MW
Michael Wouters
Thu, Mar 16, 2023 7:17 AM
Dear time-nuts
Counter specs often include an “internal resolution” error. For example,
the SR620 specs say that it is 25 ps in single-shot, but this can be
reduced to 4 ps with sufficient, repeated measurements. Can anyone offer
any enlightenment as to the origin of this error, and the statistical
distribution it has? I mentioned the SR620 but information about the 53230A
would be interesting too.
Cheers
Michael
Dear time-nuts
Counter specs often include an “internal resolution” error. For example,
the SR620 specs say that it is 25 ps in single-shot, but this can be
reduced to 4 ps with sufficient, repeated measurements. Can anyone offer
any enlightenment as to the origin of this error, and the statistical
distribution it has? I mentioned the SR620 but information about the 53230A
would be interesting too.
Cheers
Michael
BC
Bob Camp
Thu, Mar 16, 2023 11:07 PM
Hi
The 53230A will generate a cute little histogram that backs up whatever “one sigma” number it
presents. Just as one would expect, when it is down in the 10 ps one sigma range you see bins
that are empty. That said, the “eyeball" distribution still looks like a gaussian sort of thing.
Bob
On Mar 16, 2023, at 3:17 AM, Michael Wouters via time-nuts time-nuts@lists.febo.com wrote:
Dear time-nuts
Counter specs often include an “internal resolution” error. For example,
the SR620 specs say that it is 25 ps in single-shot, but this can be
reduced to 4 ps with sufficient, repeated measurements. Can anyone offer
any enlightenment as to the origin of this error, and the statistical
distribution it has? I mentioned the SR620 but information about the 53230A
would be interesting too.
Cheers
Michael
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hi
The 53230A will generate a cute little histogram that backs up whatever “one sigma” number it
presents. Just as one would expect, when it is down in the 10 ps one sigma range you see bins
that are empty. That said, the “eyeball" distribution still looks like a gaussian sort of thing.
Bob
> On Mar 16, 2023, at 3:17 AM, Michael Wouters via time-nuts <time-nuts@lists.febo.com> wrote:
>
> Dear time-nuts
>
> Counter specs often include an “internal resolution” error. For example,
> the SR620 specs say that it is 25 ps in single-shot, but this can be
> reduced to 4 ps with sufficient, repeated measurements. Can anyone offer
> any enlightenment as to the origin of this error, and the statistical
> distribution it has? I mentioned the SR620 but information about the 53230A
> would be interesting too.
>
> Cheers
> Michael
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
MD
Magnus Danielson
Fri, Mar 17, 2023 1:46 PM
Dear Michael,
On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
Dear time-nuts
Counter specs often include an “internal resolution” error. For example,
the SR620 specs say that it is 25 ps in single-shot, but this can be
reduced to 4 ps with sufficient, repeated measurements. Can anyone offer
any enlightenment as to the origin of this error, and the statistical
distribution it has? I mentioned the SR620 but information about the 53230A
would be interesting too.
First of all, the single-shot resolution is somewhat of a hallmark
measure when it comes to counters.
The interpolator resolution is part of this, but consider that there
exists non-linearities in the interpolator which makes the error larger.
I recall there being a plot of the non-linearity in the SR620 manual.
It is not uncommon to have interpolator resolution better than
non-linearities, but the later may be more subtle to most.
Averaging can help, but depending to specifics, it's hard to give a number.
Cheers,
Magnus
Dear Michael,
On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
> Dear time-nuts
>
> Counter specs often include an “internal resolution” error. For example,
> the SR620 specs say that it is 25 ps in single-shot, but this can be
> reduced to 4 ps with sufficient, repeated measurements. Can anyone offer
> any enlightenment as to the origin of this error, and the statistical
> distribution it has? I mentioned the SR620 but information about the 53230A
> would be interesting too.
First of all, the single-shot resolution is somewhat of a hallmark
measure when it comes to counters.
The interpolator resolution is part of this, but consider that there
exists non-linearities in the interpolator which makes the error larger.
I recall there being a plot of the non-linearity in the SR620 manual.
It is not uncommon to have interpolator resolution better than
non-linearities, but the later may be more subtle to most.
Averaging can help, but depending to specifics, it's hard to give a number.
Cheers,
Magnus
>
> Cheers
> Michael
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
DM
Demetrios Matsakis
Fri, Mar 17, 2023 3:57 PM
I don’t know how SR counters are today, but when we were upgrading our infrastructure over a decade ago we found other counters had better linearity. Rover et al’s open source article has a good discussion of these issues, although of course you need to have one if you are going to experiment. See G. D. Rovera, M. Siccardi, S. Romisch, and M. Abgrali, “Time delay measurements: estimation of the error budget”, Metrologia 56, 2019 035004
On Mar 17, 2023, at 9:46 AM, Magnus Danielson via time-nuts time-nuts@lists.febo.com wrote:
Dear Michael,
On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
Dear time-nuts
Counter specs often include an “internal resolution” error. For example,
the SR620 specs say that it is 25 ps in single-shot, but this can be
reduced to 4 ps with sufficient, repeated measurements. Can anyone offer
any enlightenment as to the origin of this error, and the statistical
distribution it has? I mentioned the SR620 but information about the 53230A
would be interesting too.
First of all, the single-shot resolution is somewhat of a hallmark measure when it comes to counters.
The interpolator resolution is part of this, but consider that there exists non-linearities in the interpolator which makes the error larger. I recall there being a plot of the non-linearity in the SR620 manual.
It is not uncommon to have interpolator resolution better than non-linearities, but the later may be more subtle to most.
Averaging can help, but depending to specifics, it's hard to give a number.
Cheers,
Magnus
I don’t know how SR counters are today, but when we were upgrading our infrastructure over a decade ago we found other counters had better linearity. Rover et al’s open source article has a good discussion of these issues, although of course you need to have one if you are going to experiment. See G. D. Rovera, M. Siccardi, S. Romisch, and M. Abgrali, “Time delay measurements: estimation of the error budget”, Metrologia 56, 2019 035004
> On Mar 17, 2023, at 9:46 AM, Magnus Danielson via time-nuts <time-nuts@lists.febo.com> wrote:
>
> Dear Michael,
>
> On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
>> Dear time-nuts
>>
>> Counter specs often include an “internal resolution” error. For example,
>> the SR620 specs say that it is 25 ps in single-shot, but this can be
>> reduced to 4 ps with sufficient, repeated measurements. Can anyone offer
>> any enlightenment as to the origin of this error, and the statistical
>> distribution it has? I mentioned the SR620 but information about the 53230A
>> would be interesting too.
