[time-nuts] Re: Long term ADEV of 5071
Hoi Demetrios, Sorry for the late answer, last week was a bit crazy. On Sat, 27 Mar 2021 09:58:30 -0400 Demetrios Matsakis via time-nuts wrote: > I’ve attached an old paper of mine, from PTTI-2000. Thanks! I hadn't seen this paper yet. > I’ve also attached the latest BIPM file of TT. If you want long- > term stability it is best to use that file to compute TT-EAL and > TT-TAI and then re-reference the clock data you get from the > BIPM. The BIPM algorithm for EAL/TAI/UTC changed in 2014 so if > you stick with TT you re fine. Since it is computed every 10 > days, you might want to spline-interpolate to get the in-between > points. Or just interpolate. I actually wanted to avoid extracting the data on my own, as there are a lot of pittfalls in this. And I'm sure I am not even aware of half of them. Your paper contains part of the information I was seeking. And quite a bit that I wasn't but is very intersting. I need to spend some quality time with it :-) Thanks a lot and have a nice week! Attila Kinali -- The driving force behind research is the question: "Why?" There are things we don't understand and things we always wonder about. And that's why we do research. -- Kobayashi Makoto ___ 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: Long term ADEV of 5071
The BIPM’s new algorithm, implemented around 2014, weights clock by their predictability, and also estimates the frequency drift of the masers. That’s why masers have risen to their level of prominence. But masers do have all kinds of variations at some level, which I easily saw when I worked at the USNO and had decades of data uncorrupted by time transfer noise. I was going to publish a paper in 2019, but I didn’t because getting approval was impossible. It will be interesting to see what you guys can come up with using BIPM data to create long time series of frequency variations for cesiums and masers too. Be careful because the BIPM data may not tell you when a cesium beam tube was changed, or a maser underwent repair. Or a clock was moved. So I would treat any data gap as a new clock. Maybe one year ago Microsemi started advertising lower drift in their masers, and I suspect that is because they found a way to compensate for the initial drift so the user doesn’t see it. (I have no idea if this is really true.) Years ago in a paper I published with Mike Garvey and Paul Koppang I found the frequency drift noticeably decreased after three years. Extending my unsupported theory, that might mean new masers pick up a drift over time. But components change, and whatever they do can be modeled. Another thing about the meaning of weights is that clocks used to be characterized through comparison with the EAL timescale, which does not involve primaries. But the new algorithm characterizes them against a TT-guess which carries the frequency of the primaries. So that in effect degrades masers, cesiums, and Rb fountains to the status of frequency interpolators between the primary standards. (This is an observation I have made many times and no one has contradicted me, so I guess it is obvious.) > On Mar 28, 2021, at 12:28 PM, Tom Van Baak wrote: > > The pie charts that Anders created show clocks in the UTC "flywheel". That > excludes most research fountains and optical clocks because they can't or > aren't run continuously. > > Of the 427 clocks [1] in that data set there are 247 5071A (58%) and 167 > H-masers (39%) and 6 fountains (<1.4%). So the short answer to your question > is that there are only 6 fountains in the chart: 4 Rb fountains at USNO and 2 > Cs fountains at PTB. > > When playing with charts, it's important not to confuse the number of clocks > with the weighting of clocks. And even the weighting is misleading because > for practical reasons any clock's weight in UTC is capped at about 1%. All 4 > of USNO's Rb fountains are at this level, for example. About 60 of the > H-masers are also at this level. And none of the 5071A; not even close. > > If you are a 5071A sales person you are likely to emphasize that 60% of the > clocks in UTC are 5071A. You are less likely to mention they contribute only > 8% of the weight these days. > > If you are in H-maser sales you can claim 40% of the clocks in UTC are masers > and also they contribute 88% of the weight. > > It's a good time to be in Microchip clock sales: they now own both the hp > 5071A and the Sigma Tau H-maser manufacturing plants. Yes, they still make > PIC chips too ;-) > > /tvb > > [1] https://webtai.bipm.org/database/clock.html > > - clock type 35/36 are 5071A > - clock type 40/41 are H-masers > - clock type 92/93 are Cs/Rb fountain > > > On 3/28/2021 6:15 AM, Bob kb8tq wrote: >> Hi >> >> I would *guess* that fountains would be in there somewhere ( at least in the >> 2021 version ). >> >> Bob >> > ___ > 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: Long term ADEV of 5071
