Teleconferencing System Options

This Chapter examines the current status of teleconferencing technologies for audio, audio graphic, and video systems. It defines the common factors that contribute to a shared definition of teleconferencing, presents an overview of the primary forms of teleconferencing technologies, and explains the three basic technical components that are found in any type or size of teleconferencing system. It also briefly discusses various applications or uses for teleconferencing within business, education, and government. In this book, however, specific applications are not covered since its purpose is to provide a basic understanding of the different teleconferencing technologies and to help match the right technology with the great diversity of applications that are possible with teleconferencing.

A Working Definition of Teleconferencing

The term, "teleconferencing," refers to two-way electronic communications between two or more groups, or three or more individuals, who are in separate locations. In order to interconnect people, teleconferencing systems use telecommunications channels that range from regular telephone lines to satellite links. The only requirement is that the medium be interactive, giving people at each location the opportunity to actively participate in the meeting or teleconferenced session.

We use teleconferencing as an umbrella term to cover all forms and types of conferencing activities; that is, audio as well as video, and as long as it meets each of the elements in the above definition. Any form of teleconferencing also has several common technical factors which are detailed next.

Teleconferencing Options

Audio teleconferencing is voice-only communication. It links people in remote locations via ordinary phone lines. Audio systems include telephone conference calls as well as more sophisticated systems that connect many locations via a central bridge that ties all the lines together.

Although audio teleconferencing lacks a visual dimension, it has some important advantages:

    • It uses a readily available and familiar technology - the telephone.

    • Transmission services are widely and easily accessible.

    • It is relatively inexpensive to use. And,

    • It can interconnect large numbers of locations in two-way sessions.

This Primer looks at each form of audio teleconferencing from simple operator-assisted conferences to the more complex forms in which a teleconference bridge is necessary and the public switched telephone network is used. No matter what the situation, the user must have some type of station equipment (portable or semi-portable speaker/microphone equipment), or there must be a permanent teleconferencing room.

The term "audio graphics" refers to systems that use narrow-band telecommunications channels to transmit visual information - graphics, alphanumerics, documents, video pictures - as an adjunct to voice communication. Other common terms are"audio plus" or "enhanced audio."

Audio graphic systems offer two primary advantages:

    • The flexibility and economy of using telephone lines or other narrow-band media. And,

    • The ability to transmit written, graphic, and print information to supplement audio interaction.

Audio graphic technologies include an array of end-user devices that are employed as teleconferencing tools: personal computers, electronic tablets and boards, freeze-frame video terminals, high resolution graphics systems, facsimile machines, optical graphic scanners, videotext systems, and voice/data terminals. Additionally, computer conferencing is now typically falling under the audio graphic area, and it too will be covered in this section. Facsimile is often used to transmit documents in connection with a teleconference, however, it is considered to be a general office product and is not marketed for teleconferencing per se.

A special note here about computer conferencing which, today, is considers part of the audio graphics conferencing options. While voice communication a vital shared element in audio, audio graphic, and video systems, it is absent from computer conferencing. Computer conferencing is a means by which mar people can communicate with each other through computers that are links together. These conferences are not bounded by space or time. Users can control the pace of their communications, choosing when and to what degree they wish to participate in a conference.

The transmission services most often employed for audio graphic teleconferencing are regular dial-up telephone lines, where one line is used for audio and one line for graphics; and private full-duplex networks of either voice-grade 4 data channels. As in multi-point audio conferencing, a bridging device is also required to link multiple locations for an audio graphic teleconference.

Video conferencing combines audio and video media to provide both voice communication and full-motion video images. The displays may be of people objects, graphics, video tapes - virtually anything that can be captured by television camera or fed from another video source.

The major advantage of video conferencing, in comparison to audio or audio graphics, is the ability to display moving images. The most common application is to show pictures of people. For many users, this ability creates a social presence that resembles face-to-face meetings (in teleconferencing, this is called continuous presence) and enables conferees to see the facial expressions and physic demeanor of remote participants.

The two primary forms of video conferencing are compressed video using digital transmission circuits and full-motion video using broadband analog channels (this includes one-way broadcasts as in business television as well two-way, full-motion video).

Compressed video is most often used for long-haul communications via prim or shared satellite channels. Broadband analog video is common for business television applications and for local or regional networks that employ microwave or cable. The end-user equipment of cameras, monitors or large screen projectors, audio systems, and accessories may be installed in a permanent video conferencing room or integrated into a transportable unit called a rollabout.

Admittedly, we have just provided a thumbnail sketch of each type of teleconferencing system. The details are left for subsequent chapters where we will bring in the props, roles, scenarios, and technicians. First, however, we want to do a bit more stage setting by looking at some general applications of teleconferencing and examining major issues affecting its growth.