>
> First of all, the single-shot resolution is somewhat of a hallmark measure when it comes to counters.
>
> The interpolator resolution is part of this, but consider that there exists non-linearities in the interpolator which makes the error larger. I recall there being a plot of the non-linearity in the SR620 manual.
>
> It is not uncommon to have interpolator resolution better than non-linearities, but the later may be more subtle to most.
>
> Averaging can help, but depending to specifics, it's hard to give a number.
>
> Cheers,
> Magnus
>
>>
>> Cheers
>> Michael
>> _______________________________________________
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
BC
Bob Camp
Fri, Mar 17, 2023 5:43 PM
Hi
Very interesting paper (and normal people can get to it !!!). Thanks for bringing it up.
One question: Have they ever mentioned what A, B and C actually are? If not, is there
a “best guess” ?
Bob
On Mar 17, 2023, at 11:57 AM, Demetrios Matsakis via time-nuts time-nuts@lists.febo.com wrote:
I don’t know how SR counters are today, but when we were upgrading our infrastructure over a decade ago we found other counters had better linearity. Rover et al’s open source article has a good discussion of these issues, although of course you need to have one if you are going to experiment. See G. D. Rovera, M. Siccardi, S. Romisch, and M. Abgrali, “Time delay measurements: estimation of the error budget”, Metrologia 56, 2019 035004
On Mar 17, 2023, at 9:46 AM, Magnus Danielson via time-nuts time-nuts@lists.febo.com wrote:
Dear Michael,
On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
Dear time-nuts
Counter specs often include an “internal resolution” error. For example,
the SR620 specs say that it is 25 ps in single-shot, but this can be
reduced to 4 ps with sufficient, repeated measurements. Can anyone offer
any enlightenment as to the origin of this error, and the statistical
distribution it has? I mentioned the SR620 but information about the 53230A
would be interesting too.
First of all, the single-shot resolution is somewhat of a hallmark measure when it comes to counters.
The interpolator resolution is part of this, but consider that there exists non-linearities in the interpolator which makes the error larger. I recall there being a plot of the non-linearity in the SR620 manual.
It is not uncommon to have interpolator resolution better than non-linearities, but the later may be more subtle to most.
Averaging can help, but depending to specifics, it's hard to give a number.
Cheers,
Magnus
Hi
Very interesting paper (and normal people can get to it !!!). Thanks for bringing it up.
One question: Have they ever mentioned what A, B and C actually are? If not, is there
a “best guess” ?
Bob
> On Mar 17, 2023, at 11:57 AM, Demetrios Matsakis via time-nuts <time-nuts@lists.febo.com> wrote:
>
> I don’t know how SR counters are today, but when we were upgrading our infrastructure over a decade ago we found other counters had better linearity. Rover et al’s open source article has a good discussion of these issues, although of course you need to have one if you are going to experiment. See G. D. Rovera, M. Siccardi, S. Romisch, and M. Abgrali, “Time delay measurements: estimation of the error budget”, Metrologia 56, 2019 035004
>
>> On Mar 17, 2023, at 9:46 AM, Magnus Danielson via time-nuts <time-nuts@lists.febo.com> wrote:
>>
>> Dear Michael,
>>
>> On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
>>> Dear time-nuts
>>>
>>> Counter specs often include an “internal resolution” error. For example,
>>> the SR620 specs say that it is 25 ps in single-shot, but this can be
>>> reduced to 4 ps with sufficient, repeated measurements. Can anyone offer
>>> any enlightenment as to the origin of this error, and the statistical
>>> distribution it has? I mentioned the SR620 but information about the 53230A
>>> would be interesting too.
>>
>> First of all, the single-shot resolution is somewhat of a hallmark measure when it comes to counters.
>>
>> The interpolator resolution is part of this, but consider that there exists non-linearities in the interpolator which makes the error larger. I recall there being a plot of the non-linearity in the SR620 manual.
>>
>> It is not uncommon to have interpolator resolution better than non-linearities, but the later may be more subtle to most.
>>
>> Averaging can help, but depending to specifics, it's hard to give a number.
>>
>> Cheers,
>> Magnus
>>
>>>
>>> Cheers
>>> Michael
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>> _______________________________________________
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
MD
Magnus Danielson
Fri, Mar 17, 2023 5:47 PM
I also recall one paper relating to laser ranging measurement of the
moon which also looked at temperature dependence of counters, and SR620
showed more sensitivity than some other counters. For some measurement
purposes, the impact is less than for others.
A fun experiment would be to use a delay-stepper to plot this. I
accumulated equipment for that over the years, with increasing
resolution and performance but never got around to it. Good little
practical experiment now that I was able to steer the Colby DL10
programmable trombone delay.
There is two common reasons for non-linearity, one is from the
interpolator itself where error-pulse shaper as well as pulse-to-voltage
converter has non-linearities. Another one is du to leakage of either
clock or other input shifts the trigger point due to lacking isolation.
Such non-linearities can be handled through measurement setup and at
times with averaging.
Some properties can be managed through wise use of the autocalibration.
Then again, most of the times I do not bother to go the extra stretch,
but it is good to know the effects are there so one can consider them
and if needed cope with them.
So, time to close down computer, check out and leave Vancouver after a
WSTS conference.
Cheers,
Magnus
On 2023-03-17 16:57, Demetrios Matsakis wrote:
I don’t know how SR counters are today, but when we were upgrading our
infrastructure over a decade ago we found other counters had better
linearity. Rover et al’s open source article has a good discussion of
these issues, although of course you need to have one if you are going
to experiment. See G. D. Rovera, M. Siccardi, S. Romisch, and M.
Abgrali, “Time delay measurements: estimation of the error budget”,
Metrologia 56, 2019 035004
On Mar 17, 2023, at 9:46 AM, Magnus Danielson via time-nuts
time-nuts@lists.febo.com wrote:
Dear Michael,
On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
Dear time-nuts
Counter specs often include an “internal resolution” error. For example,
the SR620 specs say that it is 25 ps in single-shot, but this can be
reduced to 4 ps with sufficient, repeated measurements. Can anyone
offer
any enlightenment as to the origin of this error, and the statistical
distribution it has? I mentioned the SR620 but information about the
53230A
would be interesting too.
First of all, the single-shot resolution is somewhat of a hallmark
measure when it comes to counters.
The interpolator resolution is part of this, but consider that there
exists non-linearities in the interpolator which makes the error
larger. I recall there being a plot of the non-linearity in the SR620
manual.
It is not uncommon to have interpolator resolution better than
non-linearities, but the later may be more subtle to most.
