Re: [time-nuts] Question about frequency counter testing

Hi Oleg, On 06/06/2018 02:53 PM, Oleg Skydan wrote: > Hi, Magnus! > > Sorry for the late answer, I injured my left eye last Monday, so had > very limited abilities to use computer. Sorry to hear that. Hope you heal up well and quick enough. > From: "Magnus Danielson" >> As long as the sums C

Re: [time-nuts] Question about frequency counter testing

Hi, Magnus! Sorry for the late answer, I injured my left eye last Monday, so had very limited abilities to use computer. From: "Magnus Danielson" As long as the sums C and D becomes correct, your path to it can be whatever. Yes. It produces the same sums. Yes please do, then I can

Re: [time-nuts] Question about frequency counter testing

It appears that I replied to the wrong message, please ignore. Glenn On 5/27/2018 11:52 AM, Oleg Skydan wrote: Hi! From: "Magnus Danielson" You build two sums C and D, one is the phase-samples and the other is phase-samples scaled with their index n in the block.

Re: [time-nuts] Question about frequency counter testing

The MSDS is here: https://simplegreen.com/data-sheets/ They claim that it is non reactive and chemically stable. It is for water tolerant surfaces and should be rinsed. Probably due to the citric acid. Glenn On 5/27/2018 11:52 AM, Oleg Skydan wrote: Hi! From: "Magnus Danielson"

Re: [time-nuts] Question about frequency counter testing

Hi Oleg, On 05/27/2018 05:52 PM, Oleg Skydan wrote: > Hi! > >>> It looks like the proposed method of decimation can be >>> efficiently realized on the current HW. > > I had some free time yesterday and today, so I decided to test the new > algorithms on the real hardware (the HW is still an old

Re: [time-nuts] Question about frequency counter testing

Hi! From: "Magnus Danielson" You build two sums C and D, one is the phase-samples and the other is phase-samples scaled with their index n in the block. From this you can then using the formulas I provided calculate the least-square phase and frequency, and using

Re: [time-nuts] Question about frequency counter testing

Hi! -- From: "Magnus Danielson" From the 2.5 ns single shot resolution, I deduce a 400 MHz count clock. Yes. It is approx. 400MHz. OK, good to have that verified. Free-running or locked to a 10 MHz reference?

Re: [time-nuts] Question about frequency counter testing

Hi Oleg, On 05/18/2018 12:25 AM, Oleg Skydan wrote: > Hi, Magnus! > > -- > From: "Magnus Danielson" >>> 2. Study how PDEV calculation fits on the used HW. If it is possible to >>> do in real time PDEV option can be

Re: [time-nuts] Question about frequency counter testing

Hi, Magnus! -- From: "Magnus Danielson" 2. Study how PDEV calculation fits on the used HW. If it is possible to do in real time PDEV option can be added. You build two sums C and D, one is the phase-samples and the

Re: [time-nuts] Question about frequency counter testing

Hi, On 05/13/2018 11:13 PM, Oleg Skydan wrote: > Hi Magnus, > > From: "Magnus Danielson" >> I would be inclined to just continue the MDEV compliant processing >> instead. If you want the matching ADEV, rescale it using the >> bias-function, which can be derived out

Re: [time-nuts] Question about frequency counter testing

Hi From: "Bob kb8tq" What I’m suggesting is that if the hardware is very simple and very cheap, simply put two chips on the board. One runs at Clock A and the other runs at Clock B. At some point in the process you move the decimated data from B over to A and finish out all

Re: [time-nuts] Question about frequency counter testing

Hi > On May 14, 2018, at 1:50 PM, Oleg Skydan wrote: > > Hi! > > From: "Bob kb8tq" >>> If such conditions detected, I avoid problem by changing the counter clock. >>> But it does not solve the effects at "about OCXO" * N or "about OCXO" / M. >>> It is

