Design and application of real-time spectrum-analyser systems

The basis of spectrum analysis in Fourier transformation is briefly examined and the principles which can be applied in determining the spectral distribution of energy considered. Classes of analysers are distinguished that operate by frequency filtering and by time-domain processing; the latter being subdivided into direct linear methods depending on dispersive components, indirect or correlation methods, methods using complex Fourier transformation, and nonlinear simplified methods useful when the signal has known characteristics. The implementations and applications selected for description are intended to convey the importance of recent developments in s.a.w., digital, c.c.d. and optical technologies.