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From: MarkThomas77@Hotmail.com (markthomas77@Hotmail.com)
Subject: Microwave Acoustic Vibration Sensor
Date: 29 Nov 2002 07:47:39 -0800
NNTP-Posting-Date: 29 Nov 2002 15:47:39 GMT
I posted an earlier thread regarding using a low power cw x-band
doppler radar unit as a non contact acoustic vibration sensor. I
received some interesting replies that gave me some more bits to the
puzzle. I very much thank all who responded for the information they
provided. However, there was one post in particular that I found very
interesting, shown below.
Well if you wanted a slick chance you would:
A) modulate the carrier to chop the audio up to higher frequency
B) recover the phase, using a low sideband noise oscillator
c) demodulate the phase carrier to extract the 1/1000 p1/2 phase
that you can expect to see with a 1 uM vibration.
I am not exactly an electronics genius. So I need some smart chap to
tell me how I would accomplish the above. For example:
A) What frequency of tone would I use to modulate the radars carrier,
what type of modulation, AM? How much modulation...25 percent...or 50
B) Suggests using a low sideband noise oscillator. What make & model
of this device would I need to connect to the mixer pin of a low power
cw x-band radar, and how would I connect it to the radar mixer pin
exactly? What circuit?
C) Next it states that the phase carrier needs to be demodulated to
extract the phase modulation. Would a PLL do this? I need help on
this. Too bad there is not an off shelf circuit board or kit that can
be connected to a radars mixer pin to easily do all of the above. Is
there anything like that? Tia.
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