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Radio frequency identification technology and its application and development trend

Abstract: as a new automatic identification technology, radio frequency identification (RFID) has been rapidly developed at home and abroad in recent years The stop speed develops when the specimen breaks. This paper briefly describes the advantages and development of RFID technology at present, introduces in detail the composition and working principle of RFID system, the classification of RFID technology, relevant technical standards, and lists four typical products. Finally, it discusses the application and development trend of RFID technology. Key words: typical product of RFID electronic tag reader

radio frequency identification (RFID), or radio frequency identification technology, is a non-contact automatic identification technology rising from the 1990s. It uses radio frequency for non-contact two-way communication to automatically identify the target object and obtain relevant data. It has many advantages, such as high precision, strong adaptability to the environment, strong anti-interference, fast operation and so on

in the current commonly used automatic recognition technology, the cost of bar code and magnetic card is low, but they are easy to wear and tear, and the amount of data is very small; The price of contact IC card is slightly higher, the data storage capacity is large, and the security is good, but it is also easy to wear and tear, and the service life is short; The RF card realizes contact free operation, convenient application, no mechanical wear, long service life, no visible light source, good penetration, strong anti pollution ability and durability. In addition, it can work in a harsh environment, with low environmental requirements, long reading distance, no need to contact with the target to get data, support writing data, no need to make new labels, reusable, and uses anti-collision technology, It can recognize high-speed moving objects and multiple RF cards at the same time

in recent years, radio frequency identification technology has developed rapidly at home and abroad. There are many kinds of RFID products. World famous manufacturers such as Ti, Motorola, Philips, microchip, etc. produce RFID products with their own characteristics and series. RFID has been widely used in many fields, such as industrial automation, commercial automation, transportation control and management, such as traffic monitoring systems for cars or trains, automatic highway toll collection systems, goods management, assembly line production automation, access control systems, financial transactions, warehousing management, animal husbandry management, vehicle theft prevention, etc. With the decline of costs and the truth of standardization, the comprehensive promotion and universal application of RFID technology will be an irreversible trend

1 radio frequency identification technology

1.1 composition and working principle of RFID system

rfid system has different composition due to different applications, but it is basically divided into three parts: electronic tag (tag), reader (Reader) and data exchange and management system (processor). Electronic tags (or RF cards, transponders, etc.) are composed of coupling elements and chips, which are full of encryption logic, Serial EEPROM (electrically erasable and programmable read only memory), microprocessor CPU, RF transceiver and related circuits. The electronic tag has the functions of intelligent reading and writing and encrypted communication. It exchanges data with the reading and writing equipment through radio waves, and the working energy is provided by the RF pulse sent by the reader. Reader, sometimes called query device, reader writer or readout device, is mainly composed of wireless transceiver module, antenna, control module and interface circuit. The reader can transmit the read-write command of the host to the electronic tag, encrypt the data sent from the host to the electronic tag, and decrypt the data returned by the electronic tag and send it to the host. The data exchange and management system mainly completes the storage and management of data information, and the reading and writing control of cards

The working principle of the RFID system is as follows: the information to be sent by the reader is encoded and loaded on the carrier signal of a certain frequency, which is sent outward through the antenna. The electronic tag entering the working area of the reader receives this pulse signal. The relevant circuit in the chip in the card modulates, decodes and decrypts this signal, and then judges the command request, password, authority, etc. If it is a read command, the control logic circuit reads the relevant information from the memory, and then sends it to the reader through the antenna in the card after encryption, coding and modulation. The reader demodulates, decodes and decrypts the received signal and sends it to the central information system for relevant data processing; If it is a write command to modify the information, the internal charge pump will raise the working voltage caused by the control logic, and the content in EEPROM will be rewritten. If the corresponding password and permission are judged to be inconsistent, an error message will be returned. The basic principle block diagram of RFID is shown in Figure 1

in RFID system, the reader must generate a suitable energy field within the readable distance range to stimulate the electronic tag. Under the current RF constraints, most of the fixtures in Europe should not cause isotropic effective radiation power of the specimen in the fracture area of the fixture to be limited to 500MW, and such radiation power can be approximately 0.7m at 870MHZ. In the United States, Canada and some other countries, the radiation restriction without authorization is that the isotropic radiation power is 4W, which will reach a reading distance of 2 meters. If authorized, transmitting 30W power in the United States will increase the reading area to about 5.5 meters

