Hi Magnus,
2009/4/14 Magnus Danielson mag...@rubidium.dyndns.org
Say I have a 1Hz input source and my counter measures the period of
the first cycle and assigns this to A1. At the end of the first cycle
the counter is able to be rest and re-triggered to capture the second
cycle and
Steve Rooke wrote:
Hi Mark,
2009/4/13 Mark Sims hol...@hotmail.com:
Hello Steve,
Try this... take Tom's sample data set, run the numbers. Then, using a
good random number generator, make another data set by randomly throwing
out half (or more) of the samples (to simulate a non
Steve,
Steve Rooke wrote:
Bruce,
2009/4/12 Bruce Griffiths bruce.griffi...@xtra.co.nz:
Steve
Steve Rooke wrote:
If I take two sequential phase readings from an input source and place
this into one data set and aniother two readings from the same source
but spaced by one cycle and put
2009/4/13 Magnus Danielson mag...@rubidium.dyndns.org:
But randomly throwing out data points would introduce ZDT.
It would introduce dead-time, it would not introduce zero dead-time
(ZDT). Dropping every second sample of a phase/time-error series can
maintain the zero dead-time property, but
Steve Rooke skrev:
2009/4/13 Magnus Danielson mag...@rubidium.dyndns.org:
But randomly throwing out data points would introduce ZDT.
It would introduce dead-time, it would not introduce zero dead-time
(ZDT). Dropping every second sample of a phase/time-error series can
maintain the zero
Mark,
Mark Sims skrev:
The whole purpose of taking a data set from a known ZDT counter and then
throwing out random samples is to simulate the kind of data that a normal
counter would produce. You could compare the results and get an idea of how
using a normal counter for calculating
...@febo.com
[mailto:time-nuts-boun...@febo.com] Im Auftrag von Steve Rooke
Gesendet: Freitag, 10. April 2009 12:55
An: Discussion of precise time and frequency measurement
Betreff: [!! SPAM] Re: [time-nuts] Characterising frequency standards
Ulrich,
2009/4/10 Ulrich Bangert df...@ulrich
Tom,
2009/4/11 Tom Van Baak t...@leapsecond.com:
Nevertheless leaving every second sample out is NOT exactly the same as
continous data with Tau0 = 2 s. Instead it is data with Tau0 = 1 s and a
DEAD TIME of 1s. There are dead time correction schemes available in the
literature.
Ulrich, and
2009/4/11 Magnus Danielson mag...@rubidium.dyndns.org:
Tom Van Baak skrev:
Nevertheless leaving every second sample out is NOT exactly the same as
continous data with Tau0 = 2 s. Instead it is data with Tau0 = 1 s and a
DEAD TIME of 1s. There are dead time correction schemes available in the
Steve
Steve Rooke wrote:
2009/4/11 Magnus Danielson mag...@rubidium.dyndns.org:
Tom Van Baak skrev:
Nevertheless leaving every second sample out is NOT exactly the same as
continous data with Tau0 = 2 s. Instead it is data with Tau0 = 1 s and a
DEAD TIME of 1s. There are dead time
Steve
Steve Rooke wrote:
If I take two sequential phase readings from an input source and place
this into one data set and aniother two readings from the same source
but spaced by one cycle and put this in a second data set. From the
first data set I can calculate ADEV for tau = 1s and can
Bruce Griffiths wrote:
...
Brice
An impostor? An alias? :-)
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Rex wrote:
Bruce Griffiths wrote:
...
Brice
An impostor? An alias? :-)
And I thought I was alluding to aliasing of the phase noise spectrum not
the characters of the alphabet.
Bruce
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Steve Rooke skrev:
2009/4/11 Magnus Danielson mag...@rubidium.dyndns.org:
Tom Van Baak skrev:
Nevertheless leaving every second sample out is NOT exactly the same as
continous data with Tau0 = 2 s. Instead it is data with Tau0 = 1 s and a
DEAD TIME of 1s. There are dead time correction
Bruce Griffiths skrev:
Rex wrote:
Bruce Griffiths wrote:
...
