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signals in the correct proportions but it is now common to
incorporate a fourth tube in a colour camera specifically to generate
the plain television signal; its light input is, of course, derived from
the scene image before this enters the colour-splitting filter.
The television camera is not the only source of video signal in a
television broadcasting system. Video tape reproducers are also used
and video signals can also be obtained from cinema film using an
equipment known as telecine. Television games also generate video
signals.
So far we have confined our discussion to transmission of sound
and vision signals as in broadcasting,