Tight-PLL - YOU DON'T NEED TO READ IT IF YOUR FED-UP WITH THE THREAD SO HIT DELETE NOW!
I think I have found the source of the "integration" issue. I've spent
some considerable time ploughing through as many sources of
descriptions on ADEV, AVAR and the tight-PLL method. I've even tried
looking for the infamous "finite time interval integrator" which seems
to be highly notable by it's complete absence on Google. Well,
eventually the answer struck me directly in the eye, the source of the
integrate issue comes directly down to the original paper that Warren
posted a link for:-
D. Tight phase lock loop method
The second type of phase lock loop method (shown in figure 1.7) is
essentially the same as the first in figure 1.6 except that in this
case the loop is in a tight phase lock condition; i.e., the response
time of the loop is much shorter than the sample times of
interest--typically a few milliseconds. In such a case, the phase
fluctuations are being integrated so that the voltage output is
proportional to the frequency fluctuations between the two oscillators
and is no longer proportional to the phase fluctuations (for sample
times longer than the response time of the loop). A bias box is used
to adjust the voltage on the varicap to a tuning point that is fairly
linear and of a reasonable value. The voltage fluctuations prior to
the bias box (biased slightly away from zero) may be fed to a voltage
to frequency converter which in turn is fed to a frequency counter
where one may read out the frequency fluctuations with great
amplification of the instabilities between this pair of oscillators.
The frequency counter data are logged with a data logging device. The
coefficient of the varicap and the coefficient of the voltage to
frequency converter are used to determine the fractional frequency
fluctuations, yi, between the oscillators, where i denotes the ith
measurement as shown in figure 1.7. It is not difficult to achieve a
sensitivity of a part in 1014 per Hz resolution of the frequency
counter, so one has excellent precision capabilities with this system.
http://tf.nist.gov/phase/Properties/one.htm
The relevant section here is "the response time of the loop is much
shorter than the sample times of interest--typically a few
milliseconds. In such a case, the phase fluctuations are being
integrated so that the voltage output is proportional to the frequency
fluctuations". So what this says is that by incorporating a PLL-loop
filter that has a B/W much wider than the sample time, the phase
fluctuations are integrated into the reference oscillator such that
the control voltage of the tight-PLL now reads frequency which is
unlike the loose-PLL which directly records the phase relationship
between the oscillators. So the term "integrated" here is used a verb
and not a noun, therefore it is an intrinsic function of the design
not a separate process.
Steve
Steve Rooke - ZL3TUV & G8KVD
The only reason for time is so that everything doesn't happen at once.
- Einstein
Wrong again.
The integration/averaging referred to occurs when one counts the output
transitions of the VFC for a fixed time interval.
This process needs to be replicated using the sampled EFC data if one is
to measure ADEV.
Bruce
Steve Rooke wrote:
I think I have found the source of the "integration" issue. I've spent
some considerable time ploughing through as many sources of
descriptions on ADEV, AVAR and the tight-PLL method. I've even tried
looking for the infamous "finite time interval integrator" which seems
to be highly notable by it's complete absence on Google. Well,
eventually the answer struck me directly in the eye, the source of the
integrate issue comes directly down to the original paper that Warren
posted a link for:-
D. Tight phase lock loop method
The second type of phase lock loop method (shown in figure 1.7) is
essentially the same as the first in figure 1.6 except that in this
case the loop is in a tight phase lock condition; i.e., the response
time of the loop is much shorter than the sample times of
interest--typically a few milliseconds. In such a case, the phase
fluctuations are being integrated so that the voltage output is
proportional to the frequency fluctuations between the two oscillators
and is no longer proportional to the phase fluctuations (for sample
times longer than the response time of the loop). A bias box is used
to adjust the voltage on the varicap to a tuning point that is fairly
linear and of a reasonable value. The voltage fluctuations prior to
the bias box (biased slightly away from zero) may be fed to a voltage
to frequency converter which in turn is fed to a frequency counter
where one may read out the frequency fluctuations with great
amplification of the instabilities between this pair of oscillators.
