From the basic principle of information transmission, RFID technology is based on transformer coupling model (energy transfer and signal transfer between master and slave) in low frequency band and spatial coupling model of radar detection target in high frequency band (electromagnetic wave signal emitted by radar returns to radar receiver with target information after hitting the target).
Communication with incident power published by Harry Stockman in 1948 laid the theoretical foundation of RFID technology.
The development of RFID technology can be divided into the following ten years:
1940- 1950: the improvement and application of radar gave birth to radio frequency identification technology, and 1948 laid the theoretical foundation of radio frequency identification technology.
1950- 1960: The early RFID technology is in the exploratory stage, mainly in laboratory experiments.
1960- 1970: developed the theory of radio frequency identification technology, and started some application attempts.
1970- 1980: RFID technology and product research and development are in a period of great development, and the testing of various RFID technologies is accelerated.
Some of the earliest applications of radio frequency identification appeared.
1980- 1990: RFID technology and products have entered the commercial stage, and applications of various scales have begun to appear.
1990-2000: More and more attention has been paid to the standardization of radio frequency identification technology, radio frequency identification products have been widely used, and radio frequency identification products have gradually become a part of people's lives.
After 2000, people pay more and more attention to standardization, and the types of RFID products are also more abundant. Active electronic tags, passive electronic tags and semi-passive electronic tags have all been developed, the cost of electronic tags has been continuously reduced, and the scale application industry has expanded.
So far, the theory of RFID technology has been enriched and improved.
Single-chip electronic tag, multi-tag reading, wireless reading and writing, long-distance identification of passive electronic tags, and radio frequency identification technology and products suitable for high-speed moving objects are becoming a reality and moving towards application.
RFID working frequency guide and its typical application
RFID products in different frequency bands will have different characteristics. The characteristics and main applications of passive sensors at different working frequencies are introduced in detail here.
At present, the working frequency of RFID products is defined as different products that meet different standards in the frequency range of low frequency, high frequency and ultra-high frequency, and RFID products in different frequency bands will have different characteristics.
There are passive and active sensors. The characteristics and main applications of passive sensors under different working frequencies are introduced in detail below.
First, low frequency (from 125KHz to 134KHz).
In fact, RFID technology was first widely used and popularized at low frequency.
This frequency mainly works by inductive coupling, that is, there is transformer coupling between the reader coil and the inductive coil. The voltage induced by the alternating field of the reader in the inductive antenna is rectified and can be used as the power supply voltage. The magnetic field area can be well defined, but the field strength drops too fast.
Features:
1. Generally, the operating frequency of inductors operating at low frequency is between 120KHz and 134kHz, and that of Ti is134.2kHz..
The wavelength of this band is about 2500 microns.
2. Except for the influence of metal materials, generally low frequency can pass through any material without reducing its reading distance.
3. There are no special licensing restrictions for readers working at low frequencies in the world.
4. Low-frequency products have different packaging forms.
A good packaging form is too expensive, but it has a service life of more than 10 years.
5. Although the magnetic field area of this frequency drops rapidly, it can produce a relatively uniform reading and writing area.
6. Compared with RFID products in other frequency bands, the data transmission rate in this frequency band is relatively slow.
7. The price of sensors is more expensive than other frequency bands.
Main applications:
1. Animal husbandry management system
2. The application of automobile anti-theft and keyless door opening system.
3. Application of Marathon Running System
4. Automatic parking charge and vehicle management system
5. Application of automatic refueling system
6. The application of hotel door lock system
7. Access control and safety management system
Meet international standards:
A) application of iso11784 RFID in animal husbandry-coding structure
B) application of iso11785 RFID in animal husbandry-technical theory
C) application of iso14223-1RFID in animal husbandry-air interface
D) application of iso14223-2 RFID in animal husbandry-protocol definition
E) ISO 18000-2 defines the physical layer, anti-collision and low-frequency communication protocols.
F) DIN 30745 is mainly the European standard for waste management application definition.
Second, high frequency (working frequency is 13.56MHz)
The inductance of this frequency no longer needs coil winding, and the antenna can be made by etching and living body printing.
Inductors generally work by load modulation.
That is to say, the voltage on the reader antenna is changed by the load resistance on the switching inductor, and the amplitude modulation of the antenna voltage is realized by using the remote inductor.
If people control the on-off of the load voltage through data, then these data can be transmitted from the sensor to the reader.
