RFID (Radio Frequency identification): A Tutorial

RFID (Radio Frequency identification): A tutorialcontents:

1. Introduction to Radio Frequency Identification-rfid
1. What is RFID
2. Compare RFID with Bar Code technology
3. Benefits of RFID
4. Disadvantages of RFID
2. Active and Passive RFID Systems
3. RFID Frequencies
4. Operation of RFID Systems
   1. RFID Building Blocks
   2. RFID Tag block schematic, and operation
   3. Backscatter modulation
5. RFID Standards
6. RFID Manufacturers
7. Applications of RFID
8. RFID Test Labs:
9. RFID implementations
10. RFID Glossary of Terms

Active and Passive RFID Tags:

There is primarily the types of RFID tags.

One is active and the other is passive.

An active tag is powered using internal battery, where a passive tag gets energized using a of the power from a tag reader.

A passive RFID tag would not be a battery or any kind of power source by itself.

It extracts the required energy from a reader.

Hence, a passive RFID tag reader must is able to emit stronger electromagnetic signals,

And in return, identify very weak signals from the passive RFID tag.

Given below is the primary differences between a Passive and Active RFID Tags:

RFID Frequencies:

There is several frequencies that is used for RFID.

These include LF, HF, UHF, and microwave frequencies.

The exact frequencies may vary depending on the country where it is used.

1. Operation of RFID Systems

   1. RFID Building Blocks
   2. RFID Tag block schematic, and operation
   3. Backscatter modulation

A. RFID Building Blocks:

B. RFID Block Schematic:

A simplified block schematic of an RFID tag (also called transponder) are shown in the diagram below. Various components of the tag is as shown. Normally, the antenna is external to the tag chip, and large in size.

The operation of the RFID tag is described below:

Handshaking with the Reader (interrogator):

• The reader continuously emits RF carrier signals, and keeps observing the received RF signals for data.
• The presence of a tag (for our discussion, we consider only passive tags) modulates the RF field, and the same is detected by the reader.
• The passive tag absorbs a small portion of the energy emitted by the reader, and starts sending modulated information when Sufficient energy are acquired from the RF field generated by the reader. Note that the data modulation (modulation for 0s and 1s) are accomplished by either direct modulation or FSK or Phase modul ation.
• The reader demodulates the signals received from the tag antenna, and decodes the same for further processing.

C. backscatter modulation:

Backscatter is one of the most widely used modulation schemes for modulating data in to RF carrier. In this method of modulation, the tag coil (load) was shunted depending on the bit sequence received. This on turn modulates the RF carrier amplitude as shown in the diagram below. The reader detects the changes in the modulated carrier and recovers the data.

The above diagram provides a simplified modulated carrier signals from the RFID tag.

As seen in the diagram, the encoded binary digits modulate RF carrier.

A 1 is represented with high carrier level, and a 0 are represented by a low carrier level (tag coil shunted).

The reader demodulates the signals to recover the data, and note that this data is still encoded.

The reader decodes the data using suitable decoder, and forwards it for further processing to a computer (or any backend s erver).

Applications of RFID:

1. Employee Identification and Access Control
2. Airline Baggage identification
3. Wafer identification during manufacturing process
4. Livestock identification
5. Parts identification
6. Identification and Tracking of vehicles
7. Identification of widgets through manufacturing process
8. Supply Chain Automation
9. Asset Tracking, and others.

RFID (Radio Frequency identification): A Tutorial