[time-nuts] σ vs s in ADEV
kb8tq at n1k.org
Tue Jan 10 17:59:14 EST 2017
> On Jan 10, 2017, at 1:22 PM, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:
> Hi Bob,
> On 01/10/2017 12:20 AM, Bob kb8tq wrote:
>>> On Jan 9, 2017, at 5:09 PM, Jeremy Nichols <jn6wfo at 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.
> I've not found much on that topic as I've searched. Care to point to a few papers?
> I've been looking at it, and you get somewhat different formulas if you consider the filter.
It never came up in a paper. It was a question asked from the audience every time the NIST
guys presented an ADEV paper. After a while it got very predictable in terms of who would
stand up and ask what.
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