The Parents the Kids and THE INTERACTIVE TV!!!!


Still under Construction!!



What can Interactive Television be used for?

Distance Learning

Video On Demand

Game Shows

Home Shopping

Electronic Programming Guides

Information Retrieval (Internet)



What equipment will you need?

Set Top Box

Remote Control


TV or PC?

What should you know before installing Interactive Television?

How will Interactive Television affect the family?

What lies ahead for Interactive Television?



Appendix - References

Appendix - Trials

British Telecom

Appendix - Glossary of ITV Terms


Have you ever sat down with your family hoping that there was a good film that you could watch? Have you ever felt like participating along with a game show that you are watching? Have you felt like checking your share prices or even ordering a pizza? Have you wanted to shop around in the comfort of your own home in front of the television? Have you ever felt that there were not enough channels?

Well, if you have then you would be interested in INTERACTIVE TELEVISION.

Interactive Television (ITV) will change the way we watch television by allowing you to interact with it more. There are many more services available - ITV can act as an education medium and information provider. All these services are available in the comfort of your own living room, and can be as easy as pressing a button. If your family wants to install ITV into your house, there are certain questions which your family should ask themselves. What knowledge should you and your family possess about ITV, and what sort of social/legal issues will you be facing? Before installing ITV, it is important that these questions are answered.

What can Interactive Television be used for?

There are many applications that Interactive Television can be used for including Distance Learning, Video On Demand, Game Shows, Home Shopping, Electronic Programming Guides, Information Retrieval (Internet), Voting, and Telebanking, all of which can be done very easily using a Remote Control, aimed at the TV with a Set Top Box on top of it.

Distance Learning

Interactive Television makes it possible for the whole family to educate themselves on all sorts of topics, in their own living room, at their own pace and in private. Children can learn to read, see what Saturn looks like, and they will be able to take their GCSEs, A-Levels,and even degrees. You can find out what the government is upto, take a course in DIY, take your A-levels, learn how to change the oil in your car and much more!!.

Distance Learning is learning where you, the student and the teacher do not physically have to be in the same location. You can experience presentations from teachers and specialists in selected fields of study from other parts of the world. Also, if you face problems which you cannot solve, you can post them to institutions all over the world and ask for help. [1] [2]

You will be able to see all the other students and the teacher at any moment in time in live transmissions but you can learn when you want to and at your own pace if you prefer.

Figure 1

A main concern for parents regarding Distance Learning is the possible failure to develop reading skills. In subjects such as literature, students may find it easier to watch a Shakespere play on television than actually read it. Watching is much easier than reading, because a picture conveys a thousand words. The use of images and sound (multimedia) makes it easier for people to learn and is also enjoyable. The rapidly increasing multimedia PC market is proof of this. More people are buying PCs for their social uses and to help educate their children. [3] [4]

Several experts think that Distance Learning will be available on mass scale within the next 10 years. Below is a quote from Bates A.W : (1993) Educational aspects of the telecommunications revolution in Teleteaching North Holland : IFIP [5]:

"The implications for education and training are immense; learning can be independent of time and place, and available at all stages of a person's life. The learning context will be technologically rich. Learners will have access not only to a wide range of media, but also to a wide range of sources of education"

Video On Demand

You can watch any movie at any time convenient to you. For example, if you missed the regular free network broadcast of Seinfeld last Thursday night, you could ask to see it again at any time for a small charge. The same applies to any movie, talk show, news reports, etc. [6] [7]

You can request a video and have it sent specifically to you, with VCR-like capabilities to pause, stop, rewind and fast-forward at any time. There are also plans to sell viewers "video storage space," so that they can save their home movies on a central video server and play them at leisure. At present, many of the companies experimenting with video-on-demand are using a system that is similar to ordering pay-per-view movies by telephone and receiving them on a special cable channel.