Averaging can help, but depending to specifics, it's hard to give a
number.
Cheers,
Magnus
Cheers
Michael
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
I also recall one paper relating to laser ranging measurement of the
moon which also looked at temperature dependence of counters, and SR620
showed more sensitivity than some other counters. For some measurement
purposes, the impact is less than for others.
A fun experiment would be to use a delay-stepper to plot this. I
accumulated equipment for that over the years, with increasing
resolution and performance but never got around to it. Good little
practical experiment now that I was able to steer the Colby DL10
programmable trombone delay.
There is two common reasons for non-linearity, one is from the
interpolator itself where error-pulse shaper as well as pulse-to-voltage
converter has non-linearities. Another one is du to leakage of either
clock or other input shifts the trigger point due to lacking isolation.
Such non-linearities can be handled through measurement setup and at
times with averaging.
Some properties can be managed through wise use of the autocalibration.
Then again, most of the times I do not bother to go the extra stretch,
but it is good to know the effects are there so one can consider them
and if needed cope with them.
So, time to close down computer, check out and leave Vancouver after a
WSTS conference.
Cheers,
Magnus
On 2023-03-17 16:57, Demetrios Matsakis wrote:
> I don’t know how SR counters are today, but when we were upgrading our
> infrastructure over a decade ago we found other counters had better
> linearity. Rover et al’s open source article has a good discussion of
> these issues, although of course you need to have one if you are going
> to experiment. See G. D. Rovera, M. Siccardi, S. Romisch, and M.
> Abgrali, “Time delay measurements: estimation of the error budget”,
> Metrologia 56, 2019 035004
>
>> On Mar 17, 2023, at 9:46 AM, Magnus Danielson via time-nuts
>> <time-nuts@lists.febo.com> wrote:
>>
>> Dear Michael,
>>
>> On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
>>> Dear time-nuts
>>>
>>> Counter specs often include an “internal resolution” error. For example,
>>> the SR620 specs say that it is 25 ps in single-shot, but this can be
>>> reduced to 4 ps with sufficient, repeated measurements. Can anyone
>>> offer
>>> any enlightenment as to the origin of this error, and the statistical
>>> distribution it has? I mentioned the SR620 but information about the
>>> 53230A
>>> would be interesting too.
>>
>> First of all, the single-shot resolution is somewhat of a hallmark
>> measure when it comes to counters.
>>
>> The interpolator resolution is part of this, but consider that there
>> exists non-linearities in the interpolator which makes the error
>> larger. I recall there being a plot of the non-linearity in the SR620
>> manual.
>>
>> It is not uncommon to have interpolator resolution better than
>> non-linearities, but the later may be more subtle to most.
>>
>> Averaging can help, but depending to specifics, it's hard to give a
>> number.
>>
>> Cheers,
>> Magnus
>>
>>>
>>> Cheers
>>> Michael
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>> _______________________________________________
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>
DM
Demetrios Matsakis
Fri, Mar 17, 2023 11:03 PM
On fact one of our best engineers concluded that there was leakage
across the inputs, as Magnus mentioned. I thought at the time he had
measured it, but I am not 100% sure of that.
On Mar 17, 2023, at 13:47, Magnus Danielson <magnus@rubidium.se>
wrote:
I also recall one paper relating to laser ranging measurement of the
moon which also looked at temperature dependence of counters, and
SR620 showed more sensitivity than some other counters. For some
measurement purposes, the impact is less than for others.
A fun experiment would be to use a delay-stepper to plot this. I
accumulated equipment for that over the years, with increasing
resolution and performance but never got around to it. Good little
practical experiment now that I was able to steer the Colby DL10
programmable trombone delay.
There is two common reasons for non-linearity, one is from the
interpolator itself where error-pulse shaper as well as
pulse-to-voltage converter has non-linearities. Another one is du to
leakage of either clock or other input shifts the trigger point due
to lacking isolation. Such non-linearities can be handled through
measurement setup and at times with averaging.
Some properties can be managed through wise use of the
autocalibration.
Then again, most of the times I do not bother to go the extra
stretch, but it is good to know the effects are there so one can
consider them and if needed cope with them.
So, time to close down computer, check out and leave Vancouver after
a WSTS conference.
Cheers,
Magnus
On 2023-03-17 16:57, Demetrios Matsakis wrote:
I don’t know how SR counters are today, but when we were upgrading
our infrastructure over a decade ago we found other counters had
better linearity. Rover et al’s open source article has a good
discussion of these issues, although of course you need to have one
if you are going to experiment. See G. D. Rovera, M. Siccardi, S.
Romisch, and M. Abgrali, “Time delay measurements: estimation of the
error budget”, Metrologia 56, 2019 035004
On Mar 17, 2023, at 9:46 AM, Magnus Danielson via time-nuts
[1]time-nuts@lists.febo.com wrote:
Dear Michael,
On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
Dear time-nuts
Counter specs often include an “internal resolution” error. For
example,
the SR620 specs say that it is 25 ps in single-shot, but this can be
reduced to 4 ps with sufficient, repeated measurements. Can anyone
offer
any enlightenment as to the origin of this error, and the
statistical
distribution it has? I mentioned the SR620 but information about the
53230A
would be interesting too.
First of all, the single-shot resolution is somewhat of a hallmark
measure when it comes to counters.
The interpolator resolution is part of this, but consider that there
exists non-linearities in the interpolator which makes the error
larger. I recall there being a plot of the non-linearity in the SR620
manual.
It is not uncommon to have interpolator resolution better than
non-linearities, but the later may be more subtle to most.
Averaging can help, but depending to specifics, it's hard to give a
number.
Cheers,
Magnus
Cheers
Michael
_______________________________________________
time-nuts mailing list -- [2]time-nuts@lists.febo.com
To unsubscribe send an email to [3]time-nuts-leave@lists.febo.com
time-nuts mailing list -- [4]time-nuts@lists.febo.com
To unsubscribe send an email to [5]time-nuts-leave@lists.febo.com
References
- mailto:time-nuts@lists.febo.com
- mailto:time-nuts@lists.febo.com
- mailto:time-nuts-leave@lists.febo.com
- mailto:time-nuts@lists.febo.com
- mailto:time-nuts-leave@lists.febo.com
On fact one of our best engineers concluded that there was leakage
across the inputs, as Magnus mentioned. I thought at the time he had
measured it, but I am not 100% sure of that.
On Mar 17, 2023, at 13:47, Magnus Danielson <magnus@rubidium.se>
wrote:
I also recall one paper relating to laser ranging measurement of the
moon which also looked at temperature dependence of counters, and
SR620 showed more sensitivity than some other counters. For some
measurement purposes, the impact is less than for others.
