Identifying and Tracking Tags with Radio-Frquency Identification

Introduction

Radio-frequency identification (RFID) is the wireless non-contact use of radio-frequency electromagnetic fields to transfer data, for the purposes of automatically identifying and tracking tags attached to objects. The tags contain electronically stored information. Some tags are powered by and read at short ranges (a few meters) via magnetic fields (electromagnetic induction), and then act as a passive transponder to emit microwaves or UHF radio waves (i.e., electromagnetic radiation at high frequencies). Others use a local power source such as a battery, and may operate at hundreds of meters. Unlike a bar code, the tag does not necessarily need to be within line of sight of the reader, and may be embedded in the tracked object.

RFID tags are used in many industries. An RFID tag attached to an automobile during production can be used to track its progress through the assembly line. Pharmaceuticals can be tracked through warehouses. Livestock and pets may have tags injected, allowing positive identification of the animal. On off-shore oil and gas platforms, RFID tags are worn by personnel as a safety measure, allowing them to be located 24 hours a day and to be quickly found in emergencies.

Since RFID tags can be attached to clothing, possessions, or even implanted within people, the possibility of reading personally-linked information without consent has raised privacy concerns.

How does RFID work?

As you can see today, in factories, production of goods takes place at a large scale; besides this, all over the world a large number of retail chains have been opening. Management of all the logistics was done manually initially but later on this started to become increasingly difficult to handle. It was due...

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... same time causing no read or loss of information. The first criterion favors PPM and PWM codes, because of their relatively stable signal. PPM and PWM codes also satisfy the second criteria. However, detecting collisions favors a Manchester code.

Modulation

Modulation is a process of changing the characteristics of a radio wave to encode an information signal and sending that information to the other end. Readers send a continuous radio wave and the tags modulate this base band signal by adding encoded information into it, which the readers decode. Modulation schemes used for RF communication are amplitude shift keying (ASK), frequency shift keying (FSK) and phase shift keying (PSK). The modulation technique’s choice is based on the power consumption, reliability and available bandwidth. ASK is most commonly used in load modulation and PSK for backscattering.