Re: [time-nuts] Question about frequency counter testing

Hi! From: "Bob kb8tq" If such conditions detected, I avoid problem by changing the counter clock. But it does not solve the effects at "about OCXO" * N or "about OCXO" / M. It is related to HW and I can probably control it only partially. I will try to improve clock and

Re: [time-nuts] Question about frequency counter testing

Hi > On May 14, 2018, at 5:25 AM, Oleg Skydan wrote: > > Hi Bob! > > From: "Bob kb8tq" >>> I think it will be more than enough for my needs, at least now. >>> From the 2.5 ns single shot resolution, I deduce a 400 MHz count clock. >>> >>> Yes. It is

Re: [time-nuts] Question about frequency counter testing

Hi Bob! From: "Bob kb8tq" I think it will be more than enough for my needs, at least now. From the 2.5 ns single shot resolution, I deduce a 400 MHz count clock. Yes. It is approx. 400MHz. I think I would spend more time working out what happens at “about 400 MHz” X N or

Re: [time-nuts] Question about frequency counter testing

Hi > On May 13, 2018, at 5:13 PM, Oleg Skydan wrote: > > Hi Magnus, > > From: "Magnus Danielson" >> I would be inclined to just continue the MDEV compliant processing >> instead. If you want the matching ADEV, rescale it using the >>

Re: [time-nuts] Question about frequency counter testing

Hi Magnus, From: "Magnus Danielson" I would be inclined to just continue the MDEV compliant processing instead. If you want the matching ADEV, rescale it using the bias-function, which can be derived out of p.51 of that presentation. You just need to figure out the

Re: [time-nuts] Question about frequency counter testing

Hi, On 05/13/2018 08:09 PM, Bob kb8tq wrote: >>> If so, that raises a whole added layer to this discussion in terms of “does >>> it do >>> what it says it does?”. >> >> This question is also important for amateur/hobby measurement equipment. I >> do not need equipment that "does not do what it

Re: [time-nuts] Question about frequency counter testing

Hi > On May 13, 2018, at 1:31 PM, Oleg Skydan wrote: > > Hi Bob! > > From: "Bob kb8tq" >> I guess it is time to ask: >> >> Is this a commercial product you are designing? > > No. I have no abilities to produce it commercially and I see no market for >

Re: [time-nuts] Question about frequency counter testing

Hi Bob! From: "Bob kb8tq" I guess it is time to ask: Is this a commercial product you are designing? No. I have no abilities to produce it commercially and I see no market for such product. I will build one unit for myself, I may build several more units for friends or if

Re: [time-nuts] Question about frequency counter testing

Hi I guess it is time to ask: Is this a commercial product you are designing? If so, that raises a whole added layer to this discussion in terms of “does it do what it says it does?”. Bob > On May 13, 2018, at 3:07 AM, Oleg Skydan wrote: > > Hi Bob! > > From: "Bob

Re: [time-nuts] Question about frequency counter testing

Hi Oleg, On 05/13/2018 09:31 AM, Oleg Skydan wrote: > Hi Magnus! > > From: "Magnus Danielson" >>> The leftmost tau values are skipped and they "stay" inside the counter. >>> If I setup counter to generate lets say 1s stamps (ADEV starts at 1s) it >>> will generate

Re: [time-nuts] Question about frequency counter testing

Hi Magnus! From: "Magnus Danielson" The leftmost tau values are skipped and they "stay" inside the counter. If I setup counter to generate lets say 1s stamps (ADEV starts at 1s) it will generate internally 1/8sec averaged measurements, but export combined data for

Re: [time-nuts] Question about frequency counter testing

Hi Bob! From: "Bob kb8tq" It’s only useful if it is accurate. Since you can “do code” that gives you results that are better than reality, simply coming up with a number is not the full answer. To be useful as ADEV, it needs to be correct. I understand it, so I try to

