General – Harmonic Distortion (sinusoid)
Step 1 – Measuring Harmonic Distortion
Use this setup to measure harmonic distortion for a single sinusoid frequency.
As default this setup is meant to be used with an external sinusoid generator and this will not work for very low frequencies.
It is a better method to use the sound card as signal generator, this will also work for low frequencies. For more information about this, please click help.
IMPORTANT: Click help for information on how to use this setup.
Step 2 – Remove Low Frequency Noise
Low frequency noise is included when computing THD + N as default (this is according to the definition).
But if you have low frequency noise you do not wish to include, you may apply a filter to filter out this noise.
To do this, go to Plot→Plot Type Settings→Time Data…. In this dialog box, make sure the Perform Filtering check box is checked. Click the Options… button to open the Filter Options settings and select the filter type (high-pass) and cutoff frequency.