초록 ▼

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 befo

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.

대표청구항 ▼

[ What is claimed is:] [1.] A communication system, comprising:signal conditioning and transmitting circuitry to produce and transmit a twice modulated data signal; anda receiver system that is remote from the signal conditioning and transmitting circuitry and that comprises:receiving and processing

[ What is claimed is:] [1.] A communication system, comprising:signal conditioning and transmitting circuitry to produce and transmit a twice modulated data signal; anda receiver system that is remote from the signal conditioning and transmitting circuitry and that comprises:receiving and processing circuitry to receive the transmitted twice modulated data signal and to produce therefrom a recovered modulated data signal including acarrier component and a data signal component;synthesizing and synchronizing circuitry to receive the recovered modulated data signal and produce a synthesized signal synchronized with the carrier component; andprocessing and comparing circuitry to receive the recovered modulated data signal and the synthesized signal, and to produce a signal indicative of the data signal component responsive to signals including the recovered modulated data signal and the synthesized signal.