Question

there should be a half line difference between odd and even fields in a TV system using interlaced scanning . explain why ? how is this made possible in practice?

Answer 1

Interlaced scan is a display signal type in which one half of the horizontal pixel rows are refreshed in one cycle and the other half in the next, meaning that two complete scans are required to display the screen image. Interlaced is very significant in broadcasting. It is used for a long time in analog between television broadcast based on the difference of even and odd fields. It was designed primarily to minimize the bandwidth requirements for video signal transmission.

The flicker problem in television was solved by this interlaced scanning. At first even and odd individual fields are created. Firstly the even scan line pass on the screen and then the odd scan line pass. Two of such even and odd scan line fields make one video frame. This means it utilizes two video field to create one frame. One field has the odd lines where as the other contains all the even lines of the image. It is a method for doubling the frame rate of a video display without taking up an additional band width.