The pie charts that Anders created show clocks in the UTC "flywheel". That excludes most research fountains and optical clocks because they can't or aren't run continuously. Of the 427 clocks [1] in that data set there are 247 5071A (58%) and 167 H-masers (39%) and 6 fountains (<1.4%). So the short answer to your question is that there are only 6 fountains in the chart: 4 Rb fountains at USNO and 2 Cs fountains at PTB. When playing with charts, it's important not to confuse the number of clocks with the weighting of clocks. And even the weighting is misleading because for practical reasons any clock's weight in UTC is capped at about 1%. All 4 of USNO's Rb fountains are at this level, for example. About 60 of the H-masers are also at this level. And none of the 5071A; not even close. If you are a 5071A sales person you are likely to emphasize that 60% of the clocks in UTC are 5071A. You are less likely to mention they contribute only 8% of the weight these days. If you are in H-maser sales you can claim 40% of the clocks in UTC are masers and also they contribute 88% of the weight. It's a good time to be in Microchip clock sales: they now own both the hp 5071A and the Sigma Tau H-maser manufacturing plants. Yes, they still make PIC chips too ;-) /tvb [1] https://webtai.bipm.org/database/clock.html - clock type 35/36 are 5071A - clock type 40/41 are H-masers - clock type 92/93 are Cs/Rb fountain On 3/28/2021 6:15 AM, Bob kb8tq wrote: Hi I would *guess* that fountains would be in there somewhere ( at least in the 2021 version ). Bob ___ 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: Long term ADEV of 5071
Bob, Check the "Ground state" section of the graph. Cheers, Magnus On 2021-03-28 15:15, Bob kb8tq wrote: > Hi > > I would *guess* that fountains would be in there somewhere ( at least in the > 2021 version ). > > Bob > >> On Mar 28, 2021, at 9:03 AM, Anders Wallin >> wrote: >> >> FWIW here are plots of TAI-weight from the 'w' file for 2021.01. The >> 5071A's are at most 8%. Masers are >87%. >> These sum up to ca 95% - not sure where the missing 5% is.. >> Going back to much before 2014 might show larger weight for the 5071As - I >> can post python code for the figures if someone is eager to try... >> >> AW >> >> >> >> [image: TAI_weight_clockype.png][image: TAI_weight_lab.png] >> >> On Sat, Mar 27, 2021 at 4:03 PM Demetrios Matsakis via time-nuts < >> time-nuts@lists.febo.com> wrote: >> >>> I’ve attached an old paper of mine, from PTTI-2000. >>> >>> I’ve also attached the latest BIPM file of TT. If you want long-term >>> stability it is best to use that file to compute TT-EAL and TT-TAI and then >>> re-reference the clock data you get from the BIPM. The BIPM algorithm for >>> EAL/TAI/UTC changed in 2014 so if you stick with TT you re fine. Since it >>> is computed every 10 days, you might want to spline-interpolate to get the >>> in-between points. Or just interpolate. >>> >>> ___ >>> 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: Long term ADEV of 5071
Anders, I am surprised to find that hydrogen masers was so dominant these days. It only shows that the ALGOS improvement that handled the linear drift that allowed their inclusion have been very effective and should have improved the stability. I am also surprised to find my local NMI SP clocks in as fourth weighted laboratory. I should rig up so they have another maser to measure. Cheers, Magnus On 2021-03-28 15:03, Anders Wallin wrote: > FWIW here are plots of TAI-weight from the 'w' file for 2021.01. The > 5071A's are at most 8%. Masers are >87%. > These sum up to ca 95% - not sure where the missing 5% is.. > Going back to much before 2014 might show larger weight for the 5071As - I > can post python code for the figures if someone is eager to try... > > AW > > > > [image: TAI_weight_clockype.png][image: