acl wrote:...I did invest 7 GBP including postage and packing from China for a NTSC to PAL converter as shown below but it didn't seem to work with a monochrome signal.
Ah! You may have been caught out as I was some 25 years ago. I bought something similar in HK. It (probably) is a PAL-NTSC convertor (and vice-versa), but that's all. It decodes PAL into YUV (Y, Pb, Pr) and then re-encodes it to NTSC. It does nothing to the number of lines, frame rate and so on. A monochrome signal (or the Y) passes through (largely) unchanged.
It's a colour format convertor, or a colour system convertor, it is not a standards convertor. A standards convertor does it all, not just NTSC-PAL but at the same time 525-625 (or the opposite). Hence that's why they call it a 'system convertor', hoodwinking using semantics. They are technically correct, that's how they get away with it.
And at seven quid, no surprise. The line conversion (all three signals, YUV) requires a lot of RAM and fast signal processing, signal and line interpolation, adding lines or deleting them, all that costs money, lots of it.
PAL/NTSC/SECAM are acronyms for colour encoding standards, not line and frame rates. Recall the BBC experimented with NTSC on 405-lines, but with a lower sub-carrier frequency than 3.58MHz at 2.6578125MHz. It's still NTSC, but with 405-lines at a 25Hz frame-rate and a different sub-carrier frequency.
Some South American countries have/had odd mixtures too, NTSC on 625-lines, well, any permutation you can think of really...
Steve A.
Another example of NTSC is here - and right 'on topic' for this forum...
http://authorityfile.co.uk/NBSC/Home/About