Origins of the 405 line system.

[Gryphon]

Lift and syncs were added to the waveform very late in the M-EMI processing chain.  I assume that the intention was to give the black-level clamps as much black level as possible to work on.

Gryphon also raises the old question of lift, or pedestal. 

In this context, lift and pedestal are not the same thing.

Pedestal is the difference between black level and blanking level. Lift determines which parts of the picture sit at black level.  Iconoscopes (and, I think, high velocity tubes generally) do not produce a defined signal level corresponding to black, even after shading correction.  Lift has thus to be controlled at some point.  In the M-EMI system, this control was very late in the chain.

(Before anyone jumps up, I do know that lift is still controlled manually as part of the vision control operation, but this is now for aesthetic reasons).