[time-nuts] σ vs s in ADEV

Magnus Danielson magnus at rubidium.dyndns.org
Tue Jan 10 13:22:28 EST 2017

Hi Bob,

On 01/10/2017 12:20 AM, Bob kb8tq wrote:
> Hi
>> 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.


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