What is radio frequency identification?
Radio Frequency identification (RFID) is a wireless communication technology that can identify a specific target through radio signals and read and write related data without establishing mechanical or optical contact between the identification system and the specific target. At present, RFID technology is widely used in libraries, logistics warehousing, asset management, personnel management, retail and other fields.
Two, radio frequency identification system composition and working principle
1, radio frequency identification system composition
The radio frequency identification system mainly consists of three parts: tag, reader, antenna. In addition, a special application system is needed to deal with the recognition of the reader.
1) Tag: electronic tag or radio frequency tag, transponder, composed of chip and built-in antenna. The electronic data in a certain format is stored in the chip, which is used as the identification information of the items to be identified and is the data carrier of the radio frequency identification system. The built-in antenna is used for communication with the radio frequency antenna.
2) Reader: The device that reads or reads/writes the electronic label information, the main task is to control the radio frequency module to transmit the read signal to the label, receive the response from the label, decode the object identification information of the label, and transmit the object identification information along with other related information on the label to the host for processing.
3) Antenna: the transmitting and receiving device for transmitting data between the label and the reader.
2, radio frequency identification system operating principle
After the electronic tag enters the antenna magnetic field, if it receives the special RF signal sent by the reader, it can send the product information stored in the chip by virtue of the energy obtained by the induced current (passive label), or actively send a signal of a certain frequency (active label), the reader reads the information and decodes it, and sends it to the central information system for data processing.
In addition, according to the coupling mode of the RF signal between the reader and the label, the communication between them can be divided into inductance coupling and electromagnetic backscatter coupling.
1) Inductive coupling: According to the law of electromagnetic induction, coupling is achieved through the space high-frequency alternating magnetic field. The inductive coupling method is generally suitable for short-range RFID systems that work at medium and low frequencies.
2) Electromagnetic backscattering coupling: according to the spatial propagation law of electromagnetic waves, the emitted electromagnetic waves are reflected after touching the target, thus carrying back the corresponding target information. The electromagnetic backscatter coupling method is generally suitable for remote RFID systems with high frequency and microwave operation.
In popular understanding, inductive coupling is mainly used in low frequency (LF) and medium frequency (HF) bands, because the low frequency RFID system has a longer wavelength and relatively weak energy, it mainly relies on proximity induction to read information. Electromagnetic backscatter coupling is mainly used in high frequency (HF) and ultra-high frequency (UHF) bands, because the high frequency wavelength is shorter and the energy is higher. Therefore, the reader antenna can radiate electromagnetic waves to the tag, and part of the electromagnetic waves are modulated by the tag and reflected back to the reader antenna, and then decoded and sent to the central information system for receiving and processing.
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