to do for now. Still need a way to get a stable ref clock to each radio to provide phase coherence I only need 50-60 meters but an optical solution with single mode fibers can go many km if I ever wanted to scale up. Anyway, my plan is to have only power carried by copper. I don't want to go with coax, twisted pair, or any other copper solution because of high ambient noise levels in my area and a desire to avoid adding to it. Stringing several 100 meters of copper about my yard, carrying 10 MHz clock signals, no matter if the cables are well shielded, doesn't seem like a great idea. Overkill? Probably. BTW, I would NEVER try to do something like this with copper Ethernet. Even shielded Ethernet cables (Cat-7 and Cat-8) radiate badly when used for 1-G and 10-G Ethernet. Thanks again to all! Jim ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Query about List and about 10 MHz Distro
Bob,
In my case simply disconnecting the long interconnecting cables at both
ends almost
completely eliminated the problem. Hence my expectation that use of fiber
optics
would be effective.
Dana
On Sat, Aug 28, 2021 at 7:27 PM Bob kb8tq wrote:
> Hi
>
> Anything you do that has a bunch of 10 MHz cables running out from here or
> there
> will impact your ability to listen to WWV at 10 MHz :) Other than killing
> all the sources,
> there is no silver bullet.
>
> Bob
>
> > On Aug 28, 2021, at 7:57 PM, Dana Whitlow wrote:
> >
> > Bob, my own motivation for going to fiber was entirely different. I
> > simply wanted to
> > run 10 MHz all over the place from reference sources in disparate
> > locations in the
> > house, and I quickly discovered that cable leakage was embarrassingly
> > severe. So
> > I shut down and began contemplating a fiber link. But then reality set
> in
> > and I realized
> > that running fiber across the house had its own big problems, so I set
> the
> > project aside.
> >
> > Dana
> >
> >
> > On Sat, Aug 28, 2021 at 3:32 PM Bob kb8tq wrote:
> >
> >> Hi
> >>
> >> With a whole variety of pretty good OCXO’s going for cheap money
> >> on eBay, it’s likely less expensive to do cleanup oscillators on the
> link
> >> compared to going crazy with low noise optical this or that. Yes, you
> >> will be getting something in the high 150’s for noise, but still pretty
> >> good
> >> for $10.
> >>
> >> If you need better, spend $50 or so on a 10811. Still less money than
> >> some of the crazy fiber stuff.
> >>
> >> With either one, send over a high enough frequency that the loop isn’t
> >> dealing with reference spurs in any significant way. Given the clock
> rates
> >> Ethernet runs at these days, that part should be fairly straightforward.
> >>
> >> This *assumes* that there is a crossover somewhere practical between
> >> the fiber noise and the noise on the optical gear. You should be able to
> >> work out what it is with some fairly normal phase noise or ADEV testing.
> >>
> >> Bob
> >>
> >>> On Aug 28, 2021, at 3:03 PM, Dana Whitlow
> wrote:
> >>>
> >>> I was looking for something similar about 18 months or so ago.
> Although
> >> I
> >>> haven't taken any
> >>> action yet, I concluded that one could do a nice job for under $200 per
> >>> segment, including the
> >>> transmitter and receiver modules and lots of connectorized multimode
> >>> fiber. What I *don't* know
> >>> is what the phase noise performance would be, except that I do know
> that
> >>> the fiber's VF *is*
> >>> materially influenced by temperature.
> >>>
> >>> I was looking primarily at the HFBR-2416 for the fiber receiver, and
> the
> >>> HFBR-1412 (standard
> >>> power) or the HFBR-1414 (high power option) for the transmitter
> Unlike
> >>> most of the available
> >>> models, these are fundamentally analog devices, meaning that you can
> >>> transmit sinewave
> >>> 10 MHz through them. At the time I was looking, Mouser was selling
> these
> >>> for about $20 each.
> >>>
> >>> See the datasheet at
> >>>
> >>
> https://www.mouser.com/datasheet/2/678/AV02-0176EN_2019-02-15-1827546.pdf
> >>> with particular attention to page 21 regarding the HFBR-2416 receiver.
> >>>
> >>> I was also looking at Fiber Instrument Sales for patch cords. We
> bought
> >> a
> >>> lot of fiber stuff from
> >>> them at Arecibo, and I was always happy with them. See:
> >>>
> >>
> https://www.fiberinstrumentsales.com/catalog-cable-assemblies?gclid=Cj0KCQjwvaeJBhCvARIsABgTDM7eNTkP2nQbyFzhcwDE38VnSEP879MBKV1ZyDq2YrnEtOn7_VfzjbkaAtpfEALw_wcB
> >>>
> >>> Somebody had pointed out yet another source of connectorized fibers
> >> ("patch
> >>> cords") to me, but I cannot find the name
> >>> at the moment.
> >>>
> >>> Dana K8YUM
> >>>
> >>>
> >>> On Sat, Aug 28, 2021 at 11:52 AM AC0XU (Jim) <
> james.schatz...@ac0xu.com>
> >>> wrote:
> >>>
> I am hoping that you can help me about a couple of things:
>
> 1) My time-nuts summaries sometimes appear unformatted and unreadable.
> >> All
> the text from all the postings is crammed together without spacing.
> How
> >> can
> I fix it?
>
> 2) I want to distribute 10 MHz references by fiber. There are
> RF-over-Fiber products available, but too expensive for me (thousands
> of
> $$$ per xmit/rcv set). I am thinking that it should be possible to
> use
> fiber Ethernet components to do this. I don't mean IEEE 1588 but a
> much
> simpler, no-computer-required, solution. Possibly just converting sine
> >> wave
> (coax) to square wave (fiber) to sine wave (coax). I am looking for a
> >> low
> cost solution. Any thoughts or recommendations??
>
> Thanks!
>
> Jim
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
> >> send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
>
> >>>
[time-nuts] Re: Query about List and about 10 MHz Distro
On 8/28/21 4:57 PM, Dana Whitlow wrote: Bob, my own motivation for going to fiber was entirely different. I simply wanted to run 10 MHz all over the place from reference sources in disparate locations in the house, and I quickly discovered that cable leakage was embarrassingly severe. So I shut down and began contemplating a fiber link. But then reality set in and I realized that running fiber across the house had its own big problems, so I set the project aside. Dana just thinking out loud here.. there's a bucket load of cheap "media converters" around from fiber to twisted pair ethernet or RS422 - including older 10 and 100 base T. I wonder if they'd be repurposeable for 10 MHz distribution. or video over fiber widgets - used a lot for cameras and such. There's been some discussion on the list about using video distribution amps for 10MHz. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Query about List and about 10 MHz Distro
Hi
Anything you do that has a bunch of 10 MHz cables running out from here or there
will impact your ability to listen to WWV at 10 MHz :) Other than killing all
the sources,
there is no silver bullet.
