Real Time Spectrum Analyzer

- a summary or tutorial about the Real Time Spectrum Analyzer with operational details and how they work.

Spectrum analyzer tutorial includes:

In recent years a form of spectrum analyser, termed a real-time spectrum analyser, RSA has grown in popularity.

These real-time spectrum analyzers are particularly useful in looking at waveforms where changes may be seen, and need to be captured. Often spectrum analysers that take time to process the waveforms may miss spurious signals and these can be particularly important when testing for compliance and out-of-band signals.

As the name implies, real-time spectrum analysers operate in real time.

Realtime spectrum analyser basics

A realtime spectrum analyser operates in a different way to that of a normal swept or superheterodyne spectrum analyser.

The realtime spectrum analyser is set to the required centre frequency. They then acquire a particular bandwidth or span either side of this. The realtime spectrum analyser captures all the signals within the bandwidth and analyses them in real time.

To achieve their performance a real time spectrum analyser captures the waveform in memory and then uses a fast Fourier transform technology to analyse the waveform very quickly, i.e. in real-time.

By analysing the waveform in this way, transient effects that may not be visible on other forms of spectrum analyser can be captured and highlighted.

There are a number of characteristics of realtime spectrum analyzers:

• They are based around an FFT - Fast Fourier Transform spectrum analyser. This will have a real-time - very fast - digital signal processing engine capable to processing the entire bandwidth with no gaps.
• An ADC - analogue to digital converter capable of digitising he entire bandwidth of the passband.
• Sufficient capture memory to enable continuous acquisition over the desired measurement period.

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