1.2 classification of RFID technology

rfid technology has the following four common classification methods:

according to the different working frequencies of electronic labels, it can usually be divided into low frequency (30kHz ~ 300kHz), intermediate frequency (3MHz ~ 30MHz) and high frequency system (300MHz ~ 3GHz). The common working frequencies of RFID system include low frequency 125kHz, 134.2khz, intermediate frequency 13.56MHz, high frequency 860MHz ~ 930mhz, 2.45GHz, 5.8GHz, etc. The low-frequency system is characterized by less data stored in the electronic tag, short reading distance, various shapes of the electronic tag, weak reading antenna directivity, etc. It is mainly used in applications where a large number of carbon fiber books will be produced in a short time at a low cost in a short distance, such as most access control, campus cards, gas meters, water meters, etc; If system is used in application systems that need to transmit a large amount of data; The high-frequency system is characterized by high cost of electronic tags and readers, large amount of data stored in tags, long reading distance (up to more than ten meters), and good performance in adapting to high-speed movement of objects. Reading antenna and electronic tag antenna have strong directionality, but their antenna wide beam direction is narrow and the price is high. They are mainly used in occasions requiring long reading and writing distance and high reading and writing speed, and are mostly used in train monitoring, highway toll collection and other systems

according to different electronic labels, it can be divided into read-write card (RW), write once read many card (worm) and read-only card (RO). RW cards are generally much more expensive than worm cards and RO cards, such as cards, credit cards, etc; Worm card is a card that users can write at one time. The data cannot be changed after writing, which is cheaper than RW card; Ro card has a unique number, which cannot be changed one by one, ensuring security

according to the active and passive of electronic tags, they can be divided into active and passive. The active electronic tag uses the energy of the current in the card and the recognition distance is long, which can reach more than ten meters, but its service life is limited (3 ~ 10 years) and the price is high; The passive electronic tag does not contain batteries. After receiving the microwave signal sent by the reader (readout device), it uses the electromagnetic wave emitted by the reader to provide energy. Generally, it can be maintenance free, light in weight, small in size, long in service life, and cheaper. However, its transmission distance is limited, which is generally dozens of centimeters, and it requires high transmission power of the reader

according to the different modulation methods of electronic labels, they can also be divided into active tags and passive tags. Active electronic tags use their own RF energy to actively send data to readers and writers. They are mainly used in applications with obstacles, with a long distance (up to 30 meters); The passive electronic tag uses the modulation scattering method 1, which is generally called the analyzer to transmit data. It must use the carrier wave of the reader writer to modulate its own signal, which is suitable for use in access control or traffic applications

1.3 RFID technical standards

at present, the commonly used RFID international standards mainly include iso11784 and ISO11785 for animal identification, iso10536 (close coupled cards), ISO 15693 (toxicity cards), iso14443 (proximity cards) for contactless smart cards, ISO 10374 for container identification, etc. At present, there are three well-known international organizations that formulate RIFD standards: ISO, EPC global led by the United States and ubiquitous ID center in Japan. These three organizations have their own goals and development plans for RFID technology application specifications. The following is a brief introduction to several common standards

iso 11784 and ISO 11785 technical standards:

iso 11784 and ISO 11785 stipulate the code structure and technical criteria of animal identification respectively. There is no corresponding answerer style and size in the standard, so it can be designed into various forms suitable for the animals involved, such as glass tubes, guards or collars. The code structure is 64 bits, of which 27 to 64 bits can be defined by each country. The technical code specifies the data transmission method of the transponder and the specification of the reader. The working frequency is 134.2khz, and the data transmission modes are full duplex and half duplex. The reader data is represented by differential biphase code, and the response device adopts FSK modulation and NRZ coding. Due to the long charging time and working frequency of the transponder, the communication rate is low

iso 10536, ISO 15693 and iso14443 technical standards:

ISO 10536 standard was developed in 1992 and 1995. Due to the high cost of this card and few advantages compared with contact IC card, this card has never been sold on the market. ISO 14443 and ISO 15693 standards began to operate in 1995, and their completion was after 2000. Both of them take 13.56MHz alternating signal as the carrier frequency. ISO 15693 has a long reading and writing distance, while ISO 14443 has a short reading and writing distance, but it is widely used. The current second-generation electronic ID card adopts ISO 14443 type B protocol. ISO 14443 defines two types of protocols, type A and type B, with a communication rate of 106kbit/s. Their differences mainly lie in the modulation depth of the carrier and the bit coding method. Type a adopts the Manchester code of on-off keying, and type B adopts the BPSK code of nrz-l. Compared with type A, type B has the advantages of uninterrupted transmission of energy, higher speed and strong anti-interference ability. The core of RFID is anti-collision technology, which is also the main difference from contact IC card. ISO specifies the anti-collision mechanism of type A and type B. The principle of the anti-collision mechanism of the two is different. The former is based on the bit collision detection protocol, while the type B Communication Series command sequence completes the anti-collision. ISO 15693 adopts the round robin mechanism and time-sharing query to complete the anti-collision mechanism. The anti-collision mechanism makes it possible to correctly operate multiple cards in the read-write area at the same time, which not only facilitates the operation, but also improves the speed of operation

iso 18000 technical standard:

iso 18000 is a series of standards. This standard is a relatively new standard at present, because it can be used in the supply chain of commodities, and some of them are also being formed. ISO basically integrates the reducer specifications of some existing RFID manufacturers and the label architecture requirements proposed by ean-ucc. ISO 18000 only stipulates the air interface protocol, which has no restrictions on data content and data structure, so it can be used for EPC


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