The digital anti-aliasing filter can only ever work on a digital -> digital signal, but they're still useful in the analog->digital process. > My understanding

The digital anti-aliasing filter can only ever work on a digital -> digital signal, but they're still useful in the analog->digital process. > My understanding: If you have a an analog filter of a given steepness the only way to further reduce aliasing effects digitally is oversampling. Or less steep (cheaper) analog filter plus oversampling is the same as steeper (more) expensive analog filter. People tend to say digital anti-aliasing filters when they really mean oversampling You're right, and it's actually both. The ADC can run at a much higher sample rate with a cheaper analog filter, and then that digital signal is again passed through a digital filter and downsampled.