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RFID


Radio frequency identification ("RFID") is a generic term for technologies that use radio waves to automatically identify objects. There are several methods of identification but the most common is to store a serial number that identifies the object. The antenna enables the RFID tag to transmit the identification information to a reader. The reader converts the radio waves reflected back from the RFID tag into digital information that can then be passed on to computers that can make use of it. Using radio waves means that the tag, and hence the object to be identified does not have to be in direct line of sight of the reader. This means that the technology is ideal for a range of applications in the retail environment, in theft prevention, logistics, patient tracking, warehousing, asset tracking, etc. where it is not possible or not easily possible to maintain line of sight. Technically what all types of RFID systems have in common is that they permit identification by electronic means, no physical contact between object and interrogator is required and that the object provides the data only when requested ("on call"). The significant "advantage" of all types of RFID systems is the non-contact, non-line-of-sight nature of the technology. Tags can be read through a variety of substances, where barcodes or other optically read technologies would be useless. RFID tags can also be read in challenging environments at remarkable speeds, in most cases responding in less than 100 milliseconds. Microwave (2.45 GHz) has a detection range of 4 m regardless of materials it passes through. RFID systems consist of three components:



An antenna or coil, which is the bulkiest part A transceiver (with decoder) A transponder (commonly called tag) usually a microchip that is electronically programmed with unique information.
To put it differently: The RFID technology process starts with a tag, which is made up of a microchip with an antenna, and a reader with an antenna. The reader sends out radio-frequency (RF) waves that form a magnetic field. A tag basically consists of an antenna connected to a microchip with a radio receiver, modulator, some memory and control logic. When a Passive tag comes within the field, the antenna on the RFID tag generates a small current from the induced magnetic field and uses it to energize the circuits of the RFID chip. The chip in the radio frequency identification tag sends information back to the reader in the form of radio-frequency waves. In the RFID systems information like the 'Electronic Product Code' (EPC) or any another unique identifier of each item may be transmitted. The RFID reader converts the returning waves into digital information and passes it to the PC for further task. TYPES OF TAGS The tags can broadly be divided into two broad categories – a) Passive Tags and b) Active Tags. Passive RFID tags Passive RFID-tags are those that receive all their energy from the energising field (i.e. the power radiated from the transmitter. The tag gathers energy from the reader antenna, and the microchip uses the energy to change the load on the antenna and reflect back an altered signal. This is called modulated backscatter. Passive tags are consequently much lighter than active tags, less expensive, and offer a virtually unlimited operational lifetime. They have however shorter reading ranges than active tags and require a higher-powered readers. Products with a lot of water and metal are particularly challenging to tag, and some antennas can be specially designed to be in tune when close to water or to couple with the metal to improve the ability to read the tag. Another solution is to create an air gap between the tag and the object. In the case of metal, an air gap can increase performance if done correctly, because waves will reflect off the metal and provide more power to the tag. Active RFID tags These tags essentially have a battery placed inside the tag making it bulky and with finite life. These use the internal power to transmit the signal. Normally the Active tag would not be transmitting (to save on battery life). Only when it receives a wake-up signal does it start to transmit its contents. The normal expected life of a battery varies from 2 to 5 years, but really depends upon the amount of usage. These tags are very useful in tracking Cars in a Car factory, etc. Various RF chips , Applications and Frequency ranges RFID systems are also distinguished by their frequency ranges, as below:


Low frequency inductive/passive RFID tags (100-500 kHz; ‘LF’) have a long-standing, well established application base. Most commonly used frequency is 125 kHz. Heavy-duty, rugged tags and associated interrogators (readers/programmers) are available for a wide range of industrial applications where low capacity and low data transfer rate are specified. Intermediate frequency inductive/passive RFID tags (10-15 Mhz; 'HF') represent the latest and most innovative products in terms of RFID technology. An expanding range of chip-based tags are appearing in the 13.56 Mhz carrier frequency range. The popularity of 13.56 Mhz (range of 1-2 m) is mainly due to the lower cost of tag, higher data transfer rate and higher data storage. It is reasonably tolerant of liquids and metals and has the advantage of a global standard. Development in both products and standardization are now favoring this frequency range. These tags have a built-in Anti-collusion facility which allows multiple tags to be read almost simultaneously for all practical purposes.
Features of 13.56 MHz frequency tags


Frequency band available worldwide as an ISM frequency Up to 1 metre reading distance in proximity/vicinity read Read/Write capability ISO 15693 and 14443 standardization for the air interface Robust reader-to-tag communication Excellent immunity to environmental noise and electrical interference Well-defined tag interrogation zones Minimal shielding effects from adjacent objects and the human body Damping effects of water relatively small, field penetrates dense materials Freedom from environmental reflections that can plague UHF systems Good data transfer rate High clock frequency and synchronous subcarrier On-chip capacitors for tuning tag coil are easily realized Thin, flexible form factors Cheap ICs, disposable tags Cost-effective antenna coil manufacturing Low RF power transmission so EM radiation/regulatory restrictions are unproblematic No user licences required for reader systems Possible to use the systems in industrial and hazardous environments with potential for explosive substances in the vicinity.
Typical applications include:


Library books Laundry identification Access Control Patient Tracking File Tracking Asset Tracking Etc.
High-frequency (850 MHz to 950 MHz UHF , and 2.4 GHz to 2.5 GHz microwave)


These systems, offering long reading ranges (greater than 30 m) at high reading speeds, are used for such applications as railway car tracking and automated toll collection. However, the higher performance of high-frequency RFID systems incurs higher system costs. These RFID tags operate in both passive backscatter and propagation/active modes.


RFID Readers


A typical reader would consist of an antennae connected to a RFID reader. The reader would generate the frequency waves to be transmitted through the Antennae. The size of the antennae and the power of the reader decide the range of read. Typically there are two varieties being used - Table top RFID Readers and Gate Readers. A gate reader is normally fitted at the entrance. It has a large antenna. The read range of a typical Gate reader is about 1 meter. The purpose of this reader is to read the tags while the tag is entering the work area and so appropriate preparation is done before the object reaches the work site.


RFID Reader cum Data Capturing Unit


This is a portable device. It has a RFID reader, a memory unit and a programming unit. Depending upon the application a program is downloaded into the DCU and this portable hand held device is used to read the tags and store the data. After the data has been collected the data is either transferred wirelessly through blue-tooth or it is connected to a PC. We provide the complete range of RFID equipment, namely


RFID Table top readers - Long range and Short range. RFID gate Readers - Single lane and multi-lane RFID Data Capturing unit Tags both soft paper tags and hard plastic tags
Along with the above hardware we also provide RFID integrated software to cater to various solutions. Like – LIBRARY AUTOMATION, WAREHOUSING, ASSET TRACKING, ACCESS CONTROL, AUTOMATIC GATE CONTROL, PARKING SOLUTION, ETC.


Electronic Article Surveillance:-


This is essentially a RFID based system, where HF of 8.22 Mhz is used. The unique feature in this is that the tag has only one bit of data – only one ON/OFF. So the tag is ON normally when the item is sold the tag is set to OFF. In OFF state the gate reader does not detect the tag and set on the alarm. This is a proven Anti-Theft system.

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