Worst possible error on a rubidium
If an old random 10 MHz Rubidium oscillator is working (i.e. powers up, and
eventually locks), what is the maximum possible frequency error it could have?
Could it remained locked with an error of 1 part in 10^7, 10^8, 10^9, 10^10 etc?
I assume there are physical limits which would simply stop it functioning too
far from the correct frequency, but don't have much clue what they are.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
David,
That's a good question, and I wouldn't be able to say, without seeing the
spec sheet on the oscillator itself. Out of lock would be out of
tolernace, but what the maximum allowable deviation is, on the unit in
question, I wouldn't know. If it does finally lock, it should be within
tolerance, but what that tolernaces maximum deviation is, it's untelling,
without seeing some literature on it.
I did have a sheet on the one I bought, and if I can find it, I'll see what
it says.
Best,
Will
*********** REPLY SEPARATOR ***********
On 7/13/2011 at 10:15 PM Dr. David Kirkby wrote:
If an old random 10 MHz Rubidium oscillator is working (i.e. powers up,
and
eventually locks), what is the maximum possible frequency error it could
have?
Could it remained locked with an error of 1 part in 10^7, 10^8, 10^9,
10^10 etc?
I assume there are physical limits which would simply stop it functioning
too
far from the correct frequency, but don't have much clue what they are.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
__________ Information from ESET Smart Security, version of virus
signature database 5851 (20110206) __________
Hi
For most Rb's most of the time, the answer is a few ppb (like say +/-3 ppb). Unfortunately there's no guarantee that it will fail to lock even with low probability / crazy stuff wrong. That opens up the window a bit...
Bob
On Jul 13, 2011, at 5:15 PM, Dr. David Kirkby wrote:
If an old random 10 MHz Rubidium oscillator is working (i.e. powers up, and eventually locks), what is the maximum possible frequency error it could have?
Could it remained locked with an error of 1 part in 10^7, 10^8, 10^9, 10^10 etc?
I assume there are physical limits which would simply stop it functioning too far from the correct frequency, but don't have much clue what they are.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
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.
David,
Below is a link to the datasheet on the FEI 5680A. I hope it will work with
those %20 in the link. If not, I think there simply blank spaces, or /FEI -
5680A.pdf
http://www.gillam-fei.be/products/pdf/others/rubidium/FEI%20-%205680A.pdf
Best,
Will
*********** REPLY SEPARATOR ***********
On 7/13/2011 at 5:24 PM Will Matney wrote:
David,
That's a good question, and I wouldn't be able to say, without seeing the
spec sheet on the oscillator itself. Out of lock would be out of
tolernace, but what the maximum allowable deviation is, on the unit in
question, I wouldn't know. If it does finally lock, it should be within
tolerance, but what that tolernaces maximum deviation is, it's untelling,
without seeing some literature on it.
I did have a sheet on the one I bought, and if I can find it, I'll see
what
it says.
Best,
Will
*********** REPLY SEPARATOR ***********
On 7/13/2011 at 10:15 PM Dr. David Kirkby wrote:
If an old random 10 MHz Rubidium oscillator is working (i.e. powers up,
and
eventually locks), what is the maximum possible frequency error it could
have?
Could it remained locked with an error of 1 part in 10^7, 10^8, 10^9,
10^10 etc?
I assume there are physical limits which would simply stop it functioning
too
far from the correct frequency, but don't have much clue what they are.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
__________ Information from ESET Smart Security, version of virus
signature database 5851 (20110206) __________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
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signature database 5851 (20110206) __________
Here is another link to the catalog on these FEI standards, and it has info
that the datasheet leaves out, especially on operation.
http://www.freqelec.com/pdf/rfs_12pg.pdf
Best,
Will
*********** REPLY SEPARATOR ***********
On 7/13/2011 at 6:27 PM Will Matney wrote:
David,
Below is a link to the datasheet on the FEI 5680A. I hope it will work
with
those %20 in the link. If not, I think there simply blank spaces, or /FEI
5680A.pdf
http://www.gillam-fei.be/products/pdf/others/rubidium/FEI%20-%205680A.pdf
Best,
Will
*********** REPLY SEPARATOR ***********
On 7/13/2011 at 5:24 PM Will Matney wrote:
David,
That's a good question, and I wouldn't be able to say, without seeing the
spec sheet on the oscillator itself. Out of lock would be out of
tolernace, but what the maximum allowable deviation is, on the unit in
question, I wouldn't know. If it does finally lock, it should be within
tolerance, but what that tolernaces maximum deviation is, it's untelling,
without seeing some literature on it.