A fun experiment would be to use a delay-stepper to plot this. I
accumulated equipment for that over the years, with increasing
resolution and performance but never got around to it. Good little
practical experiment now that I was able to steer the Colby DL10
programmable trombone delay.
There is two common reasons for non-linearity, one is from the
interpolator itself where error-pulse shaper as well as
pulse-to-voltage converter has non-linearities. Another one is du to
leakage of either clock or other input shifts the trigger point due
to lacking isolation. Such non-linearities can be handled through
measurement setup and at times with averaging.
Some properties can be managed through wise use of the
autocalibration.
Then again, most of the times I do not bother to go the extra
stretch, but it is good to know the effects are there so one can
consider them and if needed cope with them.
So, time to close down computer, check out and leave Vancouver after
a WSTS conference.
Cheers,
Magnus
On 2023-03-17 16:57, Demetrios Matsakis wrote:
I don’t know how SR counters are today, but when we were upgrading
our infrastructure over a decade ago we found other counters had
better linearity. Rover et al’s open source article has a good
discussion of these issues, although of course you need to have one
if you are going to experiment. See G. D. Rovera, M. Siccardi, S.
Romisch, and M. Abgrali, “Time delay measurements: estimation of the
error budget”, Metrologia 56, 2019 035004
On Mar 17, 2023, at 9:46 AM, Magnus Danielson via time-nuts
[1]<time-nuts@lists.febo.com> wrote:
Dear Michael,
On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
Dear time-nuts
Counter specs often include an “internal resolution” error. For
example,
the SR620 specs say that it is 25 ps in single-shot, but this can be
reduced to 4 ps with sufficient, repeated measurements. Can anyone
offer
any enlightenment as to the origin of this error, and the
statistical
distribution it has? I mentioned the SR620 but information about the
53230A
would be interesting too.
First of all, the single-shot resolution is somewhat of a hallmark
measure when it comes to counters.
The interpolator resolution is part of this, but consider that there
exists non-linearities in the interpolator which makes the error
larger. I recall there being a plot of the non-linearity in the SR620
manual.
It is not uncommon to have interpolator resolution better than
non-linearities, but the later may be more subtle to most.
Averaging can help, but depending to specifics, it's hard to give a
number.
Cheers,
Magnus
Cheers
Michael
_______________________________________________
time-nuts mailing list -- [2]time-nuts@lists.febo.com
To unsubscribe send an email to [3]time-nuts-leave@lists.febo.com
_______________________________________________
time-nuts mailing list -- [4]time-nuts@lists.febo.com
To unsubscribe send an email to [5]time-nuts-leave@lists.febo.com
References
1. mailto:time-nuts@lists.febo.com
2. mailto:time-nuts@lists.febo.com
3. mailto:time-nuts-leave@lists.febo.com
4. mailto:time-nuts@lists.febo.com
5. mailto:time-nuts-leave@lists.febo.com
MD
Magnus Danielson
Sat, Mar 18, 2023 12:59 AM
Hi,
Typically it occurs through ground-bounce. It is addressed through
isolation, so rather using a common comparator chip, one separate the
channels to separate comparators, and with relevant decoupling to
further achieve isolation. I know at least two vendors that have worked
on this, and it becomes relevant as you reach below 100 ps in overall
performance. Digital electronics signal integrity wise it is relatively
bread and butter design issues these days.
A good introductionary book is "High speed digital design - a handbook
of black magic". It is very pragmatic in teaching rule of thumbs and
illustrating things. There is a follow up which has much more practical
details.
A curious fact is that Wavecrest and their high resolution (2 ps total
performance, 800 fs to 200 fs single shot resolution) counters is
relatively unknown in the professional time and frequency field, because
they focused on signal integrity issues. Eventually their market share
was eaten as oscilloscope vendors such as Agilent and Tektronix started
to include similar features, which reduced the need for another instrument.
Having done my fair share of signal integrity work it has not been too
hard to follow.
Cheers,
Magnus
On 2023-03-18 00:03, Demetrios Matsakis wrote:
On fact one of our best engineers concluded that there was leakage
across the inputs, as Magnus mentioned. I thought at the time he had
measured it, but I am not 100% sure of that.
On Mar 17, 2023, at 13:47, Magnus Danielson magnus@rubidium.se wrote:
I also recall one paper relating to laser ranging measurement of the
moon which also looked at temperature dependence of counters, and
SR620 showed more sensitivity than some other counters. For some
measurement purposes, the impact is less than for others.
A fun experiment would be to use a delay-stepper to plot this. I
accumulated equipment for that over the years, with increasing
resolution and performance but never got around to it. Good little
practical experiment now that I was able to steer the Colby DL10
programmable trombone delay.
There is two common reasons for non-linearity, one is from the
interpolator itself where error-pulse shaper as well as
pulse-to-voltage converter has non-linearities. Another one is du to
leakage of either clock or other input shifts the trigger point due
to lacking isolation. Such non-linearities can be handled through
measurement setup and at times with averaging.
Some properties can be managed through wise use of the autocalibration.
Then again, most of the times I do not bother to go the extra
stretch, but it is good to know the effects are there so one can
consider them and if needed cope with them.
So, time to close down computer, check out and leave Vancouver after
a WSTS conference.
Cheers,
Magnus
On 2023-03-17 16:57, Demetrios Matsakis wrote:
I don’t know how SR counters are today, but when we were upgrading
our infrastructure over a decade ago we found other counters had
better linearity. Rover et al’s open source article has a good
discussion of these issues, although of course you need to have one
if you are going to experiment. See G. D. Rovera, M. Siccardi, S.
Romisch, and M. Abgrali, “Time delay measurements: estimation of the
error budget”, Metrologia 56, 2019 035004
On Mar 17, 2023, at 9:46 AM, Magnus Danielson via time-nuts
time-nuts@lists.febo.com wrote:
Dear Michael,
On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
Dear time-nuts
Counter specs often include an “internal resolution” error. For
example,
the SR620 specs say that it is 25 ps in single-shot, but this can be
reduced to 4 ps with sufficient, repeated measurements. Can anyone
offer
any enlightenment as to the origin of this error, and the statistical
distribution it has? I mentioned the SR620 but information about
the 53230A
would be interesting too.
First of all, the single-shot resolution is somewhat of a hallmark
measure when it comes to counters.
The interpolator resolution is part of this, but consider that
there exists non-linearities in the interpolator which makes the
error larger. I recall there being a plot of the non-linearity in
the SR620 manual.
It is not uncommon to have interpolator resolution better than
non-linearities, but the later may be more subtle to most.