The frequency counter data are logged with a data logging device. The
coefficient of the varicap and the coefficient of the voltage to
frequency converter are used to determine the fractional frequency
fluctuations, yi, between the oscillators, where i denotes the ith
measurement as shown in figure 1.7. It is not difficult to achieve a
sensitivity of a part in 1014 per Hz resolution of the frequency
counter, so one has excellent precision capabilities with this system.
http://tf.nist.gov/phase/Properties/one.htm
The relevant section here is "the response time of the loop is much
shorter than the sample times of interest--typically a few
milliseconds. In such a case, the phase fluctuations are being
integrated so that the voltage output is proportional to the frequency
fluctuations". So what this says is that by incorporating a PLL-loop
filter that has a B/W much wider than the sample time, the phase
fluctuations are integrated into the reference oscillator such that
the control voltage of the tight-PLL now reads frequency which is
unlike the loose-PLL which directly records the phase relationship
between the oscillators. So the term "integrated" here is used a verb
and not a noun, therefore it is an intrinsic function of the design
not a separate process.
Steve
Steve Rooke - ZL3TUV& G8KVD
The only reason for time is so that everything doesn't happen at once.
- Einstein
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
On 5 June 2010 19:07, Bruce Griffiths bruce.griffiths@xtra.co.nz wrote:
Wrong again.
No, I'm not wrong Bruce.
The integration/averaging referred to occurs when one counts the output
transitions of the VFC for a fixed time interval.
This process needs to be replicated using the sampled EFC data if one is to
measure ADEV.
This process is exactly replicated by oversampling the EFC and
determining the average for a fixed time period.
If you can't see that this performs exactly the same function, I don't
know what will convince you.
Steve
Bruce
Steve Rooke wrote:
I think I have found the source of the "integration" issue. I've spent
some considerable time ploughing through as many sources of
descriptions on ADEV, AVAR and the tight-PLL method. I've even tried
looking for the infamous "finite time interval integrator" which seems
to be highly notable by it's complete absence on Google. Well,
eventually the answer struck me directly in the eye, the source of the
integrate issue comes directly down to the original paper that Warren
posted a link for:-
D. Tight phase lock loop method
The second type of phase lock loop method (shown in figure 1.7) is
essentially the same as the first in figure 1.6 except that in this
case the loop is in a tight phase lock condition; i.e., the response
time of the loop is much shorter than the sample times of
interest--typically a few milliseconds. In such a case, the phase
fluctuations are being integrated so that the voltage output is
proportional to the frequency fluctuations between the two oscillators
and is no longer proportional to the phase fluctuations (for sample
times longer than the response time of the loop). A bias box is used
to adjust the voltage on the varicap to a tuning point that is fairly
linear and of a reasonable value. The voltage fluctuations prior to
the bias box (biased slightly away from zero) may be fed to a voltage
to frequency converter which in turn is fed to a frequency counter
where one may read out the frequency fluctuations with great
amplification of the instabilities between this pair of oscillators.
The frequency counter data are logged with a data logging device. The
coefficient of the varicap and the coefficient of the voltage to
frequency converter are used to determine the fractional frequency
fluctuations, yi, between the oscillators, where i denotes the ith
measurement as shown in figure 1.7. It is not difficult to achieve a
sensitivity of a part in 1014 per Hz resolution of the frequency
counter, so one has excellent precision capabilities with this system.
http://tf.nist.gov/phase/Properties/one.htm
The relevant section here is "the response time of the loop is much
shorter than the sample times of interest--typically a few
milliseconds. In such a case, the phase fluctuations are being
integrated so that the voltage output is proportional to the frequency
fluctuations". So what this says is that by incorporating a PLL-loop
filter that has a B/W much wider than the sample time, the phase
fluctuations are integrated into the reference oscillator such that
the control voltage of the tight-PLL now reads frequency which is
unlike the loose-PLL which directly records the phase relationship
between the oscillators. So the term "integrated" here is used a verb
and not a noun, therefore it is an intrinsic function of the design
not a separate process.
Steve
Steve Rooke - ZL3TUV& G8KVD
The only reason for time is so that everything doesn't happen at once.
- Einstein
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
--
Steve Rooke - ZL3TUV & G8KVD
The only reason for time is so that everything doesn't happen at once.
- Einstein
On 5 June 2010 22:06, Steve Rooke sar10538@gmail.com wrote:
On 5 June 2010 19:07, Bruce Griffiths bruce.griffiths@xtra.co.nz wrote:
Wrong again.
No, I'm not wrong Bruce.
The integration/averaging referred to occurs when one counts the output
transitions of the VFC for a fixed time interval.
This process needs to be replicated using the sampled EFC data if one is to
measure ADEV.
This process is exactly replicated by oversampling the EFC and
determining the average for a fixed time period.
I guess I should add that this process is called Integration
estimating with finite sums but I thought you would have already known
that so just gave the abbreviated term.
If you can't see that this performs exactly the same function, I don't
know what will convince you.
