A Teacher's Guide to Distance Learning

Video Technologies

The ability to see and hear an instructor offers opportunities for behavior modeling, demonstrations, and instruction of abstract concepts. Video techniques for distance learning are often characterized by the transmission media (videotapes, satellites, television cables, computers, and microwave). Each of the media can be described as it relates to the direction of the video and audio signals -- one-way video; two-way video; one-way audio; and two-way audio (see Figure 11).

Diagram showing video technologies.

Figure 11. Three audio and video configurations.

Videotape and DVD

Videotapes and DVDs offer popular, easy-to-use formats for instructional materials. Almost all students have access to a videotape or DVD player in the homes, and they are also common at school. Videotapes and DVDs have several advantages for the delivery of distance learning. In addition to easy access to the hardware, the tapes and discs are quite inexpensive. If a video camcorder is available, video is relatively easy to record (although professional staff and equipment provide in a much better product than will an amateur production team). Disadvantages of videotapes and DVDs include the fact that they are not interactive. In addition, they can be costly to send via the mail.

Satellite Videoconferencing

Full-motion video teleconferencing (referred to as videoconferencing) offers the "next best thing to being there." Satellite transmission is one of the oldest, most established techniques for videoconferencing. In most cases, satellite delivery offers one-way video and two-way audio.

Two sets of equipment are needed for satellite systems. The uplink (a large satellite dish) transmits the video and audio signals to the satellite. The downlink (a small dish antenna) receives and displays the signals (see Figure 12).

Satellite Videoconference diagram.

Figure 12. Configuration for satellite videoconferences.

When satellite videoconferences are used for distance learning, a studio classroom must be properly wired for the lighting, microphones, and cameras needed to produce an acceptable lesson. The cameras are usually connected to a control room, where one or more technicians control the signals. The resulting television signal is then sent to the uplink transmitter. Uplink transmitters are very expensive and are often shared with other schools or businesses.

The receiving sites of satellite videoconferences (in most cases other schools) must have satellite downlinks. These dishes select, amplify, and feed the signals into the classrooms, where they can be displayed on standard television monitors. To provide two-way audio with interactions from the remote classrooms back to the teacher, a telephone bridge is usually employed.

Satellite videoconferencing can be very expensive. It may not be cost-effective for most school systems to use uplinks to originate distance-education classes unless the school systems were in a position to market the classes over wide geographic areas. It is reasonable, however, for a school to use a downlink to receive commercial courses that are delivered through satellite channels.

Microwave Television Conferencing

Satellites are a popular method for enabling video communications over long distances. Microwave transmissions provide a cost-effective method for videoconferencing in more localized areas. Most microwave systems are designed to transmit video signals to areas that are not more than 20 miles apart (see Figure 13).

Microwave Transmission diagram.

Figure 13. Configuration for microwave transmission.

The most common microwave systems use frequencies that have been designated by the Federal Communications Commission (FCC) as Instructional Television Fixed Service (ITFS) stations. When compared with satellite or commercial broadcast television, ITFS stations operate at a lower power, and the transmission equipment is relatively inexpensive. Reception equipment is also reasonably priced, as long as the receiving sites are located within 20 miles of the transmitter and there are no hills or tall buildings to block the line-of-sight signal.

One drawback of microwave ITFS communication involves the limited number of channels available in any one area. Many metropolitan areas already have all available channels in use, so no further expansion of ITFS teleconferencing is possible in these areas.

Cable and Broadcast Television

Cable and public broadcast television have been used to distribute instruction for years. In addition to the educational networks, almost all public cable television systems allow schools to transmit television courses. This type of connection can be used to transmit one-way video and one-way audio to the community at large or between specific schools. For example, if two area high schools do not each have enough students to justify an advanced math course, they might team up to teach a single course delivered through cable television. In one school, the teacher would conduct a regular class; in the other school, the students would watch and listen through a standard cable television channel.

Distance learning through cable television systems requires both a studio and channels through which to broadcast. The cost depends largely on the "partnership" offered by the cable or broadcast system. Even though the broadcast will take place at a scheduled time, research shows that the majority of the students will record the program and play it back at a convenient time.

Desktop Videoconferencing

Desktop videoconferencing uses a computer along with a camera and microphone at one site to transmit video and audio to a computer at another site or sites. The remote sites also transmit video and audio, resulting in two-way video and two-way audio communications.

Desktop Configuration Diagram.

Figure 14. Configuration for desktop videoconferencing.

Although desktop videoconferencing is considerably less expensive than satellite or microwave systems, there are a couple of limitations. First, the images are usually transmitted at 15 images per second, half the normal video speed. This causes the video to appear somewhat jerky if any rapid motion takes place. A second concern is related to the connection between the computers. Most systems are connected either through local area networks (LANs) or through relatively fast connections (see Figure 14).

Internet Videoconferencing

It is also possible to conduct videoconferences over the Internet. You need a video camera and digitizing card/camera to transmit video signals as well as a microphone and speakers/headset (see Figure 15).

Desktop Configuration Diagram.

Figure 15. Configuration for Internet videoconferencing.

Internet videoconferencing usually results in a small image, which may be jerky (a few frames per second), depending on the speed of the Internet connection. In most cases, a regular modem is far too slow to transmit effective video.

Advantages of Video Technologies

Disadvantages of Video Technologies

Guidelines for Incorporating Video Technologies

Summary of Distance Learning Technologies

The following table summarizes the advantages and disadvantages of the major distance learning technologies.

Print Materials Inexpensive
High comfort level
Readily available
No interactions
Limited sensory involvement
Requires reading skills
Time delay
Voicemail Low cost
Easy to use
Increases interactions
Length may be limited
No visual cues
May involve toll charges
Audio files/CD Inexpensive
Easily accessible
Easily duplicated
No visual cues
No interaction
Audioconference Inexpensive
Easy to set up
No visual cues
No interaction
Requires hardware
E-mail Flexible
Requires hardware
Software variations
Online Chat Real-time interactions
Instant feedback
Requires similar software
Must be scheduled
Requires hardware
May incorporate multimedia
Worldwide access
Requires computer
Requires Web access
May be slow
Videotape/DVD Inexpensive
Easily accessible
Easily duplicated
Audio and visual elements
Complex to record
No interaction
Requires hardware
High realism
May be interactive
Expensive hardware
Must be scheduled
Usually one-way only
High realism
May be interactive
Relatively inexpensive
Must be scheduled
Small windows
Slow, jerky video
Easy to use
Easily accessible
May be videotaped
Includes audio and visual
High production costs
Requires hardware
No interaction
Must be scheduled


Table of Contents
  1. Introduction
  2. Applications in K-12 Education
  3. Benefits of Distance Learning
  4. Connectivity Issues and Alternatives
  5. Overview of Distance Learning Technologies
  6. Print Technologies
  1. Audio/Voice Technologies
  2. Computer (Data) Technologies
  3. Video Technologies
  4. Implementing Distance Learning
  5. References
  6. Glossary

Produced by the Florida Center for Instructional Technology,
College of Education, University of South Florida © 1999 2009.