This Chapter examines current audio graphic technologies for the primary types of audio graphics teleconferencing: telewriting systems, freeze frame systems, hybrids, high resolution systems, computer conferencing, voice and electronic mail. Included are major products and services and recent developments and innovations. Other equipment that could be used as audio graphic adjuncts are facsimile, voice/data terminals, optical graphic scanners and videotext systems. Because they are not usually marketed as teleconferencing products, these devices are not discussed.

The term audio graphics refers to a range of systems that are used to produce and send graphical information over a narrow-band transmission channel. Audio graphic devices customarily use the standard telephone network or, on occasion, lower-speed (1.2 - 56 kilobits per second) data channels.

In teleconferencing applications, audio graphic systems are used as adjuncts to voice communications to provide complementary visual illustrations. This information may take several forms, including freehand sketches, paper copies of documents, stationary video images, or computer graphics. Audio graphic teleconferencing is sometimes called enhanced audio or audio plus.

While the earliest uses of audio teleconferencing go back to the 1930s, audio graphics devices did not appear as a teleconferencing adjunct until 30 years later. The entry of audio graphics devices was supported initially by the education and government sectors that saw value in low-cost graphics systems for remote instruction or information transfer. Business firms were later users, adopting audio graphics in the late 1970s for meetings among remote locations.

The types of equipment included under the audio graphics umbrella are:

• Electronic pens, tablets and boards for telewriting.

• Freeze frame (slow scan) video systems that transmit still images of objects, graphics or people.

• Computer based and integrated systems for computer graphics, text freeform annotation or other graphical displays.

• Computer conferencing for exchange of textual information and message

In many cases, an organization will employ more than one type of audiographics. In other cases, an organization will have more than one form teleconferencing using audio graphics as well as full-motion video or audio-only systems.

An important feature of an audio graphic system is its ability to use the public telephone network which provides widely available and low-cost transmission channels. When used over regular dial-up lines, audio graphic equipment provides immediate access to other compatible systems anywhere in the world.

The use of the public telephone network, however, imposes restriction particularly in the narrow bandwidth of voice-grade lines and, in some cases, t quality of the signal. Nevertheless, as the telephone network is upgraded With digital switching and digital transmission, this is changing.

For teleconferencing applications, telewriting systems (electronic pens, tablets and boards) are used to send and receive freehand messages and graphics. Freeze frame terminals transmit still video images captured from a video came or other video source. Integrated graphics systems are used to produce al transmit computer graphics, alphanumeric data, still video images, and freehand graphics and annotation.

Freeze frame video units can be used to show images of people to add "humanizing" touch to a teleconference, but their primary purpose should be transmit pictures of graphics, objects and other materials. It is, therefore considered to be an audio graphic tool as opposed to a video teleconferencing system.

The primary options in audio graphic technologies can be characterized as follows:

• Telewriting systems (electronic pens, tablets, boards)

- Freehand messages and graphics
- Transmitted over a voice-grade telephone line in real time
- Usually displayed on a monitor—Monochrome or color—Portable or semi-portable

Figure: Audio Graphics Technology Options

Tolerating products include electronic pens, tablets, and boards. They have traditionally been used as stand-alone systems to create freehand information such as words, outlines, simple diagrams and line drawings. However, there is a current trend to interface electronic tablets to freeze frame video or computer graphic systems to annotate on images and create freeform graphics.

The major limitations of tolerating systems have been display legibility, limited flexibility in generating different types of information, problems in detecting accurately the pen position, and difficulty in matching pen position to desired location on the display.

• Freeze frame video system

- Still video images of illustrative materials, objects and people
- Transmitted over a voice-grade telephone line or data circuit, usually in a number of seconds
- Displayed on monitor or video projection system
- Monochrome or color
- Portable, semi-portable or installed

In order to transmit a video image over a telephone line, a freeze frame system eliminates motion, reduces picture resolution, and transmits the image during a number of seconds. The transmission time depends on the amount of picture information and channel capacity. For instance, it can take up to 75 seconds to send a monochrome picture with a resolution of 512 X 256 pixels over a grade line. However, with the newer digital systems that are designed to be used with data circuits, a 512 X 256 image can be sent in about 15 seconds at 56 kilobits per second. Other techniques include the use of multiple memories to display receive two or more images simultaneously, or the use of a disk system to images sent prior to a teleconference.

