DANOFDANGER
pfm Member
So can this be made clear to me. Since the oversampling modulator removes aliasing as you say, but not all of it. Then the digital LPF is mostly for noise just outside the passband due to noise shaping. So its not or mostly not a anti imaging filter but more just a plain old LPF for noise.
Why is this noise important to filter out ? Does it impact the passband ?
EDIT.
Further research as far as i can tell shows that the oversampling modulator preceding the SD modulator only shifts the spectral images further up the frequency band. Oversampling cannot remove "spectral images" but rather move them somewhere else or possibly transform their energy.
The answer to my question appears to be that the Digital LPF handles only the Quantization noise from the SD moduation and anti aliasing\anti imaging is still handled by the analog filters.
Still yet to figure out why we need to filter the Quantization noise outside the audible bandwidth but i assume it must be because it affects the passband somehow.
Why is this noise important to filter out ? Does it impact the passband ?
EDIT.
Further research as far as i can tell shows that the oversampling modulator preceding the SD modulator only shifts the spectral images further up the frequency band. Oversampling cannot remove "spectral images" but rather move them somewhere else or possibly transform their energy.
The answer to my question appears to be that the Digital LPF handles only the Quantization noise from the SD moduation and anti aliasing\anti imaging is still handled by the analog filters.
Still yet to figure out why we need to filter the Quantization noise outside the audible bandwidth but i assume it must be because it affects the passband somehow.