Steve
Bruce
Steve Rooke wrote:
I think I have found the source of the "integration" issue. I've spent
some considerable time ploughing through as many sources of
descriptions on ADEV, AVAR and the tight-PLL method. I've even tried
looking for the infamous "finite time interval integrator" which seems
to be highly notable by it's complete absence on Google. Well,
eventually the answer struck me directly in the eye, the source of the
integrate issue comes directly down to the original paper that Warren
posted a link for:-
D. Tight phase lock loop method
The second type of phase lock loop method (shown in figure 1.7) is
essentially the same as the first in figure 1.6 except that in this
case the loop is in a tight phase lock condition; i.e., the response
time of the loop is much shorter than the sample times of
interest--typically a few milliseconds. In such a case, the phase
fluctuations are being integrated so that the voltage output is
proportional to the frequency fluctuations between the two oscillators
and is no longer proportional to the phase fluctuations (for sample
times longer than the response time of the loop). A bias box is used
to adjust the voltage on the varicap to a tuning point that is fairly
linear and of a reasonable value. The voltage fluctuations prior to
the bias box (biased slightly away from zero) may be fed to a voltage
to frequency converter which in turn is fed to a frequency counter
where one may read out the frequency fluctuations with great
amplification of the instabilities between this pair of oscillators.
The frequency counter data are logged with a data logging device. The
coefficient of the varicap and the coefficient of the voltage to
frequency converter are used to determine the fractional frequency
fluctuations, yi, between the oscillators, where i denotes the ith
measurement as shown in figure 1.7. It is not difficult to achieve a
sensitivity of a part in 1014 per Hz resolution of the frequency
counter, so one has excellent precision capabilities with this system.
http://tf.nist.gov/phase/Properties/one.htm
The relevant section here is "the response time of the loop is much
shorter than the sample times of interest--typically a few
milliseconds. In such a case, the phase fluctuations are being
integrated so that the voltage output is proportional to the frequency
fluctuations". So what this says is that by incorporating a PLL-loop
filter that has a B/W much wider than the sample time, the phase
fluctuations are integrated into the reference oscillator such that
the control voltage of the tight-PLL now reads frequency which is
unlike the loose-PLL which directly records the phase relationship
between the oscillators. So the term "integrated" here is used a verb
and not a noun, therefore it is an intrinsic function of the design
not a separate process.
Steve
Steve Rooke - ZL3TUV& G8KVD
The only reason for time is so that everything doesn't happen at once.
- Einstein
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
--
Steve Rooke - ZL3TUV & G8KVD
The only reason for time is so that everything doesn't happen at once.
- Einstein
--
Steve Rooke - ZL3TUV & G8KVD
The only reason for time is so that everything doesn't happen at once.
- Einstein
Steve Rooke wrote:
On 5 June 2010 19:07, Bruce Griffithsbruce.griffiths@xtra.co.nz wrote:
Wrong again.
No, I'm not wrong Bruce.
Your "contribution" is largely irrelevant to the original discussion.
The effect of the PLL itself is (or should be) well understood.
However various assertions about the minimum usable value of Tau take no
account of the low pass filtering built into the 10811 EFC circuit.
The 100k series resistors plus the capacitance of the EFC varicap
(50-100pF??) will limit the minimum usable value of Tau.
The integration/averaging referred to occurs when one counts the output
transitions of the VFC for a fixed time interval.
This process needs to be replicated using the sampled EFC data if one is to
measure ADEV.
This process is exactly replicated by oversampling the EFC and
determining the average for a fixed time period.
A various times Warren has both claimed to do this and at others appears
to deny it.
A clear description of the details of the actual signal processing used
is sadly lacking.
If and only if the average is calculated sufficiently accurately.
Using a rectangular approximation with sampled data may not be as
accurate as one may expect.
It never ceases to amaze me why the well established and more accurate
methods known aren't used (details are all given in the paper I cited),
all it requires is a suitable program running on a PC. The correct
processing should have no effect on the hardware cost.
The $10 cost is also misleading as the mixers aren't free nor is the
10811 or its equivalent.
The assertion that this technique is new seems to be somewhat dubious as
it appears to have been known for several decades.
If you can't see that this performs exactly the same function, I don't
know what will convince you.
Steve
Bruce
On 6 June 2010 10:21, Bruce Griffiths bruce.griffiths@xtra.co.nz wrote:
Steve Rooke wrote:
On 5 June 2010 19:07, Bruce Griffithsbruce.griffiths@xtra.co.nz wrote:
Wrong again.
No, I'm not wrong Bruce.
Your "contribution" is largely irrelevant to the original discussion.
