27-03-2018, 06:21 PM
(27-03-2018, 02:42 PM)ppppenguin Wrote: The 0% sync tip level is shown at the bottom right of Guy's image.
No, Jeffrey, that is black level! Note the way that the K rating lines open out at the base of the raised co-sine 2T pulse, i.e: black level.
I have worked out what the 43% level relates to, though. If you look at my IBA image, there is a scale I hadn't taken much notice of down the centre of the 2T pulse which matches the BBC scales with 0% at black level. Continuing down, though, there are -20% and -40% markings and the black level line obviously crosses the scale at -43%, so it is the minus sign which is missing on Guy's scale. The missing '0.' in front of the 3 on mine is, I must confess, having now looked again at the original, due to overzealous clipping on my part whilst editing.
I can see a use for the percentage of video level markings on all but the Weaver scale, though, as the other three all have markings for centring the 2T pulse at the 50% level.