In a TCI test, Denver residents were able to choose a movie from an onscreen list of hundreds. The choice was made with a remote, and the movie played within minutes. The drawback to the system was that when a selection was made, a clerk in a TCI warehouse had to physically retrieve the movie and play it in a standard VCR. When cable services switch to digital transmission, and are able to use enhanced data compression methods, video-on-demand systems are expected to improve greatly. [8]

In addition you can choose from about 500 channels including channels such as a Movie Channel, a Children's Channel, a Sports Channel, a Shopping Channel, a cooking channel etc. (known as speciality channels) which show the same programs to all the viewers.

Game Shows

You can play games where you are a participant and not a watcher. The TV host asks you a question and you could answer using a keyboard that is connected to your Interactive Television system.

Games can run simultaneously with live football games, and the object is to predict "what is going to happen next". Players compete to be the top scorer, and send their scores in for a national ranking. In addition to sports games, game shows are a popular venue for ITV. You can play along with The Wheel of Fortune or any other game show that you want. You can even win prizes by getting a certain number of points. [8]

Home Shopping

You could order articles - ranging from supermarket items to clothes and have them in your hands the following day, ordering it by pushing a single button on your remote control, while sitting in your chair watching TV.

Consumers are increasingly choosing to shop from their homes. Many feel safer shopping from home rather than in malls/shopping centres. Most consumers feel that the sales representatives simply are not knowledgeable about the products that they sell. With ITV, you will be able to choose from catalogues which have pictures and also descriptions. Some interactive channels in the US are now offering grocery services that deliver the groceries to the consumers front door. [9]

A problem that you may face with Home Shopping is that if say, you buy a jumper by pressing the "buy" button on your remote and receive it the following day and you find out it is too small, then you would have to send it back at your own expense.

The two most popular ways of paying for item(s) is by credit-card or ecash (electronic cash). If you paid by ecash, the money (ecash) would be taken out of your account like a direct debit.

Electronic Programming Guides

With the increasing number of channels being offered, it would be convenient to select one from a list. "Channel-surfing" (or flipping through) that many channels would take quite a while if you stopped at each channel, Electronic Programming Guides will allow quick and easy scanning of current or future programming by subject (say sports or soap operas), time period or even by desired actor or actress. [10]

Information Retrieval (Internet)

You could get information on everything you want using Interactive Television. You could get phone numbers, travel guides, airline schedules, product information and even coupons for supermarkets by using a printer linked to the Interacxtive Television System. Another possibility is to browse the internet.

You can receive local and international news, traffic reports, weather, sports scores and stock quotes every morning displayed on your TV or printed on an optional letter-size printer. And instead of just providing the same old "general-purpose" news, Personalized News is tailored to you, providing news on the topics of your choice. Further, the service allows quick tracking of stocks and sports teams that are of interest to you, by providing customized details on stocks and teams that you choose. [10]


You can participate in local, regional or even national polls simply by pressing a button on the remote control. The results are quickly tabulated and shown on the screen. You will be given an individual password but problems can occur if the password is lost or is known to others.

After you have voted, and acknowledgement is sent to you confirming that your vote has been received. There is not much chance for anyone to see your vote or change it because it is encrypted but there is still a chance that someone may hack into the system!!.


Until now, payments were made using traditional payment mechanisms like regular bank-accounts, credit cards details etc.

Now you can open a special electronic cash (ecash) account to pay for services. In this system, monthly fees for a service can be transfered from your bank-account into the account of whom you want to pay. You can use this account to pay for items that you have purchased from home shopping.

Another way is to pay by credit-card. If you want to use a service, you simply send your credit-card details to the service provider involved and the credit-card organisation will handle the payment. Again encrypting, scrambling or coding of confidential information must be used. [11]

What equipment will you need?

You now know what Interactive Television can be used for, but you cannot receive it unless you have some specific equipment. The main pieces of equipment that you need are the Set Top box, the Remote Control, and the Television. You also need to be connected to a network operator providing the services that you require.

