Digital Television: the beginning of the end

Jose Maria Caro (Editor: Veronique Autphenne)

Through the Internet we already are able to use some new kind of interactive communication systems where we can be both consumers and producers of information at the same time. That is why some experts desire that television (our main source of information and entertainment) must find a way to integrate with all the incoming emerging communication technologies.

Digital Television (DTV) can be defined as the transformation of an analog signal into numeric data (sequence of bits). The signal is encoded in a binary form, which bits are zeros and ones (0-1-0-0-1-1-1-0) which are the minimal units of information that computers work with. As any analog signal, the new digital signal also varies in time and amplitude.

These new sequences of numbers are extremely big (a video image has a lot of information). ‘The bandwidth of a digital signal can be approximated as the bit rate divided by two’ (Noll 1998:5). Considering that a digital signal has a bit rates of 64,000 bits per second, it needs a lot of bandwidth. Also, a digital signal needs a bigger bandwidth in order to reduce the noise and the limitations of the communication channels.

In order to be able to transmit a digital signal, it needs to be compressed into a smaller signal. Once the signal is compressed and scrambled, it is sent to our homes in many different ways: aerial, satellite or cable. There, it goes through a terminal (set up box) which descrambles and decompresses it, letting the users to select the channels they want to watch in their TV sets.

That is why the networks are already preparing themselves to start transmitting in digital; the Federal Communications Commission (FCC) has established that by year 2007 all commercial stations must be broadcasting in digital. This is why a switch to Digital Television is more a must than a need that broadcasters have to do in order assure themselves a good place in the market.

The biggest problems for those stations are the price of going digital and transitioning the market to this new technology. The average cost to switch to this new technology can vary from $8-12 million dollars, depending on the station. Public broadcasters seek to receive around 45 per cent of the cost from the federal government. It is a fact that people won’t start buying digital TV sets unless they are able to receive full digital programming through them. Also, many experts don’t expect the change from old TV sets to new digital sets will happen in less than ten years, so it is going to be very hard for broadcasters to achieve a transition by this date.

There are already some public and private stations that are offering digital channels. Public station KCTS, in Seattle, started transmitting in January 1997. In the Los Angeles area KNBC, KTLA, KABC and KCBS have compromised to start digital broadcasting by 1 November 1998.

Most of the techniques used in direct broadcast satellite television, like compression, may be also used in DTV. In the United States some direct broadcast satellite television providers are DirectTV, PrimeStar, and EchoStar. In Europe, most satellite TV is provided via digital transmission. British BSkyB, French Canal + and Spanish Canal Satelite Digital and Via Digital are some of the most important platforms that offer digital programming. Some specialists think that might be the final use of DTV, the creation of a network of satellite broadcasters offering their programming to the entire planet.

Digital Television also offers many technical, economical and consumer advantages. Due to the use of data compression, DTV accomplishes a much better use of the bandwidth, so it offers the possibility of having more channels in the same amount of space. Now they can fit around four TV channels where before there was only room for one. The bandwidth of a TV channel is 6 MHz and a compresses digital TV signal only takes 3Mbps. Therefore, it is possible to fit four digital signals into one single channel (Noll 1998).

Digital transmission of information (whatever formats is used) is argued to be better quality, simpler, faster, economical, and multifunctional. It also offers much more security and helps to avoid theft of service.

Once Broadcasters become fully digital, the cost of putting a TV channel on the air will drop. This, together with the possibility of increasing the number of channels, opens the door for new and more specialized channels for minorities as well as for new sales windows for content (Video On Demand, Near Video On Demand, Pay Per View, etc.).

Because of cost will get lower, interactivity, data transmission (e-mail) and access to the Internet (two-way communication) through the digital television system will get easier and more feasible.

Two main applications of DTV are being discussed in the U.S.

HIGH DEFINITION TELEVISION (HDTV): this variation of DTV offers a much higher quality in both, sound and image (1,125 lines of resolution - the actual NTSC standard has 525 - and CD sound quality). It also offers an aspect ratio similar to the one used in film theaters, 16:9. The two biggest problems this new standard is going to face are compatibility with actual TV sets and bandwidth size. The amount of data that a HDTV signal has is so big that it occupies a whole channel by itself.

STANDARD DEFINITION TELEVISION (SDTV): this standard refers to ‘a digital television system in which picture quality is approximately equivalent to the current NTSC television System’ (PBS Engineering Committee 1996). This way, users (both audiences and programmers) can enjoy a greater variety of channels in the same spectrum space.

It is also important to say that digital technology is the best storage medium available for any king of content. By controlling the noise, a digital signal can be recovered easily without any degradation over time.

Do consumers really want or care about the move to digital? Do they really want to see television on a computer or vice versa? Are they really prepared to handle all the possibilities it offers? Would they be willing to pay enormous amount of money to watch higher quality images? Is it possible that the switch to digital is just being forced by an industry that is desperate searching for new resources to get more revenue and trying to have more control on consumers tastes and needs? That seems to be the right answer.

When the FCC gave the first digital channels to the broadcasters its idea was that they were use for HDTV. Finally, and after getting a lot of pressure from the broadcasters (most of them joined together in what is called ‘The Broadcaster’s Cactus’), the FCC agreed to let them choose whether they want to use the channels for one HDTV channel or for multiple SDTV ones.

As expected, most broadcasters have chosen to second option. This way they will have a bigger offer, a stronger position in the television industry and more advertising slots to sell. We must be aware that content is getting more expensive and producers want to recover their investments earlier. In other words, broadcasters are the only ones interested in going digital. Its survival depends on it.

