Signal sources

Abstract

Publisher Summary Signal sources play an important role in electronic test and measurements, but their use is far from limited to that. They form an essential part of many common types of equipment. Many pieces of electronic equipment incorporate an audio-frequency signal source as an essential part of their operation, from the mellifluous warble of a modern push-button telephone to the ear-shattering squeal of a domestic smoke detector. However, in most electronic instruments nowadays, from power supplies to digital voltmeters (DVMs), an electronic reference is used instead. Sources of AC signals can be divided into two main categories: sine wave generators, and generators of non-sinusoidal waveforms. The latter can be subdivided again into pulse generators and other types. Pulse generators provide pulses of positive- or negative-going polarity with respect to earth or to a presettable DC offset voltage. The pulse repetition frequency, pulse width, amplitude, and polarity are all adjustable; on some pulse generators, so too are the rise and fall times. Commonly also the output may be set to provide double pulses, that is pulse pairs with variable separation, and a pulse delay with respect to a prepulse, which is available at a separate output for test and synchronization purposes.