I did have a sheet on the one I bought, and if I can find it, I'll see
what
it says.
Best,
Will
*********** REPLY SEPARATOR ***********
On 7/13/2011 at 10:15 PM Dr. David Kirkby wrote:
If an old random 10 MHz Rubidium oscillator is working (i.e. powers up,
and
eventually locks), what is the maximum possible frequency error it could
have?
Could it remained locked with an error of 1 part in 10^7, 10^8, 10^9,
10^10 etc?
I assume there are physical limits which would simply stop it
functioning
too
far from the correct frequency, but don't have much clue what they are.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
__________ Information from ESET Smart Security, version of virus
signature database 5851 (20110206) __________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
__________ Information from ESET Smart Security, version of virus
signature database 5851 (20110206) __________
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To unsubscribe, go to
and follow the instructions there.
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On 07/13/11 11:27 PM, Will Matney wrote:
David,
Below is a link to the datasheet on the FEI 5680A. I hope it will work with
those %20 in the link. If not, I think there simply blank spaces, or /FEI -
5680A.pdf
http://www.gillam-fei.be/products/pdf/others/rubidium/FEI%20-%205680A.pdf
Best,
Will
Will,
thank you for the data sheet and also the other link you gave:
http://www.freqelec.com/pdf/rfs_12pg.pdf
Looking at that, the long term drift appears to be 2 x 10^-9 /year. I've no idea
how old they are, but assuming 10 years that puts a maximum drift of 2 x 10^-8.
The biggest variation however would appear to be in the C-field setting, which
has a range of 2 x 10^-7. So assuming the C-field was completely wrong, and the
maximum drift, that gives me an error of 2 x 10^-8 + 2 x 10^-7 = 2.2 x 10^-7.
Anything else, like input voltage sensitivity would appear to be negligible in
compassion to those.
I must admit, that's worst than I was expecting. I was not really expecting an
error of more than 10^-8, but it appears it could be a lot worst.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
David,
The answer to your question is quite complex. A number of factors control the
operation of a passive atomic resonator acting as a filter. Temperature, pressure,
buffer gas mixtures, external magnetic forces, coupled light excitation, the length
of the cavity, the interrogating external RF energy level are but some of those
factors.
The "Atomic" nature of the filter is based upon the extremely narrow resonance of
electron absorption of energy which occurs at a specific frequency and is influenced
by the previously mentioned factors. That specific RF excitation frequency is
different for each element in the Periodic Table. For example the Hydrogen Maser is
around 1.45 GHz; the Rubidium is in the 6 Ghz range and the Cesium is in the 9 Ghz
range.
None of the specification sheets even approach trying to answer such a question
directly. However, with certain qualifying assumptions, it could be inferred from
"certain" specs, if available, as a general idea, BUT, by no means the complete
answer.
For example, looking at Symmetricom's XPRO Rubidium spec sheet, they give a 10 year
spec of ?+/-1x10e-9. The assumption is the unit was built correctly, was adjusted
to be precisely on frequency at its intended installation site and was left powered
on, in a stable atmosphere, without failures of any kind for the entire 10 years.
If the product truly met those assumptions and specs, then I would say, with some
confidence, that if you picked up a used one working properly that it would be
reasonable to assume after powering up and allowing it to come to a stable
temperature (24 hours) and it indicated a locked condition that it would be within
1x10e-9 of the correct frequency. Unfortunately, FEI is not so forth coming with
their product literature, but I suspect their units are similar.
Also, be aware that at least one member on this list has reported buying two 5680A's
from China and they were both significantly off frequency by many hertz. Inspection
and determination of the problem is a project in motion. This same member has
further stated other reports exist on the WEB of other units exhibiting the same
problem, although I have not seen those reports.
It may prove out that the two 5680A's have a problem. It is equally possible that
they are deliberately offset for some specified yet unknown reason. Time will tell.
While a Cesium frequency standard is by definition and without question accurate,
that only applies under a narrow set of circumstances. It is possible to miss
adjust such a beast and that is why multiple standards labs constantly cross check
themselves.
Remember, to error is human and machines do what we tell them !
Bill....WB6BNQ
"Dr. David Kirkby" wrote:
If an old random 10 MHz Rubidium oscillator is working (i.e. powers up, and
eventually locks), what is the maximum possible frequency error it could have?