Bob
> On Aug 28, 2021, at 7:57 PM, Dana Whitlow wrote:
>
> Bob, my own motivation for going to fiber was entirely different. I
> simply wanted to
> run 10 MHz all over the place from reference sources in disparate
> locations in the
> house, and I quickly discovered that cable leakage was embarrassingly
> severe. So
> I shut down and began contemplating a fiber link. But then reality set in
> and I realized
> that running fiber across the house had its own big problems, so I set the
> project aside.
>
> Dana
>
>
> On Sat, Aug 28, 2021 at 3:32 PM Bob kb8tq wrote:
>
>> Hi
>>
>> With a whole variety of pretty good OCXO’s going for cheap money
>> on eBay, it’s likely less expensive to do cleanup oscillators on the link
>> compared to going crazy with low noise optical this or that. Yes, you
>> will be getting something in the high 150’s for noise, but still pretty
>> good
>> for $10.
>>
>> If you need better, spend $50 or so on a 10811. Still less money than
>> some of the crazy fiber stuff.
>>
>> With either one, send over a high enough frequency that the loop isn’t
>> dealing with reference spurs in any significant way. Given the clock rates
>> Ethernet runs at these days, that part should be fairly straightforward.
>>
>> This *assumes* that there is a crossover somewhere practical between
>> the fiber noise and the noise on the optical gear. You should be able to
>> work out what it is with some fairly normal phase noise or ADEV testing.
>>
>> Bob
>>
>>> On Aug 28, 2021, at 3:03 PM, Dana Whitlow wrote:
>>>
>>> I was looking for something similar about 18 months or so ago. Although
>> I
>>> haven't taken any
>>> action yet, I concluded that one could do a nice job for under $200 per
>>> segment, including the
>>> transmitter and receiver modules and lots of connectorized multimode
>>> fiber. What I *don't* know
>>> is what the phase noise performance would be, except that I do know that
>>> the fiber's VF *is*
>>> materially influenced by temperature.
>>>
>>> I was looking primarily at the HFBR-2416 for the fiber receiver, and the
>>> HFBR-1412 (standard
>>> power) or the HFBR-1414 (high power option) for the transmitter Unlike
>>> most of the available
>>> models, these are fundamentally analog devices, meaning that you can
>>> transmit sinewave
>>> 10 MHz through them. At the time I was looking, Mouser was selling these
>>> for about $20 each.
>>>
>>> See the datasheet at
>>>
>> https://www.mouser.com/datasheet/2/678/AV02-0176EN_2019-02-15-1827546.pdf
>>> with particular attention to page 21 regarding the HFBR-2416 receiver.
>>>
>>> I was also looking at Fiber Instrument Sales for patch cords. We bought
>> a
>>> lot of fiber stuff from
>>> them at Arecibo, and I was always happy with them. See:
>>>
>> https://www.fiberinstrumentsales.com/catalog-cable-assemblies?gclid=Cj0KCQjwvaeJBhCvARIsABgTDM7eNTkP2nQbyFzhcwDE38VnSEP879MBKV1ZyDq2YrnEtOn7_VfzjbkaAtpfEALw_wcB
>>>
>>> Somebody had pointed out yet another source of connectorized fibers
>> ("patch
>>> cords") to me, but I cannot find the name
>>> at the moment.
>>>
>>> Dana K8YUM
>>>
>>>
>>> On Sat, Aug 28, 2021 at 11:52 AM AC0XU (Jim)
>>> wrote:
>>>
I am hoping that you can help me about a couple of things:
1) My time-nuts summaries sometimes appear unformatted and unreadable.
>> All
the text from all the postings is crammed together without spacing. How
>> can
I fix it?
2) I want to distribute 10 MHz references by fiber. There are
RF-over-Fiber products available, but too expensive for me (thousands of
$$$ per xmit/rcv set). I am thinking that it should be possible to use
fiber Ethernet components to do this. I don't mean IEEE 1588 but a much
simpler, no-computer-required, solution. Possibly just converting sine
>> wave
(coax) to square wave (fiber) to sine wave (coax). I am looking for a
>> low
cost solution. Any thoughts or recommendations??
Thanks!
Jim
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
>> send
an email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.
>>> ___
>>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
>> send an email to time-nuts-le...@lists.febo.com
>>> To unsubscribe, go to and follow the instructions there.
>> ___
>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
>> an email to time-nuts-le...@lists.febo.com
>> To unsubscribe, go to and follow the instructions there.
> ___
> time-nuts
[time-nuts] Re: Query about List and about 10 MHz Distro
Bob, my own motivation for going to fiber was entirely different. I
simply wanted to
run 10 MHz all over the place from reference sources in disparate
locations in the
house, and I quickly discovered that cable leakage was embarrassingly
severe. So
I shut down and began contemplating a fiber link. But then reality set in
and I realized
that running fiber across the house had its own big problems, so I set the
project aside.
Dana
On Sat, Aug 28, 2021 at 3:32 PM Bob kb8tq wrote:
> Hi
>
> With a whole variety of pretty good OCXO’s going for cheap money
> on eBay, it’s likely less expensive to do cleanup oscillators on the link
> compared to going crazy with low noise optical this or that. Yes, you
> will be getting something in the high 150’s for noise, but still pretty
> good
> for $10.
>
> If you need better, spend $50 or so on a 10811. Still less money than
> some of the crazy fiber stuff.
>
> With either one, send over a high enough frequency that the loop isn’t
> dealing with reference spurs in any significant way. Given the clock rates
> Ethernet runs at these days, that part should be fairly straightforward.
>
> This *assumes* that there is a crossover somewhere practical between
> the fiber noise and the noise on the optical gear. You should be able to
> work out what it is with some fairly normal phase noise or ADEV testing.
>
> Bob
>
> > On Aug 28, 2021, at 3:03 PM, Dana Whitlow wrote:
> >
> > I was looking for something similar about 18 months or so ago. Although
> I
> > haven't taken any
> > action yet, I concluded that one could do a nice job for under $200 per
> > segment, including the
> > transmitter and receiver modules and lots of connectorized multimode
> > fiber. What I *don't* know
> > is what the phase noise performance would be, except that I do know that
> > the fiber's VF *is*
> > materially influenced by temperature.
> >
> > I was looking primarily at the HFBR-2416 for the fiber receiver, and the
> > HFBR-1412 (standard
> > power) or the HFBR-1414 (high power option) for the transmitter Unlike
> > most of the available
> > models, these are fundamentally analog devices, meaning that you can
> > transmit sinewave
> > 10 MHz through them. At the time I was looking, Mouser was selling these
> > for about $20 each.
> >
> > See the datasheet at
> >
> https://www.mouser.com/datasheet/2/678/AV02-0176EN_2019-02-15-1827546.pdf
> > with particular attention to page 21 regarding the HFBR-2416 receiver.
> >
> > I was also looking at Fiber Instrument Sales for patch cords. We bought
> a
> > lot of fiber stuff from
> > them at Arecibo, and I was always happy with them. See:
> >
> https://www.fiberinstrumentsales.com/catalog-cable-assemblies?gclid=Cj0KCQjwvaeJBhCvARIsABgTDM7eNTkP2nQbyFzhcwDE38VnSEP879MBKV1ZyDq2YrnEtOn7_VfzjbkaAtpfEALw_wcB
> >
> > Somebody had pointed out yet another source of connectorized fibers
> ("patch
> > cords") to me, but I cannot find the name
> > at the moment.
