Early colour TV experiments.

[ppppenguin]

Although not explicitly covered in the Mertz and Gray paper I mentioned before, the problems of interlace can be worked out from their maths. The underlying problem is that vertical and temporal information get mixed up and can be very hard to separate accurately. In some cases it's impossible to do so and the best you can do is fudge it.

Of course on it only gives enhanced vertical resolution on still pictures. As soon as you get movement on 405 you're down to 202.5 lines, less than Baird's 240 line progressive.