Averaging can help, but depending to specifics, it's hard to give a
number.
Cheers,
Magnus
Cheers
Michael
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Hi,
Typically it occurs through ground-bounce. It is addressed through
isolation, so rather using a common comparator chip, one separate the
channels to separate comparators, and with relevant decoupling to
further achieve isolation. I know at least two vendors that have worked
on this, and it becomes relevant as you reach below 100 ps in overall
performance. Digital electronics signal integrity wise it is relatively
bread and butter design issues these days.
A good introductionary book is "High speed digital design - a handbook
of black magic". It is very pragmatic in teaching rule of thumbs and
illustrating things. There is a follow up which has much more practical
details.
A curious fact is that Wavecrest and their high resolution (2 ps total
performance, 800 fs to 200 fs single shot resolution) counters is
relatively unknown in the professional time and frequency field, because
they focused on signal integrity issues. Eventually their market share
was eaten as oscilloscope vendors such as Agilent and Tektronix started
to include similar features, which reduced the need for another instrument.
Having done my fair share of signal integrity work it has not been too
hard to follow.
Cheers,
Magnus
On 2023-03-18 00:03, Demetrios Matsakis wrote:
> On fact one of our best engineers concluded that there was leakage
> across the inputs, as Magnus mentioned. I thought at the time he had
> measured it, but I am not 100% sure of that.
>
>> On Mar 17, 2023, at 13:47, Magnus Danielson <magnus@rubidium.se> wrote:
>>
>>
>>
>> I also recall one paper relating to laser ranging measurement of the
>> moon which also looked at temperature dependence of counters, and
>> SR620 showed more sensitivity than some other counters. For some
>> measurement purposes, the impact is less than for others.
>>
>> A fun experiment would be to use a delay-stepper to plot this. I
>> accumulated equipment for that over the years, with increasing
>> resolution and performance but never got around to it. Good little
>> practical experiment now that I was able to steer the Colby DL10
>> programmable trombone delay.
>>
>> There is two common reasons for non-linearity, one is from the
>> interpolator itself where error-pulse shaper as well as
>> pulse-to-voltage converter has non-linearities. Another one is du to
>> leakage of either clock or other input shifts the trigger point due
>> to lacking isolation. Such non-linearities can be handled through
>> measurement setup and at times with averaging.
>>
>> Some properties can be managed through wise use of the autocalibration.
>>
>> Then again, most of the times I do not bother to go the extra
>> stretch, but it is good to know the effects are there so one can
>> consider them and if needed cope with them.
>>
>> So, time to close down computer, check out and leave Vancouver after
>> a WSTS conference.
>>
>> Cheers,
>> Magnus
>>
>> On 2023-03-17 16:57, Demetrios Matsakis wrote:
>>> I don’t know how SR counters are today, but when we were upgrading
>>> our infrastructure over a decade ago we found other counters had
>>> better linearity. Rover et al’s open source article has a good
>>> discussion of these issues, although of course you need to have one
>>> if you are going to experiment. See G. D. Rovera, M. Siccardi, S.
>>> Romisch, and M. Abgrali, “Time delay measurements: estimation of the
>>> error budget”, Metrologia 56, 2019 035004
>>>
>>>> On Mar 17, 2023, at 9:46 AM, Magnus Danielson via time-nuts
>>>> <time-nuts@lists.febo.com> wrote:
>>>>
>>>> Dear Michael,
>>>>
>>>> On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
>>>>> Dear time-nuts
>>>>>
>>>>> Counter specs often include an “internal resolution” error. For
>>>>> example,
>>>>> the SR620 specs say that it is 25 ps in single-shot, but this can be
>>>>> reduced to 4 ps with sufficient, repeated measurements. Can anyone
>>>>> offer
>>>>> any enlightenment as to the origin of this error, and the statistical
>>>>> distribution it has? I mentioned the SR620 but information about
>>>>> the 53230A
>>>>> would be interesting too.
>>>>
>>>> First of all, the single-shot resolution is somewhat of a hallmark
>>>> measure when it comes to counters.
>>>>
>>>> The interpolator resolution is part of this, but consider that
>>>> there exists non-linearities in the interpolator which makes the
>>>> error larger. I recall there being a plot of the non-linearity in
>>>> the SR620 manual.
>>>>
>>>> It is not uncommon to have interpolator resolution better than
>>>> non-linearities, but the later may be more subtle to most.
>>>>
>>>> Averaging can help, but depending to specifics, it's hard to give a
>>>> number.
>>>>
>>>> Cheers,
>>>> Magnus
>>>>
>>>>>
>>>>> Cheers
>>>>> Michael
>>>>> _______________________________________________
>>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>>>
BC
Bob Camp
Sat, Mar 18, 2023 12:17 PM
Hi
Some of the HP counters have a leakage path between the reference input and
the measurement inputs. This shows up as frequency measurement issues at
the reference frequency and at other frequencies with fractional relations to it.
Bob
On Mar 17, 2023, at 7:03 PM, Demetrios Matsakis via time-nuts time-nuts@lists.febo.com wrote:
On fact one of our best engineers concluded that there was leakage
across the inputs, as Magnus mentioned. I thought at the time he had
measured it, but I am not 100% sure of that.
On Mar 17, 2023, at 13:47, Magnus Danielson <magnus@rubidium.se>
wrote:
I also recall one paper relating to laser ranging measurement of the
moon which also looked at temperature dependence of counters, and
SR620 showed more sensitivity than some other counters. For some
measurement purposes, the impact is less than for others.
A fun experiment would be to use a delay-stepper to plot this. I
accumulated equipment for that over the years, with increasing
resolution and performance but never got around to it. Good little
practical experiment now that I was able to steer the Colby DL10
programmable trombone delay.
There is two common reasons for non-linearity, one is from the
interpolator itself where error-pulse shaper as well as
pulse-to-voltage converter has non-linearities. Another one is du to
leakage of either clock or other input shifts the trigger point due
to lacking isolation. Such non-linearities can be handled through
measurement setup and at times with averaging.
Some properties can be managed through wise use of the
autocalibration.
Then again, most of the times I do not bother to go the extra
stretch, but it is good to know the effects are there so one can
consider them and if needed cope with them.
So, time to close down computer, check out and leave Vancouver after
a WSTS conference.
Cheers,
Magnus
On 2023-03-17 16:57, Demetrios Matsakis wrote:
I don’t know how SR counters are today, but when we were upgrading
our infrastructure over a decade ago we found other counters had
better linearity. Rover et al’s open source article has a good
discussion of these issues, although of course you need to have one
if you are going to experiment. See G. D. Rovera, M. Siccardi, S.