> >
> > Dana K8YUM
> >
> >
> > On Sat, Aug 28, 2021 at 11:52 AM AC0XU (Jim)
> > wrote:
> >
> >> I am hoping that you can help me about a couple of things:
> >>
> >> 1) My time-nuts summaries sometimes appear unformatted and unreadable.
> All
> >> the text from all the postings is crammed together without spacing. How
> can
> >> I fix it?
> >>
> >> 2) I want to distribute 10 MHz references by fiber. There are
> >> RF-over-Fiber products available, but too expensive for me (thousands of
> >> $$$ per xmit/rcv set). I am thinking that it should be possible to use
> >> fiber Ethernet components to do this. I don't mean IEEE 1588 but a much
> >> simpler, no-computer-required, solution. Possibly just converting sine
> wave
> >> (coax) to square wave (fiber) to sine wave (coax). I am looking for a
> low
> >> cost solution. Any thoughts or recommendations??
> >>
> >> Thanks!
> >>
> >> Jim
> >> ___
> >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
> send
> >> an email to time-nuts-le...@lists.febo.com
> >> To unsubscribe, go to and follow the instructions there.
> >>
> > ___
> > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
> send an email to time-nuts-le...@lists.febo.com
> > To unsubscribe, go to and follow the instructions there.
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Query about List and about 10 MHz Distro
Hi
With a whole variety of pretty good OCXO’s going for cheap money
on eBay, it’s likely less expensive to do cleanup oscillators on the link
compared to going crazy with low noise optical this or that. Yes, you
will be getting something in the high 150’s for noise, but still pretty good
for $10.
If you need better, spend $50 or so on a 10811. Still less money than
some of the crazy fiber stuff.
With either one, send over a high enough frequency that the loop isn’t
dealing with reference spurs in any significant way. Given the clock rates
Ethernet runs at these days, that part should be fairly straightforward.
This *assumes* that there is a crossover somewhere practical between
the fiber noise and the noise on the optical gear. You should be able to
work out what it is with some fairly normal phase noise or ADEV testing.
Bob
> On Aug 28, 2021, at 3:03 PM, Dana Whitlow wrote:
>
> I was looking for something similar about 18 months or so ago. Although I
> haven't taken any
> action yet, I concluded that one could do a nice job for under $200 per
> segment, including the
> transmitter and receiver modules and lots of connectorized multimode
> fiber. What I *don't* know
> is what the phase noise performance would be, except that I do know that
> the fiber's VF *is*
> materially influenced by temperature.
>
> I was looking primarily at the HFBR-2416 for the fiber receiver, and the
> HFBR-1412 (standard
> power) or the HFBR-1414 (high power option) for the transmitter Unlike
> most of the available
> models, these are fundamentally analog devices, meaning that you can
> transmit sinewave
> 10 MHz through them. At the time I was looking, Mouser was selling these
> for about $20 each.
>
> See the datasheet at
> https://www.mouser.com/datasheet/2/678/AV02-0176EN_2019-02-15-1827546.pdf
> with particular attention to page 21 regarding the HFBR-2416 receiver.
>
> I was also looking at Fiber Instrument Sales for patch cords. We bought a
> lot of fiber stuff from
> them at Arecibo, and I was always happy with them. See:
> https://www.fiberinstrumentsales.com/catalog-cable-assemblies?gclid=Cj0KCQjwvaeJBhCvARIsABgTDM7eNTkP2nQbyFzhcwDE38VnSEP879MBKV1ZyDq2YrnEtOn7_VfzjbkaAtpfEALw_wcB
>
> Somebody had pointed out yet another source of connectorized fibers ("patch
> cords") to me, but I cannot find the name
> at the moment.
>
> Dana K8YUM
>
>
> On Sat, Aug 28, 2021 at 11:52 AM AC0XU (Jim)
> wrote:
>
>> I am hoping that you can help me about a couple of things:
>>
>> 1) My time-nuts summaries sometimes appear unformatted and unreadable. All
>> the text from all the postings is crammed together without spacing. How can
>> I fix it?
>>
>> 2) I want to distribute 10 MHz references by fiber. There are
>> RF-over-Fiber products available, but too expensive for me (thousands of
>> $$$ per xmit/rcv set). I am thinking that it should be possible to use
>> fiber Ethernet components to do this. I don't mean IEEE 1588 but a much
>> simpler, no-computer-required, solution. Possibly just converting sine wave
>> (coax) to square wave (fiber) to sine wave (coax). I am looking for a low
>> cost solution. Any thoughts or recommendations??
>>
>> Thanks!
>>
>> Jim
>> ___
>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
>> an email to time-nuts-le...@lists.febo.com
>> To unsubscribe, go to and follow the instructions there.
>>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an
> email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Query about List and about 10 MHz Distro
White rabbit seems pretty good for time synced over fiber. PTP with
enhanced stability profile. It's a IEEE standard. It seems to work for
CERN. Lately I've been looking at Cisco devices that can support it. It
whould be nice if I could find hardware that'll support it more easily...
Maybe it'll come soon?
If you need optics I highly recommend AMC optics they'll code (Cisco,
Intel, NetApp) SFP+ and QSFP for any vendor you want. Prices are great and
it's all made the USA no relation to me. I've been getting into 100G
Ethernet over OM4 fiber. The new profile for PTP over fiber is legit.
Bill
On Sat, Aug 28, 2021, 12:04 PM Dana Whitlow wrote:
> I was looking for something similar about 18 months or so ago. Although I
> haven't taken any
> action yet, I concluded that one could do a nice job for under $200 per
> segment, including the
> transmitter and receiver modules and lots of connectorized multimode
> fiber. What I *don't* know
> is what the phase noise performance would be, except that I do know that
> the fiber's VF *is*
> materially influenced by temperature.
>
> I was looking primarily at the HFBR-2416 for the fiber receiver, and the
> HFBR-1412 (standard
> power) or the HFBR-1414 (high power option) for the transmitter Unlike
> most of the available
> models, these are fundamentally analog devices, meaning that you can
> transmit sinewave
> 10 MHz through them. At the time I was looking, Mouser was selling these
> for about $20 each.
>
> See the datasheet at
> https://www.mouser.com/datasheet/2/678/AV02-0176EN_2019-02-15-1827546.pdf
> with particular attention to page 21 regarding the HFBR-2416 receiver.
>
> I was also looking at Fiber Instrument Sales for patch cords. We bought a
> lot of fiber stuff from
> them at Arecibo, and I was always happy with them. See:
>
> https://www.fiberinstrumentsales.com/catalog-cable-assemblies?gclid=Cj0KCQjwvaeJBhCvARIsABgTDM7eNTkP2nQbyFzhcwDE38VnSEP879MBKV1ZyDq2YrnEtOn7_VfzjbkaAtpfEALw_wcB
>
> Somebody had pointed out yet another source of connectorized fibers ("patch
> cords") to me, but I cannot find the name
> at the moment.
