Vertical interval signals on 405

[ppppenguin]

Thanks for digging out that document. I've done it that way, or in a very similar way, when designing equipment. For video processing and switching kit I was trying to measure dP and dG down to well below 0.1 degrees/0.1%. This isn't easy. The usual video test waveform with a vectorscope (many could do dP and dG measurements) was increasingly awkward and inaccurate much below 1%. I have a vector network analyser (HP4195A) and with care I could approach 0.01degrees/0.01%.

The reason for going very low in video processing is because a lot can be cascaded in a typical broadcast system.

Analogue video was hard. Maintaining accuracy through a lot of kit took a huge amount of engineering effort. Design, maintenance and operation.