Patent ID: 6473453
Filing Date: 2002-10-29
Classification: H04B,H04J

Abstract:
A multichannel high frequency (hf) communications system comprising a spread spectrum signal transmitter including:a) means to encode a message signal by selection of at least one of a preselected number of pseudo-orthogonal binary codes: b) means to modulate a hf carrier wave with the encoded signal; and c) means to transmit the modulated hf signal, said modulated hf signal having a signal frequency spectrum symmetrical about a carrier frequency; and a receiver including: a) means for detecting the received modulated hf signal; b) means for Fourier transforming the received signal using a fast Fourier Transform (FFT) processor for producing a multiplicity of frequency channels; c) means for excising any narrow frequency band interference comprising means for comparing signal components in selected ones of the frequency channels symmetrically placed with respect to said carrier and for excising any channel components with an amplitude greater by a predetermined amount than the amplitude of a symmetrical channel component; and d) cross-correlation matched filter detection means for decoding the Fourier transformed signal to derive the original message signal.