>
> Dana K8YUM
>
>
> On Sat, Aug 28, 2021 at 11:52 AM AC0XU (Jim)
> wrote:
>
> > I am hoping that you can help me about a couple of things:
> >
> > 1) My time-nuts summaries sometimes appear unformatted and unreadable.
> All
> > the text from all the postings is crammed together without spacing. How
> can
> > I fix it?
> >
> > 2) I want to distribute 10 MHz references by fiber. There are
> > RF-over-Fiber products available, but too expensive for me (thousands of
> > $$$ per xmit/rcv set). I am thinking that it should be possible to use
> > fiber Ethernet components to do this. I don't mean IEEE 1588 but a much
> > simpler, no-computer-required, solution. Possibly just converting sine
> wave
> > (coax) to square wave (fiber) to sine wave (coax). I am looking for a low
> > cost solution. Any thoughts or recommendations??
> >
> > Thanks!
> >
> > Jim
> > ___
> > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
> send
> > an email to time-nuts-le...@lists.febo.com
> > To unsubscribe, go to and follow the instructions there.
> >
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
>
___
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email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Query about List and about 10 MHz Distro
I was looking for something similar about 18 months or so ago. Although I
haven't taken any
action yet, I concluded that one could do a nice job for under $200 per
segment, including the
transmitter and receiver modules and lots of connectorized multimode
fiber. What I *don't* know
is what the phase noise performance would be, except that I do know that
the fiber's VF *is*
materially influenced by temperature.
I was looking primarily at the HFBR-2416 for the fiber receiver, and the
HFBR-1412 (standard
power) or the HFBR-1414 (high power option) for the transmitter Unlike
most of the available
models, these are fundamentally analog devices, meaning that you can
transmit sinewave
10 MHz through them. At the time I was looking, Mouser was selling these
for about $20 each.
See the datasheet at
https://www.mouser.com/datasheet/2/678/AV02-0176EN_2019-02-15-1827546.pdf
with particular attention to page 21 regarding the HFBR-2416 receiver.
I was also looking at Fiber Instrument Sales for patch cords. We bought a
lot of fiber stuff from
them at Arecibo, and I was always happy with them. See:
https://www.fiberinstrumentsales.com/catalog-cable-assemblies?gclid=Cj0KCQjwvaeJBhCvARIsABgTDM7eNTkP2nQbyFzhcwDE38VnSEP879MBKV1ZyDq2YrnEtOn7_VfzjbkaAtpfEALw_wcB
Somebody had pointed out yet another source of connectorized fibers ("patch
cords") to me, but I cannot find the name
at the moment.
Dana K8YUM
On Sat, Aug 28, 2021 at 11:52 AM AC0XU (Jim)
wrote:
> I am hoping that you can help me about a couple of things:
>
> 1) My time-nuts summaries sometimes appear unformatted and unreadable. All
> the text from all the postings is crammed together without spacing. How can
> I fix it?
>
> 2) I want to distribute 10 MHz references by fiber. There are
> RF-over-Fiber products available, but too expensive for me (thousands of
> $$$ per xmit/rcv set). I am thinking that it should be possible to use
> fiber Ethernet components to do this. I don't mean IEEE 1588 but a much
> simpler, no-computer-required, solution. Possibly just converting sine wave
> (coax) to square wave (fiber) to sine wave (coax). I am looking for a low
> cost solution. Any thoughts or recommendations??
>
> Thanks!
>
> Jim
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
>
___
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email to time-nuts-le...@lists.febo.com
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[time-nuts] Re: 1 PPS question
On 8/28/21 10:25 AM, Robert DiRosario wrote: For GPS receivers that give 1 PPS output the spacing between pulses is, obviously, very accurate. Are the pulses synchronized to something, like UTC seconds, or does it vary from one manufacturer to another, or even one unit to another? GPS seconds (which are very close to UTC, except for the fact that UTC is an ensemble time, which technically isn't available until it's been processed). Your receiver documentation should say whether it's the rising or falling edge of the pulse. Some receivers, just to make things exciting, generate the pulse by gating an internal clock, so at the nanosecond level, there's a variation due to the internal clock not being synced with GPS, but free running. Some receivers will tell you what the offset is in some data message. Or, it won't, and you have to measure it (or average over many seconds, which is what GPSDOs do). A simple question you ask and it can lead you down such a rabbit hole with hanging bridges, steps, etc. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Query about List and about 10 MHz Distro
Look at Synchronous Ethernet. On Sat, 28 Aug 2021, 17:51 AC0XU (Jim), wrote: > I am hoping that you can help me about a couple of things: > > 1) My time-nuts summaries sometimes appear unformatted and unreadable. All > the text from all the postings is crammed together without spacing. How can > I fix it? > > 2) I want to distribute 10 MHz references by fiber. There are > RF-over-Fiber products available, but too expensive for me (thousands of > $$$ per xmit/rcv set). I am thinking that it should be possible to use > fiber Ethernet components to do this. I don't mean IEEE 1588 but a much > simpler, no-computer-required, solution. Possibly just converting sine wave > (coax) to square wave (fiber) to sine wave (coax). I am looking for a low > cost solution. Any thoughts or recommendations?? > > Thanks! > > Jim > ___ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send > an email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] 1 PPS question
For GPS receivers that give 1 PPS output the spacing between pulses is, obviously, very accurate. Are the pulses synchronized to something, like UTC seconds, or does it vary from one manufacturer to another, or even one unit to another? Thanks Robert ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Query about List and about 10 MHz Distro
On 8/28/21 9:56 AM, Andy Talbot wrote: When I asked about this on another Group a while back, I was told the phase noise made it an undesirable solution. Although I never tried it, I would imaging balanced shielded twisted pair would be a better way to go. Immune from ground loop problems than can beset coax distribution and a whole raft of ICs support the medium, from RS422 to CAN bus drivers and receivers. Andy www.g4jnt.com We use fiber to distribute high quality 10 and 100 MHz at JPL. I can visualize the rack downstairs from my office where the cables terminate, but I can't for the life of me remember the brand name. It's a 3U card.. DSN does it as well, with obsessive attention to temperature, mechanical stress, etc. From 20 years ago: https://tmo.jpl.nasa.gov/progress_report/42-148/148L.pdf - probably overkill PTS has a Fiber distribution amp: https://www.ptsyst.com/DA1-100-10-FO-B.pdf There's this, but Im going to bet it's pricey: https://emcore.com/products/reference-timing/ On Sat, 28 Aug 2021 at 17:51, AC0XU (Jim) wrote: I am hoping that you can help me about a couple of things: 1) My time-nuts summaries sometimes appear unformatted and unreadable. All the text from all the postings is crammed together without spacing. How can I fix it? 2) I want to distribute 10 MHz references by fiber. There are RF-over-Fiber products available, but too expensive for me (thousands of $$$ per xmit/rcv set). I am thinking that it should be possible to use fiber Ethernet components to do this. I don't mean IEEE 1588 but a much simpler, no-computer-required, solution. Possibly just converting sine wave (coax) to square wave (fiber) to sine wave (coax). I am looking for a low cost solution. Any thoughts or recommendations?? Thanks! Jim ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Query about List and about 10 MHz Distro
