TABLE OF CONTENTS Walt Kester
Before discussing some video applications for op amps, it is a good idea to review some basics regarding video signals and specifications. The standard video format is the specification of how the video signal looks from an electrical point of view. Light strikes the surface of an image sensing device within the camera, producing a voltage level corresponding to the amount of light hitting a particular spatial region of the surface. This information is then placed into the standard format and sequenced out of the camera. Along with the actual light and color information, synchronization pulses are added to the signal to allow the receiving device a television monitor, for instance to identify where the sequence is in the frame data.
A standard video format image is read out on a line-by-line basis from left to right, top to bottom. A technique called interlacing refers to the reading of all even-numbered lines, top to bottom, followed by all odd lines as shown in Figure 6-77.
The television picture frame is thus divided into even and odd fields. Interlacing is used to produce an apparent update of the entire frame in half the time that a full update actually occurs. This results in a television image with less apparent flicker. Typical broadcast television frame update rates are 30 Hz and 25 Hz, depending upon the line frequency. It should be noted that interlacing...