Brice
An impostor? An alias? :-)
And I thought I was alluding to aliasing of the phase noise spectrum not
the characters of the alphabet.
So it is not a case of shot noise of Bruce fingers? :)
I know mine
Hej Magnus
Magnus Danielson wrote:
Bruce Griffiths skrev:
Rex wrote:
Bruce Griffiths wrote:
...
Brice
An impostor? An alias? :-)
And I thought I was alluding to aliasing of the phase noise spectrum not
the characters of the
Bruce,
2009/4/12 Bruce Griffiths bruce.griffi...@xtra.co.nz:
Steve
Steve Rooke wrote:
If I take two sequential phase readings from an input source and place
this into one data set and aniother two readings from the same source
but spaced by one cycle and put this in a second data set. From
2009/4/13 Magnus Danielson mag...@rubidium.dyndns.org:
Dead time is when the counter looses track of time in between two
consecutive measurements. A zero dead-time counter uses the stop of one
measure as the start of the next measure.
This becomes very important when the data to be measured
Betreff: Re: [time-nuts] Characterising frequency standards
Tom,
2009/4/9 Tom Van Baak t...@leapsecond.com:
The first argument to the adev1 program is the sampling
interval t0.
The program doesn't know how far apart the input file samples are
taken so it is your job to specify
Bangert
-Ursprungliche Nachricht-
Von: time-nuts-boun...@febo.com
[mailto:time-nuts-boun...@febo.com] Im Auftrag von Steve Rooke
Gesendet: Donnerstag, 9. April 2009 14:00
An: Tom Van Baak; Discussion of precise time and frequency measurement
Betreff: Re: [time-nuts] Characterising
Tom,
2009/4/10 Tom Van Baak t...@leapsecond.com:
We need to be careful about what you mean by continuous.
Let me probe a bit further to make sure you or others understand.
My reference to continuous data would be defined as measurements
over a specific sampling period with each sample
Gesendet: Freitag, 10. April 2009 12:55
An: Discussion of precise time and frequency measurement
Betreff: [!! SPAM] Re: [time-nuts] Characterising frequency standards
Ulrich,
2009/4/10 Ulrich Bangert df...@ulrich-bangert.de:
Steve,
I think the penny has dropped now, thanks. It's
Nevertheless leaving every second sample out is NOT exactly the same as
continous data with Tau0 = 2 s. Instead it is data with Tau0 = 1 s and a
DEAD TIME of 1s. There are dead time correction schemes available in the
literature.
Ulrich, and Steve,
Wait, are we talking phase measurements
Tom Van Baak skrev:
Nevertheless leaving every second sample out is NOT exactly the same as
continous data with Tau0 = 2 s. Instead it is data with Tau0 = 1 s and a
DEAD TIME of 1s. There are dead time correction schemes available in the
literature.
Ulrich, and Steve,
Wait, are we
Bruce,
2009/4/9 Bruce Griffiths bruce.griffi...@xtra.co.nz:
Doesn't that imply that the data point should correspond to the whole
sampling period and not just half of it?
The total measurement time is only deceased by 1 sec at the most if you
delete every second line.
The resampled data
Tom,
2009/4/9 Tom Van Baak t...@leapsecond.com:
The first argument to the adev1 program is the sampling interval t0.
The program doesn't know how far apart the input file samples are
taken so it is your job to specify this. The default is 1 second.
If you have data taken one second apart
Tom,
I understand fully the points that you have made but I have obviously
not made my point clear to all and i apologise for my poor
communication skills.
This is what I'm getting at:
Using your adev1.exe from http://www.leapsecond.com/tools/adev1.htm
and processing various forms of gps.dat
Steve
It cant, it must be a matter of interpretation.
Perhaps it means something like:
1 tau means tau = 1x the interval between consecutive measurements.
2 tau means tau = 2x the interval between consecutive measurements
10 tau means tau = 100,000 x the interval between consecutive
Bruce,
But how does that explain the output of Tom's adev1 program which
still seems to give a a good measurement at tau = 1s?
