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Distance Education Systems

Explore asynchronous and synchronous communication methods, advantages, and disadvantages of various distance education systems. Discover how print, audio, video-based correspondence courses evolved. Learn about interactive telecommunications and satellite-based options.

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Distance Education Systems

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  1. Distance Education Systems Agenda

  2. Distance Education Systems Asynchronous Communication: • Delayed interaction between teacher and student. Synchronous Communication • Real-time interaction between teacher and student

  3. Asynchronous Technologies "Correspondence Study" • Print-based • Audio-based • radio • audiotape • Video-based • broadcast television • videotape

  4. Print-based Correspondence Normally, learning materials (textbook, study guide) are delivered by mail. Original form of distance education -- dates from mid-1800s.

  5. Advantages • Learner-paced • Can be used anywhere • Low cost Disadvantages • Limited interactivity • Motion cannot be shown • Tarnished reputation

  6. I opened a letter and read it. it offered me a six months' correspondence course in finger printing at a special professional discount. I dropped it into the wastebasket..." The Big Sleep. by Raymond Chandler

  7. "Allied Commissioners' Courses; be a detective, send for a one-volume correspondence course. No tests, no instructors, no salesmen will call. Free handcuffs and badge included as a special bonus if you act now." Good Behavior. by Donald Westlake

  8. Audio and Video-based Correspondence Study • Learning materials include textbook and workbook, plus audio-or videotape • Advantages: similar to print-based.with visual and/or audio component • Disadvantage: limited interactivity

  9. Interactive Telecommunications • Audioconferencing • Satellite • Microwave (ITFS) • Compressed video • Fiber-optics

  10. Audioconferencing Teacher and students linked by telephone --a "conference call." • Advantages: relatively inexpensive, flexible • Disadvantage: lacks visual component

  11. Satellite-based Distance Education • "Uplink" transmits signal to satellite in geosynchronous orbit. Transponder amplifies signal, transmits it back to earth. Signal is received by "downlinks" (satellite dishes):

  12. Satellite

  13. Advantages • Huge "footprint" means programming can be delivered virtually anywhere to virtually unlimited number of sites Disadvantages • Very expensive to purchase and operate • Normally, video is only one way and students use telephone to communicate with teacher

  14. Microwave-based (ITES) Distance Education • Essentially, low powered TV • Special frequencies/channels • Point-to-point or multipoint • Line-of-sight, 25-30 miles max. • Usually one-way video, two-way audio

  15. Advantages • Full motion video • Control over who receives signal • Excellent audio and video quality • No right-of-ways required Jones. et al., 1992

  16. Microwave

  17. Disadvantages • Transmissions affected by weather • Line-of-site only • Limited number of frequencies available Jones. et al., 1992

  18. Compressed Video-based Distance Education • Analog video signal digitized, then: • Processed to reduce unnecessary information transmitted • Copper telephone lines connect sites • Not full-motion--fewer than 30 images per second

  19. Advantages • Easy to install and use • Can be cheaper than fiber or microwave Disadvantages: • Motion can be jerky • Video quality can be poor • Can't transmit full-motion video Jones. et al., 1992

  20. Compressed Video

  21. Fiber Optics-based Distance Education • Used for telephone and cable TV main trunk lines • Only recently used for education • Cable uses optically pure glass • Transmits light energy

  22. Fiber Optics

  23. Advantages • Full-motion video • High quality • Unaffected by weather Disadvantages • High start-up costs • Slow, expensive repairs • Right-of-way costs Jones. et al., 1992

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