TAI_weight_lab.png] > > On Sat, Mar 27, 2021 at 4:03 PM Demetrios Matsakis via time-nuts < > time-nuts@lists.febo.com> wrote: > >> I’ve attached an old paper of mine, from PTTI-2000. >> >> I’ve also attached the latest BIPM file of TT. If you want long-term >> stability it is best to use that file to compute TT-EAL and TT-TAI and then >> re-reference the clock data you get from the BIPM. The BIPM algorithm for >> EAL/TAI/UTC changed in 2014 so if you stick with TT you re fine. Since it >> is computed every 10 days, you might want to spline-interpolate to get the >> in-between points. Or just interpolate. >> >> ___ >> 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: Long term ADEV of 5071
Hi I would *guess* that fountains would be in there somewhere ( at least in the 2021 version ). Bob > On Mar 28, 2021, at 9:03 AM, Anders Wallin > wrote: > > FWIW here are plots of TAI-weight from the 'w' file for 2021.01. The > 5071A's are at most 8%. Masers are >87%. > These sum up to ca 95% - not sure where the missing 5% is.. > Going back to much before 2014 might show larger weight for the 5071As - I > can post python code for the figures if someone is eager to try... > > AW > > > > [image: TAI_weight_clockype.png][image: TAI_weight_lab.png] > > On Sat, Mar 27, 2021 at 4:03 PM Demetrios Matsakis via time-nuts < > time-nuts@lists.febo.com> wrote: > >> I’ve attached an old paper of mine, from PTTI-2000. >> >> I’ve also attached the latest BIPM file of TT. If you want long-term >> stability it is best to use that file to compute TT-EAL and TT-TAI and then >> re-reference the clock data you get from the BIPM. The BIPM algorithm for >> EAL/TAI/UTC changed in 2014 so if you stick with TT you re fine. Since it >> is computed every 10 days, you might want to spline-interpolate to get the >> in-between points. Or just interpolate. >> >>> >> ___ >> 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: Long term ADEV of 5071
You can do the ADEV just fine using Circular T. Long-term 5071 does not dominate the TAI phase/frequency, but they do dominate for stability. This is the difference between EAL and TAI, the 5071's go into EAL, but EAL is then frequency corrected with a handful of primary references (cesium fointains) into TAI. EAL just try to be as stable as possible, without careing too much about phase and frequency. Cheers, Magnus On 2021-03-26 11:00, Azelio Boriani wrote: > Maybe HP5071s will get their ADEV when optical clocks will officially rule... > > On Fri, Mar 26, 2021 at 9:40 AM Magnus Danielson wrote: >> Hi, >> >> On 2021-03-25 19:21, Poul-Henning Kamp wrote: >>> >>> Attila Kinali writes: >>> Does someone of those who own a 5071 have long-term ADEV data? I'm looking for multi-year data. While there are plenty of ADEV plots online, most of them stop at 1Ms or even at 100ks. >>> As I understand it, cesium beams are considered "primary" standards >>> because once the ADEV hits the floor, it stays down there ? >> "primary" standard means different things in different context. >> >> In telecom, it means it adheres to ITU-T G.811 specifications, which >> effectively puts within 1E-11 in maximum frequency error, which is what >> analog cesiums can deliver. Most of the cesiums we attain as hobbyists >> was designed to meet this spec. The underlying specification driving it >> was to keep data-slip rate between two operators down to once in 70 >> days. It was reasonably achieveable with the technology at hand and for >> the total cost so I think it was fair. >> >> In metrology "primary standard" has a complete different meaning, and in >> practice all clocks we hobbyists gets to have would not fit, they would >> all be more or less good "secondary standards". >> >> The sales people for vendors will be happy to underblow the >> understanding of you being able to buy and have your own "primary >> standard". If it where, you would not be needing traceability to >> anything else, but you end up needing to have that anyway, and in >> reality the "primary" reference is actually one of the few that >> contributes to the international realization. I've seen a few of those, >> but not in my basement. >> >> The "primary reference" is not about ADEV hitting the floor, all devices >> do that (for a strict definition of what should be measured in ADEV). >> It's about the context one consider it "primary". >> >> It would be cool to say one has a "primary standard", and depending on >> context I have several working or none. Coolness aside, when talking to >> metrology folks and national metrology labs, I might have some clocks, >> but I do not call them "primary reference", because most of them does >> not have that either. >> >> So, I think we should be careful with the term, it's get thrown around >> too lightly. >> >> Cheers, >> Magnus >> ___ >> 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: Long term ADEV of 5071
