[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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