Signal Transmission

Abstract

We now turn to the problem of transmitting pulse signals from one part of the electronics system to the other, or, more specifically, the interconnecting cables. This may seem somewhat trivial, at first, but this will be shown to be otherwise. The goal of signal transmission, of course, is two-fold: (1) get the signal from point A to point B, and (2) preserve the information in the signal. Recalling that a pulse generally consists of a continuous spectrum of frequencies from 0 to infinity, this would mean that our interconnecting cable would have to be capable of transmitting an infinite range of frequencies uniformly and coherently over the required distance — in most systems, a few meters. Such an ideal cable, of course, does not exist. Stray capacitances, inductances and resistance, inherent in any configuration of conductors, will invariably attenuate some frequencies more than others, causing a distortion of the pulse at the receiving end. Indeed, sending a fast pulse signal through simple wire connections, for example, already results in intolerable distortion after only a few centimeters!