An instrument that measures the magnitude of an input signal against the full range of frequency range of the instrument is called spectrum analyzer. The main function of a spectrum analyzer is to measure the power of known and unknown signals of the spectrum. A spectrum analyzer generally measures electrical input. However, an appropriate transducer converts other signals, such as optical light waves and acoustic pressure waves.
A spectrum analyzer is an electronic device that is used to display variations in the signal strength. Spectrum analyzers have a close resemblance to oscilloscopes. Spectrum analyzers are used for research and study purposes in universities and laboratories and for designing, manufacturing, or repairing electronic equipment.