Re: [time-nuts] Method for comparing oscillators
I have studied the dual mixer approach and the consensus is that it is the
most accurate method. However, it seems pretty difficult to obtain that
accuracy. I do have some DBMs with IF response down to DC. I don't have a
10811 but do have a pretty good oscillator to use for the offset. The
problem comes in with the time interval counter. The only thing we have is
an old 5328A. I believe, at this time, DMTD is just not possible for me to
do. My oscilloscope method seems to work pretty well. I can't produce graphs
showing frequency stability but that isn't a big deal for me. I just want to
be able to compare a Rb source to a GPSDO and look at several OCXOs either
stand alone or in equipment we have here. If I figure correctly, an error of
1e-12 is 1 Hz every 27.7 hours if comparing 2 10 MHz sources. I don't have
to wait for a full cycle to occur, I can see pretty small phase differences.
Let's say I can see a 10 degree change. That would cut the observation time
down to just over 3 quarters of an hour. Not bad. Most OCXOs will move a lot
more than that so shorter times would work for them. I know from past
experience that this works pretty well for looking at warm up performance.
My first experiment will be the hardest. I am going to check a couple of Rb
sources against a Tbolt. I'll let you know how this works out. Thanks for
all the input.
John,
I see you in the danger to confuse accuracy and stabilility. "Accuracy" of
an oscillator and "stability" of an oscillator are (albeit the fact that our
wishful thinking usually expects both from a good oscillator) two completely
different things that you should not mix against each other.
Your oscilloscope method (without proper handling of phase ambiguities)
measures a compound of both properties and is not well suited for stability
measurements. You have to realize that one of the oscillators that you are
going to compare may be totally inaccurate so that you will see lots of
phase changes in time occuring. Nevertheless this inaccurate oscillator may
be perfectly stable running on its wrong frequency. Do you see the
difference?
Best regards
Ulrich Bangert
-----Ursprungliche Nachricht-----
Von: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] Im Auftrag von John Green
Gesendet: Montag, 3. August 2009 16:59
An: time-nuts@febo.com
Betreff: Re: [time-nuts] Method for comparing oscillators
I have studied the dual mixer approach and the consensus is
that it is the most accurate method. However, it seems pretty
difficult to obtain that accuracy. I do have some DBMs with
IF response down to DC. I don't have a 10811 but do have a
pretty good oscillator to use for the offset. The problem
comes in with the time interval counter. The only thing we
have is an old 5328A. I believe, at this time, DMTD is just
not possible for me to do. My oscilloscope method seems to
work pretty well. I can't produce graphs showing frequency
stability but that isn't a big deal for me. I just want to be
able to compare a Rb source to a GPSDO and look at several
OCXOs either stand alone or in equipment we have here. If I
figure correctly, an error of 1e-12 is 1 Hz every 27.7 hours
if comparing 2 10 MHz sources. I don't have to wait for a
full cycle to occur, I can see pretty small phase
differences. Let's say I can see a 10 degree change. That
would cut the observation time down to just over 3 quarters
of an hour. Not bad. Most OCXOs will move a lot more than
that so shorter times would work for them. I know from past
experience that this works pretty well for looking at warm up
performance. My first experiment will be the hardest. I am
going to check a couple of Rb sources against a Tbolt. I'll
let you know how this works out. Thanks for all the input.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
In message abec162c0908030758y62c9dffdq65f8341cd2bb84d1@mail.gmail.com, John Green writes:
I have studied the dual mixer approach and the consensus is that it is the
most accurate method. However, it seems pretty difficult to obtain that
accuracy.
Check the description and papers about Timing.com's way of doing it, they
are quite clever.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@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.
Rather than using a scope in Y-T mode (with triggered sweep) I find that
using a scope in X-Y mode makes it much easier to compare frequencies.
Doing this, you essentially get a synchroscope display. If the two
waveforms are sinusoidal, the trace will be a circle, the rate of
revolution is the frequency difference, the direction of rotation tells
you which frequency is high/low.
