Digital speed limit 

14 June 2001

EDITOR’S NOTE: This article is more than 20 years old. The formatting may be strange, links broken and/or images missing. The text may have been superseded by subsequent events or later research.

Anyone who has seen digital TV – either here in the USA, the UK or anywhere else – has to be impressed with the improved quality of picture and sound.

But getting to the point where everyone has a digital television receiver may take a lot longer than those pushing digital TV may think.

Recently, News Corporation chairman Rupert Murdoch stated to reporters that he felt that a 2010 date for the UK to complete conversion from analogue to digital television might be too optimistic.

Here in the United States, there is supposed to be a deadline of 2006 for the television system to be converted to digital. That deadline will also be missed.

To discover the reason why, all one needs to do is look at the history of British television and the lengthy conversion process from the original 405-line black-and-white system to the 625-line colour system that is still the analogue transmission standard.

When the BBC first experimented with colour television in the 1950s, it was with the NTSC system developed in the United States, principally by the Radio Corporation of America (RCA).

The only concession made was that the NTSC system was modified from the 525-line system it was developed for, to the 405-line system the UK then used for black-and-white television.

The British eventually came to the conclusion that their colour system should be a 625-line system, the same number of scanning lines as the black-and-white systems through most of Europe.

Instead of the NTSC system, the UK selected the PAL system that had been adopted in most of Western Europe (except France).

Since there were too few television broadcasting frequencies on the VHF bands (barely enough for one BBC and one commercial TV service), the British decided that in addition to converting from 405-line monochrome to 625-line colour, the system would migrate from VHF to UHF.

On UHF there would be room for four television services (eventually split into two BBC networks and two commercial networks).

As to help the transition along, British regulators decided that there would be a period of a number of years where the BBC’s original TV service (renamed BBC-1) and ITV’s service would broadcast both in 405-line monochrome on VHF and 625-line colour on UHF.

The first 625-line sets were black-and-white models that came out in advance of BBC-2’s (exclusively on UHF with 625 lines) debut in 1964. Colour would be introduced to BBC-2 some time later (it turned out to be 1967).

How long did it take from the introduction of the first 625-line TV sets to the 405-line monochrome VHF transmitters being turned off for the last time? Almost twenty-one years!

It took that long for the penetration of 625-line TV sets, both colour and black-and-white, to reach a point that the 405-line service could be eliminated without causing undue hardship for viewers.

Here in the United States, the first digital-TV broadcast was on 29 October 1998 when a handful of TV stations that had setup digital transmitters transmitted a digital broadcast of the blast-off of the space shuttle Discovery which launched pioneer astronaut John Glenn back into space.

Four years later, there are very few digital TV receivers in the United States, although the number of TV stations broadcasting digital signals has begun a noticeable increase.

I’m not saying that it will take two full decades for the transition from analogue to digital in either the UK or the US.

But the timetable of 2006 for TV in the US to go all-digital and 2010 for the UK to likewise complete its conversion to all-digital is too optimistic.

For this to happen, the cost of digital TV sets – or converters to translate the digital signal to existing analogue sets – needs to go down, and go down a lot. So far, there is no indication of that happening.

A date of 2015 for the completion of the transition to digital TV in both the UK and the US is more realistic.

A Transdiffusion Presentation

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