1. RFID(Radio Frequency Identification)
RFID technology is a simple method of exchanging data between two entities namely a reader/ writer and a tag. This communication allows information about the tag or the element carrying the tag to be determined and in this way it enables processes to be managed more easily.
An RFID system comprises a number of elements:
- RFID reader / writer: The reader write is used to communicate with the tags that may pass within range. The RFID reader writer will normally be located in a fixed position and will be used to interrogate an RFID tag. Dependent upon the application and the format of the system and the RFID reader / writer, data may also be written to the RFID tag
- RFID tag: RFID tags may also be called RFID transponders and are typically located on items that are mobile. They are small and generally cheap so that they can be attached to low cost (or high cost) items that need to have information associated with them. They are also generally considered as being disposable. The RFID tag contains data that is relayed to the reader, and in some systems it may also be possible to update the data within the tag to indicate that the tag and hence the item has undergone a specific stage in a process, etc.
- RFID application software: Like all systems these days, RFID systems need application software to run the overall system. With many systems there will be a number of different reader / writers and the data to and from these needs to be coordinated and analyzed. Application software will be required for these.
- Although each RFID system will vary according to its requirements, these are the main elements which can be found.
RFID technology has become widespread in its use. It offers may advantages and RFID is a particularly versatile system, being able to be used in many areas from shops, to manufacturing plants and also for general asset tracking as well as a host of other innovative applications.
How does an RFID system work :
An RFID system consists of a tag, which is made up of a microchip with an antenna, and an interrogator or reader with an antenna. The reader sends out electromagnetic waves. The tag antenna is tuned to receive these waves. A passive RFID tag draws power from field created by the reader and uses it to power the microchip’s circuits. The chip then modulates the waves that the tag sends back to the reader and the reader converts the new waves into digital data.
RFID tag types :
RFID tags or RFID transponders can take a variety of forms. There are three main categories into which they fall:
- Passive: Passive RFID tags are by far the most common. They do not contain any power and receive this from the RFID reader. This is sufficient to power any device in the RFID tag and reply with the required data. The so called RFID smart tags, or RFID smart labels are all passive.
- Semi-passive: This form of RFID tag uses a battery to supply the internal operation of the tag, but relies on the RFID reader to supply the power to transmit the signal to the reader.
- Active: An active RFID tag is one in which battery power is used to supply power to the electronics. This enables greater distances to be achieved as the tag is not dependent upon the received power to provide a reflected signal, and the control and processing circuits can be more sophisticated as in the case of the semi-passive RFID tag.
RFID frequency band allocations :
There are a number of RFID frequencies, or RFID frequency bands that systems may use. The frequency used by the RFID system determines many of the characteristics about the way in which it will operate. As a result, determining the correct RFID frequency band is an important early decision in the development process.
There is a total of four different RFID frequency bands or RFID frequencies that are used around the globe. These are placed widely different areas within the radio frequency spectrum and this enables RFID to choose frequencies that will enable the right system parameters to be obtained.