THE WHATIS.COM WORD-OF-THE-DAY September 18, 2002 transponder ______________ TODAY'S SPONSOR: VeriSign - The Value of Trust
Secure all your Web servers now - with a proven 5-part strategy. The FREE Server Security Guide shows you how to deploy the latest encryption and authentication techniques, deliver transparent protection with the strongest security without disrupting users, and more. Get your FREE Guide now: http://WhatIs.com/r/0,,5762,00.htm?FreeGuide ______________ TODAY'S WORD: transponder See our definition with hyperlinks at http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci213219,00.html A transponder is a wireless communications, monitoring, or control device that picks up and automatically responds to an incoming signal. The term is a contraction of the words transmitter and responder. Transponders can be either passive or active. A passive transponder allows a computer or robot to identify an object. Magnetic labels, such as those on credit cards and store items, are common examples. A passive transponder must be used with an active sensor that decodes and transcribes the data the transponder contains. The transponder unit can be physically tiny, and its information can be sensed up to several feet away. Simple active transponders are employed in location, identification, and navigation systems for commercial and private aircraft. An example is an RFID (radio-frequency identification) device that transmits a coded signal when it receives a request from a monitoring or control point. The transponder output signal is tracked, so the position of the transponder can be constantly monitored. The input (receiver) and output (transmitter) frequencies are preassigned. Transponders of this type can operate over distances of thousands of miles. Sophisticated active transponders are used in communications satellites and on board space vehicles. They receive incoming signals over a range, or band, of frequencies, and retransmit the signals on a different band at the same time. The device is similar to a repeater of the sort used in land-based cellular telephone networks. The incoming signal, usually originating from a point on the earth's surface, is called the uplink. The outgoing signal, usually sent to a point or region on the surface, is the downlink. These transponders sometimes operate on an interplanetary scale. RELATED TERMS: wireless http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci213380,00.html signal http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci212986,00.html band http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci331643,00.html repeater http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci212890,00.html uplink http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci214061,00.html downlink http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci214061,00.html ______________________ SELECTED LINKS: "How Stuff Works" explains how the transponder signal provides the controller with your aircraft's flight number, altitude, airspeed and destination. http://www.howstuffworks.com/air-traffic-control3.htm "How Satellite Technology Works" describes the role of transponders in satellite broadcasts. http://www.sbca.com/mediaguide/howsatworks.htm Tom Rogers provides a short paper on "Transponder Basics" for aircraft. http://www.avweb.com/articles/transpon.html ______________________ THIS DAY IN IT HISTORY | September 18, 1998 ICANN, the private non-profit corporation responsible for IP address space allocation, protocol parameter assignment, domain name system management, and root server system management functions, is formed. http://searchwebservices.techtarget.com/sDefinition/0,,sid26_gci214011,00.html ______________________ QUIZ #9 | Wireless How much do you know about wireless technology? Take our quiz and find out! http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci752723,00.html ______________________ CROSSWORD PUZZLE | #2 Improve your flexible thinking skills. Simply print out the puzzle and keep it nearby to work on throughout your day! http://whatis.techtarget.com/definition/0,,sid9_gci850861,00.html ______________________ CHALLENGE #15: What's the difference? What's the difference between POP3, IMAP, and Webmail? http://whatis.discussions.techtarget.com/WebX?[EMAIL PROTECTED]@.1dcfae0e/134!viewtype=threadDate&skip=&expand= ______________________________ RECENT ADDITIONS AND UPDATES [1] care-of address http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci849669,00.html [2] Earth's mean orbital speed http://whatis.techtarget.com/definition/0,,sid9_gci849653,00.html [3] Grace Hopper nanosecond http://whatis.techtarget.com/definition/0,,sid9_gci850361,00.html [4] relative identifier http://searchwindowsmanageability.techtarget.com/sDefinition/0,,sid33_gci850565,00.html [5] mobility agent http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci850702,00.html ____________________________________________________________________ ::::::::::::::::::: WHATIS.COM CONTACTS ::::::::::::::::::: LOWELL THING, Site Editor ([EMAIL PROTECTED]) ____________________________________________________________________ MARGARET ROUSE, Assistant Editor ([EMAIL PROTECTED]) ___________________________________________________________________ :::::::::::::::::::: ABOUT THIS NEWSLETTER ::::::::::::::::::::: Published by TechTarget (http://www.techtarget.com) TechTarget - The Most Targeted IT Media Copyright 2002, All Rights Reserved. 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