On the Potential Advantage of a Smearing-Desmearing Filter Technique in Overcoming Impulse-Noise Problems in Data Systems

Abstract

It has long been recognized that impulse noises or even very short duration line interruptions are the most vicious form of interference affecting data communications over wire lines. These noises, while annoying, are not catastrophic in voice communications because of the inherent redundancy in speech sounds. If a degree of apparent redundancy can be inserted into a data stream, the serious degradation caused by these noises can be materially reduced. Data signals which require a sizable bandwidth can be transmitted by modifying the real time placement of their frequency components (smearing) before transmission through a channel corrupted by impulse noises. A reversal of the time-vsenergy frequency modification before detection (desmear) reconstructs the data signal but "smears" the impulse or line interruption into a time-energy distribution form considerable different from that of the signal.