RFID is the abbreviation of Radio Frequency Identification (RFID). Radio frequency identification technology is an automatic identification technology that began to mature in the 1990s. Radio frequency identification technology is a radio frequency signal that passes through space. Coupling (alternating magnetic or electromagnetic fields) is a technique for achieving contactless information transfer and achieving the purpose of identification through the transmitted information. Compared with the widely used automatic identification technologies such as videography, bar code, magnetic card, IC card, etc., the radio frequency identification technology has many outstanding advantages: first, non-contact operation, long-distance identification (several centimeters to tens of meters), Therefore, the identification work does not require manual intervention and is convenient to apply. Secondly, there is no mechanical wear, long service life, and it can work in various harsh environments such as oil stains and dust pollution. Third, it can recognize high-speed moving objects and recognize multiple at the same time. Fourth, the reader has a physical interface that is not directly open to the end user to ensure its own security. Fifth, in addition to the password protection of the electronic tag, the data part can be managed by some algorithms. Sixth, there is a mutual authentication process between the reader and the tag to achieve secure communication and storage. At present, RFID technology has been widely used in industrial automation, object tracking, traffic control management, anti-counterfeiting and military applications. The RFID system consists of three parts: an electronic tag (Tag): consisting of a coupling element and a chip, and each electronic tag has a globally unique identification number (ID) that cannot be modified or copied, thus providing security. The electronic tag is attached to the object to identify the target object. The electronic tag generally stores electronic data in an agreed format. In practical applications, the electronic tag is attached to the surface of the object to be identified. The antenna (Antenna) transmits the RF signal, that is, the data information of the tag, between the tag and the reader. Reader A device that reads (or writes) electronic tag information and can be designed to be handheld or fixed. The reader can read and recognize the electronic data stored in the electronic tag without contact, thereby achieving the purpose of automatically recognizing the object. Usually the reader is connected to the computer, and the read tag information is transmitted to the computer for further processing. RFID features (1) Data read and write (Read Write) function: As long as the RFID Reader can be used to directly read information into the database without touching, and can process multiple tags at a time, and can write the status of the logistics processing to the tag. For the next stage of logistics processing. (2) Easy to miniaturize and diversify the shape: RFID is not limited in size and shape in reading, and it is not necessary to match the fixed size and printing quality of the paper for reading accuracy. In addition, RFID tags can be miniaturized and applied in different products. As a result, the production of the product can be controlled more flexibly, especially on the production line. (3) Environmental resistance: Paper can not be seen when it is dirty, but RFID has strong anti-staining properties for water, oil and medicine. RFID can also read data in a dark or dirty environment. (4) Reusable: Since RFID is electronic data, it can be overwritten repeatedly, so it can be recycled and reused. For example, passive RFID can be used without a battery and there is no need for maintenance. (v) Penetration: RFID can also be used for penetrating communication if it is covered with non-metallic or non-transparent materials such as paper, wood and plastic. However, if it is ferrous metal, communication will not be possible. (6) The memory capacity of the data is large: The data capacity will expand with the development of memory specifications, and the amount of data required for future items will become larger and larger, and the demand for capacity expansion of the volume label will also increase. Will be restricted. (VII) System security: Transferring product data from the central computer to the workpiece will provide security for the system and greatly improve the security of the system. (8) Data security: The accuracy of the data stored in the radio frequency tag is ensured by means of verification or cyclic redundancy check. Working principle of RFID system When an object with an electronic tag is close to the reader within a range of 0 to 10 meters, the reader is controlled to send a microwave inquiry signal, and the electronic tag mounted on the surface of the object receives the inquiry from the reader. After the signal, the signal is integrated with the data information in the tag and reflected back to the electronic tag reading device. The reflected microwave synthesized signal has carried the electronic tag data information. After receiving the microwave synthesis signal reflected back by the electronic tag, the reader/writer can separate and read the identification code and other information stored in the electronic tag after being processed by the internal microprocessor of the reader/writer.