synonymRFID system(Contactless information identification technology) generally refers to radio frequency identification technology (science and technology)
Radio Frequency Identification (RFID) is an abbreviation for Radio Frequency Identification.
Its principle is non-contact data communication between readers and tags to achieve the purpose of identification.RFID is widely used, with typical applications including animal chips, car chip anti-theft devices, access control, parking lot control, production line automation, and material management.[1]
Radio Frequency Identification (RFID) is a kind of automatic identification technology. It conducts non-contact two-way data communication through radio frequencyRadio frequencyMode versus recording media（Electronic tagOr RF card) to read and write, so as to achieve the goal of identification and data exchange, which is considered to be one of the most promising information technologies in the 21st century.[2]
RFID technology has passedradio wavesIt does not touch the fast information exchange and storage technology, combines the data access technology through wireless communication, and then connects the database system to realize the non-contact two-way communication, so as to achieve the purpose of identification. It is used for data exchange and connects an extremely complex system.In the recognition system, the reading, writing and communication of electronic tags are realized through electromagnetic waves.According to the communication distance, it can be divided into near field and far field. Therefore, the data exchange mode between the read/write device and the electronic tag is also correspondingly divided into loadsmodulationAnd backscatter modulation.[2]
Development process
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1940-1950: due toradarThe development and progress of technology derived RFID technology, and the theoretical basis of RFID was born in 1948.[3]
1950-1960: People began to explore RFID technology, but it was not separated from laboratory research.[3]
1960-1970: The relevant theories have been developing continuously, and this system has been applied in practice.[3]
1970-1980: RFID technology was constantly updated, product research was gradually deepened, and the testing of RFID began to be further accelerated.And the application of related systems is realized.[3]
1980-1990: RFID technology and related products were developed and applied in the market, and there were many applications in various fields.[3]
1990-2000: People began to pay attention to the standardization of RFID, and RFID systems can be seen in many areas of life.[3]
After 2000, people generally recognized the importance of standardization. The variety of RFID products was further enriched and developed. Active, passive and semi-active electronic tags began to develop. The related production costs were further reduced and the application fields were gradually increased.[3]
In 2020, RF circuit is an integrated circuit widely used in wireless communication, ranging from satellite communication to mobile phones, WiFi and shared bicycles.Design is the source of the RF industry chain. The RF electronic design automation (EDA) software is the enabling end of the RF circuit design, and also an important cornerstone of the RF industry.[11]
The technical theory of RFID has been further enriched and developed. People have developed single chip electronic tags, multi electronic tag reading, wireless read-write, and high-speed moving objectsRFIDWith the continuous development of technology, related products have also entered our lives and started to be widely used.[3]
working principle
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The basic working principle of RFID technology is not complicated: tag entryreaderAfter, receivereaderThe RF signal sent sends the product information stored in the chip with the energy obtained by the induced current（Passive Tag, passive tag or passive tag), or the tag actively sends a signal of a certain frequency (Active Tag, active tag or active tag), the reader reads the information and decodes it, and then sends it to the central information system for relevant data processing.[4]
A complete set of RFID system is composed of reader and electronic tag, namely the so-called transponder and application software system. Its working principle is reader）Emitting a specific frequencyradio wavesEnergy is used to drive the circuit to send the internal dataReaderThey receive the interpreted data in order and send it to the application program for corresponding processing.[4]
In terms of communication and energy sensing between RFID card readers and electronic tags, it can be roughly divided into two types: inductive coupling and backscattering coupling.Generally, the first mode is used for low-frequency RFID, while the second mode is used for high-frequency RFID.[4]
Depending on the structure and technology used, the reader can be a read or read/write device, which is RFIDsystem information Control and processing center.Reader usually consists of coupling module, transceiver module, control module and interface unit.The reader and tag usually use half duplex communication to exchange information, and the reader provides energy and timing for passive tags through coupling.In practical application, the collection, processing, remote transmission and other management functions of object identification information can be further realized through Ethernet or WLAN.[4]
component
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The complete RFID system consists of three parts: Reader, Tag and data management system.[5]
1. About Reader
The reader is a device that reads the information in the tag or writes the information required to be stored in the tag.Depending on the structure and technology used, the reader can be a read/write device, which is the information control and processing center of the RFID system.When the RFID system is working, the reader sends RF energy in an area to form an electromagnetic field. The size of the area depends on the transmission power.The tag in the reader coverage area is triggered to send the data stored therein, or modify the data stored therein according to the instructions of the reader, and can communicate with the computer network through the interface.The basic structure of the reader usually includes: transceiver antenna, frequency generator, phase-locked loop, modulation circuit, microprocessor, memory, demodulation circuit and peripheral interface.[5]
(1) Transceiver antenna: sends RF signals to tags and receives response signals and tag information returned by tags.[5]
(2) Frequency generator: generates the operating frequency of the system.[5]
(4)modulationCircuit: the signal sent to the tag is loaded into the carrier and sent out by the RF circuit.[5]
(5)microprocessor: Generate the signal to be sent to the tag, decode the signal returned by the tag, and send the decoded data back to the application program. If the system is encrypted, it also needs to decrypt.[5]
(7) Demodulation circuit: demodulate the signal returned by the tag and send it to the microprocessor for processing.[5]
(8) Peripheral interface: communicate with the computer.[5]
2. About Electronic Labels
The electronic tag is composed of transceiver antenna, AC/DC circuit, demodulation circuit, logic control circuit, memory and modulation circuit.[5]
(1) Transceiver antenna: receive the signal from the reader and send the required data back to the reader.[5]
(2) AC/DC circuit: use the electromagnetic energy emitted by the reader to provide a stable power supply for other circuits through the voltage stabilizing circuit output.[5]
(3) Demodulation circuit: remove the carrier from the received signal and demodulate the original signal.[5]
(4)logical control Circuit: decode the signal from the reader and send back the signal according to the requirements of the reader.[5]
(5)storage: As the location for system operation and storage of identification data.[5]
(6) Modulation circuit: the data sent by the logic control circuit is loaded into the antenna and sent to the reader through the modulation circuit.[5]
classification
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RFID technology can be divided into three categories according to the power supply mode of its tags, namely passive RFID, active RFID, and semi active RFID.[6]
