Nyquist-Shannon Sampling Theorem

The Nyquist-Shannon Sampling Theorem is the basis for all digital sampling of analog signals. Its named for Harry Nyquist, whose work on telegraph technology was instrumental in the later work by Claude Shannon in 1949. It's also often referred to as just the Nyquist Sampling Theorem or simply the Sampling Theorem.

Nyquist Frequency
The importance of the sampling theorem is that following it allows analog signals, such as audio or video, to be reproduced digitally and then converted back to analog again later. One of the key requirements for accurate conversions (sampling) is the necessary Sample Frequency. The sample frequency must be more than twice the frequency of the original signal. In order to reproduce sounds as high as 20kHz you must take at least 40,001 samples per second ( 20,000 x 2 + 1 ). Likewise, in order to Capture a 3MHz VHS signal you must sample at no less than 6,000,001Hz ( 3,000,000 x 2 + 1 ).

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PPetre 27 December, 2008 14:36
Dear Sir/Madam, Sorry, but I think that Nyquist–Shannon sampling theorem about the sampling rate is not correct. Could you please be so kind to see the papers below? http://www.ieindia.org/pdf/88/88ET104.pdf http://www.ieindia.org/pdf/89/89CP109.pdf http://www.pueron.org/pueron/nauchnakri tika/Th_Re.pdf Also I believe the following rule could be applied: "If everything else is neglected you could divide the sampling rate Fd at factor of four (4) in order to find the guaranteed bandwidth (-3dB) from your ADC in the worst case sampling of a sine wave without direct current component (DC= 0)." I hope that this is useful to clarify the subject. The feedback is welcomed. Best and kind regards Petre Petrov ppetre@caramail.com

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