TELECOM Digest OnLine - Sorted: Re: British TV License (was America the Worst For Cell Rates

Re: British TV License (was America the Worst For Cell Rates

Paul Coxwell (paulcoxwell@tiscali.co.uk)
Wed, 2 Feb 2005 12:20:25 -0000

> Note, by the way, that most PAL/NTSC TVs do not have tuners suitable
> for use in North America. Rather, their NTSC mode is designed to be
> used with a PAL/NTSC VCR which heterodynes NTSC color at the PAL
> frequency. Thus, they are not true NTSC TVs.

Add to that that most sets sold in the British market have no VHF tuner
either, since all broadcasts have been on UHF-only for 20 years.

> PAL-K, PAL-N, and even PAL-M in some places. By contrast, broadcast
> NTSC color is found universally with system M, although some
> historical references claim that NTSC-A was close to happening before
> the UK government decided to abandon system A in favor of PAL-I. The
> French SECAM system is used with systems D, K, and L.)

BBC engineering did carry out a lot of trials in the late 1950s with a
view to adapting the NTSC color system to system A (change of
sub-carrier frequency etc.). I have old GPO records which show that
this hybrid NTSC system was also tested alongside regular system M
with project Telstar in 1962.

By the early 1960s, however, it had been decided that the U.K. would
ultimately move to a 625-line system, and tests of this were already
underway. Regular 625 transmissions started in 1964, with
transmitters using UHF channels only. Even then it appears that
consideration was still being given to what would have become an
NTSC-I arrangement. If I recall correctly, the final decision to go
with PAL was not made until the very start of 1966, and the first
regular PAL color broadcasts started the following year. The old
system A using VHF channels continued to broadcast in monochrome only
until its closure in 1985.

For those not familiar with system A, it was our old 405-line system.
Scanning was 10.125kHz / 50Hz, using POSITIVE video modulation, and an
A.M. sound carrier positioned 3.5MHz below the vision carrier.

Dual-standard TV sets were produced for many years to allow the
reception of both systems A and I. The changeover switch was often a
monstrous assembly, as it had to alter so many circuit elements to
switch between the systems.

- Paul

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