FWIW,
-John
=======
John,
[snip]
Your oscilloscope method (without proper handling of phase ambiguities)
measures a compound of both properties and is not well suited for
stability measurements. [snip
John
If you want quick answers to Frequency differences,
You should think and measure Phase change differences Not Freq differences.
Example: 1e-12 freq offset causes a 1ns shift every 1000 seconds,
NO matter what the Frequencies are that you are comparing.
Any decent standard analog scope can see Sub 1 ns differences
on its fastest sweep with its time base multiplier on when viewing high speed signals.
By using a dual trace scope and syncing the scope to one of the 10 MHz signals
and watching the two signal's zero crossing drift apart on the Scope it takes no more
than 1000 seconds and more like a minute or so to be able see 1e-12 freq differences.
In a hour you can see 1e-13 or better easy, assuming of course that the signal's short term jitter
is not more than a few tens of ns and the scope has warmed up long enough to stabilize.
The same method works even if the two freq are not the same, such as 2 to1 or 4 to5.
The same method (i.e Phase change) can be used with most any counter also,
and is best when comparing low freq like 1 to 1 KHz. which are hard to see on a analog scope.
The cheap counters have less resolution than 1 ns so you need to do time interval averaging
if the counter has that and/or just let it run longer between your readings.
Example:
Start counter Time interval count on one signal, stop it on the other signal,
record what the difference is (and the uncertainty is), come back
in a minute, an hour or day or week and see what the time difference now is,
Calculate the time difference between the two reading in ns and
the time laps between the two reading in seconds or hours.
Freq difference between the signals is equal to [1e-9 * (ns_change / Sec) ]
so that 10 ns_change / sec = 1e-8, 1ns_change / 10 sec = 1e-10
Using hours instead of seconds this works out to
[1e-10 * ((ns_change /Hrs) / 360ns) ]
so that 3.6 ns / hr = 1e-12
BTW, Phase change per unit time is the same way frequency error is calculated using WWVB, the low freq 60Khz signal.
warren
----- Original Message -----
From: "John Green" wpxs472@gmail.com
To: time-nuts@febo.com
Sent: Monday, August 03, 2009 7:58 AM
Subject: Re: [time-nuts] Method for comparing oscillators
I have studied the dual mixer approach and the consensus is that it is the
most accurate method. However, it seems pretty difficult to obtain that
accuracy. I do have some DBMs with IF response down to DC. I don't have a
10811 but do have a pretty good oscillator to use for the offset. The
problem comes in with the time interval counter. The only thing we have is
an old 5328A. I believe, at this time, DMTD is just not possible for me to
do. My oscilloscope method seems to work pretty well. I can't produce graphs
showing frequency stability but that isn't a big deal for me. I just want to
be able to compare a Rb source to a GPSDO and look at several OCXOs either
stand alone or in equipment we have here. If I figure correctly, an error of
1e-12 is 1 Hz every 27.7 hours if comparing 2 10 MHz sources. I don't have
to wait for a full cycle to occur, I can see pretty small phase differences.
Let's say I can see a 10 degree change. That would cut the observation time
down to just over 3 quarters of an hour. Not bad. Most OCXOs will move a lot
more than that so shorter times would work for them. I know from past
experience that this works pretty well for looking at warm up performance.
My first experiment will be the hardest. I am going to check a couple of Rb
sources against a Tbolt. I'll let you know how this works out. Thanks for
all the input.
Ulrich
You are of course correct about Accuracy and Stability, BUT I think it is you that is confused.
I may be wrong here but it would seem to me that ALL John really cares to know for now, like most NON-Nuts, is what the freq (difference) is of several of his good oscillators.
This is all that is important to us non Allen Deviation nuts, because first that is something easy to deal with and correct with a simple adjustment and 2nd the stability and Allen numbers, while interesting, there is little that the average user can do to improve them except to get yet another unneeded oscillator, and MORE ironically, usually the numbers do not tell anything about the one thing that most want to know (because freq offset is first removed), and that is what frequency is it running at right now, not what it may change by in another sec, min or hour. All the nice Allen numbers also show nothing about how close (due to the limited freq adj resolution) that the Osc can really be set to.
ws
----- Original Message -----
From: "Ulrich Bangert" df6jb@ulrich-bangert.de
To: "'Discussion of precise time and frequency measurement'" time-nuts@febo.com
Sent: Monday, August 03, 2009 8:31 AM
Subject: Re: [time-nuts] Method for comparing oscillators
John,
I see you in the danger to confuse accuracy and stabilility. "Accuracy" of
an oscillator and "stability" of an oscillator are (albeit the fact that our
wishful thinking usually expects both from a good oscillator) two completely
different things that you should not mix against each other.
