Identification system
First Claim
1. An interrogator for use in an identification system, said identification system including one or more transponders each adapted to be attached to an article or thing to be identified, and each comprising means for receiving an interrogation signal of a specified frequency and means responding to the received interrogation signal by transmitting a frequency-shift-keyed identification signal that is indicative of the identity of the object or thing wherein said frequency-shift-keyed identification signal is varied between two different transmission frequencies, that are each substantially different than said specified frequency, each of said two transmission frequencies being of a lower frequency than said interrogation signal as is achieved by integer division of said specified frequency of said interrogation signal, and wherein said identification signal is of a signal format comprising a first synchronization portion, and a second data portion of variable length that operates to identify the article or thing, wherein said interrogator comprises:
- an antenna connected to means for transmitting an interrogation signal at a specified frequency;
means connected to said antenna and concurrently operable with said transmitting means for receiving a frequency-shift-keyed identification signal transmitted by a transponder at said two transmission frequencies that are substantially lower than that of said interrogation signal; and
means connected to said receiving means for demodulating and detecting said frequency-shift-keyed identification signal received from the transponder and including means for separately detecting the separate first and second portions of the identification signal and for responding to the same by generating a signal corresponding to the identity of the article or thing.
21 Assignments
0 Petitions
Accused Products
Abstract
A passive integrated transponder (PIT) is attached to or embedded in an item to be identified. It is excited via an inductive coupling from an interrogator. The PIT responds to the interrogator via the inductive coupling with a signal constituting a stream of data unique to the identified item. The signal is in the form of two different frequencies, a shift from one frequency to the second during a bit cell representing a data "one", and a shift from the second frequency to the first frequency representing a data "zero". The responsive signal is then detected and processed for utilization in a data storage or display device.
189 Citations
14 Claims
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1. An interrogator for use in an identification system, said identification system including one or more transponders each adapted to be attached to an article or thing to be identified, and each comprising means for receiving an interrogation signal of a specified frequency and means responding to the received interrogation signal by transmitting a frequency-shift-keyed identification signal that is indicative of the identity of the object or thing wherein said frequency-shift-keyed identification signal is varied between two different transmission frequencies, that are each substantially different than said specified frequency, each of said two transmission frequencies being of a lower frequency than said interrogation signal as is achieved by integer division of said specified frequency of said interrogation signal, and wherein said identification signal is of a signal format comprising a first synchronization portion, and a second data portion of variable length that operates to identify the article or thing, wherein said interrogator comprises:
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an antenna connected to means for transmitting an interrogation signal at a specified frequency; means connected to said antenna and concurrently operable with said transmitting means for receiving a frequency-shift-keyed identification signal transmitted by a transponder at said two transmission frequencies that are substantially lower than that of said interrogation signal; and means connected to said receiving means for demodulating and detecting said frequency-shift-keyed identification signal received from the transponder and including means for separately detecting the separate first and second portions of the identification signal and for responding to the same by generating a signal corresponding to the identity of the article or thing. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. The interrogator for use in an identification system, said system comprising a plurality of individual transponders, each of said transponders comprising memory means for storing a variable length identification code indicative of the identity of an object or thing to be identified and to which a transponder is attached, said transponders each further comprising means for receiving an interrogation signal of a specified frequency and means responsive to said interrogation signal for transmitting a frequency-shift-keyed identification signal that is derived from said interrogation signal including a first synchronization portion and a second portion of variable length corresponding to the stored identification code, said interrogator comprising:
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an antenna; an exciter portion, comprising signal source means and driver means, said signal source means and said driver means being connected to said antenna and being adapted to drive said antenna to transmit an interrogation signal at a specified frequency; a signal conditioner portion, connected to said antenna and adapted to receive a frequency-shift-keyed identification signal transmitted by one of said transponders concurrently with transmission of said interrogation signal from said antenna, said signal conditioner portion comprising filter means and amplifier means; and an identification portion, connected to said signal conditioner portion, comprising demodulator means and detector means for receiving said received frequency-shift-keyed identification signal, demodulating and detecting the same, and means coupled to detect the first and second portions of said received frequency-shift-keyed identification signal and responding thereto for generating an output signal corresponding to the identity of the object or thing to which said one of said transponders is attached. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification