Digital Television - DigitalSuperhighway

Digital Broadcasting officially began with the launch of Sky's digital satellite service on 1st October 1998. Describe from a technological point of view the benefits of digital transmission and discuss whether the technological advantages translate into benefits for the viewer.

We have been confined to 625 line television sets for almost 30 years now, the same low standard as when colour was first introduced to Britain. Now we are on the verge of a new digital age... "In allowing much more information to be transmitted, digital television will offer more choice, sharper and clearer, cinema quality widescreen pictures; improved CD quality sound; on-screen electronic programme guides and interactive services"(1).

My intention is to consider all the claims about this 'new' technology and to evaluate whether or not it is of our advantages to change our technology to accept digital transmissions. It is not only Sky who are, or will be broadcasting in digital; terrestrial and cable service providers also intend to utilise this technology. So if we are changing, which service should we change to? According to those who would have us invest in this latest craze, digital promises the earth. We need to evaluate why digital is better, which system we should change to, what advantages digital television will bring and at what cost. By the conclusion we will have seen, in terms of technology and genuine innovation whether or not digital will succeed and if it does what benefits it will ultimately pose.

At the launch of digital television in Britain, three incompatible systems (2) are vying for the market, all with their respective advantages and disadvantages. Digital television is being billed as the advancement of a new technology for television viewing, not a fundamental change in our viewing as a whole. In 1964 the 625-line standard of television was introduced to an audience of 405 line viewers. The two systems were incompatible entirely. To complicate matters further, in 1967 colour was introduced on the 625-line standard only. Duel standard televisions were needed to view all the channels available and if you'd wanted to keep up with all the available technology you would have needed to buy three sets in five years.

Is the situation different now that after 30 years of having relatively stable technology we would have learnt not to make the same mistakes again with the launch of digital television? What the staggered change situation of the 1960's highlights is that it is the consumer who is going to be the most affected by the change, who might need to change technology every couple of year to keep up. Nevertheless, it seems as though as a nation we will be moving towards digital television. As the Telegraph pointed out, "Government research suggested that the analogue frequency could be switched off in 10 to 15 years' time" (3). We are on the brink of the age of a new technology, one that it seems we will be forced into getting eventually at least. So we must ask the question, why is it so much better?

In any system which uses electronic signals noise (4) is an inherent problem. An elimination of the problems of noise is one of digital television's greatest strengths. Analogue signals are exact representations of the original information based on the amplitude or frequency of the original signal. A digital signal is comprised of a binary series formed into a series of Bit's, which is the encoding that goes to make up the signal. Essentially this is a series of 1's and 0's or 'on's' and 'off's' that make up chains of a specified length, which represent (through encoding) the transmission.

Signals & Noise

In the diagram the red represents the noise. It is clear to see that the analogue signal becomes less clear as its shape is distorted by the noise. Yet it would take a great deal of noise to distort the digital signal so much that its signal would not be intelligible to the receiving equipment. For every degree of noise, which affects an analogue signal, it gets worse. This means that even a relatively damaged digital transmission will still be viewable perfectly by the audience, whereas the quality of an analogue signal is variable. Moreover, there will be no need to tune a digital signal as the signal can be sent on a single frequency.

Although this is a great advantage of digital television transmissions, most people in Britain receive a quality of picture under analogue transmission that is at least as good as the digital counterpart. It is true that for some of the population digital transmissions will improve viewing quality, but this is certainly not a majority issue. Perhaps then we should look to the Americans, who as Gerry Kaufhold pointed out (5), are tying in digital television with HDTV (high definition television). If digital television aims to improve our viewing quality (and by this I mean technologically, not culturally) it would seem that this would be a better way to sell digital television to the public. The greatest advantage for the viewer of HDTV is that televisions could get bigger. Already any television set over 29" begins to show the problems of a low resolution as the human eyes can see the lines which make up the picture.

One of the great selling points for digital television is the greater amount of channels that we will be able to receive. In their post-launch documentation SkyDigital (6) have been able to claim 11 movie channels alone. Pre-launch the Telegraph (7) spoke about 200 channels being available. The reason that all of this is now possible is due to the fact that in terms of bandwidth, digital transmissions are less costly than their analogue counterparts. This reason for this is that digital signals can be compressed (8). There are some fears, though, that compression techniques may reduce the quality of the picture, especially for fast moving images (such as in action films or sports). This problem was particularly prevalent on LaserDisc (a digital film medium). It's quality was unsurpassed by video tape except when there was a great deal going on on-screen. At this point the picture seemed to blur slightly as a result of poor compression techniques, which ruined the audiences' viewing - people fear the same about digital television.

High Definition Television

The image on the right is a 'mock-up' of how HDTV will look when it is released (9).

Because of compression it seems that HDTV is just around the corner - formerly, in terms of bandwidth, it was prohibitively expensive. The BBC for instance are now filming, almost exclusively, their material which has a long-term shelf life in widescreen (indicating that they are expecting a change in our current television format - HDTV is expected to be entirely widescreen). However, HDTV is expensive. For a start it will mean a change in our viewing technology and the sets are more expensive (Wired magazine quotes prices for US sets from $2,800 to $8,000 (10)). Although the prices will be reduced from these unrealistic heights, there is no getting around the fact that HDTV will cost. Moreover, it will cost in terms of bandwidth too as for a few years at least transmissions will have to cater for both HDTV and our usual 625 line pictures.

