Electronic detection and identification system
First Claim
1. An electronic detection and identification system comprising, in combination, an electronic transmitter-receiver unit and a carrier member containing passive circuitry thereon for reflecting a signal comprising at least one selected harmonic of the signal transmitted thereto from said transmitter-receiver unit, said unit comprising a transmitter comprising a radio frequency source for generating a radio frequency signal, means for frequency sweeping said radio frequency signal with a frequency varying signal to produce a frequency swept signal and means for radiating said frequency swept signal towards said carrier member;
- and a receiver comprising means for receiving the signal reflected by the passive circuitry of carrier member;
amplitude detector means for detecting the instantaneous amplitude envelope of the received signal;
means for providing a predetermined reference signal representative of the expected received signal envelope profile corresponding to the selected harmonic of the transmitted signal and comparator means for comparing, in the time domain, the amplitude envelope of the detected signal with said reference signal, said comparator means comprising at least two comparators for comparing the amplitude envelope of the detected signal at at least two points in time sequence respectively representative of two different frequencies with two corresponding points of the reference signal.
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Accused Products
Abstract
An electronic detection and identification system for use in the rapid identification of vehicles at a toll stop, and like uses, is provided which employs an electronic identification card that is carried by the vehicle to be identified and a fixed transmitter-receiver unit that transmits a signal to the card and receives a reflected signal therefrom. The card contains passive resonant circuitry for producing an output signal having a frequency which is a selected harmonic of the signal transmitted thereto. In operation, the card is radiated with a signal which has a freqency in the Gigahertz range and which is produced by frequency sweeping and multiplying a frequency stable RF signal. The signal reflected by the card is narrow band-filtered and RF amplitude (envelope) detected. The detection envelope, which is the "signature" of the received signals, is compared with a reference profile to determine whether a match exists. An appropriate action, such as the generation of a "go" signal, is initiated based on the results of the comparison.
34 Citations
12 Claims
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1. An electronic detection and identification system comprising, in combination, an electronic transmitter-receiver unit and a carrier member containing passive circuitry thereon for reflecting a signal comprising at least one selected harmonic of the signal transmitted thereto from said transmitter-receiver unit, said unit comprising a transmitter comprising a radio frequency source for generating a radio frequency signal, means for frequency sweeping said radio frequency signal with a frequency varying signal to produce a frequency swept signal and means for radiating said frequency swept signal towards said carrier member;
- and a receiver comprising means for receiving the signal reflected by the passive circuitry of carrier member;
amplitude detector means for detecting the instantaneous amplitude envelope of the received signal;
means for providing a predetermined reference signal representative of the expected received signal envelope profile corresponding to the selected harmonic of the transmitted signal and comparator means for comparing, in the time domain, the amplitude envelope of the detected signal with said reference signal, said comparator means comprising at least two comparators for comparing the amplitude envelope of the detected signal at at least two points in time sequence respectively representative of two different frequencies with two corresponding points of the reference signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- and a receiver comprising means for receiving the signal reflected by the passive circuitry of carrier member;
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10. A method of detecting and identifying a moving body employing an electronic identification card, carried by said body and comprising passive resonant circuit means for generating a characteristic output signal in response to a signal containing covering a predetermined range of frequencies being transmitted thereto, said method comprising:
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generating a signal of a first frequency; frequency sweeping said signal to produce a frequency swept transmit signal; radiating said transmit signal towards said card, said transmit signal being processed so as to raise the frequency thereof to the Gigahertz range; receiving the signal reflected from said card; amplitude detecting the received signal so as to produce an output signal corresponding to the envelope of the received signal; providing a predetermined reference signal representative of the expected received signal envelope profile corresponding to the characteristic output signal produced by said card; and utilizing at least two comparators to compare in the time domain and in time sequence at least two points on said envelope respectively representative of two different frequencies with corresponding points on the reference envelope profile so as to determine the characteristics of the card from which the transmit signal was reflected. - View Dependent Claims (11, 12)
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Specification