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 a message that is represented by a sequence of symbols each corresponding to at least one bit of the 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 message therein, said receiver including a symbol clock recovery circuit and a symbol decoder, said symbol clock recovery circuit deriving timing information for transitions between symbols in the sequence of symbols encoded in the message, and said symbol decoder decoding 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 in duration than the symbol period as dictated by the timing information derived by the symbol clock recovery circuit.
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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.
18 Citations
28 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 a message that is represented by a sequence of symbols each corresponding to at least one bit of the 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 message therein, said receiver including a symbol clock recovery circuit and a symbol decoder, said symbol clock recovery circuit deriving timing information for transitions between symbols in the sequence of symbols encoded in the message, and said symbol decoder decoding 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 in duration than the symbol period as dictated by the timing information derived by the symbol clock recovery circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 27, 28)
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21. 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 a message that is represented by a sequence of symbols each corresponding to at least one bit of the 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; deriving timing information for transitions between symbols in the sequence of symbols encoded in the message; and 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 in duration than the symbol period as dictated by the timing information derived by the symbol clock recovery circuit. - View Dependent Claims (22, 23, 24, 25, 26)
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Specification