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Digital vs Analogue
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The advantages by switching from Analogue to Digital many. The transportation (transmission) and storage of digital signals more noise tolerant then for an analogue.

Besides makes the digitalization it possible to use software for compression (such as MP3, MPEG4) and encryption.

  •  We live in a world "polluted" with electric noise. If not guarded properly, will this noise be added to analogue signals and can only be removed by a filter - fitted for the purpose.

  •  If noise and signal share the same frequency range, will the filter process be difficult.

  •  Digital signals are by nature "just" analogue signals, with two possible values ('0' and '1') and hence will electric noise also be added.

  •  However will a digital component accept a difference between the output and the input levels (called noise margin) and hence will the filter process be done automatically each the signal pass through a gate.

  •  CMOS technology known to have logic-level symmetric around the half supply voltage

  •  TTL technology not symmetric (consult textbooks for more details)