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RFID and its components
Radiofrequency identification (RFID) is an automatic identification technology which first saw the light of day in the 1950's but which has only come to the force in relatively recent times.
It is a technology based on the emission of electromagnetic fields received by an aerial coupled to a microchip (transponder or tag). The field acts as a vector for information between chip and reader, and for the power activating these chips.
An automatic radio-frequency identification application therefore consists of a reader which transmits a signal on a set frequency to one or more radio labels located in its read field.
These send a signal back. When the labels are "awakened" by the reader, a dialogue starts using a pre-set communication protocol and data is exchanged. |
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 The electronic label is an information medium combining signal processing and data storage.
It consists of an electronic circuit (or integrated circuit), distributed on a printed circuit and coupled to an aerial.
Often known as "transponders" (TRANSmitter/resPONDER) owing to their response and transmission functions, the radio label or tag responds to a request sent by the reader and relating to the data it contains.
The transponder memory generally comprises a ROM (Read Only Memory), a RAM (Random Access Memory) and a non-volatile programmable memory for the retention of data according to the type and degree of complexity of the product.
The ROM contains the security data and instructions for the OS (Operating System) of the label responsible for basic functions such as response time, data flow control, and power management.
The RAM memory is used for the temporary storage of data during the interrogation and response processes. The power required for the tag to operate is supplied either by an internal cell (or battery) for active or semi-active tags, or supplied from a remote power supply via the electromagnetic field emitted by the reader (passive tags).
The base station emits radio waves within an area ranging from a few centimetres to several dozen metres, depending on the power of the supply and radio-frequency used.
When an RF label enters the electromagnetic field, it detects the signal from the base station.
The reader reads the data encoded in the transponder and it is then sent to the server for processing.
The base station may also participate in signal processing, and in parity checks, error detection and correction.
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An RFID system therefore allows information to be written and stored on and deleted from the tag microchip. In addition to contact less data transfer, communication via the aerial also allows sightless transfers between reader and label through materials that are opaque to the light, with several labels being able to be read simultaneously.
The different RFID systems are characterised mainly by their communication frequency. However, apart from this carrier frequency, other characteristics also define RFID labels and constitute the basis of their specifications:
- the origin and type of power used
- reading distance
- programmability
- physical form
- memory size
- packaging properties (material)
- number of tags read simultaneously (collision avoidance)
- and of course cost
From The traceability Valence centre |
