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Bob Amstadt wrote: > It is a very interesting topic and for those of your interested in it, > I highly recommend that you take courses or do some experimentation. > It is a fun topic to explore. I also recommend some historical background that is just amazing. From <http://www.lucent.com/minds/telstar/digital.html>: 1928 Bell Labs researcher Harry Nyquist develops Sampling Theory. It states provides that if a signal is sampled at twice its nominal highest frequency, the samples will contain all of the information in the original signal. <http://www.elecdesign.com/Articles/Index.cfm?AD=1&ArticleID=11193>: When electrical engineers hear the name "Nyquist," they think of what Harry Nyquist is best known for: his Sampling Theorem. Evidence of its importance is everywhere. Products like cell phones, audio CDs, and iPods are all based on the broad-shouldered foundation of the theorem, and that alone is enough to place Nyquist among the industry's greats. But Harry Nyquist had many other, lesser known accomplishments, a number of which resonate strongly today. (more...) <http://harry-nyquist.biography.ms>: ... In 1927 Nyquist determined that an analog signal should be sampled at regular intervals over time and at twice the frequency of its highest-frequency component in order to be converted into an adequate representation of the signal in digital form. Nyquist published his results in the paper Certain topics in Telegraph Transmission Theory (1928). This rule is now known as the Nyquist-Shannon sampling theorem. ... Cheers, Bill