Romisch, and M. Abgrali, “Time delay measurements: estimation of the
error budget”, Metrologia 56, 2019 035004
On Mar 17, 2023, at 9:46 AM, Magnus Danielson via time-nuts
[1]time-nuts@lists.febo.com wrote:
Dear Michael,
On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
Dear time-nuts
Counter specs often include an “internal resolution” error. For
example,
the SR620 specs say that it is 25 ps in single-shot, but this can be
reduced to 4 ps with sufficient, repeated measurements. Can anyone
offer
any enlightenment as to the origin of this error, and the
statistical
distribution it has? I mentioned the SR620 but information about the
53230A
would be interesting too.
First of all, the single-shot resolution is somewhat of a hallmark
measure when it comes to counters.
The interpolator resolution is part of this, but consider that there
exists non-linearities in the interpolator which makes the error
larger. I recall there being a plot of the non-linearity in the SR620
manual.
It is not uncommon to have interpolator resolution better than
non-linearities, but the later may be more subtle to most.
Averaging can help, but depending to specifics, it's hard to give a
number.
Cheers,
Magnus
Cheers
Michael
_______________________________________________
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To unsubscribe send an email to [3]time-nuts-leave@lists.febo.com
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- mailto:time-nuts@lists.febo.com
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- mailto:time-nuts-leave@lists.febo.com
- mailto:time-nuts@lists.febo.com
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To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hi
Some of the HP counters have a leakage path between the reference input and
the measurement inputs. This shows up as frequency measurement issues at
the reference frequency and at other frequencies with fractional relations to it.
Bob
> On Mar 17, 2023, at 7:03 PM, Demetrios Matsakis via time-nuts <time-nuts@lists.febo.com> wrote:
>
> On fact one of our best engineers concluded that there was leakage
> across the inputs, as Magnus mentioned. I thought at the time he had
> measured it, but I am not 100% sure of that.
>
> On Mar 17, 2023, at 13:47, Magnus Danielson <magnus@rubidium.se>
> wrote:
>
>
>
> I also recall one paper relating to laser ranging measurement of the
> moon which also looked at temperature dependence of counters, and
> SR620 showed more sensitivity than some other counters. For some
> measurement purposes, the impact is less than for others.
>
> A fun experiment would be to use a delay-stepper to plot this. I
> accumulated equipment for that over the years, with increasing
> resolution and performance but never got around to it. Good little
> practical experiment now that I was able to steer the Colby DL10
> programmable trombone delay.
>
> There is two common reasons for non-linearity, one is from the
> interpolator itself where error-pulse shaper as well as
> pulse-to-voltage converter has non-linearities. Another one is du to
> leakage of either clock or other input shifts the trigger point due
> to lacking isolation. Such non-linearities can be handled through
> measurement setup and at times with averaging.
>
> Some properties can be managed through wise use of the
> autocalibration.
>
> Then again, most of the times I do not bother to go the extra
> stretch, but it is good to know the effects are there so one can
> consider them and if needed cope with them.
>
> So, time to close down computer, check out and leave Vancouver after
> a WSTS conference.
>
> Cheers,
> Magnus
>
> On 2023-03-17 16:57, Demetrios Matsakis wrote:
>
> I don’t know how SR counters are today, but when we were upgrading
> our infrastructure over a decade ago we found other counters had
> better linearity. Rover et al’s open source article has a good
> discussion of these issues, although of course you need to have one
> if you are going to experiment. See G. D. Rovera, M. Siccardi, S.
> Romisch, and M. Abgrali, “Time delay measurements: estimation of the
> error budget”, Metrologia 56, 2019 035004
>
> On Mar 17, 2023, at 9:46 AM, Magnus Danielson via time-nuts
> [1]<time-nuts@lists.febo.com> wrote:
>
> Dear Michael,
> On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
>
> Dear time-nuts
> Counter specs often include an “internal resolution” error. For
> example,
> the SR620 specs say that it is 25 ps in single-shot, but this can be
> reduced to 4 ps with sufficient, repeated measurements. Can anyone
> offer
> any enlightenment as to the origin of this error, and the
> statistical
> distribution it has? I mentioned the SR620 but information about the
> 53230A
> would be interesting too.
>
> First of all, the single-shot resolution is somewhat of a hallmark
> measure when it comes to counters.
> The interpolator resolution is part of this, but consider that there
> exists non-linearities in the interpolator which makes the error
> larger. I recall there being a plot of the non-linearity in the SR620
> manual.
> It is not uncommon to have interpolator resolution better than
> non-linearities, but the later may be more subtle to most.
> Averaging can help, but depending to specifics, it's hard to give a
> number.
> Cheers,
> Magnus
>
> Cheers
> Michael
> _______________________________________________
> time-nuts mailing list -- [2]time-nuts@lists.febo.com
> To unsubscribe send an email to [3]time-nuts-leave@lists.febo.com
>
> _______________________________________________
> time-nuts mailing list -- [4]time-nuts@lists.febo.com
> To unsubscribe send an email to [5]time-nuts-leave@lists.febo.com
>
> References
>
> 1. mailto:time-nuts@lists.febo.com
> 2. mailto:time-nuts@lists.febo.com
> 3. mailto:time-nuts-leave@lists.febo.com
> 4. mailto:time-nuts@lists.febo.com
> 5. mailto:time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
MD
Magnus Danielson
Sun, Mar 19, 2023 12:35 AM
Hi Bob,
That's the effect of quantization of time as such. All counters have
that. The single-shot resolution creates a staircase waveform for which
it will represent any phase. In the ideal case that is linear, but what
we have discussed is uneven distribution of those steps due to leakage,
making it non-linear. If we for a moment just consider the fully linear
case with all steps being equal, then the actual value and the
stair-case differs and the error signal forms a sawtooth.
Consider now that we aim to measure the frequency of a signal, we get a
start signal comming in at some true time TA and a stop signal at some
true time TB. These will be quantized into the measured scale and each
of those time-stamps will then sample the error curve. As you now takes
f = Events/(TB-TA) estimation you actually do it with the quantized
verstions of TA and TB, so error function wise you will see the effect
of the sawtooth. So your actual frequency as you attempt to model it in
a rational number will probe the sawtooth errors in different ways and
depending on how close you are, you may very nicely fit onto the
sawtooth, in which case the error cancel, or most often not very well at
which you fare worse. On average you experience that 1/sqrt(12) number
that pops out of the geometry. There is a HP app-note showing the error,
so that is why you say "HP counters".
