Hi Mark,
What reference oscillator and measurement system did you use?
Is that with or without a sqrt(2) removed? Is your HP105 the older
style with the 00105 brick oscillator or a newer one?
The modern HP105 is essentially a well engineered wrapper around
a 10811 oscillator so the performance
How is the speed of light accounted for in the definition of UTC?
In other words, how did they solve the conflict where on one hand we'd all
expect two perfect clocks to tick at the same time but wether they do
depends on the location of the observer?
--
Chris Albertson
Redondo Beach,
AFIK it isn't.
Rob K
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Chris Albertson
Sent: 30 August 2011 8:40 AM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] UTC and the speed of light?
How is the
Le 30/08/2011 10:36, Rob Kimberley a écrit :
AFIK it isn't.
Rob K
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Chris Albertson
Sent: 30 August 2011 8:40 AM
To: Discussion of precise time and frequency measurement
Subject:
The original question asked whether the speed of light was taken into
account in the definition of UTC. From where I'm standing (and please excuse
the pun), it isn't.
Rob Kimberley
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of mike
Le 30/08/2011 11:21, Rob Kimberley a écrit :
The original question asked whether the speed of light was taken into
account in the definition of UTC. From where I'm standing (and please excuse
the pun), it isn't.
Rob Kimberley
There were 2 questions. I was agreeing to your response to the first
Sorry, I was thinking about the second bit rather than the first.
Rob
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of mike cook
Sent: 30 August 2011 11:05 AM
To: Discussion of precise time and frequency measurement
Subject: Re:
Le 30/08/2011 09:40, Chris Albertson a écrit :
How is the speed of light accounted for in the definition of UTC?
In other words, how did they solve the conflict where on one hand we'd all
expect two perfect clocks to tick at the same time but wether they do
depends on the location of the
On 8/30/11 12:40 AM, Chris Albertson wrote:
How is the speed of light accounted for in the definition of UTC?
00:00:00 UTC is the same time everywhere. propagation only affects it
if you are transmitting a signal based on UTC. If I send a signal at
00:00:00 UTC from LA to Greenwich,
Thanks Tom, the reference oscilator is a Datum FTS 1050. I've used both a HP
5370B and my Tek 2252 scope as time interval counter and looked at the data
files with Plotter and Time Lab. The results are all more or less the same for
ADEV at 100 seconds.
With regards to the sqrt(2) removal I'm
Tom,
Is there an assumption that is normally made when referring to ADEV.
For example I looked at your image and see that you the chart begins at .1
seconds, so I am assuming that the sample rate was .1 sec to acquire these
numbers.
But Mark does not specify a sample time in his ADEV number.
How is the speed of light accounted for in the definition of UTC?
In other words, how did they solve the conflict where on one hand we'd all
expect two perfect clocks to tick at the same time but wether they do
depends on the location of the observer?
--
Chris Albertson
Redondo Beach,
Hi
How many samples did you use in each case? With a small number of samples,
your results will be all over the place.
Each measurement on the 5370 is good to at best 20 ps. Over a second, that
would be 2x10^-11. Over a tenth of a second that would be 2x10^-10. With
time tagging you can get
Hi
I suspect that the typical phase noise of 0.035 degrees spec is going to
make using it as a phase detector a bit of a challenge. You would have to do
some digging to see if it really does anything that a cheap double balanced
mixer does not do.
Bob
-Original Message-
From:
Hi Paul,
Right, the averaging time, tau, is critical when quoting ADEV
numbers. In fact, the key feature of any ADEV plot is seeing
how stability changes as a function of tau. But Mark mentioned
at 100 seconds so that allowed me to compare his single
ADEV number against the tau 100 second column
Bob,
You would be correct, as I don't yet know what time tagging is.
In both cases the number of points gathered was 3600
I must be using TimeLab improperly, after reading this email, I took a
closer look.
Even though I specified 1 hour duration for each test, the tests took a far
shorter
Right, the averaging time, tau, is critical when quoting ADEV
numbers. In fact, the key feature of any ADEV plot is seeing
how stability changes as a function of tau. But Mark mentioned
at 100 seconds so that allowed me to compare his single
ADEV number against the tau 100 second column of a
To expand upon my original email, the averging time was one second when I used
the HP 5370B, .8 of a second when I used the Tek Scope as a time interval
counter.
I've also collected data with averging times as low as .1 of a second using the
5370B. When looking at the results for tau of
Mark,
Let me explain the sqrt(2) thing.
Since you have a number of oscillators you have probably already
compared them to each other to see which one is best, or which
pair is best.
When you compare the FTS1050 against the HP105 remember
that the ADEV numbers you obtain are always the rms sum
John,
Here is how I am set up currently with the HP 5370B,
I didn't understand the triggering comments you made preciously
1) UnderFunction
The counter is in the TI mode
2) Under statistics mode
The counter is in the Mean mode
3) Under Sample Size
Number 1 is selected
4) Under arming
1) UnderFunction
The counter is in the TI mode
2) Under statistics mode
The counter is in the Mean mode
3) Under Sample Size
Number 1 is selected
4) Under arming
The +TI button is selected.
5) Under display rate.
Fully clockwise the display nor the GPIB interface will
Thanks Tom that makes sense.(In this case I'm fairly sure that the FTS 1050
is at least meeting it's 100 sec ADEV spec of 1E-12 I have had results in the
13's on occasion when looking at other oscilators, and I leave it running in a
fairly stable enviornment.)
I appriceate the insight.
The 5202 down converts by switching the LO on and off at a rate that is
dependent on the input frequency. This on/off rate becomes the IF frequency. It
is sort of like fractional N but worse. There is no image rejection. Some
mixers and DDS's will clean its clock.
John Pease
Mark,
One more comment on my 1e-12 example. The measurements
that you obtain fix the limits of how bad either oscillator can be;
but it doesn't prove how good either one is.
In one extreme the oscillators could have near equal stability,
say 7e-13 each. As mentioned earlier, that would give you
The question has both a frequency and a counter part, as does any
clock.
The frequency shift with gravity has been nicely addressed by tvb
and others.
The counter of the frequency is subject to phase shift caused by the
speed of light and the distance to the measured source. Each counter
must be
The counter of the frequency is subject to phase shift caused by the
speed of light and the distance to the measured source. Each counter
must be given an initial value of time in order to be called a clock.
Hi Bill,
When not in motion it's easy to synchronize remote clocks --
you just send
John,
I don't know if I am going to understand all this.
I come from an analog world, a dinosaur, all this timing stuff as much fun
as it is, can be awful intimidating.
I am thinking there is a 1 PPS source in the Z3801a but for the moment I
have one of these devices
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