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 graph
[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 chemically
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
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
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 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
[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
[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
Said
Hi Bruce,
wow, haven't done that math since about 1987.. I remember now.
How about Cs? Seems more aggressive.
bye,
Said
In a message dated 4/23/2008 23:52:31 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
[EMAIL PROTECTED] wrote:
Hi Bruce,
last chemistry/physics class is a
Thanks guys,
funny clips.
That explains the issues.
How does one recycle a Cs tube?
bye,
Said
In a message dated 4/23/2008 23:33:14 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
This 25-second clip shows the reaction nicely:
Rubidium and Cesium in water
Are there any issues with using a video distribution amp (Rin, Rout 75R
rather than 50R) for 10MHz output of GPSDO?
Cheers
Dave
___
time-nuts mailing list -- time-nuts@febo.com
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Thank you to all those who replied, and especially Tom - I hadn't
been aware that active masers were self-oscillating, and your links
led to some excellent information.
You need to qualify what you mean by 'better' - is it:
- Improved short term stability
- Lower phase noise
- Lower ageing
Hello, Time-Nuts--
I have skimmed through a very interesting review publication
of whispering gallery-mode oscillators
http://tinyurl.com/6qsr5k
but I do not see any concise explanation of why they are referred
to with the rather strange name of whispering gallery-mode
Can anyone give me a
John Miles wrote:
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
I'm not sure about that -- at
In talking to Charles Wenzel some years back, he mentioned what he called
the quartz-to-crud ratio. i.e.: How much contamination you get while
making
a quartz crystal vs. the Q of the quartz blank itself.
It seems that through either luck/design or just demands of the industry
that
5MHz is the
John Ackermann N8UR wrote:
John Miles wrote:
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
On Thu, 2008-04-24 at 02:16 -0400, [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.
Hi Said,
What is affordable for you?
For some
Hi Bjorn,
Which $330 GPS with carrier phase output are you referring to?
Tom
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and follow the instructions there.
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
That level of performance is about average for an HP 10811 and some are
considerably better. 1
Right; I'm referring to noise past 1 kHz or so. The best VHF oscillators
are much quieter than comparable 5/10 MHz oscillators. At least, I've never
seen a 5 or 10 MHz unit that's rated below -175 dBc/Hz at 20-100 kHz.
-- john, KE5FX
-Original Message-
From: [EMAIL PROTECTED]
At 10:02 AM 4/24/2008, you wrote:
In message [EMAIL PROTECTED], David C.
Partridge writes:
From the paper:
From the paper:
... can be understood by comparison with the optical concept of total
internal reflection, or by the acoustic whispering galleryphenomenon
experienced in large
In message [EMAIL PROTECTED], Hal Murray writes:
You start as low as go can and sweep slowly upwards until you suddenly
hit a resonance of quite startling intensity.
Neat. Thanks.
The Exploratorium has a linear version. It's an amazing toy. (They call it
an exhibit.)
It's a hollow
Thanks Björn,
I did some digging and it appears to be even cheaper: navtechgps.com
sells them for $165!
(usual disclaimer about no afiliation etc.)
Regards,
Tom
On Thursday 24 April 2008 18:23, you wrote:
Novatel SuperstarII.
/Björn
On Thu, 2008-04-24 at 16:53 +0200, ScopeFreak wrote:
Hi Bjoern,
1cm RMS is not bad. That would be great to use for Auto Surveying the
Antenna position.
I meant integrated receivers with 1PPS or 10MHz etc output that are based on
Carrier Phase measurement, and are better than an M12M. I know of some
GPSDO's that are carrier phase based, and
Hi Tom,
that Superstar receiver only has +/-50ns 1PPS timing accuracy (typical).
That compares to an M12M claimed accuracy of +/-10ns corrected.
I wonder why the receiver manufacturers don't do the math on the carrier
phase, and generate very accurate 1PPS signals. Is it because they don't
Björn Gabrielsson wrote:
On Thu, 2008-04-24 at 02:16 -0400, [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.
Hi Said,
For some $330 you can get a L1 GPS receiver outputting carrier phase
Which make/model is this?
measurements at 5Hz. This receiver also have a 10MHz tcxo driving the
whole receiver. Pseudorange measurement rms of a few dm. Carrierphase
rms below 1cm.
