This post explains how to obtain a
3D RADAR image using ONE antenna.
A RADAR return involves the main reflection from a target,
plus reflections from many other points (Clutter).
The various reflections represent different views of the target.
To construct a 3D view,
the computer would have to determine the locations
of a few reflecting points,
and use an algorithm to combine the views that
have the best signal to noise ratio.
The broadband techniques used in cell phones
and the GPS system,
and the imaging techniques used in medical imaging
could be used in a system of this kind.
In other words,
a 3D, single antenna RADAR would:
1. Modulate the transmitter with a pseudo-random code.
2. Cross-correlate the return signal with the pseudo-random code
and determine the positions, and possible momentums of the
"clutter points" with the best signal-to-noise.
3. Use the best three or four "clutter points"
as spatial references.
4. Obtain output streams from cross-correlations
of the four "clutter points" and the pseudo-random code.
5. Use medical imaging techniques to construct a 3D image.
6. A 3d image could be constructed of the general area,
or the echo from the target could be used to confine the 3D view
to the area of the target.
If a RADAR was operating in a place
where the geographical location
of some "clutter points" could not be determined,
one could simply create a few known "clutter points"
by placing "pseudo-randomly shaped" targets in the vicinity.
Pseudo-randomly shaped" objects would serve as 3D templates
much as the pseudo-random code in broadband communications
serve as 1D templates.
3D pseudo-randomly shaped" object codes
would be stored in the computer,
and when a match was made between the
correlations in the incoming signals
it would indicate that a lock was made,
and that the 3D image was valid to some level.
A sophisticated system could even
rocket 3D pseudo-randomly shaped" objects
into a region to serve as templates,
if fixed templates were not available.
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