Your oscilloscope method (without proper handling of phase ambiguities)
measures a compound of both properties and is not well suited for stability
measurements. You have to realize that one of the oscillators that you are
going to compare may be totally inaccurate so that you will see lots of
phase changes in time occuring. Nevertheless this inaccurate oscillator may
be perfectly stable running on its wrong frequency. Do you see the
difference?
Best regards
Ulrich Bangert
-----Ursprungliche Nachricht-----
Von: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] Im Auftrag von John Green
Gesendet: Montag, 3. August 2009 16:59
An: time-nuts@febo.com
Betreff: Re: [time-nuts] Method for comparing oscillators
I have studied the dual mixer approach and the consensus is
that it is the most accurate method. However, it seems pretty
difficult to obtain that accuracy.
...
I can't produce graphs showing frequency
stability but that isn't a big deal for me. I just want to be
able to compare a Rb source to a GPSDO and look at several
OCXOs either stand alone or in equipment we have here.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
I have done this and I am not sure I can tell the 'direction of rotation'.
I can easily tell if it reverses but once going, I can't tell which
direction.
Joe
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of J. Forster
Sent: Monday, August 03, 2009 11:14 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Method for comparing oscillators
Rather than using a scope in Y-T mode (with triggered sweep) I find that
using a scope in X-Y mode makes it much easier to compare frequencies. Doing
this, you essentially get a synchroscope display. If the two waveforms are
sinusoidal, the trace will be a circle, the rate of revolution is the
frequency difference, the direction of rotation tells you which frequency is
high/low.
FWIW,
-John
=======
John,
[snip]
Your oscilloscope method (without proper handling of phase
ambiguities) measures a compound of both properties and is not well
suited for stability measurements. [snip
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Hi Joe,
Another BEER will take cared of that !
Bill....WB6BNQ
"J. L. Trantham" wrote:
I have done this and I am not sure I can tell the 'direction of rotation'.
I can easily tell if it reverses but once going, I can't tell which
direction.
Joe
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of J. Forster
Sent: Monday, August 03, 2009 11:14 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Method for comparing oscillators
Rather than using a scope in Y-T mode (with triggered sweep) I find that
using a scope in X-Y mode makes it much easier to compare frequencies. Doing
this, you essentially get a synchroscope display. If the two waveforms are
sinusoidal, the trace will be a circle, the rate of revolution is the
frequency difference, the direction of rotation tells you which frequency is
high/low.
FWIW,
-John
=======
John,
[snip]
Your oscilloscope method (without proper handling of phase
ambiguities) measures a compound of both properties and is not well
suited for stability measurements. [snip
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
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and follow the instructions there.
The counter circuit that I use will not only give you Allen Variance but also shows the frequency difference with the same resolution. So those that are more interested in frequency difference, this will do it. Since the raw data goes directly to the PC computer programs can be used to make all kind of observations. Bert
-----Original Message-----
From: Ulrich Bangert df6jb@ulrich-bangert.de
To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com
Sent: Mon, Aug 3, 2009 11:31 am
Subject: Re: [time-nuts] Method for comparing oscillators
John,
I see you in the danger to confuse accuracy and stabilility. "Accuracy" of
an oscillator and "stability" of an oscillator are (albeit the fact that our
wishful thinking usually expects both from a good oscillator) two completely
different things that you should not mix against each other.
Your oscilloscope method (without proper handling of phase ambiguities)
measures a compound of both properties and is not well suited for stability
measurements. You have to realize that one of the oscillators that you are
going to compare may be totally inaccurate so that you will see lots of
phase changes in time occuring. Nevertheless this inaccurate oscillator may
be perfectly stable running on its wrong frequency. Do you see the
difference?
