Spatialking...A digital waveform does not represent the information being communicated (a "one" or a "zero"). The waveform is sampled at some specific instant of time to determine if it is above or below some threshold. Where the signal goes in between sample times is completely irrelevant. All that matters is that the sample time be chosen so that it is well away from leading and trailing edges of the waveform where the signal level is changing rapidly and might be misread.
In a complex digital system that I worked on (Missile guidance) we had dozens of analog signals being sampled and digitized, and many digital signals being used to generate pulses of power (amperes) to control things like gimbals. All in the space of a 9 inch sphere, so you can imagine the electrical noise environment! By very careful selection of sampling times and signal sequences it all worked fine, although you would never have thought it possible if you looked at the raw analog signals. The bottom line is that a sampled data system does not exist except at the sample times.