Set Top Box

This decodes the signals as they arrive from the main control centre. An important point here is the price. Prices will start from about $300 [10] for a typical Interactive Television Set Top Box but can increase significantly if you want additional facilities like Distance Learning - where you would need a video camera and a keyboard so that live transmissions can take place.

Set Top Boxes with full MPEG [12] decompression capabilities is initially expensive but there are facilities where you can rent such systems. Some companies even supply free Set Top Boxes provided that you subscribe to the channels!! [13]

Remote Control

Users need a friendly interface to find their way through all the services available to them and to communicate with the main control system. This can be done by a menu system (on-screen graphics). This allows you to select a service and then specify what particular aspect of that service you require.


In order to get the Interactive Television System at home, you can either use your existing television or buy a new one. You could buy a new HDTV which has a benefit of providing a higher resolution picture so that you have a clearer picture aswell as CD-quality sound. [14] [15]

The above equipment is just the basic equipment that you need to get services like Home Shopping, Electronic Programming Guides, and Information Retrieval. For services such as Printing out coupons you would need a printer in addition to the Set Top Box, TV and Remote Control.

TV or PC?

By now you should realise that ITV is similar to PCs in certain aspects - both offer interactive services. So, which should you choose? ITV or PC? In interactive television you have home shopping, distance learning and internet access. Personal computers have on-line shopping and internet access too. Distance learning can be implemented into PCs because they can display broadcasted programmes, just like a television. It is uncertain if PCs can offer hundreds of entertainment channels like ITV, but PCs have processors which are more advanced than those in ITV settop boxes, allowing it to create and run programmes such as word processors, databases, spreadsheets and other application programmes. ITV does not have such a feature yet. It is, however, cheaper than the PC. So the choice of a PC or TV is dependent upon what applications(features?) your family requires.

What should you know before installing Interactive Television?

Legal Issues

It is difficult for governments to carry out censorship on interactive television items. Governments face pressure from human rights groups who believe that government intervention in censorship results in the inhibition of human rights to free speech and democracy. Also, different countries have different views on censorship. Being a world wide resource, the internet allows your family to access sites from other countries which may have less strict censorship laws than your own country. Therefore, you should not expect the governemnt to censor any material you dislike. [18] [19]


When surfing the World Wide Web with Interactive TV, it is common that you may need to copy parts from certain articles or save some pictures. There are certain copyright laws which you would have to take note of.

An item is copyrighted as soon as it is written. There does not have to be a notice claiming that it is copyrighted. You are allowed to use an excerpt of an article, and it must be attributed. You must not use the article in a way that will harm its commercial value. You may argue that you are giving the article free publicity, but that is dependent on whether the owner wants such publicity.

Copyright of an item is never lost unless it is explicitly given away. Trademarks cannot be used if it unfairly hurts the value of the trademark, or if someone can confuse you with the owner of it. [20]

How will Interactive Television affect the family?

Impacts on Children

ITV can have some serious impacts on your children. There has been much debate about the amount of violence and adult material on television. ITV, with its internet connections and many specialty channels, can present more of this material to our children. Specialty adult channels can show adult programmes up to 24 hours a day. If children get access to these, it can have an adverse effect on them. Through the internet, children can see and read such material easily.

How can you prevent your children from laying their eyes on these items? We have seen how censorship is difficult to achieve in ITV. You can teach children about what is wrong to see and what is not. Alternatively, there is a device under development which will filter out material unsuitable for children from ITV programmes. [21] [22]

Impacts on communication

Interactive television is going to make available the communication services provided by the internet. One such service is electronic mail. It can be sent anywhere within a short period of time. Contacts between friends and relatives can be kept easily. [23] [24]

The Internet Relay Chat (IRC) acts like a hotline where your family can join and talk to other people with common interests. You can talk about various topics ranging from religion to tips on winning video games. There are also discussion groups where sensitive issues such as abortion and political problems can be brought up. Family members who cannot talk to their families directly can get advice from the discussion groups. [1]

