[EMAIL PROTECTED] wrote:
> Hi Bruce,
>
> last chemistry/physics class is a while back :) I guess a half life of 50
> Billion years means it's not really radiating much?
>
> No problem with Cesium then either, I guess the radiation levels must be
> really really low?
>
> thanks,
> Said
>
[EMAIL PROTECTED] wrote:
> Hi Bruce,
>
> either way GPS can't give you parts to the 14 short term as was claimed.
> Also there are not many affordable carrier phase GPS receivers out there as
> far
> as I know.
>
> Also, 2 parts to the 11 over 1s - 100s is still not as good as a good OCXO
> Hi Tom,
>
> by the way, are Cesium and Rb isotopes used in these
> clocks radioactive to any degree? I remember on your
> website you mentioned that Cesiums have to be shipped
> as hazardous material..
>
> bye,
> Said
Nope. It's an unfortunate myth that "atomic clocks" have
anything to do with r
Mostly that labelling is required because of the unfortunate events that
ensue if the stuff gets wet. They're both alkali metals, in the same column
as sodium and potassium.
-- john, KE5FX
> Hi Bruce,
>
> last chemistry/physics class is a while back :) I guess a half
> life of 50
> Billion years
Hi Bruce,
last chemistry/physics class is a while back :) I guess a half life of 50
Billion years means it's not really radiating much?
No problem with Cesium then either, I guess the radiation levels must be
really really low?
thanks,
Said
In a message dated 4/23/2008 23:09:24 Pacifi
Hi Bruce,
either way GPS can't give you parts to the 14 short term as was claimed.
Also there are not many affordable carrier phase GPS receivers out there as
far
as I know.
Also, 2 parts to the 11 over 1s - 100s is still not as good as a good OCXO
(parts to 12 or even 13 possible), so c
[EMAIL PROTECTED] wrote:
> Hi Tom,
>
> by the way, are Cesium and Rb isotopes used in these clocks radioactive to
> any degree? I remember on your website you mentioned that Cesiums have to be
> shipped as hazardous material..
>
> bye,
> Said
>
>
Said
Both Caesium and Rubidium are che
> The actual FRS-C is quite a bit cleaner but still nowhere near as good as
> the Thunderbolt.
>
> Also worth noting is that the Datum's output is quite a bit
> noisier than it
> was several months ago when I measured it with (very) different
> hardware. I
> wouldn't take the green trace in this
Hi Tom,
by the way, are Cesium and Rb isotopes used in these clocks radioactive to
any degree? I remember on your website you mentioned that Cesiums have to be
shipped as hazardous material..
bye,
Said
In a message dated 4/23/2008 19:53:13 Pacific Daylight Time,
[EMAIL PROTECTED] writ
Hi,
On Wed, 2008-04-23 at 20:01 -0700, John Miles wrote:
> Adding to Tom's worthy list:
>
> 11) Short-term phase noise; the GPS-Rb sources don't seem to be as clean as
> the better GPS-OCXO packages.
>
> -- john, KE5FX
For the "normal" Rb that seems to be true. But the OP specified the XTAL
in
Ulrich,
In the 'bad part...' you mentioned, I wasn't referring to a Rb oscillator
but rather the GPS received signal from the satellites. The GPS signal from
multiple satellites over a long period of time can be a good 'Transfer
Standard'. The atmosphere (moisture, temperature, pressure) are the g
> > 11) Short-term phase noise; the GPS-Rb sources don't seem to
> > be as clean as the better GPS-OCXO packages.
>
> And EXACTLY THIS was what the OP was asking after!
More quantitatively: in this file, the red trace is from my Thunderbolt, the
green trace is from a Datum 9390 Rb-GPS standard's 1
Tom,
> I think the best of all worlds would be a double-ovenized
> SC-cut OCXO running at 5 MHz (lower mass). These OCXOs have
> the lowest phase noise and best Allen variance short term
> stability (1-100 seconds) of any xtal or Rb. Then have this
> OCXO disciplined by the GPS
this is the go
Keep up the feedback, great reading from down here
Long haul telecommunications systems rely on accurate clocks, in my line
of business our concern has been long term Wander. Wander is generally
associated with random variations of phase noise occurring below 10Hz.
