Method and apparatus for through-the-wall motion detection utilizing cw radar
First Claim
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1. A method for detecting the presence of an individual behind a wall, comprising the steps of:
- projecting a CW radar signal through a wall;
detecting portions of the CW radar signal returned by an object behind the wall;
determining the phase difference between projected and returned CW radar signals; and
, indicating the presence of an individual when the change in the detected phase difference is above a predetermined threshold, whereby individuals moving behind the wall can be detected.
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Abstract
A CW radar (10) is used to detect motion of objects (22) behind a wall (20) by projecting a radar beam through the wall and by measuring the returns from the objects behind the wall, with a change in the phase difference between the transmitted and received CW signals providing an indication of motion behind the wall and thus the presence of an individual.
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Citations
19 Claims
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1. A method for detecting the presence of an individual behind a wall, comprising the steps of:
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projecting a CW radar signal through a wall;
detecting portions of the CW radar signal returned by an object behind the wall;
determining the phase difference between projected and returned CW radar signals; and
,indicating the presence of an individual when the change in the detected phase difference is above a predetermined threshold, whereby individuals moving behind the wall can be detected. - View Dependent Claims (2, 3, 4, 5)
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6. Apparatus for the detection of a moving individual behind a wall, comprising:
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a frequency source;
a power divider coupled to said frequency source for outputting as a first output a CW signal of one predetermined magnitude for forming a radar beam and for outputting as a second output a CW signal of a diminished magnitude;
a circulator coupled to said first output;
an antenna coupled to said circulator for transmitting a CW radar beam towards said wall and for detecting radar returns from objects behind said wall;
a mixer coupled to said second output and said circulator for deriving a signal representing the phase difference between transmitted and returned signals at said antenna; and
,a detector for detecting when there is a change in the phase difference between said transmitted beam and said returns, said phase difference indicating the presence of a moving object behind said wall. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A system of determining the presence of an individual behind a wall, comprising:
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a CW radar having a directional antenna adapted to project CW radar energy through said wall, and detecting returns from objects behind said wall; and
,a phase difference detector for detecting the phase difference between CW energy directed through said wall and energy returned from objects behind said wall, a change in phase difference indicating the presence of a moving object behind said wall. - View Dependent Claims (17, 18, 19)
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Specification