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Distance Education Systems Copyright © 2003 by Pearson Education, Inc. All rights Distance Education Systems Asynchronous Communication: • Delayed interaction between teacher and student. Synchronous Communication • Real-time interaction between teacher and student. Copyright © 2003 by Pearson Education, Inc. All rights Asynchronous Technologies "Correspondence Study" • Print-based • Audio-based –radio –audiotape • Video-based –broadcast television –videotape Copyright © 2003 by Pearson Education, Inc. All rights Print-based Correspondence Normally, learning materials (textbook, study guide) are delivered by mail. Original form of distance education -dates from mid-1800s. Copyright © 2003 by Pearson Education, Inc. All rights Advantages –Learner-paced –Can be used anywhere –Low cost Disadvantages –Limited interactivity –Motion cannot be shown –Tarnished reputation Copyright © 2003 by Pearson Education, Inc. All rights “I opened a letter and read it. It offered me a six months' correspondence course in fingerprinting at a special professional discount. I dropped it into the wastebasket…” The Big Sleep by Raymond Chandler Copyright © 2003 by Pearson Education, Inc. All rights "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 Copyright © 2003 by Pearson Education, Inc. All rights 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 Copyright © 2003 by Pearson Education, Inc. All rights Interactive Telecommunications • • • • • Audioconferencing Satellite Microwave (ITFS) Compressed video Fiber-optics Copyright © 2003 by Pearson Education, Inc. All rights Audioconferencing Teacher and students linked by telephone --a "conference call." • Advantages: relatively inexpensive, flexible • Disadvantage: lacks visual component Copyright © 2003 by Pearson Education, Inc. All rights 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). Copyright © 2003 by Pearson Education, Inc. All rights Satellite Copyright © 2003 by Pearson Education, Inc. All rights 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 Copyright © 2003 by Pearson Education, Inc. All rights 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 Copyright © 2003 by Pearson Education, Inc. All rights Advantages • • • • Full-motion video Control over who receives signal Excellent audio and video quality No right-of-ways required Jones. et al., 1992 Copyright © 2003 by Pearson Education, Inc. All rights Microwave Copyright © 2003 by Pearson Education, Inc. All rights Disadvantages • Transmissions affected by weather • Line-of-site only • Limited number of frequencies available Jones. et al., 1992 Copyright © 2003 by Pearson Education, Inc. All rights 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 Copyright © 2003 by Pearson Education, Inc. All rights 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 Copyright © 2003 by Pearson Education, Inc. All rights Compressed Video Copyright © 2003 by Pearson Education, Inc. All rights 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 Copyright © 2003 by Pearson Education, Inc. All rights Fiber Optics Copyright © 2003 by Pearson Education, Inc. All rights 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 Copyright © 2003 by Pearson Education, Inc. All rights
