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 . A method of operating an interrogator comprising:
encoding a first pseudo-noise sequence with a data signal to create a first spread data signal;
randomly inverting the first spread data signal using a second pseudo-noise sequence to create a second spread data signal, wherein one or more chips in the first spread data signal are inverted when the first spread data signal has a logical low value; and
creating a tri-state signal from the second pseudo-noise sequence and the second spread data signal.
49 . The method of claim 48 , further comprising:
reducing harmonic information within the tri-state signal using a low-pass filter; and
applying an output of the low-pass filter to an attenuator.
50 . The method of claim 48 , wherein randomly inverting the first spread data signal implements phase modulation.
51 . The method of claim 48 , further comprising:
modulating a carrier signal using the tri-state signal.
52 . The method of claim 48 , further comprising:
band limiting the first spread data signal.
53 . The method of claim 48 , further comprising:
inverting a phase of a carrier signal mixed with a negative value of the tri-state signal.
54 . The method of claim 48 further comprising:
mixing a carrier signal with the tri-state signal.