Btw... the Oncore VP did carrierphase
Tom Van Baak wrote:
For some $330 you can get a L1 GPS receiver outputting carrier phase
Which make/model is this?
Novatel Superstar II?
measurements at 5Hz. This receiver also have a 10MHz tcxo driving the
whole receiver. Pseudorange measurement rms of a few dm. Carrierphase
rms
[EMAIL PROTECTED] wrote:
Hi Tom,
that Superstar receiver only has +/-50ns 1PPS timing accuracy (typical).
That compares to an M12M claimed accuracy of +/-10ns corrected.
I wonder why the receiver manufacturers don't do the math on the carrier
phase, and generate very accurate 1PPS
At 02:29 PM 4/24/2008, [EMAIL PROTECTED] wrote:
Hi Tom,
that Superstar receiver only has +/-50ns 1PPS timing accuracy (typical).
That compares to an M12M claimed accuracy of +/-10ns corrected.
I wonder why the receiver manufacturers don't do the math on the carrier
phase, and generate very
Thanks to all for the interesting discussion. I understand that,
having a thunderbolt, I might feel free to delay a bit (or even cancel)
my Rb disciplining project.
A last question to tvb. You said that
6) Turn-over -- if you flip the black box upside down, the Rb
version will show little or no
Tom Van Baak wrote:
Bruce,
Can you explain this a bit more? I know you often mention
this point. But it seems there must be something more to it;
otherwise we all would have seen low-cost carrier-phase
GPSDO products on the market over the past 15 years...
Instead there are only a few,
Too bad the navtechgps web-site makes it so difficult to find anything.
My attention span is very short, if they don't make it easy for you to
find anything, I look for another vendor.
Computers are to make life easier, not a drudge.
73, Dick, W1KSZ
-Original Message-
From: ScopeFreak
Jim Lux wrote:
Other uncertainties (multipath, ionosphere, phase center movement
with look angle, etc) are of that general magnitude as well, so even
if your little receiver could put out a 1pps with 1ns accuracy, the
other parts of the system are worse.
Jim
Receiving antenna phase
At 04:04 PM 4/24/2008, Bruce Griffiths wrote:
Jim Lux wrote:
Other uncertainties (multipath, ionosphere, phase center movement
with look angle, etc) are of that general magnitude as well, so even
if your little receiver could put out a 1pps with 1ns accuracy, the
other parts of the
Hi Antonio, Tom,
recently I had to unplug my PRS10 Rb from GPS for about 3 days. It drifted a
couple 100ns in that time frame.
When I plugged the GPS 1PPS back in, I saw a significant frequency error of
a couple of parts to the E-10 while the PRS10 was shifting the 1PPS back onto
UTC.
Hi guys,
let me play the bad cop here:
1) Since it is easy and inexpensive to get OCXO's that have stabilities of
parts to the E-012 or even E-013 (10811 on Ebay for $50 for example) over
time periods of 1/10s out to hundreds or even thousands of seconds
2) Since even the best
I suggest you follow the link at the bottom, because the original
page has a nifty video embedded in it.
Enjoy!
Tom Frank
--inline: news_logo.gif
Atomic rhythms give precise fix
By Jonathan Fildes
Science and technology reporter, BBC News
Please turn on
Hi Antonio, Tom,
recently I had to unplug my PRS10 Rb from GPS for about 3 days. It drifted a
couple 100ns in that time frame.
When I plugged the GPS 1PPS back in, I saw a significant frequency error of
a couple of parts to the E-10 while the PRS10 was shifting the 1PPS back
onto
In message [EMAIL PROTECTED], =?ISO-8859-1?Q?Pekka_Niemel=E4?= writ
es:
Hi,
I'm a bit new to this list, but I can't find information on this, but here
goes anyways:
I'm getting a Synergy Systems,LLC GSyncQ/T remote GPS receiver, that has a
nice RS-422 serial connection, what I was thinking about
Pekka Niemelä wrote:
Hi,
I'm a bit new to this list, but I can't find information on this, but here
goes anyways:
I'm getting a Synergy Systems,LLC GSyncQ/T remote GPS receiver, that has a
nice RS-422 serial connection, what I was thinking about was that this
system apparently works on an
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