[time-nuts] Doppler Design
gary
lists at lazygranch.com
Mon Jan 2 03:49:19 UTC 2012
An interesting comparison of technique. It skips right past simple
interferometers and goes into correlative interferometry. Since the XY
scheme requires triangulation, it is probably not considered useful, or
they just go right into scheme without ambiguity.
> http://www.denisowski.org/Articles/Denisowski%20-%20Comparison%20of%20Radio%20Direction-Finding%20Technologies.pdf
BTW, it is pronounced more like Road-dah rather than Road. I ran across
a video from the company and hear the pronunciation. I was really thrown
by the correct pronunciation.
Getting back to the Doppler schemes, the assumption is the signal isn't
changing, at least in the most fundamental case. So it works great for a
sine wave, OK for voice since the switching is fast enough that the
signal hasn't changed much, but poor for highly modulated signals, and
not at all for broadband noise. Meditating on my navel, it seems the
interferometer would even work for broadband noise since those noise
signals are actually very much correlated since they are identical. Thus
the autocorrelation of the signal is what determines how well a Doppler
scheme would work.
For broadband noise, the XY scheme might actually be best. The XY
display would suddenly snap to a 45 degree line when the distances are
equal.
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