On 5 June 2010 22:06, Steve Rooke <sar10...@gmail.com> wrote: > On 5 June 2010 19:07, Bruce Griffiths <bruce.griffi...@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 _______________________________________________ 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.