It can be placed in any place in the path of the video signal. The VITS generator is configurable. Lines can cross the VITS generator without modification, others are erased and recreated in the VITS generator.
The European analogue television transmission standards are based on a 625 lines image which is organized into two half-images (fields). Not all of the lines are visible on the screen, in particular the first lines of each half-image (field). In commercial and professional broadcasting one uses these available lines to transmit test signals, perfectly defined at their emission point. These “known” signals will make it possible to assess the quality of the received signal, to measure impairements, and to locate the source of them. In commercial television, the test lines are transmitted permanently, independently of the transmitted program.
The equipment which generates the test lines is the Vertical Insertion Test Signal (VITS) generator. The shape of the VITS was the subject of thorough studies and is standardized. The VITS makes it possible to measure the quality of the signal by means of a simple suitably synchronized oscilloscope. There exists in the professional field automatic measurement equipment which permanently observes the VITS and display on a screen the value of the measured parameters.
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