Could it remained locked with an error of 1 part in 10^7, 10^8, 10^9, 10^10 etc?
I assume there are physical limits which would simply stop it functioning too
far from the correct frequency, but don't have much clue what they are.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
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 think it's more in who had them and tried to calibrate them, as some of
these are actually programmed for the desired frequency. I forget which pin
that is, but I think it may show it in one of the pdfs. There's another pdf
available out there from a ham who did a lot with these, and it did show
how to program/calibrate them.
I know a few of the guy's over in Asia like to play with these before they
sell them, so I think a lot of it's all in whom you get them from.
Best,
Will
*********** REPLY SEPARATOR ***********
On 7/13/2011 at 4:56 PM WB6BNQ wrote:
David,
The answer to your question is quite complex. A number of factors control
the
operation of a passive atomic resonator acting as a filter. Temperature,
pressure,
buffer gas mixtures, external magnetic forces, coupled light excitation,
the length
of the cavity, the interrogating external RF energy level are but some of
those
factors.
The "Atomic" nature of the filter is based upon the extremely narrow
resonance of
electron absorption of energy which occurs at a specific frequency and is
influenced
by the previously mentioned factors. That specific RF excitation
frequency is
different for each element in the Periodic Table. For example the
Hydrogen Maser is
around 1.45 GHz; the Rubidium is in the 6 Ghz range and the Cesium is in
the 9 Ghz
range.
None of the specification sheets even approach trying to answer such a
question
directly. However, with certain qualifying assumptions, it could be
inferred from
"certain" specs, if available, as a general idea, BUT, by no means the
complete
answer.
For example, looking at Symmetricom's XPRO Rubidium spec sheet, they give
a 10 year
spec of ?+/-1x10e-9. The assumption is the unit was built correctly, was
adjusted
to be precisely on frequency at its intended installation site and was
left powered
on, in a stable atmosphere, without failures of any kind for the entire 10
years.
If the product truly met those assumptions and specs, then I would say,
with some
confidence, that if you picked up a used one working properly that it
would be
reasonable to assume after powering up and allowing it to come to a stable
temperature (24 hours) and it indicated a locked condition that it would
be within
1x10e-9 of the correct frequency. Unfortunately, FEI is not so forth
coming with
their product literature, but I suspect their units are similar.
Also, be aware that at least one member on this list has reported buying
two 5680A's
from China and they were both significantly off frequency by many hertz.
Inspection
and determination of the problem is a project in motion. This same member
has
further stated other reports exist on the WEB of other units exhibiting
the same
problem, although I have not seen those reports.
It may prove out that the two 5680A's have a problem. It is equally
possible that
they are deliberately offset for some specified yet unknown reason. Time
will tell.
While a Cesium frequency standard is by definition and without question
accurate,
that only applies under a narrow set of circumstances. It is possible to
miss
adjust such a beast and that is why multiple standards labs constantly
cross check
themselves.
Remember, to error is human and machines do what we tell them !
Bill....WB6BNQ
"Dr. David Kirkby" wrote:
If an old random 10 MHz Rubidium oscillator is working (i.e. powers up,
and
eventually locks), what is the maximum possible frequency error it could
have?
Could it remained locked with an error of 1 part in 10^7, 10^8, 10^9,
10^10 etc?
I assume there are physical limits which would simply stop it
functioning too
far from the correct frequency, but don't have much clue what they are.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
__________ Information from ESET Smart Security, version of virus
signature database 5851 (20110206) __________
Here's a link to the other pdf that I spoke of on the programming. It goes
into some of the same, but it does have other info.
http://www.dd1us.de/Downloads/precise%20reference%20frequency%20rev%200_4.pd
f
Best,
Will
*********** REPLY SEPARATOR ***********
On 7/13/2011 at 8:06 PM Will Matney wrote:
I think it's more in who had them and tried to calibrate them, as some of
these are actually programmed for the desired frequency. I forget which
pin
that is, but I think it may show it in one of the pdfs. There's another
available out there from a ham who did a lot with these, and it did show
how to program/calibrate them.
I know a few of the guy's over in Asia like to play with these before they
sell them, so I think a lot of it's all in whom you get them from.
Best,
Will
*********** REPLY SEPARATOR ***********
On 7/13/2011 at 4:56 PM WB6BNQ wrote:
David,
The answer to your question is quite complex. A number of factors
control
the
operation of a passive atomic resonator acting as a filter. Temperature,
pressure,
buffer gas mixtures, external magnetic forces, coupled light excitation,
the length
of the cavity, the interrogating external RF energy level are but some of
those
factors.
