Spectrum analyzer is a device used to examine the spectral composition of some electrical, acoustic, or optical waveform. Often, it measures the power spectrum. Spectrum analysis is concerned primarily with characterizing signal components
(such as its spurious and harmonic components, modulation, noise, etc.) Spectrum analyzer is used to locate frequencies where microwave energy exists.
There are analogue and digital spectrum analyzers:
- An analogue spectrum analyzer uses either a variable bandpass
filter whose mid-frequency is automatically tuned (shifted, swept) through the range
of frequencies of which the spectrum is to be measured or a superheterodyne receiver where the
local oscillator is swept through a range of frequencies.
- A digital spectrum analyzer uses the Fast
Fourier Transform (FFT), a mathematical process that transforms a waveform into its frequency components in the spectrum. As a result, computer programs can compute such transforms, and makes audio processing easier. FFTs have applications in much wider fields.
Spectrum analyzer is used in the following areas of measurement analysis:
- Distortion measurements
- Distortion in amplifiers
- Third order intercept measurement
- Distortion in mixers
- Distortion in oscillators
- Modulation measurements
- Amplitude modulation (AM) measurement
- Frequency modulation (FM) measurement
- Pulsed RF measurements
- Noise measurements
- Noise figure (NF) measurement
- Electromagnetic interference (EMI) measurement