A hardware device or software used to examine the frequency and power components of a signal. It provides more information than an oscilloscope, because it can display the signals over a range of frequencies. For example, whereas an oscilloscope would show total noise level, a spectrum analyzer would show the noise as related to frequency. Available in both analog and digital models, digital analyzers sample the incoming waveforms and convert them to fast fourier transforms (FFTs).
The range of frequencies being analyzed is the "bandwidth," while the width of the individual samples is the "bandwidth resolution." In the following example, the bandwidth is 86 Hz to 20 kHz, and the bandwidth resolution is 40 Hz. Each sample represents a 40 Hz section of the displayed 19,914 Hz band. See oscilloscope
An Audio Analysis
This example shows the power levels and frequencies of an audio signal as displayed in a software-based spectrum analyzer.