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Originally Posted by NewVista
I don't know what GB did in the 30's but can't see how they would achieve the necessary H/V relationship starting w/ 50hz ref. I would like to see a reference/link on this early SPG scheme.
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Any SPG was a complex thing in the 1930s. Some were mechanical, like a Hammond tonewheel organ, others used lots of valves (tubes) to do frequency division. FOr 405 you start at 20250Hz. Divide by 2 to get 10125Hz for line pulses, divide by 405 for 50Hz field pulses. 405 = 3*3*3*3*5 The small numbers were essential for early frequency dividers. The 20250Hz master oscillator could be locked to 50Hz mains using a slow acting phase lock.
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the sad part of the UK not moving into colour broadcasting with 405 NTSC is that all those great programs from the early 60s from the Beeb were only made in b/w
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And many of the tapes were wiped for re-use because they were so expensive. I believe that in the US many shows were shot on film. This was rare in the UK, possibly due to the high cost.