Best regards
Ulrich Bangert
-----Ursprungliche Nachricht-----
Von: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] Im Auftrag von John Green
Gesendet: Montag, 3. August 2009 16:59
An: time-nuts@febo.com
Betreff: Re: [time-nuts] Method for comparing oscillators
I have studied the dual mixer approach and the consensus is
that it is the most accurate method. However, it seems pretty
difficult to obtain that accuracy. I do have some DBMs with
IF response down to DC. I don't have a 10811 but do have a
pretty good oscillator to use for the offset. The problem
comes in with the time interval counter. The only thing we
have is an old 5328A. I believe, at this time, DMTD is just
not possible for me to do. My oscilloscope method seems to
work pretty well. I can't produce graphs showing frequency
stability but that isn't a big deal for me. I just want to be
able to compare a Rb source to a GPSDO and look at several
OCXOs either stand alone or in equipment we have here. If I
figure correctly, an error of 1e-12 is 1 Hz every 27.7 hours
if comparing 2 10 MHz sources. I don't have to wait for a
full cycle to occur, I can see pretty small phase
differences. Let's say I can see a 10 degree change. That
would
cut the observation time down to just over 3 quarters
of an hour. Not bad. Most OCXOs will move a lot more than
that so shorter times would work for them. I know from past
experience that this works pretty well for looking at warm up
performance. My first experiment will be the hardest. I am
going to check a couple of Rb sources against a Tbolt. I'll
let you know how this works out. Thanks for all the input.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Poul-Henning Kamp wrote:
In message abec162c0908030758y62c9dffdq65f8341cd2bb84d1@mail.gmail.com, John Green writes:
I have studied the dual mixer approach and the consensus is that it is the
most accurate method. However, it seems pretty difficult to obtain that
accuracy.
Check the description and papers about Timing.com's way of doing it, they
are quite clever.
Poul-Henning,
Can you give a more specific reference to the documentation? I took a
look around www.symmetricom.com/resources/ (where timing.com redirects)
but it is not clear to me that anything I found describes their way of
doing it.
Rex wrote:
Poul-Henning Kamp wrote:
In message
abec162c0908030758y62c9dffdq65f8341cd2bb84d1@mail.gmail.com, John
Green writes:
I have studied the dual mixer approach and the consensus is that it
is the
most accurate method. However, it seems pretty difficult to obtain that
accuracy.
Check the description and papers about Timing.com's way of doing it,
they
are quite clever.
Poul-Henning,
Can you give a more specific reference to the documentation? I took a
look around www.symmetricom.com/resources/ (where timing.com
redirects) but it is not clear to me that anything I found describes
their way of doing it.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Rex
Look at the TSC5115A and the TSC5120A (download and read the manuals)
plus the associated patents.
Bruce
Bruce Griffiths wrote:
Rex wrote:
Poul-Henning Kamp wrote:
In message
abec162c0908030758y62c9dffdq65f8341cd2bb84d1@mail.gmail.com, John
Green writes:
I have studied the dual mixer approach and the consensus is that it
is the
most accurate method. However, it seems pretty difficult to obtain that
accuracy.
Check the description and papers about Timing.com's way of doing it,
they
are quite clever.
Poul-Henning,
Can you give a more specific reference to the documentation? I took a
look around www.symmetricom.com/resources/ (where timing.com
redirects) but it is not clear to me that anything I found describes
their way of doing it.
Rex
Look at the TSC5115A and the TSC5120A (download and read the manuals)
plus the associated patents.
Bruce
Bruce,
Thanks, that looks interesting. I found the manual here...
http://www.symmetricom.com/media/files/support/ttm/product-manual/5120A-MAN.pdf
But I haven't figured out where to get a list of related patents. Can
anyone provide key number(s) or point me to a list?
Bruce,
Thanks, that looks interesting. I found the manual here...
http://www.symmetricom.com/media/files/support/ttm/product-
manual/5120A-MAN.pdf
But I haven't figured out where to get a list of related patents. Can
anyone provide key number(s) or point me to a list?
patent search
quick
symmetricom in "Assignee Name"
47 patents assigned to symmetricom.
