Understanding Modulation Technology in RFID Systems
Explore the world of RFID technology, including backscattering modulation and digital modulation. Discover the motivations behind RFID use and the mechanisms involved in near-field and far-field coupling.
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Presentation Transcript
Modulation Technology in RFID Li He
Outline Motivation Brief Introduction to RFID Backscattering Modulation Digital Modulation
Motivation RFID is a new technology mainly used for Item Identification VS. o not require human intervention o tag placement is less constrained
Motivation RFID is a new technology mainly used for Indoor Localization VS. o No energy source o More accurate
Introduction RFID = radio frequency identification devices( Reader Antenna RFID tag
Introduction Overall structure
Backscattering Modulation Definition: tag receives energy from reader and backscatter the signal modulated with information in it Two types of design approaches: Near-field coupling Far-field coupling
Backscattering Modulation NEAR-FIELD COUPLING: Mechanism: magnetic induction(Faraday s principle)
Backscattering Modulation NEAR-FIELD COUPLING: Mechanism: magnetic induction(Faraday s principle) Limitation: o 1) The range for which we can use magnetic induction approximates to ?. o 2) Energy available for induction as a function of distance from the reader coil. 1 ?6 ????? ????
Backscattering Modulation FAR-FIELD COUPLING Mechanism: electromagnetic (EM) wave capture
Backscattering Modulation FAR-FIELD COUPLING Mechanism: electromagnetic (EM) wave capture Limitation: o Energy reflected to the reader 1 ?4 ?????? ???? ?? ? ? ??????
Digital Modulation Circuit in the tag
Digital Modulation ASK: amplitude shift keying( ) Pros: provide a high data rate Circuit easy to implement Cons: low noise immunity
Digital Modulation FSK PSK
Thanks Q&A
