A SINUSOID-FREE SPREAD SPECTRUM COMMUNICATIONS SYSTEM EMPLOYING PURE NOISE AS A CARRIER

SPREAD SPECTRUM TECHNIQUES ARE WIDELY ACKNOWLEDGED TO PROVIDE LOW PROBABILITY OF INTERCEPT (LPI) CAPABILITY. CONVENTIONAL DIRECT SEQUENCE SPREADING, HOWEVER, SUFFERS FROM THE SHORTCOMING THAT AN INTERCEPTOR REQUIRES ONLY VERY SIMPLE PROCESSING TO COLLASPE THE SPREAD SIGNAL TO A NEADILY DETECTABLE UNMODULATED SIMUSOID. FURTHERMORE, HIGH LEVELS OF LPI ARE ONLY ACHIEVED BY USING HIGH SPEED GENERATORS FOR THE SPREADING SIGNALS, NECESSITATING COMPLEX SYNCHRONIZATION ALGORITHMS. THE APPROACH DESCRIBED HERE ELIMINATES THESE UNDERSIRABLE CHARACTERISTICS BY REPLACING THE SINUSOIDAL CARRIER WITH A PURE NOISE WAVEFORM. THIS PREVENTS AN INTERCEPTOR FROM USING NON-LINEAR TECHNIQUES TO EXPLOIT SOME DETERMINISTIC ELEMENT OF THE SIGNAL BECAUSE THERE ARE NONE TO EXPLOIT. IN ADDITION, SINCE THE SPECTRAL SPREADING IS NOT A FUNCTION OF THE RATE AT WHICH THE TRANSEC GENERATOR IS CLOCKED, VERY SLOWLY CHANGING (OR FIXED) TRANSEC CAN BE USED, THEREBY GREATLY SIMPLIFYING (OR ELIMINATING) THE SYNCHRONIZATION PROCESS. THE OBJECT OF THIS EFFORT IS TO INVESTIGATE THIS BASIC CONCEPT, DETERMINE THE LPI PERFORMANCE ACHIEVED FOR A WIDE RANGE OF DESIGN PARAMETERS, AND DEVELOP A BREADBOARD FOR EVALUATION. THE METHODOLOGY MAKES EXTENSIVE USE OF COMPUTER SIMULATION TO PROVIDE BOTH QUALITATIVE INSIGHT AND A QUANTITATIVE EVALUATION OF THE TECHNIQUE'S PERFORMANCE.