The Three Main Types of Spectrum Analysers You Need to Know About

August 5, 2016

When it comes right down to it, you can’t deny the importance of a spectrum analyser. These wonder machines are built with 3 goals in mind: 1) to provide valuable insight into a different dimension-the frequency domain, 2) to capture your signal no matter how fast and complex it is, and 3) to make an accurate set of measurements that provide insight to your device.


Swept Frequency – This type of spectrum analyser is essentially a frequency-sensitive volt meter, capturing the RMS value of a sine wave through a selected range of frequencies. The analyser sweeps through frequency bands similar to turning the frequency dial of a radio. While it is unable to detect phase information, this type of analyser is well-suited to high-frequency applications where other methods have historically been too slow to capture the signal.


Fast Fourier Transform – The FFT analyser uses digital methods to gather waveform data in relation the time domain. The sample is processed using FFT methods to map the signal into the frequency domain. There are several advantages to this type of analyser over the swept frequency models, including waveform storage, phase detection, and transient detection. FFT analysers are more expensive than swept frequency analysers, and they are useless at frequencies above the Nyquist frequency of the Analog to Digital converter due to signal aliasing


Vector Signal and Real-Time – The vector signal analyser is something of a hybrid between the FFT and swept frequency. It uses attributes of both methods to create a more robust analyser capable of the frequency range of the swept and the detection capabilities of the FFT.  It does have the limitation of only looking at one frequency band at a time, allowing possible transients to escape undetected. This gap in coverage motivated the development of the real-time analyser. The entire spectrum is digitally sampled in the time domain, and often much of the signal is only displayed if a transient occurs.


 Electro Rent carries the right kind of spectrum analyser for your application: various types, models and brands. Our measurement experts will help you decide the best fit instrument and the best method to get that instrument in your hands, utilizing rent options, finance alternatives and options such as selling equipment from our internal X-inventory pool.


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