Students should become familiar with the settings to perform measurements in the frequency domain.
The FFT spectrum analyzer
- acquires a N-point discrete-time signal - N is a power of two, e.g. 8, 128, 1024,
- computes the spectrum using the FFT algorithm,
- displays these frequency components.
Sampling time determines the spectrum's highest available frequency.
Capture time determines the resolution bandwidth.
The figure below illustrates these relationships for FFT measurements.
FFT measurements: Maximum detectable frequency is half the sampling rate. Frequency resolution is the reciprocal of the record length.
Sampling time and the number of samples taken determine the spectrum's highest frequency and resolution bandwidth.
||Number of samples (FFT length)|
||Sample record length|
||Maximum detectable frequency|