The "Atomic" nature of the filter is based upon the extremely narrow
resonance of
electron absorption of energy which occurs at a specific frequency and is
influenced
by the previously mentioned factors. That specific RF excitation
frequency is
different for each element in the Periodic Table. For example the
Hydrogen Maser is
around 1.45 GHz; the Rubidium is in the 6 Ghz range and the Cesium is in
the 9 Ghz
range.
None of the specification sheets even approach trying to answer such a
question
directly. However, with certain qualifying assumptions, it could be
inferred from
"certain" specs, if available, as a general idea, BUT, by no means the
complete
answer.
For example, looking at Symmetricom's XPRO Rubidium spec sheet, they give
a 10 year
spec of ?+/-1x10e-9. The assumption is the unit was built correctly, was
adjusted
to be precisely on frequency at its intended installation site and was
left powered
on, in a stable atmosphere, without failures of any kind for the entire
10
years.
If the product truly met those assumptions and specs, then I would say,
with some
confidence, that if you picked up a used one working properly that it
would be
reasonable to assume after powering up and allowing it to come to a
stable
temperature (24 hours) and it indicated a locked condition that it would
be within
1x10e-9 of the correct frequency. Unfortunately, FEI is not so forth
coming with
their product literature, but I suspect their units are similar.
Also, be aware that at least one member on this list has reported buying
two 5680A's
from China and they were both significantly off frequency by many hertz.
Inspection
and determination of the problem is a project in motion. This same
member
has
further stated other reports exist on the WEB of other units exhibiting
the same
problem, although I have not seen those reports.
It may prove out that the two 5680A's have a problem. It is equally
possible that
they are deliberately offset for some specified yet unknown reason. Time
will tell.
While a Cesium frequency standard is by definition and without question
accurate,
that only applies under a narrow set of circumstances. It is possible to
miss
adjust such a beast and that is why multiple standards labs constantly
cross check
themselves.
Remember, to error is human and machines do what we tell them !
Bill....WB6BNQ
"Dr. David Kirkby" wrote:
If an old random 10 MHz Rubidium oscillator is working (i.e. powers up,
and
eventually locks), what is the maximum possible frequency error it
could
have?
Could it remained locked with an error of 1 part in 10^7, 10^8, 10^9,
10^10 etc?
I assume there are physical limits which would simply stop it
functioning too
far from the correct frequency, but don't have much clue what they are.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
__________ Information from ESET Smart Security, version of virus
signature database 5851 (20110206) __________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
__________ Information from ESET Smart Security, version of virus
signature database 5851 (20110206) __________
Will,
Did you actually read what I wrote ? I ask because your response, below, would
suggest a low comprehension rate. I noted a number of your responses fall into
the same category. Such responses, having no substantive material, do nothing
but add noise to the list. This list is suppose to be a low noise level list.
Technical discussions on topics specific to the list is one thing, but protracted
BS where everyone chimes in on what kind of watch they wear is another matter.
How do you know these "guys" in Asia "LIKE TO PLAY" with them ? Do you know
"them" personally ? They are business people and yes they investigated some
units to determine what is needed to make the product useable to their
customers. It is a business effort, not a play ground. By the way, I think I
can safely say one seller did the work and others are just copying him to a large
degree.
I like how you feel it is more about who had them and your not sure about the pin
number but it is out there in a PDF somewhere. How does that apply to the two
units that are stated as having a problem where it is indicated it may be other
then programming ?
Another example is the "Broadband synthesizer" thread. The asking party, while
being way too generalized, did use the word synthesizer and referred to
milli-Hertz resolution. Clearly not at all within the realm of a 8640B, yet you
did it three times. But, then again, I guess you missed that part of it in your
enthusiastic effort to make a response.
Yes ! I am jumping your case a bit, but it also applies to others and hopefully
they are smart enough to realize it. No, I have no intention of being
politically correct. I also think a kid who failed a school year should not get
passed on. If they are screwing up they should get told about it, even if it
hurts their feelings.
I guess what I am saying is for people to have some respect for the stated
intentions of this mail list and try to rise to that ideal. I am also saying
some effort ought to be put forth in trying some critical thinking.
Oh, by the way, as they say in Chicago; Its nothing personal, just business.