On 8/28/21 9:51 AM, AC0XU (Jim) wrote: I am hoping that you can help me about a couple of things: 1) My time-nuts summaries sometimes appear unformatted and unreadable. All the text from all the postings is crammed together without spacing. How can I fix it? 2) I want to distribute 10 MHz references by fiber. There are RF-over-Fiber products available, but too expensive for me (thousands of $$$ per xmit/rcv set). I am thinking that it should be possible to use fiber Ethernet components to do this. I don't mean IEEE 1588 but a much simpler, no-computer-required, solution. Possibly just converting sine wave (coax) to square wave (fiber) to sine wave (coax). I am looking for a low cost solution. Any thoughts or recommendations?? Take a look at the standard fiber optic modules that plug into a switch. They typically have a very simple logic level interface to the diode. here's a $27 dollar example - but I think you might want to iterate around - I recall finding cheaper ones - part of it is which fiber cable/connector you use, and part of it is what the backside interface looks like. I can't find it now, but you can get the mating electrical connector, or you can solder wires. https://www.fs.com/products/11555.html?attribute=77=219732 The OVRO-LWA uses fiber to connect the remote antenna preamp with ~1km fiber to the receiver at 30-90 MHz - they use a laser diode on the Tx end and a receiver on the Rx end. They're pretty cheap. They've done quite a bit of testing of various schemes, and measuring noise performance and loss. dig around here: http://www.tauceti.caltech.edu/LWA/lwamemos.html In particular memo 12 http://www.tauceti.caltech.edu/LWA/memos/memo12.pdf - gives a couple part numbers. If you need Sandy Weinreb's report (from 2019, referenced by Larry D'Addario in memo 12) - you could probably email him, or I can look for a copy. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Query about List and about 10 MHz Distro
When I asked about this on another Group a while back, I was told the phase noise made it an undesirable solution. Although I never tried it, I would imaging balanced shielded twisted pair would be a better way to go. Immune from ground loop problems than can beset coax distribution and a whole raft of ICs support the medium, from RS422 to CAN bus drivers and receivers. Andy www.g4jnt.com On Sat, 28 Aug 2021 at 17:51, AC0XU (Jim) wrote: > I am hoping that you can help me about a couple of things: > > 1) My time-nuts summaries sometimes appear unformatted and unreadable. All > the text from all the postings is crammed together without spacing. How can > I fix it? > > 2) I want to distribute 10 MHz references by fiber. There are > RF-over-Fiber products available, but too expensive for me (thousands of > $$$ per xmit/rcv set). I am thinking that it should be possible to use > fiber Ethernet components to do this. I don't mean IEEE 1588 but a much > simpler, no-computer-required, solution. Possibly just converting sine wave > (coax) to square wave (fiber) to sine wave (coax). I am looking for a low > cost solution. Any thoughts or recommendations?? > > Thanks! > > Jim > ___ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send > an email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Query about List and about 10 MHz Distro
I am hoping that you can help me about a couple of things: 1) My time-nuts summaries sometimes appear unformatted and unreadable. All the text from all the postings is crammed together without spacing. How can I fix it? 2) I want to distribute 10 MHz references by fiber. There are RF-over-Fiber products available, but too expensive for me (thousands of $$$ per xmit/rcv set). I am thinking that it should be possible to use fiber Ethernet components to do this. I don't mean IEEE 1588 but a much simpler, no-computer-required, solution. Possibly just converting sine wave (coax) to square wave (fiber) to sine wave (coax). I am looking for a low cost solution. Any thoughts or recommendations?? Thanks! Jim ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Stanford Research SR620 GBIB
Perhaps use the rs232 interface with a USB adapter? On 2021-08-28 04:29, Julien Goodwin wrote: On 28/8/21 5:33 pm, Volker Esper wrote: Julien, Can you please tell us wich GPIB-adapter you are using? Thanks Volker Didn't have that info to hand when I wrote the mail, one of these: http://www.galvant.ca/#!/store/gpibusb (possibly an earlier rev, but there's nothing on the PCB to indicate, other than a year of 2014) I should have an alternative *somewhere* around here, but I doubt my luck finding it, and it's a similar sort of device, just a different implementation. On 28/8/21 5:50 pm, Dave Baxter via time-nuts wrote: I'd be inclined to check the SR620's exact needs re command/query terminators, and also how exactly it terminates its responses. From your description, it sounds like that sort of issue. It may be, your GPIB device or its handler code is not recognising the end of the instruments response, and also buffers are not being flushed before starting another query transaction. So youre software get "out of step" between what it sends to the instrument and what it sees coming back. The eventual lockup, is also indicating potential buffer problems. I absolutely agree, except that it's not quite consistent behavior, and it's just the SR620 that does it. If I was consistently getting a reading delayed every time I'd assume one of the commands is responding that I don't expect, but that's not what it seems to be. Possibly adding a few extra sleep calls into my init code will help. You need to see "exactly" what data is happening on the GPIB itself, does your device/support code have any sort of bus analyzer capability? Nope, I could rig up an adapter on my MSO scope, or possibly pick up an old HP one, but the cost in almost any of these options (especially by the time you include shipping to Australia) is getting up there with just buying a newer HPAK counter. Given that such a logic analyser adapter is easy enough to design that I might as well do that, putting the PCBs and connectors on my next orders with those suppliers. 73. Dave G8KBV. Message: 4 Date: Sat, 28 Aug 2021 17:03:09 +1000 From: Julien Goodwin Subject: [time-nuts] Stanford Research SR620 GBIB To: Discussion of precise time and frequency measurement Message-ID: <4e137f33-67e5-c00c-0293-16276e591...