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Sharp-eyed viewers watching some episodes of the BBC’s recent prime
time series CIA or Saturday morning children’s programmes may have noticed
black borders at the top and bottom of their screens. Perhaps some decided
it was time to get their set serviced, but few realised that the source
was the BBC. Unannounced, it is testing a new broadcasting mode to try to
prepare for Europe’s next generation of television – widescreen and high-definition.

Yet the BBC can only guess at the likely shape of future TV standards.
Across Europe, broadcasters, licensing authorities and manufacturers are
in a dilemma: should they stick with analogue standards, which have served
TV well so far, or go for new digital ones that may be costly, unpopular
and hard to distinguish from their forebears?

Everything else in consumer electronics – from wrist watches to compact
discs – is rapidly becoming digital, and consequently offering better reproduction
quality, albeit at a higher price. But the world’s home video recorders
and TV picture transmissions are still firmly analogue; in Europe, the standard
is the PAL system set down 25 years ago.

For Europe’s electronics industry, a rapid move towards high definition
and widescreen TV may be key to survival. The market in Western Europe is
near saturation, and UK sales of sets in 1992 are forecast to be the lowest
for 10 years, 25 per cent below the high point of 1988. The next generation
of TV, whether analogue or digital, could offer better and bigger pictures
with enhanced sound. But before manufacturers can provide it, they have
to overcome two obstacles: a public reluctant to replace perfectly adequate
equipment, and lack of agreement over broadcast standards.

No one has yet demonstrated that enough consumers will pay two or three
times the price of a standard set for a widescreen or digital model. The
only experience so far, in Japan, is not encouraging. Since analogue high-definition
sets were launched there last November, only a few hundred have been sold,
and most of those have probably gone to rival manufacturers investigating
each other’s models.

In Europe, broadcasters are not keen on a wholesale change, though they
are not actively resisting it. Their tacit assumption so far has been that
future standards will build on analogue transmission technology. But recent
events have called this into question. There is now a shift towards a wholesale
leap into digital TV, with no intermediate ‘enhanced analogue’ stage.

The principal loser in that case will be the multiplexed analogue components
(MAC) transmission system, developed in Europe about 10 years ago by researchers
in electronics companies and broadcasting organisations as a step towards
higher-definition TV. Using the same 625 horizontal lines as PAL but a different
method of signal coding, it gives clearer pictures and widescreen viewing,
as well as an easy upgrade path to the high-definition version, HD-MAC,
which uses 1250 lines.

But MAC has never prospered commercially. Electronics companies initially
found it difficult to make the microchips on which MAC receivers rely. Sky
TV decided to shun MAC in favour of the old-fashioned but trustworthy PAL
system when broadcasts began from the Astra satellite. German broadcasters
transmitting from Astra followed suit. The British satellite broadcaster
BSB was obliged by its broadcasting licence to use MAC, and was late on
air because no chips were available for decoders by the scheduled launch
in autumn 1989.

Unfriendly games

HD-MAC has also struggled to win friends. In April, European broadcasters
and the main manufacturers Philips of Holland and Thomson of France announced
that live broadcasts from the Olympics in Barcelona would provide the first
public showcase for HD-MAC in Europe. The publicity surrounding the games,
they said, would encourage people to watch on high-definition widescreen
sets at over 600 sites.

Although the broadcasters went to Barcelona in force, and recorded the
games in high definition for posterity, the manufacturers’ readiness to
show off HD-MAC receivers in public cooled noticeably. In the UK Thomson,
Philips and Nokia of Finland together mustered around a dozen public sites,
half of them shops. There was very little publicity. The companies admitted
beforehand they were unhappy with both the quality of the 1250-line HDTV
pictures available from HD-MAC and its promised compatibility with 625-line
MAC receivers. But their lack of enthusiasm is more deeply rooted. When
Jacques Caumartin, senior vice-president of Thomson’s Professional Broadcast
Systems division, recently left the company after 26 years his parting shot
was a blistering article in an industry newsletter, Advanced Television
Markets, saying HD-MAC is dead unless someone can find a way of broadcasting
it from terrestrial transmitters, which are the outlets for the vast majority
of broadcasters. And at the biennial International Broadcasting Convention,
held in Amsterdam shortly before the Olympics, delegates were quietly describing
MAC technology as outdated.

For manufacturers who have committed millions of pounds to developing
analogue systems this will make depressing news. The tone was set by the
keynote speaker, James McKinney, chairman of the US Advanced Television
Systems Committee which is evaluating widescreen HDTV systems to set a standard
for North America. It is already clear that America’s next system will be
digital, not an attempt to build on or enhance its existing analogue NTSC
system. In McKinney’s words, ‘we in the United States have no interest in
‘enhanced’ television . . . we want one step, not two’.