Bill....WB6BNQ
Will Matney wrote:
I think it's more in who had them and tried to calibrate them, as some of
these are actually programmed for the desired frequency. I forget which pin
that is, but I think it may show it in one of the pdfs. There's another pdf
available out there from a ham who did a lot with these, and it did show
how to program/calibrate them.
I know a few of the guy's over in Asia like to play with these before they
sell them, so I think a lot of it's all in whom you get them from.
Best,
Will
*********** REPLY SEPARATOR ***********
On 7/13/2011 at 4:56 PM WB6BNQ wrote:
?David,
?
?The answer to your question is quite complex. A number of factors control
the
?operation of a passive atomic resonator acting as a filter. Temperature,
pressure,
?buffer gas mixtures, external magnetic forces, coupled light excitation,
the length
?of the cavity, the interrogating external RF energy level are but some of
those
?factors.
?
?The "Atomic" nature of the filter is based upon the extremely narrow
resonance of
?electron absorption of energy which occurs at a specific frequency and is
influenced
?by the previously mentioned factors. That specific RF excitation
frequency is
?different for each element in the Periodic Table. For example the
Hydrogen Maser is
?around 1.45 GHz; the Rubidium is in the 6 Ghz range and the Cesium is in
the 9 Ghz
?range.
?
?None of the specification sheets even approach trying to answer such a
question
?directly. However, with certain qualifying assumptions, it could be
inferred from
?"certain" specs, if available, as a general idea, BUT, by no means the
complete
?answer.
?
?For example, looking at Symmetricom's XPRO Rubidium spec sheet, they give
a 10 year
?spec of ?+/-1x10e-9. The assumption is the unit was built correctly, was
adjusted
?to be precisely on frequency at its intended installation site and was
left powered
?on, in a stable atmosphere, without failures of any kind for the entire 10
years.
?If the product truly met those assumptions and specs, then I would say,
with some
?confidence, that if you picked up a used one working properly that it
would be
?reasonable to assume after powering up and allowing it to come to a stable
?temperature (24 hours) and it indicated a locked condition that it would
be within
?1x10e-9 of the correct frequency. Unfortunately, FEI is not so forth
coming with
?their product literature, but I suspect their units are similar.
?
?Also, be aware that at least one member on this list has reported buying
two 5680A's
?from China and they were both significantly off frequency by many hertz.
Inspection
?and determination of the problem is a project in motion. This same member
has
?further stated other reports exist on the WEB of other units exhibiting
the same
?problem, although I have not seen those reports.
?
?It may prove out that the two 5680A's have a problem. It is equally
possible that
?they are deliberately offset for some specified yet unknown reason. Time
will tell.
?
?While a Cesium frequency standard is by definition and without question
accurate,
?that only applies under a narrow set of circumstances. It is possible to
miss
?adjust such a beast and that is why multiple standards labs constantly
cross check
?themselves.
?
?Remember, to error is human and machines do what we tell them !
?
?Bill....WB6BNQ
?
?
?"Dr. David Kirkby" wrote:
?
?? If an old random 10 MHz Rubidium oscillator is working (i.e. powers up,
and
?? eventually locks), what is the maximum possible frequency error it could
have?
??
?? Could it remained locked with an error of 1 part in 10^7, 10^8, 10^9,
10^10 etc?
??
?? I assume there are physical limits which would simply stop it
functioning too
?? far from the correct frequency, but don't have much clue what they are.
??
?? --
?? A: Because it messes up the order in which people normally read text.
?? Q: Why is top-posting such a bad thing?
?? A: Top-posting.
?? Q: What is the most annoying thing in e-mail?
??
?? _______________________________________________
?? 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.
?
?__________ Information from ESET Smart Security, version of virus
signature database 5851 (20110206) __________
?
?The message was checked by ESET Smart Security.
?
?http://www.eset.com
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This is a very interesting question, same as "if someone can't
afford a GPSDO, Cesium or other time-nutty contraption, but buys a
second-hand, uncalibrated Rubidium as his primary timebase, how accurate
would it be"?
One whole class of units, the 'programmable' or 'synthesized' ones,
have to be removed from this discussion, as it can theoretically be off as
much as the range of the DDS. It can only be considered after being properly
calibrated, programmed against a known primary or traceable secondary.
Most units nowadays on eBay are rated 1E-9 to 2E-10/yr aging, so it
might be safe to assume none would be off more than 1E-8?
It would be interesting for people to dig their aged Rb and post the
measured frequency against Cesium or GPSDO.
