R F I D Presented by Kerry Wong

What is RFID? Radio Frequency IDentification –Analogous to electronic barcode –Uses radio waves to send info Serial numbers for identifying product –Allows automatic collection of data –Keep track of large number of movable items –Can send info to computer for storage

Components: Reader Transmitter –carrier frequency generator, gap signal gate, and an antenna circuit Constantly sends out radio signal ~ one carrier frequency Receiver –peak detector, a signal amplifier/filter, signal-collision detector, and microcontroller –Uses envelop detector of received AM modulated signal to get the FSK ‘0’ or ‘1’ Half Wave Rectifier

Components: Tag Transponder –Microchip (silicon chip) with LC antenna –Passive Tags ~ Smart Labels Induced Current from receiver –Active Tags Needs battery –Reflects back or transmit signal Amplitude Modulates Carrier Frequency –Uses FSK for ‘1’ or ‘0’ Ie: ‘1’ = fc/10 ‘0’=fc/8

Advantages Don’t need line of sight Allows movement Variety of Ranges –10-20 feet (passive); feet (active) Can have several Bi-directional –Tag data content can be altered Stores about 2Kbytes of data

Disadvantages Can’t use around metal and liquids Reader Collision –One tag read twice for overlapped readers Tag Collision –Sol’n: Uses type of TDMA Gap pulse begins random countdown

Anti-Collision Protocol

Applications Car Identification Animal Tagging –Pets and livestock Airport Baggage Tracking Product Tracking Wireless payment systems Building access cards