Computer simulations on CD music signals were performed. With no upsampling the distortion due to PWM gave a signal-to-noise-ratio (SNR) of approximately 45-50 dB. Using the prefiltering scheme developed in this work, dramatic improvements of the reconstructed signal quality was demonstrated. The 9th order prefilter gave an SNR of well above 90 dB for the music signals tested.
Experiments using the same signals upsampled with N=8 showed that a 3rd order prefilter was sufficient for removing PWM-induced distortion.