Re: [time-nuts] Question about frequency counter testing

On 05/12/2018 09:41 PM, Bob kb8tq wrote: > Hi > > >> On May 12, 2018, at 1:20 PM, Oleg Skydan wrote: >> >> Hi! >> >> From: "Bob kb8tq" >>> There is still the problem that the first post on the graph is different >>> depending >>> on the technique. >> >>

Re: [time-nuts] Question about frequency counter testing

Hi, On 05/12/2018 08:38 PM, Oleg Skydan wrote: > Hi! > > From: "Magnus Danielson" >> ADEV assumes brick-wall filtering up to the Nyquist frequency as result >> of the sample-rate. When you filter the data as you do a Linear >> Regression / Least Square estimation,

Re: [time-nuts] Question about frequency counter testing

Hi > On May 12, 2018, at 1:20 PM, Oleg Skydan wrote: > > Hi! > > From: "Bob kb8tq" >> There is still the problem that the first post on the graph is different >> depending >> on the technique. > > The leftmost tau values are skipped and they "stay"

Re: [time-nuts] Question about frequency counter testing

Hi Oleg, On 05/12/2018 07:20 PM, Oleg Skydan wrote: > Hi! > > From: "Bob kb8tq" >> There is still the problem that the first post on the graph is >> different depending >> on the technique. > > The leftmost tau values are skipped and they "stay" inside the counter. > If I setup

Re: [time-nuts] Question about frequency counter testing

Hi! From: "Magnus Danielson" ADEV assumes brick-wall filtering up to the Nyquist frequency as result of the sample-rate. When you filter the data as you do a Linear Regression / Least Square estimation, the actual bandwidth will be much less, so the ADEV measures

Re: [time-nuts] Question about frequency counter testing

Hi! From: "Bob kb8tq" There is still the problem that the first post on the graph is different depending on the technique. The leftmost tau values are skipped and they "stay" inside the counter. If I setup counter to generate lets say 1s stamps (ADEV starts at 1s) it will

Re: [time-nuts] Question about frequency counter testing

Hi, On 05/11/2018 05:35 PM, Bob kb8tq wrote: > Hi > > If you do the weighted average as indicated in the paper *and* compare it to > a “single sample” computation, > the results are different for that time interval. To me that’s a problem. To > the authors, the fact that the rest of > the

Re: [time-nuts] Question about frequency counter testing

Oleg, On 05/11/2018 04:42 PM, Oleg Skydan wrote: > Hi > > -- > From: "Bob kb8tq" >> The most accurate answer is always “that depends”. The simple answer >> is no. > > I have spent the yesterday evening and quite a bit of the night

Re: [time-nuts] Question about frequency counter testing

Hi Dana, On 05/10/2018 06:17 PM, Dana Whitlow wrote: > I'm a bit fuzzy, then, on the definition of ADEV. I was under the > impression that one measured a series of > "phase samples" at the desired spacing, then took the RMS value of that > series, not just a single sample, > as the ADEV value.

Re: [time-nuts] Question about frequency counter testing

Oleg, On 05/10/2018 10:46 AM, Oleg Skydan wrote: > Hi > > Now I have some questions. As you know I am experimenting with the > counter that uses LR calculations to improve its resolution. The LR data > for each measurement is collected during the gate time only, also > measurements are

Re: [time-nuts] Question about frequency counter testing

Hi If you do the weighted average as indicated in the paper *and* compare it to a “single sample” computation, the results are different for that time interval. To me that’s a problem. To the authors, the fact that the rest of the curve is the same is proof that it works. I certainly agree

Re: [time-nuts] Question about frequency counter testing

Hi -- From: "Bob kb8tq" The most accurate answer is always “that depends”. The simple answer is no. I have spent the yesterday evening and quite a bit of the night :) reading many interesting papers and several related

Re: [time-nuts] Question about frequency counter testing

Hi > On May 10, 2018, at 1:44 PM, Oleg Skydan wrote: > > Bob, thanks for clarification! > > From: "Bob kb8tq" >> If you collect data over the entire second and average that down for a >> single point, then no, your ADEV will not be correct. > > That