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Dr. David Kirkby
Sent: Wednesday, July 13, 2011 2:15 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Worst possible error on a rubidium
If an old random 10 MHz Rubidium oscillator is working (i.e. powers up, and
eventually locks), what is the maximum possible frequency error it could
have?
Could it remained locked with an error of 1 part in 10^7, 10^8, 10^9, 10^10
etc?
I assume there are physical limits which would simply stop it functioning
too
far from the correct frequency, but don't have much clue what they are.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
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On Wed, Jul 13, 2011 at 7:10 PM, Jose Camara camaraq1@quantacorp.com wrote:
This is a very interesting question, same as "if someone can't
afford a GPSDO, Cesium or other time-nutty contraption, but buys a
second-hand, uncalibrated Rubidium as his primary timebase, how accurate
would it be"?
I think that is actually an interesting question. Kind of like asking
the spec's on the cheapest wrist watch sold at Wallmart. Is that $5
watch really usable?" Had
For years I was even cheaper and used a square can TTL oscillator
salvaged from some dead computer part as my primary reference. and
for most uses even the 100PPM can was over kill
Chris Albertson
Redondo Beach, California
Hi
I've looked at a random sample of a couple dozen Rb's that are in the 5 to
30 year old range. In about 90% of the cases I'm reasonably certain they
haven't been adjusted since they left the factory. If they still worked,
they all came in at or below +/- 3x10^-9.
Bob
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Chris Albertson
Sent: Wednesday, July 13, 2011 10:21 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Worst possible error on a rubidium
On Wed, Jul 13, 2011 at 7:10 PM, Jose Camara camaraq1@quantacorp.com
wrote:
This is a very interesting question, same as "if someone can't
afford a GPSDO, Cesium or other time-nutty contraption, but buys a
second-hand, uncalibrated Rubidium as his primary timebase, how accurate
would it be"?
I think that is actually an interesting question. Kind of like asking
the spec's on the cheapest wrist watch sold at Wallmart. Is that $5
watch really usable?" Had
For years I was even cheaper and used a square can TTL oscillator
salvaged from some dead computer part as my primary reference. and
for most uses even the 100PPM can was over kill
Chris Albertson
Redondo Beach, California
time-nuts mailing list -- time-nuts@febo.com
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Like this polemic didn't worsen the S/N ratio?
On Wed, Jul 13, 2011 at 10:07 PM, WB6BNQ wb6bnq@cox.net wrote:
Will,
Did you actually read what I wrote ? I ask because your response, below,
would
suggest a low comprehension rate. I noted a number of your responses fall
into
the same category. Such responses, having no substantive material, do
nothing
but add noise to the list. This list is suppose to be a low noise level
list.
Technical discussions on topics specific to the list is one thing, but
protracted
BS where everyone chimes in on what kind of watch they wear is another
matter.
How do you know these "guys" in Asia "LIKE TO PLAY" with them ? Do you
know
"them" personally ? They are business people and yes they investigated
some
units to determine what is needed to make the product useable to their
customers. It is a business effort, not a play ground. By the way, I
think I
can safely say one seller did the work and others are just copying him to a
large
degree.
I like how you feel it is more about who had them and your not sure about
the pin
number but it is out there in a PDF somewhere. How does that apply to the
two
units that are stated as having a problem where it is indicated it may be
other
then programming ?
Another example is the "Broadband synthesizer" thread. The asking party,
while
being way too generalized, did use the word synthesizer and referred to
milli-Hertz resolution. Clearly not at all within the realm of a 8640B,
yet you
did it three times. But, then again, I guess you missed that part of it in
your
enthusiastic effort to make a response.
Yes ! I am jumping your case a bit, but it also applies to others and
hopefully
they are smart enough to realize it. No, I have no intention of being
politically correct. I also think a kid who failed a school year should
not get
passed on. If they are screwing up they should get told about it, even if
it
hurts their feelings.
I guess what I am saying is for people to have some respect for the stated
intentions of this mail list and try to rise to that ideal. I am also
saying
some effort ought to be put forth in trying some critical thinking.
Oh, by the way, as they say in Chicago; Its nothing personal, just
business.
Bill....WB6BNQ
Will Matney wrote:
I think it's more in who had them and tried to calibrate them, as some of
these are actually programmed for the desired frequency. I forget which
pin
that is, but I think it may show it in one of the pdfs. There's another
available out there from a ham who did a lot with these, and it did show
how to program/calibrate them.
I know a few of the guy's over in Asia like to play with these before
they
sell them, so I think a lot of it's all in whom you get them from.
