[time-nuts] List Noise Level [was...]

William H. Fite omniryx at gmail.com
Thu Jul 14 14:58:10 UTC 2011


Like this polemic didn't worsen the S/N ratio?



On Wed, Jul 13, 2011 at 10:07 PM, WB6BNQ <wb6bnq at 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
> 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?
> > ??
> > ?? _______________________________________________
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> > ?
> > ?
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