[time-nuts] ADEV

[Magnus Danielson]

Hi Bob,

On 11/13/2010 03:05 PM, Bob Camp wrote:
> Hi
>
> I see ADEV not as a solution to a system design problem, but an oscillator measurement issue.
> If you look at the measures being used in the 60's, most of them had serious statistical flaws.
> You could measure them several ways and get multiple results. What ADEV gave us is a measure
> that could be done repeatably. You still have to do it right, but if you do it repeats.  If
> there is a systems rationale in the development of the measurement it's awfully well hidden
> in the early papers.

I completely agree, having spent quite some time in those early papers. 
They had problems to handle the noise of oscillators, and having those 
problems, how can you attack the system design problems? They had 
obvious needs for it in developing doppler radars for instance, but also 
for the space program. One of the big meetings on this topic was in the 
NASA Goddard space center, and the result of that is found in the NASA 
Special Publication 80 (SP-80):
http://hdl.handle.net/2060/19660001092

Un the part 1 "User's viewpoint and requirements"
First article in there is "Short-term stability for a doppler radar: 
Requirements, Measurements and Techniques" by D.B. Leeson and G.F. Johnsson.
Fifth article is "Satellite Range and Tracking Accuracy as a function of 
Oscillator STability" by J.J. Caldwell Jr.
Sixth article is "Short-term Stability Requirements for Deep Space 
Tracking and Communications systems" by R. L. Sydnor.

I think the system applications for short-term stability measurements 
was quite clear, and was brought out specifically.

ADEV addresses the oscillator noise issues, but isn't particularly well 
suited for the numerous of systematic effects that comes on top of the 
oscillator noise in the system.

Cheers,
Magnus