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); 100-1000 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