WAVEFORM SYNTHESIS FOR RFID TRANSMITTERS
First Claim
1. A radio frequency identification (RFID) system comprising:
- a storage medium comprising a plurality of stored waveforms, each stored waveform representing an RFID symbol usable in a sequence of RFID symbols; and
a polarity generator to selectively impart a required polarity to each stored waveform to assemble the sequence of RFID symbols.
1 Assignment
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Accused Products
Abstract
A waveform synthesis technique for radio frequency identification (RFID) transmitters and an RFID system making us of the technique are disclosed. The RFID transmitter in example embodiments synthesizes a continuous transmitter waveform from a symbol alphabet without Nyquist or interpolation filters. High spectral occupancy waveforms are achieved which include the ability to do both linear and nonlinear predistortion with no increase in computational load once the signal set has been adapted to compensate for linear and nonlinear distortion in the transmitter analog circuitry. A polarity generator can be used to impart the required polarity to each waveform. The RFID transmitter can be employed in RFID readers to reduce the computational requirements of the digital signal processor (DSP).
11 Citations
26 Claims
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1. A radio frequency identification (RFID) system comprising:
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a storage medium comprising a plurality of stored waveforms, each stored waveform representing an RFID symbol usable in a sequence of RFID symbols; and a polarity generator to selectively impart a required polarity to each stored waveform to assemble the sequence of RFID symbols. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 12)
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11. (canceled)
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13. A method of synthesizing an RFID transmitter waveform, the method comprising:
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repeatedly retrieving, by a processor, a stored waveform from a plurality of stored waveforms, each stored waveform representing an RFID symbol usable in a sequence of RFID symbols; imparting, by the processor, a polarity to each stored waveform, the polarity being selectively set based on the RFID symbol represented; and assembling, by the processor, the sequence of RFID symbols each based on the corresponding stored waveform and the selectively set polarity. - View Dependent Claims (14, 15, 16, 17, 18, 20)
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19. (canceled)
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21. Apparatus comprising:
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means for storing a plurality of waveforms; means for retrieving a stored waveform from the plurality of waveforms, each stored waveform representing an RFID symbol usable in a sequence of RFID symbols; means for imparting a polarity to the stored waveform, the polarity being selectively set based on the RFID symbol represented by the stored waveform; and means for assembling the sequence of RFID symbols each based on the corresponding stored waveform and the selectively set polarity. - View Dependent Claims (22)
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23. A method of making an RFID system to synthesize a transmitter waveform, the method comprising:
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assembling a prototype waveform using sinusoidal rising and falling edges for each symbol from among a plurality of RFID symbols; creating lower and upper bounds for the prototype waveform so that rise and fall times are preserved; constructing a periodic waveform from the prototype waveform; executing an optimization algorithm using the periodic waveform to extract a run time waveform; and similarly extracting the run time waveform for each symbol to obtain and store a plurality of run time waveforms. - View Dependent Claims (24, 26)
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25. (canceled)
Specification