Features:
1. The working frequency is 13.56MHz, and the wavelength of this frequency is about 22m.
2. Except for metal materials, the wavelength of this frequency can pass through most materials, but it often reduces the reading distance.
The sensor needs to keep a certain distance from the metal.
This frequency band is recognized all over the world, and there is no special restriction.
4. Sensors are usually in the form of electronic tags.
5. Although the magnetic field area of this frequency drops rapidly, it can produce a relatively uniform reading and writing area.
6. The system has anti-collision characteristics and can read multiple electronic tags at the same time.
7. You can write some data information into the label.
8. Data transmission rate is faster than low frequency, and the price is not very expensive.
Main applications:
1. Application of book management system
2. Management and use of gas cylinders
3. Management and application of clothing production line and logistics system
4. Three-meter prepayment system
5. Management and application of hotel door locks
6. Large conference personnel access system
7. Fixed assets management system
8. Management and application of medical logistics system
9. Management of intelligent shelves
Meet international standards:
A) ISO/IEC 14443 is close to the coupled IC card, and the maximum reading distance is 10cm.
B) ISO/IEC 15693 loosely coupled IC card, maximum reading distance1m.
C) ISO/IEC 18000-3 This standard defines the physical layer, anti-collision algorithm and communication protocol of 13.56MHz system.
D) 13.56MHz ISM band Class 1 definition 13.56MHz conforms to the interface definition of EPC.
Third, ultra-high frequency (working frequency is between 860 MHz and 960 MHz)
Ultra-high frequency system transmits energy through electric field.
The energy of the electric field does not drop rapidly, but the reading area is not well defined.
The reading distance of this frequency band is relatively long, and the passive frequency can reach about 10m.
It is mainly realized by capacitive coupling.
Features:
1. In this frequency band, the definitions are different all over the world-the frequency defined in Europe and some Asia is 868MHz, the frequency defined in North America is between 902 and 905 MHz, and the recommended frequency band in Japan is between 950 and 956.
The wavelength of this frequency band is about 30cm.
2. At present, the power output of this frequency band is uniformly defined (defined as 4W in the United States and 500mW in Europe).
Maybe the limit of Europe will rise to 2W EIRP.
3. UHF radio waves cannot pass through many substances, especially suspended particulate substances such as water, dust and fog.
Compared with high-frequency electronic tags, electronic tags in this frequency band do not need to be separated from metals.
4. The antenna of electronic tag is usually long and tag-shaped.
The antenna has linear polarization and circular polarization design to meet the needs of different applications.
5. This frequency band has a good reading distance, but it is difficult to define the reading area.
6. It has a high data transmission rate and can read a large number of electronic tags in a short time.
Main applications:
Management and application in supply chain
2. Management and application of production line automation
3. Management and application of air parcels
4. Management and application of containers
5. Management and application of railway parcels
6. The application of logistics management system
Meet international standards:
A) ISO/IEC 18000-6 defines the physical layer and communication protocol of UHF; The air interface defines two parts: type A and type B; Supports both readable and writable operations.
B) EPCglobal defines the structure of electronic article coding, VHF air interface and communication protocol.
For example: class 0, 1 class, UHF Gen2.
C) Ubiquitous ID Japan organization, which defines UID coding structure and communication management protocol.
In the future, UHF products will be widely used.
For example, Wal-Mart, Tesco, U.S. Department of Defense and Metro Supermarket all applied RFID technology in their supply chains.
Active RFID technology (2.45GHz, 5.8G)
Active RFID has the characteristics of low transmitting power, long communication distance, large amount of transmitted data, high reliability and good compatibility. Compared with passive RFID, it has obvious technical advantages.
Widely used in highway toll collection, port freight management and other application fields.
As a new automatic identification technology, radio frequency identification has great development potential in China.
Radio frequency identification (RFID) is actually the specific application and development of automatic equipment identification (AEI) in radio technology.
The basic idea of this technology is to realize people's automatic identification and management of objects or equipment (people, goods) in different States (moving, static or harsh environment) by adopting some advanced technical means.
Radio frequency identification (RFID) band navigation;
At present, the working frequency of RFID products is defined as different products that meet different standards in the frequency range of low frequency, high frequency and very high frequency, and RFID products in different frequency bands will have different characteristics.
