A spectrum analyzer looks very much like an oscilloscope; in fact, some models of this type of laboratory equipment function as both a spectrum analyzer and an oscilloscope. The spectrum analyzer, as the name implies, analyzes the RF spectrum, so the typical input is radio frequency and audio signals.

The spectrum analyzer can reveal details and elements about the signal that would otherwise be unknown, such as the efficiency and performance of the circuit or equipment producing the signal. It can perform different types of measurements, which means that it is an indispensable tool for designing RF-generating devices and for use in test laboratories and specialized field services dealing with RF waves.