To be honest, though, none of the titles look relevant.
You might need to search on the name of someone who worked on it, or the company that originally developed it.
For instance, S.R. Stein signed the DoC, and is also a co-author of the paper they cite.
Lux, Jim (337C) wrote:
Bruce,
Thanks, that looks interesting. I found the manual here...
http://www.symmetricom.com/media/files/support/ttm/product-
manual/5120A-MAN.pdf
But I haven't figured out where to get a list of related patents. Can
anyone provide key number(s) or point me to a list?
patent search
quick
symmetricom in "Assignee Name"
47 patents assigned to symmetricom.
To be honest, though, none of the titles look relevant.
You might need to search on the name of someone who worked on it, or the company that originally developed it.
For instance, S.R. Stein signed the DoC, and is also a co-author of the paper they cite.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Actually Timing Solutions corp would be better choice of assignee as
they developed the concept until swallowed/absorbed by Symmetricom
Bruce
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Lux, Jim (337C)
Sent: Tuesday, August 04, 2009 5:01 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Method for comparing oscillators
Bruce,
Thanks, that looks interesting. I found the manual here...
http://www.symmetricom.com/media/files/support/ttm/product-
manual/5120A-MAN.pdf
But I haven't figured out where to get a list of related patents. Can
anyone provide key number(s) or point me to a list?
patent search
quick
symmetricom in "Assignee Name"
47 patents assigned to symmetricom.
To be honest, though, none of the titles look relevant.
You might need to search on the name of someone who worked on it, or
the company that originally developed it.
For instance, S.R. Stein signed the DoC, and is also a co-author of the
paper they cite.
Try patent 5,128,909.
Advanced Clock Measurement System, July 1992 (so it's still in force)
(Assigned to Ball Corp.. although S.R. Stein is in Boulder). Didn't Ball used to be in the clock business? Ball-Efratom seems to ring a bell.
The present invention relates to a method and system for measuring the time difference between a plurality of high-precision clocks. More particularly, the present invention relates to a simplified extended dual mixer time difference measurement system which employs a common oscillator as opposed to a synthesizer, thereby reducing the cost of the system and eliminating noise produced by a synthesizer.
Following links, one might also want to look at
6,194,918 and 6,172,533, both titled "Phase and Frequency detector with high resolution"
The latter refers to 4,634,967 and 4,912,734
Lux, Jim (337C) wrote:
Bruce,
Thanks, that looks interesting. I found the manual here...
http://www.symmetricom.com/media/files/support/ttm/product-
manual/5120A-MAN.pdf
But I haven't figured out where to get a list of related patents. Can
anyone provide key number(s) or point me to a list?
patent search
quick
symmetricom in "Assignee Name"
47 patents assigned to symmetricom.
To be honest, though, none of the titles look relevant.
You might need to search on the name of someone who worked on it, or the company that originally developed it.
For instance, S.R. Stein signed the DoC, and is also a co-author of the paper they cite.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
See US patent 7227346
Bruce
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Bruce Griffiths
Sent: Tuesday, August 04, 2009 5:06 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Method for comparing oscillators
Actually Timing Solutions corp would be better choice of assignee as
they developed the concept until swallowed/absorbed by Symmetricom
Bruce
1 7,436,166 Full-Text Direct digital synthesizer producing a signal representing an amplitude of a sine wave
2 7,227,346 Full-Text Two channel digital phase detector
3 5,315,566 Full-Text Time scale computation system
4 5,155,695 Full-Text Time scale computation system including complete and weighted ensemble definition
The second one, to Wayne Solbrig, looks interesting.
The present invention is directed to a digital phase detector that is capable of being used in a phase measurement system to make very low phase noise measurements and, in one embodiment, as low as about 180 dB/Hz below the carrier frequency
It would appear that some folks from Cal Tech and JPL, have used a similar technique in 7,511,469, for measuring small changes in laser frequencies.
Lux, Jim (337C) wrote:
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Bruce Griffiths
Sent: Tuesday, August 04, 2009 5:06 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Method for comparing oscillators
Actually Timing Solutions corp would be better choice of assignee as
they developed the concept until swallowed/absorbed by Symmetricom
Bruce
1 7,436,166 Full-Text Direct digital synthesizer producing a signal representing an amplitude of a sine wave
2 7,227,346 Full-Text Two channel digital phase detector
3 5,315,566 Full-Text Time scale computation system
4 5,155,695 Full-Text Time scale computation system including complete and weighted ensemble definition
The second one, to Wayne Solbrig, looks interesting.
The present invention is directed to a digital phase detector that is capable of being used in a phase measurement system to make very low phase noise measurements and, in one embodiment, as low as about 180 dB/Hz below the carrier frequency
It would appear that some folks from Cal Tech and JPL, have used a similar technique in 7,511,469, for measuring small changes in laser frequencies.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
The first 2 are the relevant patents.
You may also find it useful to download the 5125A manual.
This instrument uses subNyquist sampling together with a bank of
switched antialiasing bandpass filters to compare 2 sources over the
1-400MHz frequency range.
There may be additional patents pending for this.
Bruce
Rex,
time-nuts-bounces@febo.com wrote on 08/04/2009 07:35:51 PM:
Date:
08/04/2009 07:43 PM
Subject:
Re: [time-nuts] Method for comparing oscillators
Sent by:
Bruce Griffiths wrote:
Rex wrote:
Poul-Henning Kamp wrote:
In message
abec162c0908030758y62c9dffdq65f8341cd2bb84d1@mail.gmail.com, John
Green writes:
I have studied the dual mixer approach and the consensus is that it
is the
most accurate method. However, it seems pretty difficult to
obtain that
accuracy.
Check the description and papers about Timing.com's way of doing it,
they
are quite clever.
Poul-Henning,
Can you give a more specific reference to the documentation? I took a
look around www.symmetricom.com/resources/ (where timing.com
redirects) but it is not clear to me that anything I found describes
their way of doing it.
Rex
Look at the TSC5115A and the TSC5120A (download and read the manuals)
plus the associated patents.
Bruce
Bruce,
Thanks, that looks interesting. I found the manual here...
http://www.symmetricom.com/media/files/support/ttm/product-
manual/5120A-MAN.pdf
But I haven't figured out where to get a list of related patents. Can
anyone provide key number(s) or point me to a list?
I dug this up a year or two ago. It was not easy to find, but the main
patent is US Patent 7,227,346 to Solbrig. The patent text may be obtained
from www.pat2pdf.org or Google Patents.
There may be another patent, but I don't know its number.
The main article was "Direct-Digital Phase-Noise Measurement", J. Grove,
J. Hein, J. Retta, P. Schweiger, W. Solbrig, and S.R. Stein, 2004 IEEE
International Ultrasonics, Ferroelectrics, and Frequency Control Joint
50th Anniversary Conference, pages 287-291,
0-7803-8414-8/04/$20.00 (c)2004 IEEE. Much of the text of this article
also appears in an appendix to the 5120 manual.
Joe Gwinn
Joseph M Gwinn wrote:
Rex,
time-nuts-bounces@febo.com wrote on 08/04/2009 07:35:51 PM:
Date:
08/04/2009 07:43 PM
Subject:
Re: [time-nuts] Method for comparing oscillators
Sent by:
Bruce Griffiths wrote:
Rex wrote:
Poul-Henning Kamp wrote:
In message
abec162c0908030758y62c9dffdq65f8341cd2bb84d1@mail.gmail.com, John
Green writes:
I have studied the dual mixer approach and the consensus is that it
is the
most accurate method. However, it seems pretty difficult to
obtain that
accuracy.
Check the description and papers about Timing.com's way of doing it,
they
are quite clever.
Poul-Henning,
Can you give a more specific reference to the documentation? I took a
look around www.symmetricom.com/resources/ (where timing.com
redirects) but it is not clear to me that anything I found describes
their way of doing it.
Rex
Look at the TSC5115A and the TSC5120A (download and read the manuals)
plus the associated patents.
