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Discrete Total Harmonic Distortion

Purpose

Calculate the total harmonic distortion (THD) of the input signal.

Library

Extras/Discrete Analysis

Description

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This block calculates the total harmonic distortion of a periodic input signal based on discrete samples. The sample time and the number of samples can be specified. The THD is defined as

       ┌│ -∑---2  ∘ --------------
       │∘ ν≥2U ν     U2  - U2 - U 2
THD  =   ---2--=    -rms---02----1-
           U1            U1

where Uν   is the RMS value of the ν  th harmonic of the input signal and Urms   is its overall RMS value. The fundamental frequency f1   of the running window is

                  1
f1 = sample-time-×-number-of samples.


Note  This block is only available for Matlab 7.0 or newer.

Parameters and Dialog Box

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Sample time
The time interval between samples.
Number of samples
The number of samples used to calculate the THD.