Amplitude-Distribution Analyzer

Abstract

Instrumentation to automatically record amplitude distribution curves is described. Basically the method employed is that proposed by Landon in which one measures the relative lengths of time that a signal is equal to, or less than, a given amplitude. A digital approach, similar to that of Davenport, is made. However, instead of modulating a pulse train with the studied signal, as done by Davenport, the described analyzer mixes the amplitude of a high frequency sinusoid with the studied signal, producing greater stability and requiring less bandwidth. The amplitude is scanned by reducing the amplitude of the carrier sinusoid, while keeping the rms value of the studied signal constant. The distribution curves of a random noise sample and of two sinusoids, the latter of which are used in calibration of the amplitude axis, are presented.