Backscatter interrogators, communication systems and backscatter communication methods
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 - 47 . (canceled)
48 . An interrogator comprising:
a code generator for generating a first pseudo-noise sequence;
a code generator for generating a second pseudo-noise sequence;
first logic circuitry for encoding the first pseudo-noise sequence with a data signal to create a spread data signal;
second logic circuitry for randomly inverting the spread data signal using the second pseudo-noise sequence; and
a summing amplifier for outputting a tri-state signal using the second pseudo-noise signal and a randomly inverted spread data signal.
49 . The interrogator of claim 48 , wherein the first logic circuitry is an exclusive OR device.
50 . The interrogator of claim 48 , wherein the second logic circuitry is an exclusive OR device.
51 . The interrogator of claim 48 , wherein logical high values in the tri-state signal are represented by both positive voltages and negative voltages.
52 . The interrogator of claim 48 , further comprising:
a low pass filter coupled to the output of the summing amplifier for reducing harmonic information in the tri-state signal.
53 . The interrogator of claim 48 , further comprising:
a mixer for receiving the tri-state signal and a carrier signal.
54 . The interrogator of claim 53 , wherein the mixer inverts a phase of the carrier signal in response to a negative value in the tri-state signal.