Maybe HP5071s will get their ADEV when optical clocks will officially rule... On Fri, Mar 26, 2021 at 9:40 AM Magnus Danielson wrote: > > Hi, > > On 2021-03-25 19:21, Poul-Henning Kamp wrote: > > > > Attila Kinali writes: > > > >> Does someone of those who own a 5071 have long-term ADEV data? > >> I'm looking for multi-year data. While there are plenty of ADEV > >> plots online, most of them stop at 1Ms or even at 100ks. > > As I understand it, cesium beams are considered "primary" standards > > because once the ADEV hits the floor, it stays down there ? > > "primary" standard means different things in different context. > > In telecom, it means it adheres to ITU-T G.811 specifications, which > effectively puts within 1E-11 in maximum frequency error, which is what > analog cesiums can deliver. Most of the cesiums we attain as hobbyists > was designed to meet this spec. The underlying specification driving it > was to keep data-slip rate between two operators down to once in 70 > days. It was reasonably achieveable with the technology at hand and for > the total cost so I think it was fair. > > In metrology "primary standard" has a complete different meaning, and in > practice all clocks we hobbyists gets to have would not fit, they would > all be more or less good "secondary standards". > > The sales people for vendors will be happy to underblow the > understanding of you being able to buy and have your own "primary > standard". If it where, you would not be needing traceability to > anything else, but you end up needing to have that anyway, and in > reality the "primary" reference is actually one of the few that > contributes to the international realization. I've seen a few of those, > but not in my basement. > > The "primary reference" is not about ADEV hitting the floor, all devices > do that (for a strict definition of what should be measured in ADEV). > It's about the context one consider it "primary". > > It would be cool to say one has a "primary standard", and depending on > context I have several working or none. Coolness aside, when talking to > metrology folks and national metrology labs, I might have some clocks, > but I do not call them "primary reference", because most of them does > not have that either. > > So, I think we should be careful with the term, it's get thrown around > too lightly. > > Cheers, > Magnus > ___ > 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: Long term ADEV of 5071
Hi, On 2021-03-25 19:21, Poul-Henning Kamp wrote: > > Attila Kinali writes: > >> Does someone of those who own a 5071 have long-term ADEV data? >> I'm looking for multi-year data. While there are plenty of ADEV >> plots online, most of them stop at 1Ms or even at 100ks. > As I understand it, cesium beams are considered "primary" standards > because once the ADEV hits the floor, it stays down there ? "primary" standard means different things in different context. In telecom, it means it adheres to ITU-T G.811 specifications, which effectively puts within 1E-11 in maximum frequency error, which is what analog cesiums can deliver. Most of the cesiums we attain as hobbyists was designed to meet this spec. The underlying specification driving it was to keep data-slip rate between two operators down to once in 70 days. It was reasonably achieveable with the technology at hand and for the total cost so I think it was fair. In metrology "primary standard" has a complete different meaning, and in practice all clocks we hobbyists gets to have would not fit, they would all be more or less good "secondary standards". The sales people for vendors will be happy to underblow the understanding of you being able to buy and have your own "primary standard". If it where, you would not be needing traceability to anything else, but you end up needing to have that anyway, and in reality the "primary" reference