Object detection method and apparatus
First Claim
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1. A method of determining a presence of an object associated with a target, the method comprising the steps of:
- illuminating a target with polarized illuminating radiation;
collecting first radiation reflected from the target which has a same polarization as the illuminating radiation;
collecting second radiation reflected from the target which has an opposite polarization from the illuminating radiation; and
employing a weighted plurality of criteria of the first radiation and the second radiation converted to a time domain by a Chirp-Z Transform process to determine the presence of the object, the criteria selected from the group consisting of a first magnitude of the first radiation at zero time after conversion to the time domain by the Chirp-Z Transform process, a second magnitude of the second radiation at zero time after conversion to the time domain by the Chirp-Z Transform process, and a difference between the first magnitude and the second magnitude; and
employing a time of arrival difference between the first radiation and the second radiation.
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Abstract
Method and apparatus for detecting objects. In one embodiment, a person entering a secured zone is illuminated with low-power polarized radio waves. Differently polarized waves which are reflected back from the person are collected. Concealed weapons are detected by measuring various parameters of the reflected signals and then calculating various selected differences between them. These differences create patterns when plotted as a function of time. Preferably a trained neural network pattern recognition program is then used to evaluate these patterns and autonomously render a decision on the presence of a weapon.
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Citations
21 Claims
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1. A method of determining a presence of an object associated with a target, the method comprising the steps of:
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illuminating a target with polarized illuminating radiation; collecting first radiation reflected from the target which has a same polarization as the illuminating radiation; collecting second radiation reflected from the target which has an opposite polarization from the illuminating radiation; and employing a weighted plurality of criteria of the first radiation and the second radiation converted to a time domain by a Chirp-Z Transform process to determine the presence of the object, the criteria selected from the group consisting of a first magnitude of the first radiation at zero time after conversion to the time domain by the Chirp-Z Transform process, a second magnitude of the second radiation at zero time after conversion to the time domain by the Chirp-Z Transform process, and a difference between the first magnitude and the second magnitude; and
employing a time of arrival difference between the first radiation and the second radiation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus for detecting an object associated with a target, said apparatus comprising:
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a transmit antenna for illuminating the target with polarized illuminating radiation; a first receive antenna for collecting first radiation reflected from the target which has a same polarization as the illuminating radiation; a second receive antenna for collecting second radiation reflected from the target which has an opposite polarization from the illuminating radiation; and a processor for employing a weighted plurality of criteria of the first radiation and the second radiation converted to a time domain by a Chirp-Z Transform process to determine a presence of the object, the criteria selected from the group consisting of a first magnitude of said first radiation at zero time after conversion to the time domain by the Chirp-Z Transform process, a second magnitude of said second radiation at zero time after conversion to the time domain by the Chirp-Z Transform process, and a difference between said first magnitude and said second magnitude; and
said processor employs a time of arrival difference between said first radiation and said second radiation. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification