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What is a spectrum analyzer

A spectrum analyzer is a device for measuring the magnitude of different frequencies in a signal across the frequency range of the instrument.

We use spectrum analyzers when we are interested in the spectral composition of a signal, which can be difficult to see from the waveform that an oscilloscope would display.Picture1-Jul-29-2022-12-08-43-20-PM

If we observe the complex voltage signal above, with a spectrum analyzer we would see the following:


Instead of a waveform of voltage over time, we get a display of amplitude on the Y axis and frequency on X axis. If we analyze the outputs of a spectrum analyzer we can learn about the dominant frequency, power, distortion, harmonics, bandwidth and other spectral components.

Spectrum analyzers usually come in one of four form factors:

  • Benchtop spectral analyzers are used where they can be plugged into AC power and their larger size and weight are not a factor
  • Portable spectral analyzers are smaller than benchtop ones and are equipped with a battery which allows for use outside the laboratory.
  • Handheld spectrum analyzers are used whenever there is a need for the instrument to be lightweight and mobile.
  • Networked spectrum analyzers do not include a screen and are commonly used for monitoring geographically distant locations. To allow for this, they tend to be more affordable and smaller in size.

Red Pitaya Spectrum Analyzer

Picture3-Jul-29-2022-12-10-23-06-PMRed Pitaya offers two input channels which can be used as a spectrum analyzer using a DFT (Discrete Fourier Transform) algorithm. Similar to networked spectrum analyzers, Red Pitaya does not have a screen and buttons, so all the interaction is done through a web interface and a dedicated 'Spectrum Analyzer' application.

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