The effect of the PLL itself is (or should be) well understood.
Ah, the pathetic attempts to discredit opposition through insults and
dismissal. This is the desperate attempt of a man grasping at straws
trying to prevent going under. First they ignore you, then they mock
you, then they fight you, then you win...
Indeed, it does seem that the effects of the PLL are well understood
by some but perhaps others have yet to learn. We seem to have got over
the integration issue by remembering our our pre-calculus-101 dividing
the area under a graph into strips, oversampling, to perform
integration of a polynomial or any graph shape for that matter.
However various assertions about the minimum usable value of Tau take no
account of the low pass filtering built into the 10811 EFC circuit.
The 100k series resistors plus the capacitance of the EFC varicap
(50-100pF??) will limit the minimum usable value of Tau.
Wrong again!
And now a new red herring rears it's ugly head. So what have we here
then, "low pass filtering built in", well this forms the biasing
circuit of the varicap diode. The varicap itself forms part of the
tuned circuit with the crystal acting as an inductor in this colpits
oscillator Seeing as how that's the case, the hot end of the varicap
which is connected to the EFC control via a resistor is in fact
oscillating at 10Mh, having a period of 10^-7s, directly against that
EFC feed. Now, considering that Warren's daq can only achieve a rate
of about 400 sps, 2.5x10^-3, it is extremely unlikely that the "low
pass filtering built in" will have any bearing on this matter.
This process is exactly replicated by oversampling the EFC and
determining the average for a fixed time period.
A various times Warren has both claimed to do this and at others appears to
deny it.
Maybe Warren is not the person who is confused here.
A clear description of the details of the actual signal processing used is
sadly lacking.
What need for "signal processing" is there? Is this some way that you
feel there is a need to "massage" the results of actual measured data.
I think there was a very loud discussion about "massaging" and
"processing" data in a very large issue that came up a while ago.
If and only if the average is calculated sufficiently accurately.
So, say, 10 samples of the EFC voltage are taken over time T, then the
average of the samples is the sum of the samples / T. This is the
principal of oversampling and I cannot see why there is any continued
discussion on this point.
Using a rectangular approximation with sampled data may not be as accurate
as one may expect.
Well, if we had an infinite number of samples over time T then we
would have an absolutely accurate answer. Is this your point I wonder,
so it has to be infinitely accurate, let alone and other points of
error in the system which will obviously swamp this out like errors in
the reference oscillator which are impossible to resolve because no
one has yet come up with with an oscillator which is accurate to 1 /
10^(infinity). So lets get real shall we, if we take ten samples of a
waveform over a period and calculate the integral using the
rectangular method the results will be very close to the Riemann
integral. Don't take my word for it, try it for yourself. Perhaps you
believe that the method adopted by other to integrate the measurement
over the whole time period with a filter that has a wider BW than the
fundamental (because it has to let noise through) would give a more
accurate answer, even though its settling time is not optimal for the
measurement time.
It never ceases to amaze me why the well established and more accurate
methods known aren't used (details are all given in the paper I cited), all
it requires is a suitable program running on a PC. The correct processing
should have no effect on the hardware cost.
And it never ceases to amaze me how some stick-in-the-muds think that
what was done 50 years ago is the be-all and end-all of research in
any field. I guess if we had sent some ships out to see if the Earth
was flat and they did not come back, we should believe in our
assumptions and think that they must have fallen over the edge of the
Earth. I guess it's a good job that some intrepid researchers
discovered that there was no edge to the Earth and found out that it
was round. Mind you if they stopped there they wound not have
understood they were wrong as some later researchers found it was an
oblate spheroid.
And we are back to "correct processing" again, for some reason the
measured data seems to need some form of manipulation. Well, you are
correct to a certain extent, the oversamples need to added together
and divided by the oversample rate. That is all the processing needed,
just some logical processing of the data as part of the ADEV
calculation.
The $10 cost is also misleading as the mixers aren't free nor is the 10811
or its equivalent.
But it's closer to $10 than a TSC or a dual mixer setup.
The assertion that this technique is new seems to be somewhat dubious as it
appears to have been known for several decades.
So who has made this assertion, all along it's been understood that
this was an improved way of implementing the tight-PLL method. Did you
not get that?
Now I'm finding this petty attack on someone else's research, without
fully understanding it, quite tiresome, it's seriously cutting into my
quality porn time but won't lay down and play dead.
Regards,
Steve
Steve Rooke - ZL3TUV & G8KVD
The only reason for time is so that everything doesn't happen at once.
- Einstein