One should be aware of the friends that they make on IRC or the discussion groups. It is easy to fake one's identity on the internet. People take on a different identity to make themselves more popular, or to satisfy some feelings which they cannot recieve in the real world. Of course, there are some who take on a different identity for fun, with no intention of doing harm. Butt there are poeple who change their identity to cause harm to others. We should therefore not take IRC too seriously. [25] [22]

There are dangers associated with the communication services mentioned above. Some discussion groups may discuss about adult material which is not suitable for children. Some may be spreading race hate propaganda. Newsgroups exist for people to post and obtain information on certain topics. Some internet users set up newsgroups for the sake of stirring up anti-racial feelings, or to post articles with adult material. These newsgroups can be accessed easily, and could affect your family. Again, there is little the government can do about censorship. It is up to proper guidance to minimise the effects of these material. [22]

The internet presents certain bad elements in society an alternative to to carry out their wicked trade. Web-stalkers can follow a person through the internet. They can defame a person by posting false stories on the newsgroups, or sending offensive email to the victim. As said earlier it is easy to hide one's identity on the internet. Children can also face harm. Adult material can be sent easily through email. Some adults may even pose as children, befriending other children on the internet, and then asking them out. [22] [26]

The erosion of privacy

There is a fear that interactive television could lead to a loss of privacy. In home shopping, the company providing the service has to record your credit card details to make a transaction. These details can include information about your family and your buying habits. With this information, the company will know your income, your preferences and can start sending you advertisements through emails and pamphlets regarding products which you may or may not need. Even governments try to obtain such data to check for possible cases of espionage, or just to do a survey on habits of the citizens. [27]

There are other people who may be interested in information, such as your television viewing hours, when your television is switched off etc. Hackers can find out about your family as well as your viewing habits and other personal details. Even your email can be intercepted. Intimate matters and secrets can be made known to strangers. With such information, people can harrass you on the internet, and criminals can harm you and your property. [26]

To prevent the evasion of privacy, encryption is used to protect data. Email is encrypted before sending, and data regarding your family is encrypted as well. Only people who legally have a right to view these material can have the knowledge of decryption. However, smart hackers can also have the abilty to decrypt your data. And decryption does not prevent Home Shopping companies from obtaining information about you. [26]

What lies ahead for Interactive Television?

Our Thoughts of The Future

What is the future for interactive television? With the advent of newer technologies, our programmes and applications can become more interactive. The television may not be what it used to be. Instead of a flat screen version, we may have a 3-d television, where you can view a programme at any angle you like, at a size you prefer. ITV would mean more than just being able to see and hear. Through sensory equipment, we may be able to touch, smell and even taste through ITV.

Virtual reality can play a vital role in the future of ITV. We can participate in virtual reality games in our homes. We can "go" to places, not just read about them. In education, we can participate in active learning through virtual worlds. We can take part in historic battles, or find out how a blood cell travels in the human body.

There is great potential for the development of ITV. We are not certain what the future holds for ITV, but some are certain that ITV will not merge with PCs. One of these is Bill Gates, who felt that PCs and TVs will not merge because of their different uses and technology :

"....the form and function of communications appliances such as TVs, computers and telephones will tend to remain distinct-because we use the tools in different ways." [17]

His views are shared by Jerry McCarthy, president of Zenith Sales Company:

"Television sets and computers will never become one unit. Sure, there will be more interactivity in television sets...... But we look at interactivity that complements TV viewing rather than supplants it." [16]


ITV is going to change the way we watch television. We have seen the services which are offered by ITV. These services are interactive, allowing the viewer to communicate, not only by receiving signals, but by the ability to send signals as well. This two way communication allows us to have services like video on demand, Distance Learning and Home Shopping. Internet access makes it possible for us to send emails, join in discussion groups on the internet, and to search for information.

Knowledge of the equipment required for ITV is necessary for the family. They should understand which components they would require for a particular type of application. Distance learning, for example would require more equipment than Video on demand. Knowledge of legal issues is also important if you do not want to be sued.

