Harmonic distortion

In Tina you can also calculate the harmonic distortion.

To illustrate this, run the transient analysis with the above circuit (ampli.sch) then the following figure appears:

Select the output curve then press the right button of the mouse and select Fourier Series from the popup menu: the dialog box of the Fourier series will appear. Set Sampling start time to 1ms and the Number of samples to 4096. Note that for best accuracy, it is very important to set the starting time for the Fourier Series analysis to after the initial transient has died away. Now press Calculate. Tina calculates you the Fourier coefficients and the harmonic distortion, which is defined to be the ratio of the root-mean-square (RMS) sum of the magnitude of the harmonics to the magnitude of the fundamental, or as a percentage: , called percent total harmonic distortion (%THD).