Re: [time-nuts] Question about frequency counter testing

Bob, thanks for clarification! From: "Bob kb8tq" If you collect data over the entire second and average that down for a single point, then no, your ADEV will not be correct. That probably explains why I got so nice (and suspicious) plots :) There are a number of papers on

Re: [time-nuts] Question about frequency counter testing

Hi More or less: ADEV takes the *difference* between phase samples and then does a standard deviation on them. RMS of the phase samples makes a lot of sense and it was used back in the late 50’s / early 60’s. The gotcha turns out to be that it is an ill behaved measure. The more data you

Re: [time-nuts] Question about frequency counter testing

I'm a bit fuzzy, then, on the definition of ADEV. I was under the impression that one measured a series of "phase samples" at the desired spacing, then took the RMS value of that series, not just a single sample, as the ADEV value. Can anybody say which it is? The RMS approach seems to make

Re: [time-nuts] Question about frequency counter testing

Hi If you collect data over the entire second and average that down for a single point, then no, your ADEV will not be correct. There are a number of papers on this. What ADEV wants to see is a single phase “sample” at one second spacing. This is also at the root of how you get 10 second ADEV.

Re: [time-nuts] Question about frequency counter testing

Hi I have got a pair of not so bad OCXOs (Morion GK85). I did some measurements, the results may be interested to others (sorry if not), so I decided to post them. I ran a set of 5minutes long counter runs (two OCXOs were measured against each other), each point is 1sec gate frequency

Re: [time-nuts] Question about frequency counter testing

The CNT91 is really a CNT90 with some detailed improvements to reduce time-errors to be conform with 50 ps rather than 100 ps resolution. In the CNT90 the comparators where in the same IC, which caused ground-bounce coupling between channels, but separating them was among the things that went in.

Re: [time-nuts] Question about frequency counter testing

Hi As you have noticed already, it is amazingly easy to get data plots with more than the real number and less than the real number of digits. Only careful analysis of the underlying hardware and firmware will lead to an accurate estimate of resolution. This is by no means unique to what

Re: [time-nuts] Question about frequency counter testing

Hi From: "Bob kb8tq" Sent: Friday, April 27, 2018 4:38 PM Consider a case where the clocks and signals are all clean and stable: Both are within 2.5 ppb of an integer relationship. ( let’s say one is 10 MHz and the other is 400 MHz ). The amount of information in your data

Re: [time-nuts] Question about frequency counter testing

From: "Azelio Boriani" Sent: Friday, April 27, 2018 12:16 AM If your hardware is capable of capturing up to 10 millions of timestamps per second and calculating LR "on the fly", it is not a so simple hardware, unless you consider simple hardware a 5megagates Spartan3

Re: [time-nuts] Question about frequency counter testing

Hi So what’s going on here? With any of a number of modern (and not so modern) FPGA’s you can run a clock in the 400 MHz region. Clocking with a single edge gives you a 2.5 ns resolution. On some parts, you are not limited to a single edge. You can clock with both the rising and falling

Re: [time-nuts] Question about frequency counter testing

i" <azelio.bori...@gmail.com> > To: "Discussion of precise time and frequency measurement" > <time-nuts@febo.com> > Sent: Friday, April 27, 2018 7:39 AM > Subject: Re: [time-nuts] Question about frequency counter testing > > > You can measure your clocks

Re: [time-nuts] Question about frequency counter testing

sage - From: "Azelio Boriani" <azelio.bori...@gmail.com> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Friday, April 27, 2018 7:39 AM Subject: Re: [time-nuts] Question about frequency counter testing You can measure your clocks do

Re: [time-nuts] Question about frequency counter testing

You can measure your clocks down to the ps averaged resolution you want only if they are worse than your one-shot base resolution one WRT the other. In a resonable time, that is how many transitions in your 2.5ns sampling interval you have in 1 second to have a n-digit/second counter. On Fri, Apr

