A signal generator, also called a test signal generator, is an electronic device designed to produce electrical impulses. These devices are most often used in troubleshooting, testing, and repairing other electronic or acoustic devices. They are also sometimes used for artistic applications.
There are many types of signal generators, suited to a variety of uses. Because they have so many possible applications, no one signal generator is suited to every purpose. Signal generators generally fall into one of two categories: function generators and arbitrary waveform generators.
Function generators are the simpler of the two types. They produce simple repetitive signals in a wave-like form. This signal is produced by a circuit which creates the repeating wave, usually a sine wave. A function generator would most often be used in the process of designing or repairing simple electronics.
In these applications they are used to send a signal through the particular circuit that is being tested. Typically, another device such as an oscilloscope will be connected to the other end of the circuit to measure its output. Because of the many different ways in which electronic devices operate, many types of function generators are available, which vary in frequency range, accuracy, and other parameters.
Arbitrary waveform generators (AWGs) are so called because unlike function generators, the waves they produce can be in many forms, rather than just sine waves. This type of signal generator can produce waves with a sawtooth, square, pulse, or triangular form, among others. Because of this increased versatility, AWGs are the more expensive of the two varieties, and are thus limited to higher-end design and testing applications.
Before the advent of signal generators, such as in the early days of radio, the only method for the testing of new equipment and formats was to use another similar device to generate the signal. Such was the case with new equipment and modulation formats in radio. One radio’s performance parameters were measured and then used as the standard or “golden radio,” as it was called.
This test technique had many advantages, mainly low cost. However, one disadvantage was that the golden radio’s performance could drift over time, making it unreliable as a piece of test equipment. A modern signal generator, while more costly, is much better suited to the more specific and precise operations of electronics testing and design.