Generalized Analytic Signal Construction and Modulation Analysis

Abstract

This thesis deals with generalizations of the analytic signal (AS) construction proposed by Gabor. Functional extensions of the fractional Hilbert Transform (FrHT) are proposed using which families of analytic signals are obtained. The construction is further applied in the design of a secure communication scheme. A demodulation scheme is developed based on the generalized AS, motivated by perceptual experiments in binaural hearing. Demodulation is achieved using a signal and its arbitrary phase-shifted version which, in turn translated to demodulation using a pair of flat-top bandpass filters that form an FrHT parir. A new family of wavelets based on the popular Gammatone auditory model is proposed and is shown to lead to a good characterization of singularities/transients in a signal. Allied problems of computing smooth amplitude, phase, and frequency modulations from the AS. Construction of FrHT pair of wavelets, and temporal envelope fit of transient audio signals are also addressed.