405 Colour
The British 405 line NTSC Colour TV System
Colour Subcarrier 2.6578125 Mc/s

405 Line Colour Test Cards with 377 active lines as they would appear on the TV screen. Click on the pictures for the full size version.

1955 Colour Test Chart
(377 x 503)

Test Card F (377 x 503)

Introduction
405 line NTSC Colour was used experimentally in the 1950's and early 1960's.
Test transmissions of colour slides were made after closedown on BBCtv, which were seen in colour on specially built 405 line NTSC Colour TV sets.
The system was never officially launched, and the TV sets were never put on sale to the public, but they were designed and built, as were 405 line NTSC Colour TV studios, Telecines, and slide scanners.
As late as 1965, ITV were lobbying heavily for the adoption of 405 line NTSC Colour. It would have made a lot of commercial sense. If today's political climate had existed then, the government would very likely have chosen 405 Colour because of these commercial benefits.
In 1965 Colour TV had taken off on a large scale in the U.S.A., with production of most network peak-time shows being switched to Colour. It was time to Britain to catch up.
The alternatives were:
405 line NTSC Colour or
625 line Colour using NTSC or a new system like PAL.


Advantages & Disadvantages of 625
Advantages:
Consistent with the Pilkington Committee recommendation that we change over to using a 625 line TV system.
Disadvantages:
99% of all TV viewing is 405
All ITV viewers are on 405
Colour has to wait for many years while a whole new transmitter network for 625 lines is built at enormous cost.


Advantages & Disadvantages of 405
Advantages:
The main TV networks can start Colour immediately using the exisiting transmitters at much lower cost.
Disadvantages:
Not consistent with the Pilkington Committee recommendation.
BBC2 which has already launched on a small scale on 625 would be left out in the cold. It would have to remain monochrome, revert to 405, or we would have to embark on implementing dual-standard colour. In today's political climate we would probably revert BBC2 to 405 Colour on UHF.
Advantages:
We would have had much more space for more TV channels for many years.
BBC 1 and ITV would have remained on VHF, and the majority of our TV viewing would have been in NTSC on VHF, as it still is today (2001) in the U.S.A.
The UHF bands would have had space for 6 or 7 networks, (instead of the 4 or 5 we have today) meaning 8 or 9 networks in total.
In 1989, Sky television could have been offered 1 or 2 of the unused UHF networks, and there would still have been room for a
complete "Channel 5" network 10 years later.
In the Digital world, 405 would have allowed twice as many channels in the same bandwidth, and Digital Terrestrial TV could have been a true rival to Digital Satellite, having an almost equal number of available channels.


X Links marked X are under construction
(I already have the info/pictures)

X OFF SCREEN PHOTOS OF 405 LINE NTSC COLOUR TV

X 405 line NTSC Colour Subcarrier Frequency: 2.6578125 Mc/s

X 405 line NTSC Colour Line Blanking & Colour Burst specification

X 405 line Field Blanking

X Adjusting the Sound - Vision carrier spacing for 405 line NTSC Colour

X References


Links

"405 Alive"
http://www.sigtel.com/tv_index.html

The UK 405-Line Television Network
http://www.pembers.freeserve.co.uk/405-Lines/index.html


Please send questions or comments to
405colour@sptv.demon.co.uk


405 colour website last updated 10 June 2001