A Fourier transform, transforms time domain data (zero span) into the frequency domain. The fast Fourier transform (FFT) function of the spectrum analyzer allows measurements of amplitude modulation (AM). It is commonly used to measure AM at rates that cannot be measured in the normal frequency domain due to spectrum analyzer limitations on narrow resolution bandwidths. For a given AM rate, the FFT function can generate a trace faster than using the frequency domain for the equivalent spectrum analyzer measurement.
The FFT function calculates the magnitude of each frequency component from a block of
When (MEAS~USER), FFT Menu, and SINGLE FFT are pressed,