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Abstract

Communication apparatus and method that includes generating a series of successive spread-spectrum chirp signals, which are progressively swept within a defined bandwidth. The chirps are divided into two frequency-swept portions, one beginning at an intermediate frequency within the bandwidth being swept to one end of the frequency range of the chirp, and a second beginning at the other end of the frequency range and being swept to the intermediate frequency. This has the effect of moving the frequency transition from the boundaries of the chirp to its center, with the result that the discontinuities introduced at the boundaries by phase reversals due to successive modulated chirps generate less out-of-band energy. In preferred embodiments, the full frequency range of the chirp is at least about two octaves (two doublings of frequency), and the intermediate frequency is at least about one octave (one doubling of frequency) from the either end of the range, whereby the one-half and double frequency components that result from phase reversals remain within the band. The method and apparatus may be used for communication over power lines.

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First Claim