1. Passive RFID.
Among the three types of RFID products, passive RFID is the earliest, most mature and most widely used.In passive RFID, the electronic tag receives the microwave signal transmitted by the RFID reader, and obtains energy through the electromagnetic induction coil to supply power to itself for a short time, thus completing the information exchange.Because the power supply system is omitted, the passive RFID products can reach the centimeter scale or even smaller, and have simple structure, low cost, low failure rate and long service life.However, as a cost, the effective recognition distance of passive RFID is usually short, which is generally used for close contact recognition.Passive RFID mainly works in the lower frequency band 125KHz, 13.56MKHz, etc. Its typical applications include: bus card, second-generation ID card, canteen meal card, etc.[6]
2. Active RFID.
Active RFID has not risen for a long time, but it has played an indispensable role in various fields, especially in the electronic toll collection system of expressway.Active RFID is powered by an external power supply and actively sends signals to the RFID reader.Its volume is relatively large.But it also has a longer transmission distance and higher transmission speed.A typical active RFID tag can establish contact with RFID readers 100 meters away, with a reading rate of 1700 read/sec.Active RFID mainly works in higher frequency bands such as 900MHz, 2.45GHz and 5.8GHz, and has the function of identifying multiple tags at the same time.Active RFID is indispensable in some RF identification applications requiring high performance and wide range due to its long-distance and high efficiency.[6]
3. Semi active RFID.
Passive RFID does not supply power itself, but the effective recognition distance is too short.The active RFID identification distance is long enough, but it needs external power supply, and the volume is large.Semi active RFID is the product of compromise for this contradiction.Semi active RFID is also called low-frequency activation trigger technology.In general, semi active RFID products are in a sleep state and only supply power to the part of the tag that holds data, so the power consumption is small and can be maintained for a long time.When the tag enters the identification range of the RFID reader, the reader will activate the tag accurately in a small range with a 125KHz low-frequency signal to make it enter the working state, and then transmit information with it through 2.4GHz microwave.That is to say, first use low-frequency signals to accurately locate, and then use high-frequency signals to quickly transmit data.Its common application scenario is to place multiple low-frequency readers at different locations in a large range covered by a high-frequency signal to activate semi-active RFID products.This not only completes the positioning, but also realizes the collection and transmission of information.[6]
characteristic
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Generally speaking, RFID technology has the following characteristics:[6]
1. Applicability: RFID technology relies on electromagnetic waves and does not need to connect the physical contact between the two parties.This enables it to establish connections and communicate directly without regard to dust, fog, plastic, paper, wood and various obstacles.[6]
2. Efficiency: The read and write speed of the RFID system is extremely fast, and a typical RFID transmission process is usually less than 100 milliseconds.High frequency RFID readers can even identify and read the contents of multiple tags at the same time, greatly improving the efficiency of information transmission.[6]
3. Uniqueness: Each RFID tag is unique. Through the one-to-one correspondence between RFID tags and products, you can clearly track the subsequent circulation of each product.[6]
4. Simplicity: RFID tags have simple structure, high recognition rate and simple reading equipment.Especially with the gradual popularization of NFC technology on smart phones, each user's mobile phone will become the simplest RFID reader.[6]
Advantages and disadvantages
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advantage
RFID technology can be widely used in many industries and fields, which must have its "excellence".