GPS disciplined Rubidium pr
> 11) Short-term phase noise; the GPS-Rb sources don't seem to
> be as clean as the better GPS-OCXO packages.
And EXACTLY THIS was what the OP was asking after!
> -Ursprungliche Nachricht-
> Von: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] Im Auftrag von John Miles
> Gesendet: Donners
From: "Tom Duckworth" <[EMAIL PROTECTED]>
Subject: Re: [time-nuts] Disciplining Rubidium
Date: Wed, 23 Apr 2008 20:57:40 -0700
Message-ID: <[EMAIL PROTECTED]>
> Joe,
>
> tau, the Greek symbol for a defined measured time (1 sec., 10 sec., etc.)
> when using it in a timing application measurement.
>I have truly enjoyed 'reading the mail' on this group.
>
> However, I need some help or a 'refresher' on the lingo.
>
> I am a Clinical Cardiac Electrophysiologist but in a bygone millennium, I
> received a BEE and a MSEE from Georgia Tech before I went to Medical School.
>
> 'tau'?
>
> Thanks
Phase noise generally gets better with the higher-frequency OCXOs, though.
I think the best of all possible worlds would be a 5-MHz OCXO like the one
you describe, being used to discipline a 10 MHz or higher-frequency part.
-- john, KE5FX
> -Original Message-
> From: [EMAIL PROTECTED] [ma
John,
I think the best of all worlds would be a double-ovenized SC-cut OCXO
running at 5 MHz (lower mass). These OCXOs have the lowest phase noise and
best Allen variance short term stability (1-100 seconds) of any xtal or Rb.
Then have this OCXO disciplined by the GPS, with an ephemeris of variat
Tom Duckworth wrote:
> Tom,
>
> Great list! Your number 8 (magnetic field) will effect both. We tried this
> when I was with XL Microwave. The Rb's noticeable effect depends on how
> strong the magnetic field in the physics package is compared to the external
> magnetic field. In the Rb, the extern
Tom,
Great list! Your number 8 (magnetic field) will effect both. We tried this
when I was with XL Microwave. The Rb's noticeable effect depends on how
strong the magnetic field in the physics package is compared to the external
magnetic field. In the Rb, the external field would need to be quite
No idea, really. It may not even be a universal principle but it sure seems
that way.
Something in the Datum 9390 I have also degrades the noise quite a bit,
relative to what comes out of the FRS-C Rb module.
-- john, KE5FX
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:[EMAIL P
Joe,
tau, the Greek symbol for a defined measured time (1 sec., 10 sec., etc.)
when using it in a timing application measurement. In nuclear physics it has
a very different meaning (weakly interacting subatomic particle).
Tom
Tom Duckworth
510-886-1396
-Original Message-
From: [EMAIL PR
> 11) Short-term phase noise; the GPS-Rb sources don't seem to be as
> clean as the better GPS-OCXO packages.
Is there something fundamental that causes that, or is it just an engineering
quirk?
One guess would be that they don't use as good/expensive a crystal in the Rb
setup because they do
I have truly enjoyed 'reading the mail' on this group.
However, I need some help or a 'refresher' on the lingo.
I am a Clinical Cardiac Electrophysiologist but in a bygone millennium, I
received a BEE and a MSEE from Georgia Tech before I went to Medical School.
'tau'?
Thanks,
Joe
WB4BPP
Adding to Tom's worthy list:
11) Short-term phase noise; the GPS-Rb sources don't seem to be as clean as
the better GPS-OCXO packages.
-- john, KE5FX
> > More precisely, if I had two black boxes, one containing
> > a GPS-Rb-XTAL setup and another containing GPS-XTAL,
> > what measurement would y
> More precisely, if I had two black boxes, one containing
> a GPS-Rb-XTAL setup and another containing GPS-XTAL,
> what measurement would you make from outside the boxes
> to distinguish from one another?
Ah, clever question. Here's ten ways to distinguish them:
1) Use a scale or ruler -- the GP
I purchased this unit for the box and power supply, but now I hate to dissemble
it. Dallas Instruments was acquired by Lansmont.com which was acquired by
Pira/Ciba Expert Services I think, not much trace of the company or product
left on the web.
http://www.acsol.net/~funkyjnqtech/EBAY/MAR08/DA
[EMAIL PROTECTED] wrote:
> One more comment:
>
> the GPS disciplining doesn't affect performance of parts to the 14th short
> term. GPS is used for long-term (>1000s or so) error correction, where it
> can
> achieve parts the 14th, but only after a day or much longer.
