nyquist theorem การใช้

• The Nyquist theorem relates this time-domain condition to an equivalent frequency-domain condition.
• If a proper ( no clipping / saturation ) analog signal is converted to digital via A / D with sufficient samples, and then reconverted to analog via D / A then Nyquist theorem guarantees that there will be no problem in the analog domain due to " peak " issues because the restored analog signal will be an exact copy of the original analog signal.
• Taking the example of a current high definition ( HD ) video system, with 1920 by 1080 pixels, the Nyquist theorem states that it should be possible, in a perfect system, to resolve fully ( with true black to white transitions ) a total of 1920 black and white alternating lines combined, otherwise referred to as a spatial frequency of 1920 / 2 = 960 line pairs per picture width, or 960 cycles per picture width, ( definitions in terms of cycles per unit angle or per mm are also possible but generally less clear when dealing with cameras and more appropriate to telescopes etc . ).