RFID Interrogator With Improved Symbol Decoding And Systems Based Thereon
First Claim
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1. 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 each corresponding to at least one bit of the uplink message, the sequence of symbols being transmitted at a symbol rate with a corresponding symbol period, an Interrogator comprising:
- a transmitter that transmits the radio frequency signal; and
a receiver that receives, demodulates and decodes the modulated radio frequency signal in order to recover the uplink message therein, said receiver including a symbol decoder that decodes a given symbol by operating on portions of a component of the modulated radio frequency signal that are received over an extended processing window, wherein the extended processing window is greater than the symbol period.
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Abstract
An improved Interrogator for use in a radio frequency identification system wherein at least one tag modulates a radio frequency signal by modulated backscatter operations.
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Citations
25 Claims
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1. 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 each corresponding to at least one bit of the uplink message, the sequence of symbols being transmitted at a symbol rate with a corresponding symbol period, an Interrogator comprising:
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a transmitter that transmits the radio frequency signal; and a receiver that receives, demodulates and decodes the modulated radio frequency signal in order to recover the uplink message therein, said receiver including a symbol decoder that decodes a given symbol by operating on portions of a component of the modulated radio frequency signal that are received over an extended processing window, wherein the extended processing window is greater than the symbol period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 16, 17, 18, 19, 20, 21)
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15. An interrogator according to claim 14, wherein:
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the first squaring means is substituted by first means for deriving absolute value of the output of the first summing means; the second squaring means is substituted by second means for deriving absolute value of the output of the second summing means; the third squaring means is substituted by third means for deriving absolute value of the output of the third summing means; and the fourth squaring means is substituted by fourth means for deriving absolute value of the output of the fourth summing means.
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22. 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 each corresponding to at least one bit of the uplink message, the sequence of symbols being transmitted at a symbol rate with a corresponding symbol period, 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 operating on portions of the resultant signals produced by the demodulation over an extended processing window, wherein the extended processing window is greater than the symbol period. - View Dependent Claims (23, 24, 25)
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Specification