Bruce
Bruce,
Thanks, that looks interesting. I found the manual here...
http://www.symmetricom.com/media/files/support/ttm/product-
manual/5120A-MAN.pdf
But I haven't figured out where to get a list of related patents. Can
anyone provide key number(s) or point me to a list?
I dug this up a year or two ago. It was not easy to find, but the main
patent is US Patent 7,227,346 to Solbrig. The patent text may be obtained
from www.pat2pdf.org or Google Patents.
There may be another patent, but I don't know its number.
The main article was "Direct-Digital Phase-Noise Measurement", J. Grove,
J. Hein, J. Retta, P. Schweiger, W. Solbrig, and S.R. Stein, 2004 IEEE
International Ultrasonics, Ferroelectrics, and Frequency Control Joint
50th Anniversary Conference, pages 287-291,
0-7803-8414-8/04/$20.00 (c)2004 IEEE. Much of the text of this article
also appears in an appendix to the 5120 manual.
Joe Gwinn
Joe
7436166 is the other relevant patent.
Bruce
Thanks, everyone!
-Rex
Bruce Griffiths wrote:
Lux, Jim (337C) wrote:
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Bruce Griffiths
Sent: Tuesday, August 04, 2009 5:06 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Method for comparing oscillators
Actually Timing Solutions corp would be better choice of assignee as
they developed the concept until swallowed/absorbed by Symmetricom
Bruce
1 7,436,166 Full-Text Direct digital synthesizer producing a signal representing an amplitude of a sine wave
2 7,227,346 Full-Text Two channel digital phase detector
3 5,315,566 Full-Text Time scale computation system
4 5,155,695 Full-Text Time scale computation system including complete and weighted ensemble definition
The second one, to Wayne Solbrig, looks interesting.
The present invention is directed to a digital phase detector that is capable of being used in a phase measurement system to make very low phase noise measurements and, in one embodiment, as low as about 180 dB/Hz below the carrier frequency
It would appear that some folks from Cal Tech and JPL, have used a similar technique in 7,511,469, for measuring small changes in laser frequencies.
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and follow the instructions there.
The first 2 are the relevant patents.
You may also find it useful to download the 5125A manual.
This instrument uses subNyquist sampling together with a bank of
switched antialiasing bandpass filters to compare 2 sources over the
1-400MHz frequency range.
There may be additional patents pending for this.
Bruce
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In message: ECE7A93BD093E1439C20020FBE87C47FEB74C94DE9@ALTPHYEMBEVSP20.RES.AD.JPL
"Lux, Jim (337C)" james.p.lux@jpl.nasa.gov writes:
: >
: > Bruce,
: >
: > Thanks, that looks interesting. I found the manual here...
: > http://www.symmetricom.com/media/files/support/ttm/product-
: > manual/5120A-MAN.pdf
: >
: > But I haven't figured out where to get a list of related patents. Can
: > anyone provide key number(s) or point me to a list?
:
:
: http://www.uspto.gov/
:
: patent search
: quick
: symmetricom in "Assignee Name"
:
:
: 47 patents assigned to symmetricom.
:
: To be honest, though, none of the titles look relevant.
:
: You might need to search on the name of someone who worked on it, or the company that originally developed it.
:
: For instance, S.R. Stein signed the DoC, and is also a co-author of the paper they cite.
Sam Stein works for Symmetricom these days. Many of the patents might
be under "Timing Solutions", the name of his old company.
Warner
I had a quick look at the manual. From the block diagram of the technique,
seems that one could use the USRP board (Ettus Research) and GNU Radio
functions to do the whole thing. Oddly, the OSRP board clock is 64 MHz....
Don Latham
----- Original Message -----
From: "M. Warner Losh" imp@bsdimp.com
To: time-nuts@febo.com; james.p.lux@jpl.nasa.gov
Sent: Tuesday, August 04, 2009 11:03 PM
Subject: Re: [time-nuts] Method for comparing oscillators
In message:
ECE7A93BD093E1439C20020FBE87C47FEB74C94DE9@ALTPHYEMBEVSP20.RES.AD.JPL
"Lux, Jim (337C)" james.p.lux@jpl.nasa.gov writes:
: >
: > Bruce,
: >
: > Thanks, that looks interesting. I found the manual here...