The divisions between ITV and PCs were briefly discussed. We feel that the main difference between these two technologies lies in the type of uses. It seems that ITV is more for entertainment, whereas PCs can be used for running programs. What you choose reflects what applications you want.

A major topic presented here is that of impacts of ITV on the family. Currently, the average person spends about 20 hours a week watching television [28]. Through ITV, we can do many things in our own homes, such as Home Shopping and Distance learning. This, together with the availability of more TV channels and Video on Demand, is going to make the number of hours we spend in front of the television much longer. We believe this could lead to families exercising less, and spending most of their time watching television. This can affect the health of your family members.

If families spend too much time in front of televisions, families may isolate themselves from the rest of the community. This could lead to the breakdown of society - where neighbours do not know one another, and seldom see one another. Even within the families, erosion of family bonding can take place. If each member of the family has access to his or her own ITV, they may spend more time on these machines instead of interacting with one another.

The power of communication through ITV cannot be underestimated. It is possible that IRC, Discussion groups and email can present new dangers to us and our children, as seen above. These dangers include web stalking, harassement, defamation and spread of offensive material. However, we strongly feel that communication through ITV can help us reach other people around the world. This is particularly useful for people who are handicapped. Through ITV, these people can interact with other people without leaving their beds. They can make friends, find out information which they require, at the click of a button. They can buy their groceries through Home shopping. In the past, these people were isolated from the world, unable to make any contact except through the window or the occasional walk out of their beds. Through ITV, they can be part of the community again.

Earlier, we mentioned that through ITV, families may spend more time in front of the TV set and less time outside their houses. Some may say that this could lead to a breakdown of society, where families isolate themselves from the rest of the community. We feel that this is not the case. Through ITV, we can still maintain contacts with our friends and neighbours. The use of email and irc makes this possible. Electronic community meetings can help to maintain relationships between community members.

Another topic discussed here concerns the type of material on ITV. One should be aware of the powers of the government concerning censorship. Since there is little the government can do, it is up to parents to teach children.

So what does the future hold for ITV. As mentioned above, we are not certain of the actual developments that might take place. But we believe that it will head in the direction of developing more interactive forms of television viewing. Features like VOD and Distance learning will still be present, except with greater interactivity.

The impacts on ITV on your family is going to be great. As ITV develops, and becomes more well defined, you can expect more families to install interactive television into their homes. Your family should be aware of the uses, equipment, legal issues and how ITV will affect you. If you have such knowlege, your family can harness the power of ITV to serve them well. It will provide a new world of communication and entertainment for your family. [29]


Appendix - References

Below is a list of all the sources that we used in the survey in order of usefulness:

Academic papers, Technical Reports, Magazine/Newspaper articles, Books





Further Details

Interactive Television : A Comprehensive Guide for Multimedia Technologists

Hodge, WW

First Issue

Publisher : McGraw-Hill Series on Visual Technology


Wired for Interactivity

Comerford, R; Perry, T

Apr 1996



The trails and travails of INTERACTIVE TV

Perry, T

Apr 1996



An introduction to interactive television

Sweeney, JOP

Sep 1995

IBC 94. International Broadcasting Convention p503-8


Interactive Television

Blahut, DE; Nichols, TE; Schell WM; Story GA; Szurkowski, ES

Jul 1995

Proceedings of the IEEE Vol:83 Iss:7 p1071-85


Video on demand - competing technologies and services

Cleary, K

Sept 1995

IBC 95 International Broadcasting Convention p432-7


Marketability and social implications of Interactive TV and the information superhighway

Cronin, G

Mar 1995

IEEE Transactions on Professional Communications Vol:38 Iss:1 p24-32


The AT&T interactive consumer video services platform

Blahut, DE; Nichols, TE; Schell WM; Story GA; Szurkowski, ES

Jul 1994

Proceedings of the 1st International Workshop on Community Networking Integrated Multimedia Services to the Home p3-10

