|
There were substantial patent cross licensing arrangments between M-EMI and RCA at the time. It is still a matter of research as to how much M-EMI's work owes to RCA and vice versa. The terms of the pre-war competition in the UK stipulated that HD meant a minimum of 240 lines. Baird offered exactly this while M-EMI worked on 243 lines interlaced. It has often been stated that the move from 243 to 405 was a leap of faith. However it has been pointed out by Paul Marshall that 405/50i and 343/60i are essentially equivalent in terms of required bandwidth. In modern parlance the pixel clock rate would have been almost equal. (The 525/60 and 625/50 standards are likewise equivalent)
After WW2 the 405 system was continued. The reasons for this are debated and I'm sure there is further research to be done. In my opinion 405 was retained because we wanted to restart the TV service ASAP and there was no other affordable option for a country that was victorious but nearly bankrupt.
The 405 services were duplicated on 625 starting in 1969 so the changeover period was inordinately long, lasting until 1985. It would have been less expensive to shut down the 405 service a few years earlier and compensate the owners of 405 only sets. Even allowing for spurious claims (imagine somebody handing over a long defunct 1950s set to get the compensation) this could have saved a lot of money, though possibly at the expense of destroying a lot of older sets.
|