: > http://www.symmetricom.com/media/files/support/ttm/product-
: > manual/5120A-MAN.pdf
: >
: > But I haven't figured out where to get a list of related patents. Can
: > anyone provide key number(s) or point me to a list?
:
:
: http://www.uspto.gov/
:
: patent search
: quick
: symmetricom in "Assignee Name"
:
:
: 47 patents assigned to symmetricom.
:
: To be honest, though, none of the titles look relevant.
:
: You might need to search on the name of someone who worked on it, or the
company that originally developed it.
:
: For instance, S.R. Stein signed the DoC, and is also a co-author of the
paper they cite.
Sam Stein works for Symmetricom these days. Many of the patents might
be under "Timing Solutions", the name of his old company.
Warner
time-nuts mailing list -- time-nuts@febo.com
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https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Sam gave a thorough paper on the 5120 technology at the 2009
FCS/EFTF. I don't know if the proceedings are published on the IEEE
archive yet, but they should be soon.
He has also given a tutorial on digital phase measurement for the
past 5-6 years at the NIST Time & Frequency Seminar
(http://tf.nist.gov/seminars/T&Foverview.html).
Occasionally, he also gives a tutorial on phase measurement at the
FCS. See, for example,
http://www.ieee-uffc.org/frequency_control/teaching/stein_2002_files/frame.htm
-RL
Robert Lutwak
Symmetricom - Technology Realization Center
mhtml:mid://00000000/mailto:RLutwak@Symmetricom.comRLutwak@Symmetricom.com
(Business)
mhtml:mid://00000000/mailto:Lutwak@Alum.mit.eduLutwak@Alum.mit.edu
(Personal)
(978) 232-1461 (Desk)
(339) 927-7896 (Mobile)
(978) 927-4099 (Facsimile)
At 03:13 AM 8/5/2009, you wrote:
I had a quick look at the manual. From the block diagram of the
technique, seems that one could use the USRP board (Ettus Research)
and GNU Radio functions to do the whole thing. Oddly, the OSRP board
clock is 64 MHz....
Don Latham
----- Original Message ----- From: "M. Warner Losh" imp@bsdimp.com
To: time-nuts@febo.com; james.p.lux@jpl.nasa.gov
Sent: Tuesday, August 04, 2009 11:03 PM
Subject: Re: [time-nuts] Method for comparing oscillators
In message:
ECE7A93BD093E1439C20020FBE87C47FEB74C94DE9@ALTPHYEMBEVSP20.RES.AD.JPL
"Lux, Jim (337C)" james.p.lux@jpl.nasa.gov writes:
: >
: > Bruce,
: >
: > Thanks, that looks interesting. I found the manual here...
: > http://www.symmetricom.com/media/files/support/ttm/product-
: > manual/5120A-MAN.pdf
: >
: > But I haven't figured out where to get a list of related patents. Can
: > anyone provide key number(s) or point me to a list?
:
:
: http://www.uspto.gov/
:
: patent search
: quick
: symmetricom in "Assignee Name"
:
:
: 47 patents assigned to symmetricom.
:
: To be honest, though, none of the titles look relevant.
:
: You might need to search on the name of someone who worked on it,
or the company that originally developed it.
:
: For instance, S.R. Stein signed the DoC, and is also a co-author
of the paper they cite.
Sam Stein works for Symmetricom these days. Many of the patents might
be under "Timing Solutions", the name of his old company.
Warner
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
-RL
Robert Lutwak
Symmetricom - Technology Realization Center
mhtml:mid://00000000/mailto:RLutwak@Symmetricom.comRLutwak@Symmetricom.com
(Business)
mhtml:mid://00000000/mailto:Lutwak@Alum.mit.eduLutwak@Alum.mit.edu
(Personal)
(978) 232-1461 (Desk)
(339) 927-7896 (Mobile)
(978) 927-4099 (Facsimile)