Now, curious as I am, I set about to investigate the 1/tau shape,
knowing that noise and other signal tends to smooth out quantization in
average. This is done to audio and other processes called dithering,
it's done to magnetic tape where it is called bias tone but it is also
done in counters if you pick up the good old HP5328A with OPTION 040,
041 or 042 or the HP5328B and turn the measurement knob onto TI AVG, at
which time the front-end digitization card swaps the regular 10 MHz
reference into the 100 MHz PLL to a 10 MHz which has been deeply
phase-modulated with the white noise of a diode. This modulate the phase
location of the 100 MHz to sample the phase of the input signal at more
phase-locations, thus probing the error function at more places, which
makes the net effect of the error function to smooth out.
I wrote a paper on that, which Demetrios has the mixed fortune to read,
as I ended up not doing a good job explain it all. However, I analyzed
what noise does, and it starts to reduce the narrow edge when there is a
little noise, and the more noise you apply the more of the large step
noise becomes averaged out. Plotting the overall error, one can see that
for very little noise, the noise is actuall exagerated by quantization,
but the more noise you add the less the error. This is a form of
compression, where low levels of noise experience gain, which is reduced
the higher the noise is in relation to the quantization step. With
enough noise, the noise reaches a minimum since it is actuall somewhat
oversupressed until for noise above the quantization noise, the noise is
being characterized fairly well after quantization, so the gain is about 1.
So, if you do averaging on your estimation, you simply lack to little
white noise for your quantization. You need to add noise to improve your
measurements.
I did try a HP5328A with GPIB and pull into TimeLab and tried different
settings. It was doing better than the traditional analysis of the HP
engineers have anticipated according to manual. I can try to dig that
measurement up or redo it.
That 1/tau slope is not all random noise. It is systematic noise mixed
with random noise, and it interact to modulate.
Another thing, systematic noise rolls of quicker with MDEV, since the
averaging just of the different points of the error function ends to do
that, which a delta-counter frequency estimation benefits from. Same
would go for omega-counter and PDEV.
So, in conclusion, your final resolution of counter will be limited by
single point resolution systematics, lack of white noise to average
quantization steps and lack of averaging phase/frequency estimator. This
is the way to improve beyond the single-step resolution for arbitrary
frequencies.
The exact same thing happens on the output side of a DDS. It's the same
thing happening in reverse order, so the error function creates all the
spurs you see. As you analyze DDSes, you have sawtooth functions
overlayed with various periods.
So much fun.
Cheers,
Magnus
On 2023-03-18 13:17, Bob Camp wrote:
Hi
Some of the HP counters have a leakage path between the reference input and
the measurement inputs. This shows up as frequency measurement issues at
the reference frequency and at other frequencies with fractional relations to it.
Bob
On Mar 17, 2023, at 7:03 PM, Demetrios Matsakis via time-nuts time-nuts@lists.febo.com wrote:
On fact one of our best engineers concluded that there was leakage
across the inputs, as Magnus mentioned. I thought at the time he had
measured it, but I am not 100% sure of that.
On Mar 17, 2023, at 13:47, Magnus Danielson <magnus@rubidium.se>
wrote:
I also recall one paper relating to laser ranging measurement of the
moon which also looked at temperature dependence of counters, and
SR620 showed more sensitivity than some other counters. For some
measurement purposes, the impact is less than for others.
A fun experiment would be to use a delay-stepper to plot this. I
accumulated equipment for that over the years, with increasing
resolution and performance but never got around to it. Good little
practical experiment now that I was able to steer the Colby DL10
programmable trombone delay.
There is two common reasons for non-linearity, one is from the
interpolator itself where error-pulse shaper as well as
pulse-to-voltage converter has non-linearities. Another one is du to
leakage of either clock or other input shifts the trigger point due
to lacking isolation. Such non-linearities can be handled through
measurement setup and at times with averaging.
Some properties can be managed through wise use of the
autocalibration.
Then again, most of the times I do not bother to go the extra
stretch, but it is good to know the effects are there so one can
consider them and if needed cope with them.
So, time to close down computer, check out and leave Vancouver after
a WSTS conference.
Cheers,
Magnus
On 2023-03-17 16:57, Demetrios Matsakis wrote:
I don’t know how SR counters are today, but when we were upgrading
our infrastructure over a decade ago we found other counters had
better linearity. Rover et al’s open source article has a good
discussion of these issues, although of course you need to have one
if you are going to experiment. See G. D. Rovera, M. Siccardi, S.
Romisch, and M. Abgrali, “Time delay measurements: estimation of the
error budget”, Metrologia 56, 2019 035004
On Mar 17, 2023, at 9:46 AM, Magnus Danielson via time-nuts
[1]time-nuts@lists.febo.com wrote:
Dear Michael,
On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
Dear time-nuts
Counter specs often include an “internal resolution” error. For
example,
the SR620 specs say that it is 25 ps in single-shot, but this can be
reduced to 4 ps with sufficient, repeated measurements. Can anyone
offer
any enlightenment as to the origin of this error, and the
statistical
distribution it has? I mentioned the SR620 but information about the
53230A
would be interesting too.
First of all, the single-shot resolution is somewhat of a hallmark
measure when it comes to counters.
The interpolator resolution is part of this, but consider that there
exists non-linearities in the interpolator which makes the error
larger. I recall there being a plot of the non-linearity in the SR620
manual.
It is not uncommon to have interpolator resolution better than
non-linearities, but the later may be more subtle to most.
Averaging can help, but depending to specifics, it's hard to give a
number.
Cheers,
Magnus
Cheers
Michael
_______________________________________________
time-nuts mailing list -- [2]time-nuts@lists.febo.com
To unsubscribe send an email to [3]time-nuts-leave@lists.febo.com
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References
- mailto:time-nuts@lists.febo.com
- mailto:time-nuts@lists.febo.com
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time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hi Bob,
That's the effect of quantization of time as such. All counters have
that. The single-shot resolution creates a staircase waveform for which
it will represent any phase. In the ideal case that is linear, but what
we have discussed is uneven distribution of those steps due to leakage,
making it non-linear. If we for a moment just consider the fully linear
case with all steps being equal, then the actual value and the
stair-case differs and the error signal forms a sawtooth.
Consider now that we aim to measure the frequency of a signal, we get a
start signal comming in at some true time TA and a stop signal at some
true time TB. These will be quantized into the measured scale and each
of those time-stamps will then sample the error curve. As you now takes
f = Events/(TB-TA) estimation you actually do it with the quantized
verstions of TA and TB, so error function wise you will see the effect
of the sawtooth. So your actual frequency as you attempt to model it in
a rational number will probe the sawtooth errors in different ways and
depending on how close you are, you may very nicely fit onto the
sawtooth, in which case the error cancel, or most often not very well at
which you fare worse. On average you experience that 1/sqrt(12) number
that pops out of the geometry. There is a HP app-note showing the error,
so that is why you say "HP counters".
