The AM buzz was always the issue with using the colour carrier but FM + carrier could have been added early on and AM – carrier quietly dropped. Incidentally the french system used AM for a while on 625 the buzz was noticeable if not properly tuned of course they did actually have a filter.

On a different note Band 1 is a nightmare in the summer months as high power transmitters for long distance reception can suddenly be received at greatly longer distances at certain times. BBC1 405 line on Ch 1. was actually received in New York on one occasion. That is over 3000 miles. So imagine trying to plan out a group of channels that will be shared in the UK, that cannot be received at much over 70 miles one day. Thus sharing the same channels more than once within the UK and Europe is perfectly sensible and reasonable. However, the next day some or all those transmitters will then suddenly be receivable at a given location simultaneously. I can always remember someone who used to watch the BBC on Ch 1. from Croydon commenting how it would be perfect one day only to be unwatchable the next due to a Spanish transmitter on almost exactly the same frequency. To add insult to injury the Spanish station wasn’t using 405 lines of course.

Mostly during the analog color days you would reduce the bandwidth by reducing the luminescence horizontal resolution and leaving the vertical the same to comply with the TV standard (NTSC 525 PAL 625). VHS is known to only have about 320 lines of horizontal luminescence resolution.

If you have the spectrum though you could also do this to increase chroma horizontal resolution, decreasing regular luminescence as a sort of trade off.

But no one ever thought of reducing or increasing the number of horizontal lines as well, as need be to even things out. The picture would look different depending on if there was more or less horizontal luminescence and chroma than was needed for an aspect ratio of 4:3. essentially you would be changing the shape of the vertical lines depending on how much horizontal resolution was being sent from the video source. In digital production you can do the same thing by increasing the number of horizontal pixels beyond a that of a 4:3 aspect ratio for 4:3 viewing. the vertical pixels become more rectangular in shape to make room for more horizontal pixels. They call that using non-square pixels. So in analog terms the vertical lines become smaller and more squashed, more rectangular in shape as the horizontal lines are increased.

If you had reduced the spectrum by using less horizontal lines as well, making it a part of the standard in use that, TVs should be able to adjust to a minimum number of horizontal lines, say 405 being the minimum you could have had studios being able to adjust the picture quality with greater control. You could have increased luminescence quality and reduced smearing by reducing the number of horizontal lines and therefore the horizontal frequency required for the video. You would have less lines, but more lines would have their own luma and chroma information rather than some lines having the same as adjacent lines.

By allowing this as part of a a standard this it would have also been easier for newer TVs to display older 405 line content broadcasts, without converters at the transmitter or studio. It would also mean that content from countries where standards with different horizontal lines are uses (NTSC 525) could have been broadcast here without any changes to the horizontal line content.

Some VGA screens could adjust really easily to different resolutions, different numbers of horizontal and vertical lines. And so could multistandard TVs such as those that used both PAL and SECAM. Even the original RCA CT-100 NTSC TV could be used with 625 line PAL without much modification. All that was required was a change to the colour demodulation circuits for a PAL signal and the vertical hold control adjusting for 50 fields.

This would be the colour sequel at the end of the 1959 film “This is the BBC”.

It wouldn’t have been a good idea to sell it to the United States, though, as the Vietnam War was getting from bad to worse, so there were strong anti-war feelings at the time.

Maybe it was all for the best. …oh, well.

Thanks David.

Yes, there were. The BBC carried out colour 405-line tests at Alexandra Palace in the 1950s, using a system that was a modified version of NTSC. The cameras were based on the RCA TK41, but were clones manufactured by Marconi.