is actually one of the few that contributes to the international realization. I've seen a few of those, but not in my basement. The "primary reference" is not about ADEV hitting the floor, all devices do that (for a strict definition of what should be measured in ADEV). It's about the context one consider it "primary". It would be cool to say one has a "primary standard", and depending on context I have several working or none. Coolness aside, when talking to metrology folks and national metrology labs, I might have some clocks, but I do not call them "primary reference", because most of them does not have that either. So, I think we should be careful with the term, it's get thrown around too lightly. Cheers, Magnus ___ 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: Long term ADEV of 5071
Dear Attila We have clock comparison data going back 25 years so you could DIY. But I thought I sent that to you a couple of years ago? Cheers Michael On Fri, 26 Mar 2021 at 3:34 am, Attila Kinali wrote: > Moin, > > Does someone of those who own a 5071 have long-term ADEV data? > I'm looking for multi-year data. While there are plenty of ADEV > plots online, most of them stop at 1Ms or even at 100ks. > > Background: I'm involved in a project where long term frequency > stability is important. And I need some rule of thumb to evaluate > whether what we are trying to do makes sense or not. > > Thanks in advance! > > Attila Kinali > > -- > The driving force behind research is the question: "Why?" > There are things we don't understand and things we always > wonder about. And that's why we do research. > -- Kobayashi Makoto > ___ > 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: Long term ADEV of 5071
The ADEV of the 5071 follows the typical curve of improving at a constant rate vs increasing Tau until it levels out due to limiting by flicker. AFAIK, this flicker noise never turns back up. There is no observable aging either. Nor are there any observable environmental effects. The 5071's traditionally counted for 85% of the weight in the TAI weighted average. You might as well start by asking what is the long term stability of the TAI. Just based on what you are saying, your client reminds me of many consulting clients I have had who started out asking the wrong question. I usually responded, not by attempting to answer the question, but rather explain why it was the wrong question and then proceed to figuring out the right question. Just a comment; maybe that is not what is going on in your case. Rick N6RK On 3/25/2021 9:29 AM, Attila Kinali wrote: Moin, Does someone of those who own a 5071 have long-term ADEV data? I'm looking for multi-year data. While there are plenty of ADEV plots online, most of them stop at 1Ms or even at 100ks. Background: I'm involved in a project where long term frequency stability is important. And I need some rule of thumb to evaluate whether what we are trying to do makes sense or not. Thanks in advance! Attila Kinali ___ 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: Long term ADEV of 5071
Attila Kinali writes: > Does someone of those who own a 5071 have long-term ADEV data? > I'm looking for multi-year data. While there are plenty of ADEV > plots online, most of them stop at 1Ms or even at 100ks. As I understand it, cesium beams are considered "primary" standards because once the ADEV hits the floor, it stays down there ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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: Long term ADEV of 5071
Hi, On 2021-03-25 17:29, Attila Kinali wrote: > Moin, > > Does someone of those who own a 5071 have long-term ADEV data? > I'm looking for multi-year data. While there are plenty of ADEV > plots online, most of them stop at 1Ms or even at 100ks. > > Background: I'm involved in a project where long term frequency > stability is important. And I need some rule of thumb to evaluate > whether what we are trying to do makes sense or not. > > Thanks in advance! Look at the BIPM data, as each clock is identified and you have continuous measurement of a whole bunch of 5071s there so you can even line them up and make statistics of the spread that way, just a bit of number crunching away. There may be articles available also that gives relevant hints. Cheers, Magnus ___ 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.
