I'm an electrical department student studying signals and systems.
The RMS value of the general AC electrical signal is 6.31V, and the first harmonic value is 6.30932V(rms). (THD is approximately 1.5% at this time.)
How much does the std value of the white noise added to the signal affect the THD value of the signal?
When tested in the simulation, thd became 2.8 to 3% when the std value of white noise was 0.16. However, in the fft distribution of white noise, it was too complicated to calculate because the value of the harmonics was very small, such as 0.015, or a minus value.
When white noise is added to the signal, how should the THD value calculation expression be constructed?