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 ).

---

Related Guides Digital Video Fundamentals - Resolution and Aspect Ratio It would be hard to find two more important aspects of digital video than resolution and aspect ratio. They're equally important for dealing with purely digital content and also understanding conversions from analog to digital and back again.... (Read More) Digital Video Fundamentals - Color Formats Color seems like a fairly straight forward concept. You probably started learning about color as a child, and may even have some understanding of different video connections like Composite, S-Video, Component cables. When you're working with digital video there are a lot more options available. Understanding those options and what they're used for may help you find your way through the maze of standards and formats.... (Read More)