Best,
Will
*********** REPLY SEPARATOR ***********
On 7/13/2011 at 4:56 PM WB6BNQ wrote:
?David,
?
?The answer to your question is quite complex. A number of factors
control
the
?operation of a passive atomic resonator acting as a filter.
Temperature,
pressure,
?buffer gas mixtures, external magnetic forces, coupled light excitation,
the length
?of the cavity, the interrogating external RF energy level are but some
of
those
?factors.
?
?The "Atomic" nature of the filter is based upon the extremely narrow
resonance of
?electron absorption of energy which occurs at a specific frequency and
is
influenced
?by the previously mentioned factors. That specific RF excitation
frequency is
?different for each element in the Periodic Table. For example the
Hydrogen Maser is
?around 1.45 GHz; the Rubidium is in the 6 Ghz range and the Cesium is in
the 9 Ghz
?range.
?
?None of the specification sheets even approach trying to answer such a
question
?directly. However, with certain qualifying assumptions, it could be
inferred from
?"certain" specs, if available, as a general idea, BUT, by no means the
complete
?answer.
?
?For example, looking at Symmetricom's XPRO Rubidium spec sheet, they
give
a 10 year
?spec of ?+/-1x10e-9. The assumption is the unit was built correctly,
was
adjusted
?to be precisely on frequency at its intended installation site and was
left powered
?on, in a stable atmosphere, without failures of any kind for the entire
10
years.
?If the product truly met those assumptions and specs, then I would say,
with some
?confidence, that if you picked up a used one working properly that it
would be
?reasonable to assume after powering up and allowing it to come to a
stable
?temperature (24 hours) and it indicated a locked condition that it would
be within
?1x10e-9 of the correct frequency. Unfortunately, FEI is not so forth
coming with
?their product literature, but I suspect their units are similar.
?
?Also, be aware that at least one member on this list has reported buying
two 5680A's
?from China and they were both significantly off frequency by many hertz.
Inspection
?and determination of the problem is a project in motion. This same
member
has
?further stated other reports exist on the WEB of other units exhibiting
the same
?problem, although I have not seen those reports.
?
?It may prove out that the two 5680A's have a problem. It is equally
possible that
?they are deliberately offset for some specified yet unknown reason.
Time
will tell.
?
?While a Cesium frequency standard is by definition and without question
accurate,
?that only applies under a narrow set of circumstances. It is possible
to
miss
?adjust such a beast and that is why multiple standards labs constantly
cross check
?themselves.
?
?Remember, to error is human and machines do what we tell them !
?
?Bill....WB6BNQ
?
?
?"Dr. David Kirkby" wrote:
?
?? If an old random 10 MHz Rubidium oscillator is working (i.e. powers
up,
and
?? eventually locks), what is the maximum possible frequency error it
could
have?
??
?? Could it remained locked with an error of 1 part in 10^7, 10^8, 10^9,
10^10 etc?
??
?? I assume there are physical limits which would simply stop it
functioning too
?? far from the correct frequency, but don't have much clue what they
are.
??
?? --
?? A: Because it messes up the order in which people normally read text.
?? Q: Why is top-posting such a bad thing?
?? A: Top-posting.
?? Q: What is the most annoying thing in e-mail?
??
?? _______________________________________________
?? 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.
?
?__________ Information from ESET Smart Security, version of virus
signature database 5851 (20110206) __________
?
?The message was checked by ESET Smart Security.
?
?http://www.eset.com
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In message CANy2iXooqeTudE05iktHEmP3GhS2SqcGmbPoPAs+vN4Wtw+ybw@mail.gmail.com
, "William H. Fite" writes:
Like this polemic didn't worsen the S/N ratio?
If you take a clue from it, it will improve the S/N ratio.
Seeing that you sent a 1-line reply, quoting the entire message,
in a discussion about S/N ratio does not give me high hopes however,
and I will happily be the first to move that you get thrown off
the list, if you don't acquire clue rapidly.
--
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.
why reply at all?
From: Poul-Henning Kamp phk@phk.freebsd.dk
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Thu, July 14, 2011 8:00:43 AM
Subject: Re: [time-nuts] List Noise Level [was...]
In message CANy2iXooqeTudE05iktHEmP3GhS2SqcGmbPoPAs+vN4Wtw+ybw@mail.gmail.com
, "William H. Fite" writes:
Like this polemic didn't worsen the S/N ratio?
If you take a clue from it, it will improve the S/N ratio.