Trials/ Development

Some legal issues raised by electronic trading

Wakefield, G; Collier, A

Nov 1992

TENCON 92. 'Technology Enabling Tomorrow' 1992 IEEE Region 10 International Conference. Computers, Communications and Automation towards the 21st Century p520-4 vol:1


Understanding how interactive television set-top box works...and what it will mean to the customer

Droitcourt, JL

Sept 1995

IBC 95. International Broadcasting Convention p382-94

Good for set-top box design

Consumer electronics

Perry, TS

Jan 1995

IEEE Spectrum Vol:32 Iss:1 p40-43

trends/ developments

Services. technology and standards for broadcast-related multimedia

Dobbie, W

Oct 1995

BT Technology Journal Vol:13, No.4 p44-54

Very Technical

Servers for BT's interactvie TV services

Kerr, GW

Oct 1995

BT Technology Journal Vol:13, No.4 p55-65

Very Technical

The Set-top box for interactive services

Bissell, RA; Eales A

Oct 1995

BT Technology Journal Vol:13, No.4 p66-77

Very Technical (BT Trials)

Broadband multimedia delivery over copper

Young, G; Foster, KT; Cook, JW

Oct 1995

BT Technology Journal Vol:13, No.4 p78-95

Very Technical (ADSL)

Web pages

Publishing on the internet:
Some Legal Protections and Pitfalls

Marketability and social implications of Interactive TV
and the information superhighway
by Cronin, G
IEEE Transactions on Professional Communications
vol :38 Iss:1 p24-32 March 1995

10 Big Myths about copyright explained

Violence on Television: The V-chip

A Background Paper

On-line Television

Dilip's Research: Social Aspects of the Web


Information and Interactive Technology:
The impact of the Information Age.

Techno Prisoners

Ask Bill:
Will TVs and PCs merge in the age of the Internet? 4/10/96

TV or PC?

Trends in Television

Using Hybrid-Coax Networks for Demand and Interactive Services
by C Carroll and W Clement
International Broadcasting Convention, 14-18 September 1995
Conference Publication No. 413 IEE 1995

"The Evolution of Cable Television to Interactive
Communications Service Provider

Interactive Systems Inc's Articles on Interactive TV

"Markettrack #2: Interactive Television, May 1994

IEEE Spectrum April 1996: The trials and travils of Interactive TV
by Tekla S. Perry

Television An International History
edited by A. Smith

Our Problem is Defining Violence: The Statistics are Frightening

Pulling the Plug on Television's Sex and Violence

The Impact of Television on Children's Education

Impact of Television Violence

Weighing the Internet: The Human Factor

Appendix - Trials

Interactive TV Trials Outside the US






Number of

British Telecom






Cambridge Cable



Online Media



Bell/Nynex/ TeleWest






Deutsche Telekom


ADSL/ATM/HFC Satellite

Alcatel Nokia IBM HP



French Telecom


ADSL, Fibre to home

Phillips, SEMA






Sony Pioneer Sagem Phillips Thompson



Swiss Telecom






Svenska Kabel TV



Digital, Vela Research



Telecom Italia



B.Atlantic, OS-9/David



Telecom Australia



CLI, OS-9/David



Hong Kong Telecom

Hong Kong

Fiber to building, ATM

NEC, OS-9/David



Israel Telecom

Two city trial


Celerity Server, David Settop



Korean Telecom



Celerity Server Samsung/David Settop



Nakano City TV



Fujitsu, OS-9/David









Singapore Telecom








DBS Satellite




The table shows details of trials on Interactive Television outside the US. We will go into detail the services provided by British Telecom.

British Telecom - BT Interactive TV [30]

BT started recruiting customers for Interactive TV, its world-leading market trial of interactive multimedia services. The trial, started last summer (1995), will involves about 2,500 customers in Colchester and Ipswich. All customers were recruited by market research to allow BT to achieve a representative demographic sample of the UK population, and a wide range of data was collected about them before service was connected.

