Hi > On Jan 9, 2017, at 5:09 PM, Jeremy Nichols <jn6...@gmail.com> wrote: > > In the late 1960s, Hewlett-Packard engineers worked up a program to have > the 5360A "Computing Pig" (so-called from its weight, 55 pounds without > plug-ins) compute a "fractional frequency standard deviation." It appears > to be similar to the Allen Deviation; I've never figured out the difference > and would appreciate hearing from someone with stronger math skills who can > explain the two.
The 5360A did ADEV. It only started being called ADEV after a few years had passed. The 5360A program and it’s various quirks became the topic of a number of post paper questions in the early 1970’s. The main focus of most of the questions was on bandwidth limiting ahead of the counter. That question really didn’t get a proper answer for several more decades. Bob > > Jeremy > > > On Mon, Jan 9, 2017 at 2:00 PM Bob kb8tq <kb...@n1k.org> wrote: > >> Hi >> >> >> >>> On Jan 9, 2017, at 4:49 PM, Magnus Danielson <mag...@rubidium.dyndns.org> >> wrote: >> >>> >> >>> Scott, >> >>> >> >>> On 01/09/2017 07:41 PM, Scott Stobbe wrote: >> >>>> I could be wrong here, but it is my understanding that Allan's >> pioneering >> >>>> work was in response to finding a statistic which is convergent to 1/f >> >>>> noise. Ordinary standard deviation is not convergent to 1/f processes. >> So I >> >>>> don't know that trying to compare the two is wise. Disclaimer: I could >> be >> >>>> totally wrong, if someone has better grasp on how the allan deviation >> came >> >>>> to be, please correct me. >> >>> >> >>> There where precursor work to Allans Feb 1966 article, but essentially >> that where he amalgamed several properties into one to rule them all >> (almost). It is indeed the non-convergent properties which motivates a >> stronger method. >> >> >> >> >> >> A number of outfits were measuring and spec’ing short term stability in >> the 1950’s and early 1960’s. Some were doing measures that are pretty close >> to ADEV. Others were doing straight standard deviation of frequency >> measurements. Since both got tossed up as “short term stability” confusion >> was the main result. NIST came in (as it rightly should) and gave us a >> measurement that does converge. They also spend the next two decades >> >> thumping on a bunch of hard heads to get everybody to use the measurement >> rather than something with more issues. Once that effort was underway, we >> got a whole raft of alternatives that each have benefits in certain areas. >> >> ADEV is far from the only measure that could be properly be used today to >> characterize short term stability. >> >> >> >> Bob >> >> >> >>> Standard statistics is relevant for many of the basic blocks, bit things >> work differently with the non-convergent noise. >> >>> Another aspect which was important then was the fact that it was a >> counter-based measure. Some of the assumptions is due to the fact that they >> used counters. I asked David some questions about why the integral looks >> the way it does, and well, it reflects the hardware at the time. >> >>> >> >>> What drives Allan vs. standard deviation is that extra derive function >> before squaring >> >>> The bias functions that Allan derives for M-sample is really the >> behavior of the s-deviation. See Allan variance wikipedia article as there >> is good references there for the bias function. That bias function is >> really illustrating the lack of convergence for M-sample standard >> deviation. The Allan is really a power-average over the 2-sample standard >> deviation. >> >>> >> >>> Cheers, >> >>> Magnus >> >>> >> >>>> On Wed, Jan 4, 2017 at 3:12 PM, Attila Kinali <att...@kinali.ch> wrote: >> >> >> >> _______________________________________________ >> >> 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. >> >> -- > Sent from Gmail Mobile > _______________________________________________ > 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.