Why does digital signaling usually perform better than analogue signaling in a noisy communications channel?

Question

Why does digital signaling usually perform better than analogue signaling in a noisy communications channel?

Answer 1

In digital signalling the receiver must only detect discrete levels.  Detecting when a signal crosses a limited number of thresholds of voltages and/or phases is inherently less prone to noise than trying to detect an "infinite" number of analog levels and phases.

In the best case (albiet a slower method of transmitting digital info.) all the receiver has to do is detect a single "high" and a "low".  Those levels may be set *far* above the noise level.  Even in the real world, there are rarely more than 64 voltage/phase 'level's to detect by modern modems.  A far cry from the minute changes in an analog signal.

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