Certainly it seems therefore that in the immediate future there are going to be problems implementing the technological side of digital television. In this type of scenario it would seem as if the real loser would be the viewer. However when there was technological upheaval in the 1960's the public managed to compensate by renting rather than buying (indeed this is when companies such as Radio Rentals evolved). So perhaps we can consider that in spite of all its inherent teething problems, this technology will mature to the point where it is considered entirely beneficial (as 625-line colour television is today). Yet this is not the whole picture. Initially, at least, the digital television provider are trying to sell digital television to us for a variety of reasons. Yet perhaps it is best to look at the future to see why we are beginning this transition now.

Professor Patrick Barwise and Dr. Kathy Hammond have taken a look at the long term future (11). They do a 'case-study' of a family in the future (2010), looking at how they live in a developed digital home. One of the things that we notice is that they speak of an H-COM. This device is akin to a home computer network that is connected to an advanced version of the Internet and to television service providers. The technological advances of digital television are part of the means to shaping this 'fantasy' world.

The key to this world can be unlocked by examining the differences between the three types of digital service. In terms of bandwidth terrestrial digital television is much worse off than its cable and satellite counterparts. It will have around 30 channels (12) in 625 line PAL format (Phase Alternate Line - the standard that we already use in Britain). In a long term view of HDTV and many channels DTT (Digital Terrestrial Television) must be seen as merely an interim solution to getting people to 'upgrade' to digital. Of the other two methods of receiving digital transmissions (DSat - Digital Satellite - and Digital Cable) only one of these is truly a two-way system. Cable will be (when it launches in 1999) the only digital transmission technology that is inherently two way. SkyDigital are also planning a two-way network, using the existing telephone lines by building a modem into their 'set-top-boxes'. "Open..." will begin their service alongside Sky's own digital service in the spring of 1999 to provide Sky with a means of having two way communications.

Today the Internet allows us to download or stream (play as the signal is transmitted to you) music or film as we order it. The quality is relatively poor due to a lack of bandwidth and very crude compression techniques being implemented. The Internet allows us to home shop. The Internet is a source of information and computer connectivity. Essentially it is a network of sorts. We've examined all the 'advantages' of digital television, which will be implemented over the next few years at least. Yet the fact that digital television is being connected with interactive television belies the greatest technological advantage of digital television. Digital television and computer will speak the same language - binary; digital electronic signals. The H-COM shows that the 'digital revolution' is at least being thought about. The fact that Sky and Cable both plan to use two-way transmissions show that it is not just being thought about, it is being implemented. This is not the distant future. "Open..." will begin its service in spring 1999! The greatest advantage for the viewer of digital television is that it is the means to allow television to be replaced by a system that is a convergence of the Internet and Television. Films will be able to be ordered and paid for directly controlled by the viewer. Advertisements could be more interactive (you could visit the web page of a product that you like) and tailored (13). If your television is to be considered a two-way device, not just a receiver of transmissions, then it can tailor what the viewer receives, even to the detail of shopping tastes.

If the above all sounds very far fetched, the recent movements of Microsoft should be able convince the sceptic of the real advantage to the viewer made possible by the technology of digital television.

"Mundie himself met with Perlman and had what he describes as 'an epiphany': the realization that he and Perlman had virtually identical visions of how digital television would emerge. Mundie spoke to Gates and to Paul Maritz, group vice president for platforms and applications; within weeks, Microsoft bought WebTV in a $425 million deal." (14)

Microsoft certainly consider that digital television and the Internet are intimately linked, or at least enough to spend $425 million to be a part of that possibility.

We have looked at digital television from an immediate point of view. October 1st 1998 was not just the beginning of better quality television, or more channels though. It seems that in the current hubbub of press releases and digital hype the companies have very little to sell digital television on at present. It's not so radically different to current analogue Satellite or Cable and if we hold with commentators such as Kaufhold (15) the next few years won't be television heaven, but will be a period where digital television irons out its problems.

October 1st 1998 might well be seen in the future as the beginning of the 'digital revolution' in Britain though. It seems as though there must be better reasons why the government are 'forcing' the public over to digital television, rather than "great pictures, great sound and more widescreen movies" (16). There must be better reasons why huge multinational companies such as BSkyB and Microsoft are spending huge sums on digital television other than, "an on-screen guide (which) will show viewers what programmes are on now and next on all channels, without interrupting their viewing" (17). It seems as though perhaps Barwise and Hammond's predictions might be nearer the mark with their 'fantasy' view of the future. Ironically digital television looks like it will mean the end for television as we now view it. The technology doesn't seem like it will be used for mere television, but for a more interactive television where our content is tailored individually. And does this translate to a benefit for the viewer? The unsatisfying answer is that only time will tell. Yet it seems as though digital television will be happening and it seems as though it will be a very important evolution that converges two of the most important technologies which we have today - the computer and the television.

Notes