Because a freeze frame picture is displayed as a still image, it is appropriately used for objects, graphics or other non-moving material.

The basic units in a freeze frame system are the transceiver (transmit receiver), video camera, and display monitor. Multiple cameras and monitors or large screen video projection systems can also be used, as can such per devices as video pointers, video hard copiers, and disk systems for images.

Three of the primary problems faced by freeze frame systems are time, bandwidth capacity versus display quality, and the misuse of this technology as a substitute for video teleconferencing to show images of people.

• Integrated graphics systems

- Images of alphanumerics, computer graphics, freehand graph annotation, or still video pictures (systems differ in capability)
- Transmitted over a voice-grade telephone line or data circuit time, in a number of seconds, or prior to a teleconference

Using a microcomputer or processor as a core component, these provide integrated, multi-function capabilities that include computer-generated graphics, freehand graphics, still video images, and annotation or images.

The information generated on the system is transmitted over a voice telephone line or data circuit to remote locations and displayed on a moo large-screen video projection system. In the case of freehand graphics annotation, the information is usually transmitted in real-time during the teleconference. Still video images, as in freeze frame, take a number of sect transmit. With more sophisticated computer graphics systems, the images usually created and transmitted prior to the teleconference and stores remote sites for later display during the meeting or program.

With limited bandwidth on a voice-grade line, there is a tradeoff of transmission time and the capacity to send images with high resolution, color and detail.  Freeze frame video and integrated graphics systems, therefore better performance when used with data circuits.  Another alternative is to send the images ahead of time and store them at the receive site until needed.

One of the primary advantages of audio graphic systems is that they can use regular dial-up telephone lines to send and receive visual information. With millions of telephones in the world, voice circuits extend to virtually every part of the globe.

As discussed earlier, however, the narrow bandwidth of a dial-up, voicegrade line presents a tradeoff between image quality and transmission time. Channel impairments, such as noise, echo, and loss can also distort image information during transmission, creating drop-out or "noise" on the display.

Some users, particularly those with computer-based or freeze frame systems, may opt for private lines that have better transmission quality and, in some cases, more bandwidth. A variety of private-line services are available, including full-duplex analog circuits that are voice-grade or data-grade and digital circuits that operate at higher transmission rates.

The type of telecommunications service chosen depends on user requirements. Considerations include image content and quality, transmission time, site locations, level of teleconference usage, cost and system compatibility. Users must also determine if they should have separate transmission channels for voice and images. To be able to talk and transmit graphics simultaneously, two channels will most likely be needed - one for voice and one for graphics.

Teleconferencing should also be considered in a total communications context. Some organizations may need or already have private transmission channels for data communications that could also accommodate teleconferencing.

In general, transmission options currently available for voice and data are:

1. Dial-up, voice-grade telephone lines, usually the equivalent of up to 4800 bits per second.
2. (2) Private analog service with either voice-grade or data-grade channels up to 9600 bits per second.
3. (3) Private digital service at lower-speed data rates, usually from 2400 bits per second to 56 kilobits per second.
4. (4) Private digital service for high-speed transmission, usually up to 1.544 megabits per second; that is, a T1 carrier.
5. (5) Packet-switched service for data communications, usually on public networks operated by value-added carriers.

Many of the newest services show the merging of voice and data communications. With T1 carriers for wide-band digital services, a single channel can be used for integrated voice, data and video. It can include combinations of voice, low and high-speed data, graphics, facsimile, electronic mail, and video conferencing.

Another option is switched 56-kilobit service that allows users to send voice, graphics, data or compressed video over a dial-up telephone line.

Recent developments that affect voice and data communications and, therefore, audio graphic teleconferencing includes the following:

• The introduction of new bridges to interconnect multiple locations for audio graphic teleconferencing. The future will also see commercial bridging services offering bridging capabilities for audio graphic teleconferences.

• The expansion of long distance telephone services and the entry of new market to provide voice and data communications.

• The availability of switched 56-kilobit service over dial-up telephone lines.

• The growth of multi-tenant shared services that provide enhanced voice, data and video services to tenants of office buildings, including audio teleconferencing, electronic mail, facsimile and so forth.

• The availability of fiber optic networks to expand telecommunications capacity for voice, data, and video.

• The availability of wide-band digital services for high-volume voice, data and video communications.

