Patent ID: 6061388
Filing Date: 2000-05-09
Classification: H04B

Abstract:
A spread spectrum communication system comprising:a transmitter includinga modulator for modulating an information input signal with a carrier frequency f.sub.1,a spreading signal generator,a first mixer for combining the modulated carrier signal with a spreading signal from said spreading signal generator,a second mixer for combining the spreading signal from said spreading signal generator with a second frequency f.sub.2 different from said carrier frequency f.sub.1, the difference frequency f.sub.1 -f.sub.2 being sufficiently low that any delay less than a maximum expected delay spread does not result in a 180.degree. phase shift, anda summer for adding output signals of said first and second mixers to produce a transmitted signal; anda receiver includingradio frequency receiver means for receiving said transmitted signal from said transmitter,a nonlinear device for squaring an input signal supplied thereto,circuit means coupling said nonlinear device to said radio frequency receiver means, anda demodulator for demodulating the squared output signal at a carrier frequency of f.sub.2 -f.sub.1.