Randall R.B. Frequency Analysis

Monograph. — Nærum: Brüel & Kjær, 1987. — 344 с. — ISBN 87-87355-07-8.In the years since the First and Second Editions of this book were published a great many developments have occurred; in particular there has been a huge swing from analog to digital analysis techniques, even tor day-to-day analysis. The main reason for this development has been the increase in power and reduction in cost of FFT (Fast Fourler Transform) analyzers, but "digital filters have also increasingly taken over some of the application areas formerly covered by analog filters. At the same time it has been realised that the primary distinction is not between digital and analog analysis, but rather between the FFT process, where the signal is analyzed in blocks, and analysis using filters, where the signal is processed continuously. Digital filters are a special case of the latter, but otherwise have very similar properties to analog filters. For this reason the layout of the book has been modified considerably, with digital filters generally being treated along with analog filters, and FFT techniques treated separately. The basic theory has been expanded to include a discussion of the Hilbert transform, and in particular how a model of frequency analysis, based on an analytic signal, relates to the model promulgated earlier, which is based on a sum of positive and negative frequency phasors. In particular in the case of modulated signals (involving amplitude, phase and frequency modulation) the approach using an analytic signal Is useful, because its amplitude represents the amplitude modulation signal (plus DC offset) while its phase represents the phase (or frequency) modulation signal superimposed on the carrier compo