PureBasic
Active member
Here's a question I'm asking myself about lower harmonics distortion in ADC and input LP filter.
As you know, signal with frequency above Nyquist Shannon limit (SamplingRate/2) will fold and induce lower harmonics artefacts in the record.
As long as we didn't invented the analog brick-wall filter, even if we filter the input of a 44.1 ADC at 20kHz, a 30kHz signal will still fold. We only have 12 or 24dBu attenuation for a good LP (20kHz LP and 30kHz signal). So, given the >100dBu S/N for good 24 bits ADC, the alias will be non negligible.
I've never thinked about that before. And also higher order filters or Chebychev will overshoot, screw the highs and also generate harmonics higher harmonics (which will fold etc....)
Did somebody measured aliases in this case ?? Is there white paper on it ?
As you know, signal with frequency above Nyquist Shannon limit (SamplingRate/2) will fold and induce lower harmonics artefacts in the record.
As long as we didn't invented the analog brick-wall filter, even if we filter the input of a 44.1 ADC at 20kHz, a 30kHz signal will still fold. We only have 12 or 24dBu attenuation for a good LP (20kHz LP and 30kHz signal). So, given the >100dBu S/N for good 24 bits ADC, the alias will be non negligible.
I've never thinked about that before. And also higher order filters or Chebychev will overshoot, screw the highs and also generate harmonics higher harmonics (which will fold etc....)
Did somebody measured aliases in this case ?? Is there white paper on it ?