[kragen]

that is not correct. digital sensors detect frequencies above the nyquist limit all the time, which is why they need an analog antialiasing filter in front of them. what they can't do is distinguish them from baseband aliases

you could just as correctly say 'nyquist-shannon theory is not generally applicable; it requires a bandlimited signal' (which is why compressed sensing doesn't violate it)

[nico]

Thank you for the clarification, great point about the importance of distinguishing the acts of "detecting" and "making sense of" some signal/data/information