Greed or caution?

He accused European TV makers of ‘unconscionable greed’ for still expecting
European viewers to buy enhanced analogue TV sets, and then pay again a
few years later for a full-blown digital HDTV system. ‘We in the US know
that Europe is spending a lot of money and a lot of time researching compressed
digital HDTV,’ McKinney went on. Squeezing the digital data from a widescreen
picture into the limited bandwidth of a ground transmitter is the broadcasters’
Holy Grail. But it would also be the death-knell for enhanced analogue systems.

Soon after McKinney’s speech, three engineers from Thomson CSF revealed
to a technical seminar that they had been test-broadcasting digital HDTV
signals from terrestrial transmitters for two years. They had not previously
admitted it publicly for fear of undermining confidence in analogue HD-MAC.

Nearby, a group of Scandinavian broadcasters, manufacturers and telecommunications
operators demonstrated HD-Divine (digital video narrow-band emission), which
converts a 1250-line widescreen HDTV signal into digital code running at
1.2 gigabits per second, and then compresses it to a data stream of just
27 megabits per second (comparable to an analogue bandwidth of 27 megahertz).
This month the Scandinavians expect to have a modulator which can squeeze
that into a conventional 8 megahertz terrestrial TV channel, paving the
way for a domestic widescreen high-definition service.

Being digital, the broadcast signal can be transmitted at much lower
power than a conventional analogue TV programme because a TV receiver’s
decoder only needs to distinguish between ‘on’ and ‘off’ bits; it does
not have to follow the range of amplitudes present in an analogue signal.
This means that HD-Divine signals could be broadcast in parallel with existing
analogue PAL services without causing interference, and viewers could upgrade
at will to digital systems. In the UK earlier this year, National Transcommunications,
which operates the commercial TV and radio transmitters around the country,
tested its own experimental digital TV transmission method from terrestrial
sources without causing interference to PAL sets.

Elsewhere, Thomson’s engineers have secretly tested a different system
which uses less compression, to 70 megabits per second, but then spreads
the data stream over 512 very narrow transmission channels together taking
up only 8 megahertz. This slows the data rate in each channel, making the
signal very resistant to echoes and interference. The receiver decodes all
the channels separately and combines their data to reconstruct the HDTV
signal. Thomson is developing microchips for the system and plans more broadcast
trials later this year.

Despite this progress in terrestrial digital broadcasts, Philips and
Thomson still profess complete faith in analogue HD-MAC, and cooperated
in Amsterdam on a demonstration of a terrestrial version. However, it relies
on sharing the signal between two TV channels, so it would be unworkable
in almost every European country.

They are also involved in PAL Plus, developed over the past three years
by a European consortium of terrestrial broadcasters and electronics companies.
Being an enhanced widescreen version of PAL, it is exactly the kind of transitional
technology which McKinney advised Europe to eschew. Yet its compatibility
with existing sets may carry the day with a doubting public.

Wide and clear

PAL Plus will let terrestrial broadcasters transmit widescreen pictures
which are compatible with conventional PAL receivers. When PAL Plus signals
are received on sets fitted with PAL Plus chips, the picture will be both
wider and clearer.

However, on conventional sets with a screen that has a width-to-height
aspect ratio of 4:3, the broadcasts will only produce ‘letterbox’ pictures
– a widescreen image with black borders at the top and bottom. The borders
conceal digital code which carries information for the extra picture detail
displayed by a PAL Plus widescreen set, where the aspect ratio is 16:9.

The German broadcaster ZDF tested the system in March, and again in
June from Hilversum. The trials were judged a success, and the consortium’s
four electronics manufacturers will now start building PAL Plus circuitry
for new widescreen sets, ready for a commercial launch in 1995. Albrecht
Ziemer, technical director of ZDF and chairman of the PAL Plus steering
committee, talks of introducing the new broadcasts by a ‘soft start’. Some
material may be transmitted in 14:9 aspect ratio, as a temporary compromise
between the old 4:3 (equivalent to 12:9) and new 16:9 formats. Viewers with
4:3 sets will see narrow black borders at the top and bottom of the screen;
viewers with new widescreen sets will see narrow black curtains at each
side.

Yet in the US, Philips and Thomson have abandoned their proposals for
enhancing analogue tv, and switched their support to all-digital alternatives,
despite their public support in Europe for the analogue MAC and PAL Plus.
A more confused, and confusing, attitude would be hard to imagine.