Blanking time

Where A/ is the available bandwidth frequency in Hz. The constants 30 and 525 represent the frame and fine frequencies, respectively in the conventional U.S. vision system. A factor of 2 is introduced because in one complete cycle both a black and a white fine are obtainable. The factor 0.75 is necessary because of the receiver aspect ratio the picture height is three-fourths of the picture width. There is an additional reduction of about 15% (not included in the equation) in the theoretical value because of horizontal blanking time during which retrace takes place. A bandwidth of 4.25 MHz—typically that of the conventional terrestrial television system—thus makes possible a maximum resolution of about 345 fines. 

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