>
> GPS is not good e
Interesting article in the April issue of Microwave Journal; Pg 72.
Phase Noise: Theory versus Practicality
Pretty well centered around Oscillators and Time Bases.
Had
K7MLR
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https:
Hi Antonio,
in my opinion the Rb in the chain gives you two distinct advantages (and a
lot of drawbacks):
1) Warmup time. Rb's can warm up very quickly, much quicker than the Crystal
itself even under GPS discipline. This is especially so with new Crystals,
or long power-off times, or whe
One more comment:
the GPS disciplining doesn't affect performance of parts to the 14th short
term. GPS is used for long-term (>1000s or so) error correction, where it can
achieve parts the 14th, but only after a day or much longer.
GPS is not good enough to give you more than parts to the 8
Antonio,
Weight and power consumption are the first methods that come to mind :-)
You are hitting the time-nuts nail right on the head. You cannot rank just
two clocks, you need at least three, so that you can compare them 2 by 2 and
determine statistically the performance of each by comparaison
More precisely, if I had two black boxes, one containing a GPS-Rb-XTAL setup
and another containing GPS-XTAL, what measurement would you make from outside
the boxes to distinguish from one another?
Antonio I8IOV
> Tom Duckworth wrote:
>
> > Antonio,
> >
> > Absolutely! With a good XTAL you ha
Tom Duckworth wrote:
> Antonio,
>
> Absolutely! With a good XTAL you have parts in the 9th, short term. With a
> XTAL controlled by a Rubidium, in the phase-lock feedback loop, you have
> parts in the 12th, short term. With the Rubidium disciplined by the GPS,
> with its on-board Rubidium/Cesium
But doesn't it matter what your definition of "short term" really is?
I have some Wenzel OCXOs that hit 5E-13 for a 1 second tau. No Rb or Cs
or Z3801 that I have running get that good at 1 sec tau! Over 10,000
is a different matter, however.
-Brian, WA1ZMS
-Original Message-
From: [EM
Antonio,
Absolutely! With a good XTAL you have parts in the 9th, short term. With a
XTAL controlled by a Rubidium, in the phase-lock feedback loop, you have
parts in the 12th, short term. With the Rubidium disciplined by the GPS,
with its on-board Rubidium/Cesium oscillators updated from the groun
On Thu, Apr 24, 2008 at 12:11:16AM +0200, [EMAIL PROTECTED] wrote:
> Does it make any sense "GPS disciplining" a rubidium oscillator?
> In such a case we have a chain made of
> GPS - Rubidium - XTAL
> as opposed to the simpler case of
> GPS - XTAL
> (assume that XTALs are of the same quality, and
Does it make any sense "GPS disciplining" a rubidium oscillator?
In such a case we have a chain made of
GPS - Rubidium - XTAL
as opposed to the simpler case of
GPS - XTAL
(assume that XTALs are of the same quality, and so the control loops).
Does the addition of Rb in the middle of the chain add
Peter,
You need to qualify what you mean by 'better' - is it:
- Improved short term stability
- Lower phase noise
- Lower ageing rate
- Reduced influence of environmental effects (load, temperature,
radiation, G, vibration, barometric pressure, humidity or what have you!
Quartz alone or combined
> Over the years, better and better long-term accuracy has been
> achieved with various "atomic" references, but if I understand
> correctly, the actual oscillating element is still a quartz crystal,
> albeit in a tightly controlled loop. None-the-less, from discussions
> in this group I belie
Peter,
you really do know how to start a lively discussion!!
For more on sapphire google for "whispering gallery oscillators", for
the latest in quarz development google for "bva resonators". And yes,
what you are saying is true. Most atomic standards need an xtal
oscillator as an "flywheel" to
Over the years, better and better long-term accuracy has been
achieved with various "atomic" references, but if I understand
correctly, the actual oscillating element is still a quartz crystal,
albeit in a tightly controlled loop. None-the-less, from discussions
in this group I believe that th
43 matches
Mail list logo
