Микроконтроллеры PIC

"4 выборки за период" хороши, когда нет помех на частоте третьей гармоники сигнала. А вот когда эти помехи есть, а на входе АЦП дешевенький anti-aliasing-filter на основе обычной RC цепочки, тогда караул..

Oversampling can make it easier to realize analog anti-aliasing filters.[1] Without oversampling, it is very difficult to implement filters with the sharp cutoff necessary to maximize use of the available bandwidth without exceeding the Nyquist limit. By increasing the bandwidth of the sampling system, design constraints for the anti-aliasing filter may be relaxed.[2] Once sampled, the signal can be digitally filtered and downsampled to the desired sampling frequency. In modern integrated circuit technology, the digital filter associated with this downsampling are easier to implement than a comparable analog filter required by a non-oversampled system.