In terms of its external manifestations, the carrier of radio frequency identification technology is generally waterproof, antimagnetic, high temperature resistant and other characteristics to ensure the stability of radio frequency identification technology in application.In terms of its use, RFID has advantages in updating data in real time, storing information, service life, work efficiency, security, etc.Under the premise of reducing manpower, material resources and financial resources, RFID can more conveniently update existing data and make work more convenient;RFID technology stores information according to computers, up to several megabytes, which can store a large amount of information to ensure smooth work;RFID technology has a long service life. As long as the staff pay attention to protection when using it, it can be reused;The radio frequency identification technology has changed the previous inconvenience of information processing, realized the simultaneous identification of multiple targets, and greatly improved the work efficiency;RFID is also protected by password, which is not easy to be forged and has high security.The technology similar to RFID technology is the traditional barcode technology. The traditional barcode technology is inferior to RFID technology in updating data, storing information, service life, work efficiency, security and other aspects. It can not meet the needs of China's current social development, and it is also difficult to meet the needs of industry and related fields.[7]
shortcoming
(1) The technology maturity is not enough.RFID technology has appeared for a short time and is not very mature technically.It is difficult to apply UHF RFID tags in metal, liquid and other commodities due to their reflective characteristics.[8]
(2) High cost.The price of RFID electronic tags is higher than that of ordinary barcode tags, which is dozens of times higher than that of ordinary barcode tags. If the usage is large, the cost will be too high, which will greatly reduce the enthusiasm of the market for using RFID technology.[8]
(3) The security is not strong enough.The security problems faced by RFID technology are mainly manifested in the illegal reading and malicious tampering of RFID electronic tag information.[8]
(4) Technical standards are not unified.[8]
application area
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1. Logistics
Logistics warehousing is one of the most potential applications of RFID. International logistics giants such as UPS, DHL, Fedex are actively experimenting with RFID technology, with a view to large-scale application in the future to improve their logistics capabilities.The applicable processes include: cargo tracking, automatic information collection, warehouse management application, port application, postal parcel, express delivery, etc.[9]
2. Transportation
There are many successful cases in taxi management, bus hub management, railway locomotive identification, etc.[9]
3. Identification
RFID technology is widely used in personal identification documents because of its fast reading and difficult forgery.Such as the e-passport project, the second generation ID card, student ID card and other electronic documents.[9]
4. Anti-counterfeiting
RFID is difficult to forge, but how to apply it to anti-counterfeiting needs the active promotion of the government and enterprises.The fields that can be applied include anti-counterfeiting of valuables (cigarettes, alcohol, drugs) and tickets.[9]
5. Asset management
It can be applied to the management of all kinds of assets, including valuables, goods with high similarity in quantity or dangerous goods.With the decrease of tag price, RFID can manage almost all items.[9]
6. Food
It can be applied to the management of fruits, vegetables, fresh food, food, etc.The application in this field requires innovation in label design and application mode.[9]
7. Information statistics
With the application of RFID technology, information statistics has become a simple and fast job.The query software of the archive information management platform sends out the statistical inventory signal, and the reader quickly reads the data information and relevant storage information of the library archives, and intelligently returns the obtained information and the information in the central information database for proofreading.For example, for files that cannot be matched, the administrator uses a reader to carry out on-site verification, adjust the system information and on-site information, and then complete the information statistics.[10]
8. View app
When querying the file information, the file manager uses the query management platform to find the file number, and the system reads the data in the central information database according to the file number. After verification, the file outbound signal is sent out. The file intelligent identification function module of the storage location management platform will find the specific location of the file storage in combination with the file number corresponding to the relevant storage location number.After the manager sends out the file delivery signal, the indicator light on the storage site lights up immediately.When the materials are delivered out of the warehouse, the RFID reader will feed back the obtained information to the management platform, and the manager will verify again. The materials will be delivered out of the warehouse after checking the same files as the checked files.In addition, the system will record the information delivery time.If the feedback file does not match the query file, the alarm module in the security management platform will transmit an exception alert.[10]
9. Security control
The security control system can realize the functions of timely monitoring and abnormal alarm to the archives, so as to avoid the destruction and theft of the archives.When the files are borrowed and returned, especially the physical files, they are often used for exhibition, evaluation and inspection. The managers carefully check the returned files and verify with the information before the files are lent, so that they can timely find whether the files are damaged or missing.[10]
Development trend
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1. RFID tag trend
With the development of standards, the wide range of application fields, the increase of the number of applications, the continuous improvement of technology, and the rapid progress of technology (for example, in the case of books, RF identification antennas are printed directly on the cover or copyright page with conductive ink), the cost will be lower;Secondly, the identification distance is longer, even passive RFID tags can reach tens of meters;The volume will also be smaller.[2]
2. High frequency
Compared with low-frequency system, UHF RFID system has the advantages of long recognition distance, faster data exchange speed, higher forgery difficulty, stronger anti-interference ability to the outside world, and small size. With the reduction of manufacturing cost and further improvement of high-frequency technology, UHF system will be more widely used.[2]
3. Networking
In some applications, the data collected by different systems (or multiple readers) need to be processed uniformly and then provided to users. For example, we use second-generation ID cards to pick up train tickets at the automatic ticket machine, which requires the network management of the RFID system to achieve remote control and management of the system.[2]
4. Pluripotency
With the continuous improvement and popularization of mobile computing technology, the development trend of RFID reader design and manufacturing will be multi-functional, multi interface, multi system, and modular, miniaturized, portable, and embedded;At the same time, multi reader coordination and networking technology will become one of the future development directions.[2]
