Students should become familiar with the settings to perform measurements in the frequency domain.
The FFT spectrum analyzer
 acquires a Npoint discretetime 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.
Sampling time and the number of samples taken determine the spectrum's highest frequency and resolution bandwidth.
$\Delta T=N\cdot {t}_{S}$
and ${f}_{\mathrm{max}}=\frac{1}{2{t}_{S}}$
and $\Delta f=\frac{1}{\Delta T}$
where
${t}_{S}$  Sampling time 
$N$  Number of samples (FFT length) 
$\Delta T$  Sample record length 
${f}_{\mathrm{max}}$  Maximum detectable frequency 
$\Delta f$  Resolution bandwidth 
This experiment illustrates the basic settings to control the FFT spectrum analyzer. The FFT spectrum analyzer acquires a discretetime signal, computes the spectrum using the FFT algorithm and displays these frequency components. In this example, the number of samples (FFT length) $N$ is $128$.



Start the simulation and open the spectrum analyzer settings and reduce the resolution bandwidth. Also switch Averaging off and on.
Note that:
 The resolution bandwidth values are shown as 1, 2, 5, 10, 20, 50 kHz etc., i.e. 15.625 kHz is shown as 20 kHz.
 The labAlive simulation framework provides the Spectrum Analyzer with a sampled input signal. Therefore, the spectrum analyzer needs no antialiasing filter.
 Samples are represented as floatingpoint numbers (Java doubleprecision values)  no further quantization is applied.
This simulation app provides an online spectrum analyzer. It allows frequency domain analysis with similar control settings to RF spectrum analyzers. Students should become familiar with the settings to perform measurements in the frequency domain.


Open the spectrum analyzer settings:
 Click on .
 Click on to view more details. Adjust Resolution Bandwidth.
 Click on to view more details. Switch Averaging off and on.