Re: [time-nuts] Question about frequency counter testing

Yes, this is the problem when trying to enhance the resolution from a low one-shot resolution. Averaging 2.5ns resolution samples can give data only if clocks move one with respect to the other and "cross the boundary" of the 2.5ns sampling interval. You can measure your clocks down to the ps

Re: [time-nuts] Question about frequency counter testing

> That might be an interesting way to analyze TICC data. It would work > better/faster if you used a custom divider to trigger the TICC as fast as it > can print rather than using the typical PPS. Hi Hal, Exactly correct. For more details see this posting:

Re: [time-nuts] Question about frequency counter testing

Hi Consider a case where the clocks and signals are all clean and stable: Both are within 2.5 ppb of an integer relationship. ( let’s say one is 10 MHz and the other is 400 MHz ). The amount of information in your data stream collapses. Over a 1 second period, you get a bit better than 9

Re: [time-nuts] Question about frequency counter testing

olegsky...@gmail.com said: > No, it is much simpler. The hardware saves time-stamps to the memory at each > (event) rise of the input signal (let's consider we have digital logic input > signal for simplicity). So after some time we have many pairs of {event > number, time-stamp}. We can plot

Re: [time-nuts] Question about frequency counter testing

Hi The degree to which your samples converge to a specific value while being averaged is dependent on a bunch of things. The noise processes on the clock and the measured signal are pretty hard to avoid. It is *very* easy to over estimate how fast things converge. Bob > On Apr 26, 2018, at

Re: [time-nuts] Question about frequency counter testing

If your hardware is capable of capturing up to 10 millions of timestamps per second and calculating LR "on the fly", it is not a so simple hardware, unless you consider simple hardware a 5megagates Spartan3 (maybe more is needed). Moreover: if your clock is, say, at most in an FPGA, 300MHz, your

Re: [time-nuts] Question about frequency counter testing

From: "Hal Murray" Sent: Thursday, April 26, 2018 10:28 PM Is there a term for what I think you are doing? I saw different terms like "omega counter" or multiple time-stamp average counter, probably there are others too. If I understand (big if), you are doing the

Re: [time-nuts] Question about frequency counter testing

olegsky...@gmail.com said: > The plots I showed were made with approx. 5*10^6 timestamps per second, so > theoretically I should get approx. 4ps equivalent resolution (or 11+ > significant digits in one second). Is there a term for what I think you are doing? If I understand (big if), you

Re: [time-nuts] Question about frequency counter testing

Hi Even with a fast counter, there are going to be questions about clock jitter and just how well that last digit performs in the logic. It’s never easy to squeeze the very last bit of performance out ….. Bob > On Apr 26, 2018, at 3:06 AM, Azelio Boriani wrote: >

Re: [time-nuts] Question about frequency counter testing

From: "Azelio Boriani" Sent: Thursday, April 26, 2018 10:06 AM Very fast time-stamping like a stable 5GHz counter? No, it is not 5GHz counter. It does the trick I first saw in CNT91 counters. The hardware is capable of capturing up to 10 millions of timestamps per

Re: [time-nuts] Question about frequency counter testing

Very fast time-stamping like a stable 5GHz counter? The resolution of a 200ps (one shot) interpolator can be replaced by a 5GHz time-stamping counter. On Thu, Apr 26, 2018 at 12:28 AM, Bob kb8tq wrote: > Hi > > Unfortunately there is no “quick and dirty” way to come up with an

Re: [time-nuts] Question about frequency counter testing

Hi Unfortunately there is no “quick and dirty” way to come up with an accurate “number of digits” for a math intensive counter. There are a *lot* of examples of various counter architectures that have specific weak points in what they do. One sort of signal works one way, another signal works

[time-nuts] Question about frequency counter testing

Dear Ladies and Gentlemen, Let me tell a little story so you will be able to better understand what my question and what I am doing. I needed to check frequency in several GHz range from time to time. I do not need high absolute precision (anyway this is a reference oscillator problem, not