Now, curious as I am, I set about to investigate the 1/tau shape,
knowing that noise and other signal tends to smooth out quantization in
average. This is done to audio and other processes called dithering,
it's done to magnetic tape where it is called bias tone but it is also
done in counters if you pick up the good old HP5328A with OPTION 040,
041 or 042 or the HP5328B and turn the measurement knob onto TI AVG, at
which time the front-end digitization card swaps the regular 10 MHz
reference into the 100 MHz PLL to a 10 MHz which has been deeply
phase-modulated with the white noise of a diode. This modulate the phase
location of the 100 MHz to sample the phase of the input signal at more
phase-locations, thus probing the error function at more places, which
makes the net effect of the error function to smooth out.
I wrote a paper on that, which Demetrios has the mixed fortune to read,
as I ended up not doing a good job explain it all. However, I analyzed
what noise does, and it starts to reduce the narrow edge when there is a
little noise, and the more noise you apply the more of the large step
noise becomes averaged out. Plotting the overall error, one can see that
for very little noise, the noise is actuall exagerated by quantization,
but the more noise you add the less the error. This is a form of
compression, where low levels of noise experience gain, which is reduced
the higher the noise is in relation to the quantization step. With
enough noise, the noise reaches a minimum since it is actuall somewhat
oversupressed until for noise above the quantization noise, the noise is
being characterized fairly well after quantization, so the gain is about 1.
So, if you do averaging on your estimation, you simply lack to little
white noise for your quantization. You need to add noise to improve your
measurements.
I did try a HP5328A with GPIB and pull into TimeLab and tried different
settings. It was doing better than the traditional analysis of the HP
engineers have anticipated according to manual. I can try to dig that
measurement up or redo it.
That 1/tau slope is not all random noise. It is systematic noise mixed
with random noise, and it interact to modulate.
Another thing, systematic noise rolls of quicker with MDEV, since the
averaging just of the different points of the error function ends to do
that, which a delta-counter frequency estimation benefits from. Same
would go for omega-counter and PDEV.
So, in conclusion, your final resolution of counter will be limited by
single point resolution systematics, lack of white noise to average
quantization steps and lack of averaging phase/frequency estimator. This
is the way to improve beyond the single-step resolution for arbitrary
frequencies.
The exact same thing happens on the output side of a DDS. It's the same
thing happening in reverse order, so the error function creates all the
spurs you see. As you analyze DDSes, you have sawtooth functions
overlayed with various periods.
So much fun.
Cheers,
Magnus
On 2023-03-18 13:17, Bob Camp wrote:
> Hi
>
> Some of the HP counters have a leakage path between the reference input and
> the measurement inputs. This shows up as frequency measurement issues at
> the reference frequency and at other frequencies with fractional relations to it.
>
> Bob
>
>> On Mar 17, 2023, at 7:03 PM, Demetrios Matsakis via time-nuts <time-nuts@lists.febo.com> wrote:
>>
>> On fact one of our best engineers concluded that there was leakage
>> across the inputs, as Magnus mentioned. I thought at the time he had
>> measured it, but I am not 100% sure of that.
>>
>> On Mar 17, 2023, at 13:47, Magnus Danielson <magnus@rubidium.se>
>> wrote:
>>
>>
>>
>> I also recall one paper relating to laser ranging measurement of the
>> moon which also looked at temperature dependence of counters, and
>> SR620 showed more sensitivity than some other counters. For some
>> measurement purposes, the impact is less than for others.
>>
>> A fun experiment would be to use a delay-stepper to plot this. I
>> accumulated equipment for that over the years, with increasing
>> resolution and performance but never got around to it. Good little
>> practical experiment now that I was able to steer the Colby DL10
>> programmable trombone delay.
>>
>> There is two common reasons for non-linearity, one is from the
>> interpolator itself where error-pulse shaper as well as
>> pulse-to-voltage converter has non-linearities. Another one is du to
>> leakage of either clock or other input shifts the trigger point due
>> to lacking isolation. Such non-linearities can be handled through
>> measurement setup and at times with averaging.
>>
>> Some properties can be managed through wise use of the
>> autocalibration.
>>
>> Then again, most of the times I do not bother to go the extra
>> stretch, but it is good to know the effects are there so one can
>> consider them and if needed cope with them.
>>
>> So, time to close down computer, check out and leave Vancouver after
>> a WSTS conference.
>>
>> Cheers,
>> Magnus
>>
>> On 2023-03-17 16:57, Demetrios Matsakis wrote:
>>
>> I don’t know how SR counters are today, but when we were upgrading
>> our infrastructure over a decade ago we found other counters had
>> better linearity. Rover et al’s open source article has a good
>> discussion of these issues, although of course you need to have one
>> if you are going to experiment. See G. D. Rovera, M. Siccardi, S.
>> Romisch, and M. Abgrali, “Time delay measurements: estimation of the
>> error budget”, Metrologia 56, 2019 035004
>>
>> On Mar 17, 2023, at 9:46 AM, Magnus Danielson via time-nuts
>> [1]<time-nuts@lists.febo.com> wrote:
>>
>> Dear Michael,
>> On 2023-03-16 08:17, Michael Wouters via time-nuts wrote:
>>
>> Dear time-nuts
>> Counter specs often include an “internal resolution” error. For
>> example,
>> the SR620 specs say that it is 25 ps in single-shot, but this can be
>> reduced to 4 ps with sufficient, repeated measurements. Can anyone
>> offer
>> any enlightenment as to the origin of this error, and the
>> statistical
>> distribution it has? I mentioned the SR620 but information about the
>> 53230A
>> would be interesting too.
>>
>> First of all, the single-shot resolution is somewhat of a hallmark
>> measure when it comes to counters.
>> The interpolator resolution is part of this, but consider that there
>> exists non-linearities in the interpolator which makes the error
>> larger. I recall there being a plot of the non-linearity in the SR620
>> manual.
>> It is not uncommon to have interpolator resolution better than
>> non-linearities, but the later may be more subtle to most.
>> Averaging can help, but depending to specifics, it's hard to give a
>> number.
>> Cheers,
>> Magnus
>>
>> Cheers
>> Michael
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>> References
>>
>> 1. mailto:time-nuts@lists.febo.com
>> 2. mailto:time-nuts@lists.febo.com
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>> 4. mailto:time-nuts@lists.febo.com
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