• An increase in satellite transponder capacity and improved access to satellites from urban areas via teleports.

Like other forms of teleconferencing, use of audio graphics reflects the specific needs of each organization. Systems range from a rather simple application of audio and facsimile using and internal switchboard linking a small number of locations to one that has over a dozen teleconference rooms outfitted with an array of audio graphics equipment.

Audio graphics systems generally are used for the same types of applications as audio teleconferencing - administrative and staff meetings, problem solving, information updates, and training. There is a tendency, however, for some audio graphics systems to be employed in more technical areas such as research and engineering.

It may be tempting to assume that the addition of a visual element would be advantageous to almost all teleconferences. If audio is good, would not audio plus graphics be even better? That assumption raises important questions about when and how to apply audio graphic systems.

As relatively low-cost adjuncts to voice communications, audio graphics can provide a visual representation of ideas to illustrate or clarify a point, direct attention to a detail, demonstrate words and numbers, or show relationships and trends among data. If used inappropriately, however, they may add nothing to the communication process and even detract from the verbal message by creating confusion or misconception. The application of audio graphics, like all teleconferencing technologies, ultimately depends on communication needs and information about how to use a system effectively.

In matching audio graphics technologies to user applications, several important factors need to be considered:

• Resolution. Do documents contain a great deal of detail - complicated text, charts, drawings - that would require in-depth explanation, careful modification or instant approval? In this case, higher resolution would be necessary to assure the exact image at every participating site. If documents are less complex, then resolution might be compromised in favor of other features.

•Bandwidth options. Is it important to have instantaneous exchange of information? If it is, then a dial-up 56-kilobit network would be the solution.

Take for example, NASA's use of audio graphics when launching space shuttles. The "go/no go" decisions that launch space shuttles with "mission critical" documents are made using audio graphics teleconferencing between Cape Canaveral and Houston. The NASA network includes 23 sites that are linked via standard telephone lines that are part of a dedicated 56 kilobit network. Transmittal of these critical documents can occur in just seconds with audio graphics teleconferencing. The result? NASA’s Launch Systems Evaluation Advisory Team can advise the Mission Management Team whether or not to go ahead with a launch when weather or environmental conditions are questionable.

If immediacy is not so critical, then a transmission medium that results in a delayed exchange could be the answer. Additionally, many organizations will opt for using a regular, dial-up telephone circuit for audio graphics and will send and store documents or graphics before a scheduled meeting or session, recalling each just as if using a view graph or slide.

• Reliability. What is the track record for the specific type of audio graphics equipment you are considering? Is it proven and will it be reliable when you need it? What is its maintenance record?

• Number of locations or sites. How many sites do you need to link together? Today, special digital bridges are appearing to be used in audio graphic teleconferencing. (Not all audio teleconferencing bridges will accommodate audio graphic conferences.) The bridge you choose - for in-house or as a commercial bridging service - needs to support the number of sites that comprise your network.

• Facilities and staffing. Will you dedicate special room for audio graphic conferences, provide portable units to be used in any environment or do you want to support desktop audio graphics conferences? The answer to this question will dictate the type of audio graphics equipment you choose. Staffing to support the use of audio graphics conferencing can be as simple as delegating to one or two I individuals the additional responsibility of being a "key operator" who is well-versed in operation and troubleshooting, or a full-blown staff of many individuals who can support a complex, multi-faceted network and its operation.

• Usage. Should you designate and design a room especially for audio graphics teleconferencing or can any existing facility be used, including individual offices? The amount of use an audio graphics system gets will dictate how a system should be established -- in permanent facilities or as a flexible, portable system that might be used in any environment.

• Maintenance/Service. The customer service and support of any audio graphics equipment or system is an important consideration. The type of services that an audio graphics vendor offers to stand behind their equipment might include tutorials, on-line user training, user conferences, newsletters and special consultations with technical personnel. Maintenance programs are also available in which full warranty coverage is provided for a specified period of time, or other options might be on a time and materials basis. Typically, vendors will supply loaner units while equipment is being repaired.

• Cost. The range of costs for audio graphics is divers. For a simple electronic tablet with accompanying software for audio graphics teleconferencing, the cost would be approximately $2,000. Mid-range systems cost between $4,000 and $12,000, while high-end, fully integrated audio graphic systems cost about $34,000.