System for interrogating a passive transponder carrying phase-encoded information
First Claim
1. System for interrogating a transponder carrying encoded information, said system comprising:
- (a) at least one transponder means for receiving a first signal and for transmitting a second signal in reply thereto, said transponder means including signal transforming means, coupled to receive said first signal as an input, for producing said second signal as an output, said signal transforming means including;
(1) a plurality of signal conditioning means coupled to receive said first signal, each signal conditioning means providing an intermediate signal having a known delay and a known amplitude modification to said first signal; and
(2) signal combining means coupled to all of said signal conditioning means, for combining said intermediate signals to produce said second signal, said signal conditioning means and said signal combining means imparting a known informational code to said second signal associated with said transponder means;
(b) means for transmitting said first signal having a first frequency, said first frequency successively assuming a plurality of frequency values across a prescribed frequency range which is sufficiently wide to resolve the differences in time between the known delays of different ones of said signal conditioning means;
(c) means for receiving said second signal from said transponder means;
(d) means, coupled to said transmitting means, for producing a third signal derived from said first signal;
(e) means, coupled to said receiving means, for producing a fourth signal derived from said second signal;
(f) means, arranged to receive said third signal and said fourth signal for mixing together said third signal and said fourth signal, thereby to produce a fifth signal; and
(g) signal processing means, responsive to said fifth signal, for detecting at least some of the frequencies contained in said fifth signal, thereby to determine said informational code associated with said transponder means.
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Accused Products
Abstract
A "passive interrogator label system" (PILS) comprises an interrogator for transmitting an interrogation signal, one or more "labels" or passive transponders which produce a reply signal containing coded information in response to the interrogation signal, and a receiver and decoder for receiving the reply signal and decoding the information contained in it. The frequency of the interrogation signal assumes a plurality of frequency values within a prescribed frequency range. The decoder includes a mixer (4 quadrant multiplexer) for mixing together the interrogation and reply signals (or signals derived therefrom) to produce a further signal containing frequencies which are the sum and difference of the interrogation and reply signals. A signal processor, responsive to this further signal produced by the mixer, detects at least some of the frequencies contained in this further signal and determines the informational code associted with the transponder.
131 Citations
56 Claims
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1. System for interrogating a transponder carrying encoded information, said system comprising:
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(a) at least one transponder means for receiving a first signal and for transmitting a second signal in reply thereto, said transponder means including signal transforming means, coupled to receive said first signal as an input, for producing said second signal as an output, said signal transforming means including; (1) a plurality of signal conditioning means coupled to receive said first signal, each signal conditioning means providing an intermediate signal having a known delay and a known amplitude modification to said first signal; and (2) signal combining means coupled to all of said signal conditioning means, for combining said intermediate signals to produce said second signal, said signal conditioning means and said signal combining means imparting a known informational code to said second signal associated with said transponder means; (b) means for transmitting said first signal having a first frequency, said first frequency successively assuming a plurality of frequency values across a prescribed frequency range which is sufficiently wide to resolve the differences in time between the known delays of different ones of said signal conditioning means; (c) means for receiving said second signal from said transponder means; (d) means, coupled to said transmitting means, for producing a third signal derived from said first signal; (e) means, coupled to said receiving means, for producing a fourth signal derived from said second signal; (f) means, arranged to receive said third signal and said fourth signal for mixing together said third signal and said fourth signal, thereby to produce a fifth signal; and (g) signal processing means, responsive to said fifth signal, for detecting at least some of the frequencies contained in said fifth signal, thereby to determine said informational code associated with said transponder means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 56)
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46. In a system for interrogating a plurality of transponders, each carrying encoded information, said system comprising:
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(a) at least one transponder for receiving a first signal and transmitting a second signal in reply thereto, said transponder comprising signal transforming means, coupled to receive said first signal as an input, for producing said second signal as an output, said signal transforming means including; (1) a plurality of signal delay means coupled to receive said first signal, each signal delay means providing an intermediate signal having a nominal, known delay time with respect to said first signal; and (2) signal combining means, coupled to at least some of said signal delay means, for combining at least some of said intermediate signals in a known manner to produce said second signal, said signal delay means and/or said signal combining means imparting a prescribed informational code to said second signal associated with said transponder; (b) interrogator/receiver means for transmitting said first signal to, and receiving said second signal from said at least one transponder; and (c) signal decoding and processing means, coupled to said interrogator/receiver means, for determining said informational code associated with each transponder; the improvement comprising a method for determining said informational code, said method comprising the steps of; (A) generating said first signal with a known first frequency, said first frequency successively assuming a plurality of frequency values across a prescribed frequency range which is sufficiently wide to resolve the differences in time between the known delays of different ones of said signal delay means; (B) transmitting said first signal; (C) receiving said second signal; and (D) determining the amplitudes of said second signal at a plurality of frequencies which are different from said first frequency of said first signal. - View Dependent Claims (47, 48, 49, 50, 51, 52, 53, 54, 55)
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Specification