@studio442.com.au> Content-Type: text/plain; charset=utf-8 For an upcoming (very time-nutty, and hopefully to be shared soon) project I need to finally do some frequency datalogging. I've had a Stanford SR620 sitting around, and plugged it in to a handy GPIB adapter (*not* a major commercial one, one of the community ones). While I can get it to talk GPIB there seems to be some reliability issues, with what looks to be some form of read buffering happening, with measurement results coming in as the answer to some later command. A few times I've even restarted it as it stopped responding (luckily that hasn't happened once measurements had started). Since I'm hoping to actually use measurements as part of a control loop this is obviously a bad thing. Does anyone have any experience with the SR620 & GPIB as to why this might be happening? I've not experienced this with other instruments (ancient HP, modern Keysight, recent Keithley, 90s Anritsu) I've used with the same GPIB adapter. The SR620 has version 1.48 firmware. -- On Sat, 28 Aug 2021 08:31 , wrote: Send time-nuts mailing list submissions to time-nuts@lists.febo.com To subscribe or unsubscribe via email, send a message with subject or body 'help' to time-nuts-requ...@lists.febo.com You can reach the person managing the list at time-nuts-ow...@lists.febo.com When replying, please edit your Subject line so it is more specific than "Re: Contents of time-nuts digest..." Today's Topics: 1. Re: Leviton VTP24 Is this Time Accurate enough? (Dana Whitlow) 2. Re: Leviton VTP24 Is this Time Accurate enough? (Lux, Jim) 3. Re: uncertainty/SNR of IQ measurements (Joseph Gwinn) 4. Stanford Research SR620 GBIB (Julien Goodwin) -- Message: 1 Date: Fri, 27 Aug 2021 05:30:14 -0500 From: Dana Whitlow Subject: [time-nuts] Re: Leviton VTP24 Is this Time Accurate enough? To: Discussion of precise time and frequency measurement Message-ID: Content-Type: text/plain; charset="UTF-8" If my watch were that bad, I'd toss it out and go shopping for a new one. I wonder if Leviton offers a version with an external ref input. Dana On Fri, Aug 27, 2021 at 12:12 AM D. Resor wrote: I inquired with Leviton as to the accuracy of the VTP24 24 Hour Programmable Timer with DST. https://www.leviton.com/en/products/vpt24-1pz Don Resor Here is the reply I received: Hello, Thank you for contacting Leviton technical support. According to the code it meets, it is required to have time keeping accuracy
[time-nuts] Re: Comparison/evaluation of u-blox timing receivers
John: I missed this on its intro to the group. Great paper and effort. It's also a very useful intro/primer to measurement methodology beyond application to only the u-blox family. Thanks for leveraging the NSF for our benefit! Don On 2021-08-28 05:02, Julien Goodwin wrote: On 24/8/21 11:51 am, John Ackermann N8UR wrote: In 2020 I did an extensive evaluation of the timing ability of the u-blox LEA-M8F, NEO-M8N, NEO-M8T, NEO-M9N, ZED-F9P, and ZED-F9T. The work was made possible by support from the HamSci consortium (https://hamsci.org) under NSF grants supporting HamSci activities. I was sure I'd posted about the paper on time-nuts, but I can't find any record that I did, so this is a belated announcement. It's available for download from https://hamsci.org/sites/default/files/publications/2020_TAPR_DCC/N8UR_GPS_Evaluation_August2020.pdf As BobC says, "Lots of fun!" Neat. For a project I might eventually get back to I was looking at using the M8F controlling an external oscillator. I built a test board[1], but I stopped once I had the GPS working, I can't recall if I even enabled the control of the external oscillator, but I certainly didn't make any attempt to characterize it. Once I get my frequency datalogging issue solved for my other project I might try and see what I get. 1: https://laptop006.livejournal.com/60072.html the DAC, oscillator and supporting components are all in the bottom-left. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there. The whole world is a straight man. -- Dr. Don Latham AJ7LL PO Box 404, Frenchtown, MT, 59834 VOX: 406-626-4304 ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Subject: Re: Leviton VTP24 Is this Time Accurate enough? - Line Frequency and TXOs
We have been running long term tests on a TXO chip we use for time keeping vs line frequency vs NIST time. Over 4 years the TXO is within 4 minutes Line Frequency 9 minutes The TXO is well within specification - and the line frequency is off because we lose power in our leafy Boston suburb a lot - and the control fall over to an older time keeping chip. Thomas D. Erb p:508-359-4396 f:508-359-4482 a:97 West Street, Medfield, MA 02052 USA e: t...@electrictime.com w:www.electrictime.com Tower & Street Clocks Since 1928 ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Comparison/evaluation of u-blox timing receivers
On 24/8/21 11:51 am, John Ackermann N8UR wrote: > In 2020 I did an extensive evaluation of the timing ability of the > u-blox LEA-M8F, NEO-M8N, NEO-M8T, NEO-M9N, ZED-F9P, and ZED-F9T. The > work was made possible by support from the HamSci consortium > (https://hamsci.org) under NSF grants supporting HamSci activities. > > I was sure I'd posted about the paper on time-nuts, but I can't find any > record that I did, so this is a belated announcement. It's available > for download from > > https://hamsci.org/sites/default/files/publications/2020_TAPR_DCC/N8UR_GPS_Evaluation_August2020.pdf > > > As BobC says, "Lots of fun!" Neat. For a project I might eventually get back to I was looking at using the M8F controlling an external oscillator. I built a test board[1], but I stopped once I had the GPS working, I can't recall if I even enabled the control of the external oscillator, but I certainly didn't make any attempt to characterize it. Once I get my frequency datalogging issue solved for my other project I might try and see what I get. 1: https://laptop006.livejournal.com/60072.html the DAC, oscillator and supporting components are all in the bottom-left. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: Stanford Research SR620 GBIB
On 28/8/21 5:33 pm, Volker Esper wrote: > Julien, > Can you please tell us wich GPIB-adapter you are using? > Thanks > Volker Didn't have that info to hand when I wrote the mail, one of these: http://www.galvant.ca/#!/store/gpibusb (possibly an earlier rev, but there's nothing on the PCB to indicate, other than a year of 2014) I should have an alternative *somewhere* around here, but I doubt my luck finding it, and it's a similar sort of device, just a different implementation. On 28/8/21 5:50 pm, Dave Baxter via time-nuts wrote: > I'd be inclined to check the SR620's exact needs re command/query > terminators, and also how exactly it terminates its responses. > > From your description, it sounds like that sort of issue. > > It may be, your GPIB device or its handler code is not recognising the end > of the instruments response, and also buffers are not being flushed before > starting another query transaction. > > So youre software get "out of step" between what it sends to the instrument > and what it sees coming back. > > The eventual lockup, is also indicating potential buffer problems. I absolutely agree, except that it's not quite consistent behavior, and it's just the SR620 that does it. If I was consistently getting a reading delayed every time I'd assume one of the commands is responding that I don't expect, but that's not what it seems to be. Possibly adding a few extra sleep calls into my init code will help. > You need to see "exactly" what data is happening on the GPIB itself, does > your device/support code have any sort of bus analyzer capability? Nope, I could rig up an adapter on my MSO scope, or possibly pick up an old HP one, but the cost in almost any of these options (especially by the time you include shipping to Australia) is getting up there with just buying a newer HPAK counter. Given that such a logic analyser adapter is easy enough to design that I might as well do that, putting the PCBs and connectors on my next orders with those suppliers. > 73. > > Dave G8KBV. > > > Message: 4 > Date: Sat, 28 Aug 2021 17:03:09 +1000 > From: Julien Goodwin > Subject: [time-nuts] Stanford Research SR620 GBIB > To: Discussion of precise time and frequency measurement > > Message-ID: <4e137f33-67e5-c00c-0293-16276e591...@studio442.com.au> > Content-Type: text/plain; charset=utf-8 > > For an upcoming (very time-nutty, and hopefully to be shared soon) > project I need to finally do some frequency datalogging. > > I've had a Stanford SR620 sitting around, and plugged it in to a handy > GPIB adapter (*not* a major commercial one, one of the community ones). > > While I can get it to talk GPIB there seems to be some reliability > issues, with what looks to be some form of read buffering happening, > with measurement results coming in as the answer to some later command. > > A few times I've even restarted it as it stopped responding (luckily > that hasn't happened once measurements had started). > > Since I'm hoping to actually use measurements as part of a control loop > this is obviously a bad thing. > > Does anyone have any experience with the SR620 & GPIB as to why this > might be happening? > > I've not experienced this with other instruments (ancient HP, modern > Keysight, recent Keithley, 90s Anritsu) I've used with the same GPIB > adapter. > > The SR620 has version 1.48 firmware. > > -- > > On Sat, 28 Aug 2021 08:31 , wrote: > >> Send time-nuts mailing list submissions to >> time-nuts@lists.febo.com >> >> To subscribe or unsubscribe via email, send a message with subject or >> body 'help' to >> time-nuts-requ...@lists.febo.com >> >> You can reach the person managing the list at >> time-nuts-ow...@lists.febo.com >> >> When replying, please edit your Subject line so it is more specific >> than "Re: Contents of time-nuts digest..." >> >> Today's Topics: >> >>1. Re: Leviton VTP24 Is this Time Accurate enough? (Dana Whitlow) >>2. Re: Leviton VTP24 Is this Time Accurate enough? (Lux, Jim) >>3. Re: uncertainty/SNR of IQ measurements (Joseph Gwinn) >>4. Stanford Research SR620 GBIB (Julien Goodwin) >> >> >> -- >> >> Message: 1 >> Date: Fri, 27 Aug 2021 05:30:14 -0500 >> From: Dana Whitlow >> Subject: [time-nuts] Re: Leviton VTP24 Is this Time Accurate enough? >> To: Discussion of precise time and frequency measurement >> >> Message-ID: >> > uq...@mail.gmail.com> >> Content-Type: text/plain; charset="UTF-8" >> >> If my watch were that bad, I'd toss it out and go shopping for a new one. >> I wonder if Leviton offers a version with an external ref input. >> >> Dana >> >> >> On Fri, Aug 27, 2021 at 12:12 AM D. Resor wrote: >> >>> I inquired with Leviton as to the accuracy of the VTP24 24 Hour >>> Programmable >>> Timer with DST. >>> >>> https://www.leviton.com/en/products/vpt24-1pz >>> >>> Don Resor >>> >>> Here
[time-nuts] Re: Efratom LPRO-101 Rubidium question....
On Dienstag, 24. August 2021 00:00:41 CEST Dana Whitlow wrote: > I connect one signal to the LO input of the demodulator, and the other > signal to the > RF input. I should draw up a schematic of this, and will do so. It's basically "half" of a DMTD, an "SMTD", so to speak, but without the "difference" part ;) > > Dana > > On Mon, Aug 23, 2021 at 4:59 PM Robert DiRosario wrote: > > Dana, > > > > >I make phase comparisons between the 10 MHz outputs of a GPSDO and the Rb > > >under test using a simple quadrature demodulator, with the I & Q outputs > > >displayed on a 2-chan DSO. > > > > Can you explain what you do? Do you just connect the two 10 MHz signals > > to the input of the demodulator? > > > > Robert > > > > On 08/22/2021 11:16 AM, Dana Whitlow wrote: > > > C'mon guys- when you speak of a frequency error in Hz, you should also > > > specify "at > > > what frequency" *in the same breath*. Or better yet, always specify > > > frequency errors in > > > relative terms. > > > > > > Hundreds of Hz at 10 Mhz is unthinkable for a Rb. Even at 8.2 GHz, 100 > > > > Hz > > > > > error is about > > > 12E-9, which is likely to be outside the EFC tuning range of some (if > > > not > > > most) Rb standards. > > > Both of my Rbs have a tuning range of only roughly 2E-9 via the EFC > > > > input. > > > > > Outside that > > > range, much sterner measures must be taken, which I frankly dread. > > > > > > The two Rbs that I own (an L-Pro and a PRS-10) both tend to drift > > > upwards > > > in frequency > > > to the tune of about 1E-11 or 2E-11 per month. Superimposed on that are > > > random > > > variations of around 1E-11 on a time scale of a few hours. > > > > > > I make phase comparisons between the 10 MHz outputs of a GPSDO and the > > > Rb > > > under > > > test using a simple quadrature demodulator, with the I & Q outputs > > > displayed on a 2-chan > > > DSO. I use the "roll mode" display feature on the DSO at its slowest > > > > speed > > > > > (1000 sec/div) > > > and just leave things running continuously for up to several days. On > > > my > > > DSO a full screen > > > width is 14000 sec (slightly under 4 hours), and I just take a glance > > > > from > > > > > time to time as I > > > happen to pass by. > > > > > > Someone suggested a 100 sec measurement with a counter, but that is > > > right > > > in the realm > > > where GPSDOs are typically the most noisy, so a single measurement is > > > likely to have > > > rather large errors. One would have to record a fairly large number of > > > such measurements > > > (several hundreds of them) and plot them out to get a good assessment of > > > what the Rb is > > > actually doing. WIth the IQ phase difference display, one can get a > > > > pretty > > > > > decent estimate of > > > the needed tuning correction, without doing any real work at all, in a > > > > day > > > > > or so. > > > > > > When I'm doing something requiring the best frequency accuracy, I keep > > > > the > > > > > 'scope display > > > running while I'm doing the serious work, and note the frequency error > > > of > > > the Rb at the time > > > for use in correcting the final result. BTW, I don't see much > > > "settling" > > > effect after making > > > tuning changes- the correction made seems to take effect essentially > > > immediately (as best > > > as one can tell in the presence of GPS noise). By comparing two Rbs, I > > > > can > > > > > investigate > > > settling effects quite well without the noise having anything to do with > > > > it. > > > > > Dana > > > > > > > > > On Sun, Aug 22, 2021 at 8:41 AM Matthias Welwarsky < > > > > time-n...@welwarsky.de> > > > > > wrote: > > >> Hi, > > >> > > >> a Rb will not be long-term accurate. I'd trust a GPSDO to be long-term > > >> accurate. A hundreds-of-Hz offset between the LPRO and the GPSDO > > > > certainly > > > > >> points into the direction of the LPRO being off the mark. > > >> > > >> When you adjust the LPRO, be sure to give it ample time to stabilize. > > >> > > >> BR, > > >> Matthias > > >> > > >> On Samstag, 21. August 2021 14:50:24 CEST mp...@clanbaker.org wrote: > > >>> Hello Time-Nutters-- > > >>> > > >>> I am working on building a downlinking AZ/EL tracking dish set up to > > >>> receive the 8.2 GHz telemetry from the Suomi JPSS polar orbit > > >>> meteorological/environmental satellite. The receiver seems to be > > >>> working OK but it periodically appears to slowly drift frequency by > > >>> 300 Hz to 400 Hz. I need some way to accurately determine what > > >>> the actual RX receive frequency is. > > >>> > > >>> I have a vintage Efratom LPRO-101 Rubidium 10 MHz oscillator. > > >>> I originally got it thinking that it would provide a decent > > >>> phase-lock reference for my freq-counters, o-scopes, spectrum > > >>> analyzers and Agilent/HP vector network analyzer. > > >>> > > >>> The only other item I have that has (or should have) a reasonably > > >>> accurate 10 MHz