BT Interactive TV consists of nine main services:

In addition there are two services, games on demand and Adland (an interactive advertising service). The services are ordered and controlled via a standard remote control, and delivered to a normal television over copper telephone lines for the majority of homes and over fibre to the remainder.

The aim of the BT Interactive TV trial was to find out what customers want and how much they are willing to pay for the various services.

There were two options to pay :

Summary of payment options (June 1995):

Pay and Play
(indicative price per item)

Monthly Subscription


1.50 to 3.99

(not available)


99p to 3.99



free to 1.50






99p to 3.99


See Technical Notes for a description of equipment used.

Appendix - Glossary of ITV Terms

BANDWIDTH - A measurement of transmission capacity; the greater the bandwidth, the greater the information-carrying capability of the transmission medium. Analogue transmission is measured in cycles per second. Digital transmission is measured in bits of information per second.

CABLE TELEVISION - Communications system that distributes broadcast and non-broadcast signals, as well as a multiplicity of satellite signals, original programming and other signals by means of a coaxial cable and/or optical fiber

CENTRAL OFFICE - A telecommunications facility where calls are switched. It generally represents a 10,000-line service area.

COAXIAL CABLE - Actual line of transmission for carrying television signals. Its principal conductor is either a pure copper or copper-coated wire, surrounded by insulation and then encased in aluminum. A coaxial cable is capable of carrying many TV or radio signals simultaneously.

COMMUNITY ANTENNA TELEVISION (CATV)- Association primarily composed of cable system operators with a small number of subscribers, usually less than 3,000.

DECODER- An electronic device used for converting a scrambled TV signal in a viewable picture.

DESCRAMBLER - Electronic circuit that restores a scrambled video signal to its standard form.

DIGITAL COMPRESSION - An engineering technique for converting a cable television signal into a digital format (in which it can easily be stored and manipulated) which may then be processed so as to require a smaller portion of spectrum for its transmission. It could allow many channels to be carried in the capacity currently needed for one signal.

FIBRE OPTICS - Very thin and pliable tubes of glass or plastic used to carry wide bands of frequencies.

HDTV - A television signal with greater detail and fidelity than the current TV systems used. The USA currently uses a system called NTSC; HDTV would provide a picture with twice the visual resolution as NTSC as well as CD-quality audio.

HEADEND - Electronic control center of the cable system. This is the site of the receiving antenna and the signal processing equipment essential to proper functioning of a cable system.

HOME SHOPPING - Programs allowing customers to view products and/or order them by cable television, including catalogues, shopping shows, etc.

LOCAL AREA NETWORK - Network within a building of office complex.

MULTIPLEXING - The potential transmission of several feeds of the same cable network with the same programming available at different times of the day. This is seen as one possible use of the additional channel capacity that may be made available by digital compression. Multiplexing is also used by some cable networks to mean transmitting several slightly different versions of the network, for example several MTV channels carrying different genres of music.

SATELLITE - Device located in geostationary orbit above the earth which receives transmissions from separate points and retransmits them to cable systems, DBS and others over a wide area.

SCRAMBLING - A signal security technique for rendering a TV picture unviewable, while permitting full restoration with a properly authorized decoder or descrambler.

SUBSCRIBER - Customer paying a monthly fee to cable system operators for the capability of receiving a diversity or programs and services.

TRUNKING - Transporting signals from one point (an antenna site for instance) to another point (such as a headend), usually without serving customers directly. Trunking can be accomplished by using coaxial cable, fiber optics or microwave radio.

SET TOP BOX - Any of several different electronic devices that may by used in a customer's home to enable services to be on that customer's television set. If the "set top" device is for extended tuning of channels only, it is called a CONVERTER. It restores scrambled or otherwise protected signals, it is a DESCRAMBLER.

VIDEO ON DEMAND - An entertainment and information service that allows customers to order programs from library of material at any time they desire.

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Copyright Keval Pindoria, Gerald Wong 1996