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
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