[time-nuts] Re: Stanford Research SR620 GBIB
I'd be inclined to check the SR620's exact needs re command/query terminators, and also how exactly it terminates its responses. >From your description, it sounds like that sort of issue. It may be, your GPIB device or its handler code is not recognising the end of the instruments response, and also buffers are not being flushed before starting another query transaction. So youre software get "out of step" between what it sends to the instrument and what it sees coming back. The eventual lockup, is also indicating potential buffer problems. You need to see "exactly" what data is happening on the GPIB itself, does your device/support code have any sort of bus analyzer capability? 73. Dave G8KBV. Message: 4 Date: Sat, 28 Aug 2021 17:03:09 +1000 From: Julien Goodwin Subject: [time-nuts] Stanford Research SR620 GBIB To: Discussion of precise time and frequency measurement Message-ID: <4e137f33-67e5-c00c-0293-16276e591...@studio442.com.au> Content-Type: text/plain; charset=utf-8 For an upcoming (very time-nutty, and hopefully to be shared soon) project I need to finally do some frequency datalogging. I've had a Stanford SR620 sitting around, and plugged it in to a handy GPIB adapter (*not* a major commercial one, one of the community ones). While I can get it to talk GPIB there seems to be some reliability issues, with what looks to be some form of read buffering happening, with measurement results coming in as the answer to some later command. A few times I've even restarted it as it stopped responding (luckily that hasn't happened once measurements had started). Since I'm hoping to actually use measurements as part of a control loop this is obviously a bad thing. Does anyone have any experience with the SR620 & GPIB as to why this might be happening? I've not experienced this with other instruments (ancient HP, modern Keysight, recent Keithley, 90s Anritsu) I've used with the same GPIB adapter. The SR620 has version 1.48 firmware. -- On Sat, 28 Aug 2021 08:31 , wrote: > Send time-nuts mailing list submissions to > time-nuts@lists.febo.com > > To subscribe or unsubscribe via email, send a message with subject or > body 'help' to > time-nuts-requ...@lists.febo.com > > You can reach the person managing the list at > time-nuts-ow...@lists.febo.com > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of time-nuts digest..." > > Today's Topics: > >1. Re: Leviton VTP24 Is this Time Accurate enough? (Dana Whitlow) >2. Re: Leviton VTP24 Is this Time Accurate enough? (Lux, Jim) >3. Re: uncertainty/SNR of IQ measurements (Joseph Gwinn) >4. Stanford Research SR620 GBIB (Julien Goodwin) > > > -- > > Message: 1 > Date: Fri, 27 Aug 2021 05:30:14 -0500 > From: Dana Whitlow > Subject: [time-nuts] Re: Leviton VTP24 Is this Time Accurate enough? > To: Discussion of precise time and frequency measurement > > Message-ID: > uq...@mail.gmail.com> > Content-Type: text/plain; charset="UTF-8" > > If my watch were that bad, I'd toss it out and go shopping for a new one. > I wonder if Leviton offers a version with an external ref input. > > Dana > > > On Fri, Aug 27, 2021 at 12:12 AM D. Resor wrote: > > > I inquired with Leviton as to the accuracy of the VTP24 24 Hour > > Programmable > > Timer with DST. > > > > https://www.leviton.com/en/products/vpt24-1pz > > > > Don Resor > > > > Here is the reply I received: > > > > Hello, > > > > Thank you for contacting Leviton technical support. According to the code > > it > > meets, it is required to have time keeping accuracy within 5 minutes > every > > year. > > > > It also uses a crystal to keep time, as it must maintain the time even > > during power outages. > > > > Regards, > > > > Virgilio Dominguez > > Technical Services Representative II > > Leviton Manufacturing Co., Inc. > > 201 North Service Road., Melville, NY 11747 > > > > ___ > > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe > send > > an email to time-nuts-le...@lists.febo.com > > To unsubscribe, go to and follow the instructions there. > > > > -- > > Message: 2 > Date: Fri, 27 Aug 2021 06:25:06 -0700 > From: "Lux, Jim" > Subject: [time-nuts] Re: Leviton VTP24 Is this Time Accurate enough? > To: time-nuts@lists.febo.com > Message-ID: > Content-Type: text/plain; charset=utf-8; format=flowed > > On 8/27/21 3:30 AM, Dana Whitlow wrote: > > If my watch were that bad, I'd toss it out and go shopping for a new one. > > I wonder if Leviton offers a version with an external ref input. > > > > Dana > > When your requirement is "turn the lights on and off with the sun" 5 > min/year is pretty good. > > OTOH, Perhaps there's an aftermarket for a modified version. Maybe > you've got a niche business opportunity there,
[time-nuts] Re: Stanford Research SR620 GBIB
Julien, Can you please tell us wich GPIB-adapter you are using? Thanks Volker Am 28. August 2021 09:03:09 MESZ schrieb Julien Goodwin : >For an upcoming (very time-nutty, and hopefully to be shared soon) >project I need to finally do some frequency datalogging. > >I've had a Stanford SR620 sitting around, and plugged it in to a handy >GPIB adapter (*not* a major commercial one, one of the community ones). > >While I can get it to talk GPIB there seems to be some reliability >issues, with what looks to be some form of read buffering happening, >with measurement results coming in as the answer to some later command. > >A few times I've even restarted it as it stopped responding (luckily >that hasn't happened once measurements had started). > >Since I'm hoping to actually use measurements as part of a control loop >this is obviously a bad thing. > >Does anyone have any experience with the SR620 & GPIB as to why this >might be happening? > >I've not experienced this with other instruments (ancient HP, modern >Keysight, recent Keithley, 90s Anritsu) I've used with the same GPIB >adapter. > >The SR620 has version 1.48 firmware. >___ >time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an >email to time-nuts-le...@lists.febo.com >To unsubscribe, go to and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Stanford Research SR620 GBIB
For an upcoming (very time-nutty, and hopefully to be shared soon) project I need to finally do some frequency datalogging. I've had a Stanford SR620 sitting around, and plugged it in to a handy GPIB adapter (*not* a major commercial one, one of the community ones). While I can get it to talk GPIB there seems to be some reliability issues, with what looks to be some form of read buffering happening, with measurement results coming in as the answer to some later command. A few times I've even restarted it as it stopped responding (luckily that hasn't happened once measurements had started). Since I'm hoping to actually use measurements as part of a control loop this is obviously a bad thing. Does anyone have any experience with the SR620 & GPIB as to why this might be happening? I've not experienced this with other instruments (ancient HP, modern Keysight, recent Keithley, 90s Anritsu) I've used with the same GPIB adapter. The SR620 has version 1.48 firmware. ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
