Why is an anti-aliasing filter required in a decimator?
It removes high-frequency signal components that would otherwise be reproduced as lower frequency components✓Richtige Antwort
It peaks the response of the decimator, improving bandwidth
It removes low-frequency signal components to eliminate the need for DC restoration
It notches out the sampling frequency to avoid sampling errors
Erklärung
Lowering the sample rate lowers the Nyquist frequency with it. Anything still present above half the new rate would fold down and reappear as a false lower-frequency signal, so an anti-aliasing stage must remove those components before samples are thrown away.