After a long wait, on 18 February 1998, the FCC finally assigned 1,600 more digital channels to the broadcasters. This way, broadcasters have a second digital channel, which they can use either for HDTV or SDTV. With this new assignment most channels, like KTLA, will increase their digital coverage in about 5 per cent and there will be less room for interference among the different channels. In other words, 5 per cent more of the population of Los Angeles will be able to reach those channels, and they will have better quality and less noise.

Knowing that the digital spectrum is worth billions of dollars, Congress decided that broadcasters should give something in exchange. By the end of 1997, the White House took the position that broadcasters should give more free television space to politicians in return for the new channels. This way, parties are getting more free advertising time for their campaigns, so their money needs for the campaigns is smaller and the chances of illegal fundraising fewer.

Plus, The White House thinks of DTV as a way to support other American industries, like the computer manufacturers. If television and computers finally converge, as it may happen with digital television, computers manufacturers could start introducing themselves into the TV sets manufacturing market.

Standards were and still are a big problem to solve. During the early nineties there was a lot of competition to develop them. It wasn’t until 1995 that PBS finally completed the DTV Standard, and it was in December 1996 when the FCC adopted the definitive digital transmission standard for terrestrial broadcasting.

Still, the biggest problem DTV has is that it is not backwards-compatible with the actual broadcasting system. From an international point of view standards are also a problem. The American standard has to share the market with the Japanese and the European one (DVB: Digital Video Broadcasting). These three standards are not compatible so, if the main goal of digital technology is to give users both more access and more content, it is mandatory to develop a Universal Standard so the whole planet can benefit together of this technology and can share the programming.

According to the studies DTV has a great future: 95 per cent of households have TV sets and once all broadcasters become fully digital, these sets shall must be also digital. Good deal, don’t you think?

It is true that this technology will also have positive things. At least that is how broadcasters are trying to sell it. Video on Demand is an example: here, people will be able to choose the programming they want to see and manage it as if they were using a VCR.

Digital technology will also bring the TV and computer closer together. In other words, people will have access to TV channels through their personal computers and vice versa (-Web TV-). This way we could get the universalization of content which allow the audience to select whatever shows, movies, data, etc. they want to work with or enjoy from an extremely large number of digital databases located all around the world.

A FEW WORDS ON COMPRESSION TECHNOLOGY: VIDEO DIGITAL

Any system based on the digital technology is based on digital data compression. Once an analog TV signal is captured it produces such a large amount of data that it would require a bandwidth that would make transmission very hard to achieve. That is why information gets compressed: a digital compressed signal saves from four to twelve times more space than an uncompressed one.

To make compression possible, broadcasters use an International Standard called MPEG 2. The Moving Pictures Expert Group (MPEG) is an association belonging to the International Standards Organization that creates and defines standards for digital video so data around the world gets compatible even under different systems.

MPEG compression makes use of several characteristics of video signals in order to increase the quality of the transported signal and to reduce its bandwidth:

Redundancy: MPEG compression takes away any repeated frame to reduce the size of the signal. Once the signal gets decompressed the system rebuilds those frames and puts them back into their original position.

Motion Prediction/Uniformity: the system eliminates redundancy within a single frame.

It is important to point out that MPEG compression also takes advantages of the properties

of human vision (lower sensitivity to high frequencies of luminance and chrominance).

DIGITAL ASSIGNMENTS

Source: Stern and Richmond 1998:34.

This figure indicates the channels the FCC has given to broadcasters and the percent of population the different channels will reach.

Baldwin, T., McVoy, D.S. and Steinfield, C. (1996) Convergence: Integrating media, information & communication, SAGE Publications.

Bhatt, B., Birks, D., and Hermreck, D. (1997) ‘Digital television: making it work’, Spectrum 3.

Kuhn, M. (1996) ‘The new European digital video broadcast (DVB) standard’: online. Available FTP: ftp://ftp.informatik.uni-erlangen.de/pub/multimedia/tv-crypt/dvb.txt.ftp://ftp.informatik.uni-erlangen.de/pub/multimedia/tv-crypt/dvb.txt.

MPEG FAQ, ‘The MPEG Standard’: online. Available HTTP: http://www.gti.ssr.upm.es/~vadis/faq_MPEG/mpeggeneral.htm.

Noll, M. A. (1997) ‘Digital television, analog consumers’, Telecommunications, September.

Noll, M. A. (1998) ‘The digital mystique: a review of digital technology and its application to television.’

PBS Engineering Committee (1996) ‘ATV transmission planning questions for public television stations’: online. Available HTTP: http://www.current.org/atvfaq.htm.

Stern, C. (1998) ‘L.A. gets digital break’, Daily Variety, 18 February.

Stern, C. and Richmond, R. (1998) ‘FCC unveils digital TV assignments’, Daily Variety, 19 February.

Stevens, E.L. and Grover, R. (1998) ‘The entertainment glut’, BusinessWeek, 16 February.

(1997) Canal Satellite Digital: online. Available HTTP: http://www.csatelite.es.

(1997) ‘Modelo y agentes de la television digital’: online. Available HTTP: http://www.gtic.ssr.upm.es/soci/regulaci/tvdigital/modtvdigit.htm.

(1997) ‘Public TV and the transition to digital broadcasting’: online. Available HTTP:

http://www.current.org/atv1.html.

(1997) Via Digital: online. Available HTTP: http://www.viadigital.com.

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