Seeing that you sent a 1-line reply, quoting the entire message,
in a discussion about S/N ratio does not give me high hopes however,
and I will happily be the first to move that you get thrown off
the list, if you don't acquire clue rapidly.
--
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.
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.
On 07/14/11 01:27 PM, Bob Camp wrote:
Hi
I've looked at a random sample of a couple dozen Rb's that are in the 5 to
30 year old range. In about 90% of the cases I'm reasonably certain they
haven't been adjusted since they left the factory. If they still worked,
they all came in at or below +/- 3x10^-9.
Bob
Thank you.
Of the couple of dozen, how many worked? Clearly if only two worked, the data is
not very useful. But if 15 or more worked, then it's interesting. It would give
me reasonable confidence the unit is sufficient for my needs without bothering
with calibration.
I do have a friend with a GPS locked rubidium. At some point I'll get the unit
to him, but I recently sold my HP 5370B to someone on this list (regretting I
sold it now!)
I guess a scope would be OK to check for gross errors by one 10 MHz signal to
the X input and another to the Y input.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
Hi
At least 90% of the units worked fine. Of the other 10% some of the issues
were pretty minor. I only have seen one or two that would not lock.
Bob
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Dr. David Kirkby
Sent: Thursday, July 14, 2011 4:47 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Worst possible error on a rubidium
On 07/14/11 01:27 PM, Bob Camp wrote:
Hi
I've looked at a random sample of a couple dozen Rb's that are in the 5 to
30 year old range. In about 90% of the cases I'm reasonably certain they
haven't been adjusted since they left the factory. If they still worked,
they all came in at or below +/- 3x10^-9.
Bob
Thank you.
Of the couple of dozen, how many worked? Clearly if only two worked, the
data is
not very useful. But if 15 or more worked, then it's interesting. It would
give
me reasonable confidence the unit is sufficient for my needs without
bothering
with calibration.
I do have a friend with a GPS locked rubidium. At some point I'll get the
unit
to him, but I recently sold my HP 5370B to someone on this list (regretting
I
sold it now!)
I guess a scope would be OK to check for gross errors by one 10 MHz signal
to
the X input and another to the Y input.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
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
Should have added - one of the ones that would not lock was an easy fix
(signal to the connector was the issue).
Bob
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Dr. David Kirkby
Sent: Thursday, July 14, 2011 4:47 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Worst possible error on a rubidium
On 07/14/11 01:27 PM, Bob Camp wrote:
Hi
I've looked at a random sample of a couple dozen Rb's that are in the 5 to
30 year old range. In about 90% of the cases I'm reasonably certain they
haven't been adjusted since they left the factory. If they still worked,
they all came in at or below +/- 3x10^-9.
Bob
Thank you.
Of the couple of dozen, how many worked? Clearly if only two worked, the
data is
not very useful. But if 15 or more worked, then it's interesting. It would
give
me reasonable confidence the unit is sufficient for my needs without
bothering
with calibration.
I do have a friend with a GPS locked rubidium. At some point I'll get the
unit
to him, but I recently sold my HP 5370B to someone on this list (regretting
I
sold it now!)
I guess a scope would be OK to check for gross errors by one 10 MHz signal
to
the X input and another to the Y input.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
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.
A scope with one 10Mhz on two Y channels is enough. Say you get 1 cycle
phase displacement every 15 minutes - that's 1E-10. You can get better than
these 10 digits per 15min by counting divisions per minute or so. Not as
nice as a 12 digits/s counter, but way cheaper...
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Dr. David Kirkby
Sent: Thursday, July 14, 2011 1:47 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Worst possible error on a rubidium
On 07/14/11 01:27 PM, Bob Camp wrote:
Hi
I've looked at a random sample of a couple dozen Rb's that are in the 5 to
30 year old range. In about 90% of the cases I'm reasonably certain they
haven't been adjusted since they left the factory. If they still worked,
they all came in at or below +/- 3x10^-9.
Bob
Thank you.
Of the couple of dozen, how many worked? Clearly if only two worked, the
data is
not very useful. But if 15 or more worked, then it's interesting. It would
give
me reasonable confidence the unit is sufficient for my needs without
bothering
with calibration.
I do have a friend with a GPS locked rubidium. At some point I'll get the
unit
to him, but I recently sold my HP 5370B to someone on this list (regretting
I
sold it now!)
I guess a scope would be OK to check for gross errors by one 10 MHz signal
to
the X input and another to the Y input.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
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.