I'm new to digital filters. So I'm trying to get things right and I can't find an explicit answer to my question on the internet.

Question: Digital filters only accept samples as input? I mean the input can not be zeros nor ones. It can only be samples. If that's the case, then the typical position for a digital filter would be after the receiver (I mean before converting to bits).

So receiver would be like:

$$ \mbox{antenna} \rightarrow \mbox{amplifier} \rightarrow \mbox{Sampler} \rightarrow \mbox{Digital Filter} \rightarrow \underbrace{\mbox{DAC}}_{\tiny \mbox{here I should have filtered samples}} $$

Please correct me and kindly ignore any coding or LNAs and stuff like that.

  • $\begingroup$ Welcome to DSP.SE! Why do you have a DAC after the digital filter in your flow? There is nothing stopping you applying a digital filter to zeros and ones, but that would not be the normal use. Usually one or more filters is/are applied to the received (probably downconverted) signal. $\endgroup$
    – Peter K.
    May 17, 2016 at 11:37

1 Answer 1


You are almost right: digital filters do deal with samples, but a sample can be any numerical representation of a given signal value at a given instant (so in general, they may accept zeros or ones).

Moreover, a sample is usually represented by a binary word (e.g. 0001), so a digital filter actually deals with 0s and 1s.

  • $\begingroup$ Sounds like he's confusing the value with the representation? Could talk about ternary or decimal computers to clarify? $\endgroup$
    – endolith
    Jun 16, 2016 at 13:58

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