Access to eBooks is limited to institutions that have purchased or currently subscribe to the SPIE eBooks program. eBooks are not available via an individual subscription. SPIE books (print and digital) may be purchased individually on SPIE.Org.

Contact your librarian to recommend SPIE eBooks for your organization.
Chapter 1:
Introduction
Abstract

Time-varying signals are commonly observed in the laboratory as well as many other applied settings. Consider, for example, the voltage level that is present at a specific point in a circuit. In theory, the voltage level can be represented by a real number. More specifically, the voltage level can theoretically be represented by any real number at any instant in time, a feature that conforms to the main characteristics of an analog signal. Suppose that an analog voltage level is measured (sampled) using an oscilloscope (o-scope). The o-scope displays a graph of the voltage level, with time depicted in the horizontal direction (t axis) and voltage level in the vertical direction (y axis). Each (t, y(t)) point on the o-scope graph represents a measurement of the line voltage at the corresponding time when the measurement was made. The o-scope displays the voltage signal in the time domain, i.e., how the voltage varies through time.

As a practical example, suppose a waveform generator is used to create a signal by summing three sinusoids and a noise component. To program the waveform generator, several characteristics of each sinusoid must be entered. A sinusoidal waveform is specified using four critical features: frequency, peak amplitude, phase, and vertical offset. A (simplistic) noise component can be specified by declaring its peak amplitude, with the understanding that the noise values are distributed around zero in some manner, e.g., "random (uniform) noise" has a uniform distribution with zero mean, and "band-limited white noise" has a normal distribution with zero mean (see Section 5.2).

Online access to SPIE eBooks is limited to subscribing institutions.
CHAPTER 1
7 PAGES


SHARE
Back to Top