Modulated spread spectrum in RF identification systems method
DCFirst Claim
1. A communication system, comprising:
- an interrogator adapted to produce and transmit a spread spectrum signal which includes an original data signal component; and
a plurality of receiver systems adapted to connect to articles remote from the interrogator, each receiver system comprising;
receiving and processing circuitry adapted to receive the transmitted spread spectrum signal and in response thereto to produce an extracted data signal;
signal production circuitry adapted to receive the extracted data signal and selectively produce a return signal including information regarding an article; and
transmitting circuitry adapted to transmit the return signal to the interrogator.
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Abstract
A method for RF communication between transceivers in a radio frequency identification system that improves range, decreases multipath errors and reduces the effect of outside RF source interference by employing spread spectrum techniques. By pulse amplitude modulating a spread spectrum carrier before transmission, the receiver can be designed for simple AM detection, suppressing the spread spectrum carrier and recovering the original data pulse code waveform. The data pulse code waveform has been further encrypted by a direct sequence pseudo-random pulse code. This additional conditioning prevents the original carrier frequency components from appearing in the broadcast power spectra and provides the basis for the clock and transmit carrier of the transceiver aboard an RFID tag. Other advantages include high resolution ranging, hiding transmissions from eavesdroppers, and selective addressing.
129 Citations
16 Claims
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1. A communication system, comprising:
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an interrogator adapted to produce and transmit a spread spectrum signal which includes an original data signal component; and a plurality of receiver systems adapted to connect to articles remote from the interrogator, each receiver system comprising; receiving and processing circuitry adapted to receive the transmitted spread spectrum signal and in response thereto to produce an extracted data signal; signal production circuitry adapted to receive the extracted data signal and selectively produce a return signal including information regarding an article; and transmitting circuitry adapted to transmit the return signal to the interrogator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A communication system, comprising:
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an interrogator adapted to produce and transmit a spread spectrum signal comprising a pseudo noise signal component; and at least one receiver system adapted to connect to an article remote from the interrogator, the at least one receiver system comprising; receiving and processing circuitry adapted to receive the transmitted spread spectrum signal and in response thereto to produce a synthesized pseudo noise signal corresponding to the pseudo noise signal component of the transmitted spread spectrum signal; signal production circuitry adapted to receive the transmitted spread spectrum signal and selectively produce a return signal comprising information regarding the article; and transmitting circuitry adapted to transmit the return signal to the interrogator. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A communication system, comprising:
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an interrogator adapted to produce and transmit a spread spectrum signal comprising a pseudo noise signal component; and at least one receiver system adapted to connect to an article remote from the interrogator and comprising; receiving and processing circuitry adapted to receive the transmitted spread spectrum signal and in response thereto to produce a clock waveform corresponding to a clock frequency of the pseudo noise signal component of the transmitted spread spectrum signal; signal production circuitry adapted to receive the transmitted spread spectrum signal and selectively produce a return signal comprising information regarding the article; and transmitting circuitry adapted to transmit the return signal to the interrogator. - View Dependent Claims (16)
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Specification