What is a spectrum analyser and what measurements you can make?

Posted By : Lanna Cooper

Learn what a spectrum analyser is and the various measurements you can make with one. What is a spectrum analyser and what measurements can it make? A spectrum analyser displays received signals with respect to amplitude vs. frequency. This is called frequency domain analysis.

The terms spectrum analyser and signal analyser are used almost interchangeably, however, there are some slight differences. Spectrum analysers, by definition, measure the phase of a signal. Signal analysers, on the other hand, measure the amplitude and phase of the input signal at a single frequency.

If you transmit an RF signal from your device, a signal analyser can down convert the signal to a digital signal and the signal analyser can display your device’s signal in terms of constellations, spectrum, spectral masks, etc.

Basically, a signal analyser analyses both amplitude and frequency and phase of your signal of interest, which you can’t do on a spectrum analyser.

The main use of a spectrum analyser is to measure the power of a signal’s various frequency components like radio frequency and audio signals. A spectrum analyser allows you to analyse a device’s signal and circuit performance in a way that isn’t possible using other means, say, looking at it in the time-domain.

Spectrum and signal analysers can make a large variety of measurements ranging from harmonic distortion tests for transmitters, WLAN and spectral masks for showing limits of unwanted emissions to two-tone tests on an RF power amplifier.

Because of how powerful a spectrum analyser is, it’s practically owned across all engineering labs for design development and testing of engineers’ devices. If you need to see the frequency make-up of your signals a spectrum analyser is a great tool to have.

Tune in for future What The RF (WTRF) episodes covering more spectrum analyser capabilities and fundamental measurements to see how you can test more efficiently.

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