73,
Steve
2009/4/8 Bruce Griffiths bruce.griffi...@xtra.co.nz:
Steve
If you delete every second measurement then your effective minimum
sampling time is now 2s and
Bruce,
I hear what you say but the results seem to correlate quite well:-
1 tau, 3.0127e-009 adev(n=38), 3.0127e-009 oadev(n=38)
1 tau, 3.0257e-009 adev(n=18), 3.0257e-009 oadev(n=18)
And using the first half of the data:-
1 tau, 3.0411e-009 adev(n=18), 3.0411e-009
Steve
The data file doesn't include the time interval between samples so do
you set this in some way?
If so you need to set it to 1s for the unaltered data, to 2s when you
take every 2nd sample, and 1s when you take the first 200,000 samples.
In principle you could use CANVAS (available on
Bruce,
I set nothing, as indicated in my text, I just delete data points, IE.
a file of 40 records now becomes 20. I'm trying to get my head
round this as the absolute requirement for continuous data seems
unneeded. What you have to remember here is that the data set I'm
working with
Steve
Therein lies your problem.
adev1 defaults to a sampling interval of 1 sec. (read the C source code).
TvB's documentation explicitly states that you should supply the
sampling interval. (its a command line argument for adev1.c).
adev1.c is a simple command line program that uses stdin and
I've compiled adev1 under Linux with no changes required; don't recall
the exact gcc line I used but it was pretty much the obvious one.
Steve, one other point -- your results with every sample versus
every-other-sample aren't hugely different because ADEV doesn't usually
change dramatically
Bruce,
But the sampling interval is still 1 sec and you can see by my notes
that I explicitly give this on the command line for adev1.exe.
OK, I'll have a go at compiling it as it is just a command line program.
73,
Steve
2009/4/9 Bruce Griffiths bruce.griffi...@xtra.co.nz:
Steve
Therein
John,
OK, I see what you mean if I re-run with a 2 second period:-
C:\Documents and Settings\Steve Rooke\Desktopadev1.exe 2 gps1.dat
** Sampling period: 2 s
** Phase data scale factor: 1.000e+000
** Total phase samples: 20
** Normal and Overlapping Allan deviation:
2 tau,
Steve Rooke wrote:
Bruce,
But the sampling interval is still 1 sec and you can see by my notes
that I explicitly give this on the command line for adev1.exe.
The sampling interval is indeed 1sec in the original data.
However, if you delete every second sample the sampling interval in the
Yes, it compiles cleanly with gcc -o adev1 -lm adev1.c and works
just like a bought one, thanks.
73,
Steve
2009/4/9 John Ackermann N8UR j...@febo.com:
I've compiled adev1 under Linux with no changes required; don't recall
the exact gcc line I used but it was pretty much the obvious one.
2009/4/9 Bruce Griffiths bruce.griffi...@xtra.co.nz:
The sampling interval is indeed 1sec in the original data.
However, if you delete every second sample the sampling interval in the
resultant data is then 2 sec.
Doesn't that imply that the data point should correspond to the whole
sampling
Steve Rooke wrote:
2009/4/9 Bruce Griffiths bruce.griffi...@xtra.co.nz:
The sampling interval is indeed 1sec in the original data.
However, if you delete every second sample the sampling interval in the
resultant data is then 2 sec.
Doesn't that imply that the data point should
But how does that explain the output of Tom's adev1 program which
still seems to give a a good measurement at tau = 1s?
The first argument to the adev1 program is the sampling interval t0.
The program doesn't know how far apart the input file samples are
taken so it is your job to specify this.
Steve Rooke wrote:
A while back when we were discussing the performance of the Shortt
free pendulum clock a reference was made to tvb's paper on allen
deviation, http://www.leapsecond.com/hsn2006/ch2.pdf, which I found to
be an excellent primer on the subject. It was interesting to see that
In message 49db496e.6030...@xtra.co.nz, Bruce Griffiths writes:
Steve Rooke wrote:
It is essential to measure the phase differences between every Nth zero
crossing without missing any such cycles.
And he does, except it is only every 2N instead of 1N.
--
Poul-Henning Kamp | UNIX since
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