There is a need to be able to monitor the television signal amplitude to establish the quantity of picture signal. The principles of the television scanning system and television waveform are well documented, but they are reproduced here as a précis for reference.
Television is the process of transmitting moving pictures by ‘scanning’ a series of still pictures at a rapid enough rate so that the change from one picture to the next picture is seen as continuous movement. The persistence of vision of the eye/brain means that this is possible.
Aspect ratio – Ratio of picture width and picture height. Originally 4:3, gradually moving to 16:9 with 14:9 as an interim measure.