Pulse response: a new approach to a.c. electric-network theory and measurement

Abstract

The a.c. theory of electric networks advocated in this paper provides a method parallel to the conventional steady-state method as based on the sine wave, with the difference that the variables of time and frequency are interchanged. Practical application of this theory is recommended, using a signal generator to develop pulse-type signals. The advantages are discussed, and details given, of the use of such a generator and of the resulting “pulse response” or “time characteristics” for the direct assessment of a network's behaviour and a determination of its transient response, without the need for Fourier analysis and synthesis.An interpretation is given of the transient response of networks with the most general types of steady-state characteristics, using the method of paired echoes 11, 12; this interpretation is made in terms of the response to pulse-type signals, and a proof is given showing that this method follows directly from the superposition theorem.A simple theorem is given relating the real and imaginary parts of the direct or transfer impedance of a physical network, which distinguishes all such networks from arbitrary “idealized” ones.The effects are discussed of relying on practical forms of pulse having a finite time of duration, rather than the ideal ones of infinitesimal time on which the theory depends; figures are quoted for assessment of the resulting errors.