Distance Education Systems Agenda Distance Education Systems Asynchronous

Distance Education Systems Agenda

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

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

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

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

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

"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

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

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

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

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):

Satellite

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

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

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

Microwave

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

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

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

Compressed Video

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

Fiber Optics

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