Rfid Tag, Interrogator and System with Improved Symbol Encoding and Decoding
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Accused Products
Abstract
An improved RFID Tag, Interrogator, and system wherein at least one tag modulates a radio frequency signal by modulated backscatter operations.
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Citations
96 Claims
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1-60. -60. (canceled)
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61. In a radio frequency identification system wherein at least one RFID tag generates an uplink message represented by an uplink signal transmitted by backscatter modulation of a radio frequency signal, the uplink signal comprising a sequence of symbols, an Interrogator comprising:
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a transmitter that transmits the radio frequency signal; and a receiver that receives, demodulates, and decodes the backscatter-modulated radio frequency signal transmitted by the at least RFID tag in order to recover the uplink message therein, said receiver including symbol decoding means that operates in one of a first mode of operation and a second mode of operation to decode the sequence of symbols of the uplink signal; wherein, in said first mode of operation, the symbol decoder generates a first set of reference waveforms that are derived by multiplying first-type bi-phase baseband waveforms by a square wave, wherein the first-type bi-phase baseband waveforms each have a phase inversion at least on every symbol boundary and each have a first symbol rate SR1, and wherein the square wave has a rate M*SR1, where M is selected from a number of different integer values, and wherein, in said second mode of operation, the symbol decoder generates a second set of reference waveforms that comprise second-type bi-phase baseband waveforms each having a phase inversion at least on every symbol boundary and each having a second symbol rate SR2, wherein said second symbol rate is different from said first symbol rate SR1. - View Dependent Claims (62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79)
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80. In a radio frequency identification system wherein at least one tag modulates a radio frequency signal by modulated backscatter operations, wherein the modulated radio frequency signal transmitted by the at least one tag encodes an uplink message that is represented by a sequence of symbols, a method for receiving the modulated radio frequency signal comprising:
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receiving the modulated radio frequency signal at an antenna; amplifying components of the received modulated radio frequency signal; demodulating the amplified components of received modulated radio frequency signal; decoding a given symbol by selectively operating in one of a first operational mode and a second operation mode, wherein, in said first mode of operation, the decoding generates a first set of reference waveforms that are derived by multiplying first-type bi-phase baseband waveforms by a square wave, wherein the first-type bi-phase baseband waveforms each have a phase inversion at least on every symbol boundary and each have a first symbol rate SR1, and wherein the square wave has a rate M*SR1, where M is selected from a number of different integer values, and wherein, in said second mode of operation, the decoding generates a second set of reference waveforms that comprise second-type bi-phase baseband waveforms each having a phase inversion at least on every symbol boundary and each having a second symbol rate SR2, wherein said second symbol rate is different from said first symbol rate SR1. - View Dependent Claims (81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96)
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Specification