Methods and apparatus for RFID tag communications
View Patent ↗The present invention provides backscatter interrogators, communication systems and backscatter communication methods. According to one aspect of the present invention, a backscatter interrogator includes a data path configured to communicate a data signal; a signal generator configured to generate a carrier signal; and a modulator coupled with the data path and the signal generator, the modulator being configured to spread the data signal to define a spread data signal and amplitude modulate the carrier signal using the spread data signal, the modulator being further configured to phase modulate the carrier signal.
1. An interrogator comprising:
a data path configured to communicate a data signal;
a signal generator configured to generate a carrier signal; and
a modulator coupled with the data path and the signal generator, the modulator being configured to spread the data signal to define a spread data signal and to both amplitude modulate and phase modulate the carrier signal using the spread data signal before communication of the carrier signal;
wherein the modulator is configured to phase modulate the carrier signal by selectively inverting the phase of the carrier signal using the spread data signal;
wherein the modulator is further configured to band limit the inverted spread data signal; and
wherein the modulator is configured to invert the spread data signal responsive to the spread data signal being a predetermined value.
2. The interrogator according to claim 1 , wherein the signal generator is configured to output a microwave carrier signal.
3. The interrogator according to claim 1 , wherein the modulator is further configured to modulate the carrier signal using the band limited data signal.
4. The method according to claim 1 wherein the phase modulation is responsive to the inversion of the spread data signal.