ELF Noise Processing

Abstract : The report describes noise processing experiments with ELF (3 to 300 Hz) atmospheric noise and signals in the 40- to 80-Hz range. The primary purpose of the experiments was to design the noise processing portion of a submarine-borne receiver which would minimize the required transmitter power of the Sanguine communications system. The recommended noise processor included a nonlinearity followed by a matched-filter and consisted of the following functions: (1) a compensating (or whitening) fiber, (2) a pre-notch filter clipper, (3) notch filters at power line frequencies, (4) a post-notch filter clipper, and (5) a phase-coherent linear matched filter.