There are passive and active sensors. The characteristics and main applications of passive sensors under different working frequencies are introduced in detail below.
First, low frequency (from 125KHz to 134KHz).
In fact, RFID technology was first widely used and popularized at low frequency.
This frequency mainly works by inductive coupling, that is, there is transformer coupling between the reader coil and the inductive coil. The voltage induced by the alternating field of the reader in the inductive antenna is rectified and can be used as the power supply voltage. The magnetic field area can be well defined, but the field strength drops too fast.
Features:
1. Generally, the operating frequency of inductors operating at low frequency is between 120KHz and 134kHz, and that of Ti is134.2kHz..
The wavelength of this band is about 2500 microns.
2. Except for the influence of metal materials, generally low frequency can pass through any material without reducing its reading distance.
3. There are no special licensing restrictions for readers working at low frequencies in the world.
4. Low-frequency products have different packaging forms.
A good packaging form is too expensive, but it has a service life of more than 10 years.
5. Although the magnetic field area of this frequency drops rapidly, it can produce a relatively uniform reading and writing area.
6. Compared with RFID products in other frequency bands, the data transmission rate in this frequency band is relatively slow.
7. The price of sensors is more expensive than other frequency bands.
Main applications:
1. Animal husbandry management system
2. The application of automobile anti-theft and keyless door opening system.
3. Application of Marathon Running System
4. Automatic parking charge and vehicle management system
5. Application of automatic refueling system
6. The application of hotel door lock system
7. Access control and safety management system
Meet international standards:
A) application of iso11784 RFID in animal husbandry-coding structure
B) application of iso11785 RFID in animal husbandry-technical theory
C) application of iso14223-1RFID in animal husbandry-air interface
D) application of iso14223-2 RFID in animal husbandry-protocol definition
E) ISO 18000-2 defines the physical layer, anti-collision and low-frequency communication protocols.
F) DIN 30745 is mainly the European standard for waste management application definition.
Second, high frequency (working frequency is 13.56MHz)
The inductance of this frequency no longer needs coil winding, and the antenna can be made by etching and living body printing.
Inductors generally work by load modulation.
That is to say, the voltage on the reader antenna is changed by the load resistance on the switching inductor, and the amplitude modulation of the antenna voltage is realized by using the remote inductor.
If people control the on-off of the load voltage through data, then these data can be transmitted from the sensor to the reader.
Features:
1. The working frequency is 13.56MHz, and the wavelength of this frequency is about 22m.
2. Except for metal materials, the wavelength of this frequency can pass through most materials, but it often reduces the reading distance.
The sensor needs to keep a certain distance from the metal.
This frequency band is recognized all over the world, and there is no special restriction.
4. Sensors are usually in the form of electronic tags.
5. Although the magnetic field area of this frequency drops rapidly, it can produce a relatively uniform reading and writing area.
6. The system has anti-collision characteristics and can read multiple electronic tags at the same time.
7. You can write some data information into the label.
8. Data transmission rate is faster than low frequency, and the price is not very expensive.
Main applications:
1. Application of book management system
2. Management and use of gas cylinders
3. Management and application of clothing production line and logistics system
4. Three-meter prepayment system
5. Management and application of hotel door locks
6. Large conference personnel access system
7. Fixed assets management system
8. Management and application of medical logistics system
9. Management of intelligent shelves
Meet international standards:
A) ISO/IEC 14443 is close to the coupled IC card, and the maximum reading distance is 10cm.
B) ISO/IEC 15693 loosely coupled IC card, maximum reading distance1m.
C) ISO/IEC 18000-3 This standard defines the physical layer, anti-collision algorithm and communication protocol of 13.56MHz system.
D) 13.56MHz ISM band Class 1 definition 13.56MHz conforms to the interface definition of EPC.
Third, very high frequency (working frequency is between 860MHz and 960MHz)
Very high frequency system transmits energy through electric field.
The energy of the electric field does not drop rapidly, but the reading area is not well defined.
The reading distance of this frequency band is relatively long, and the passive frequency can reach about 10m.
It is mainly realized by capacitive coupling.
Features:
1. In this frequency band, the definitions are different all over the world-the frequency defined in Europe and some Asia is 868MHz, the frequency defined in North America is between 902 and 905 MHz, and the recommended frequency band in Japan is between 950 and 956.
The wavelength of this frequency band is about 30cm.
2. At present, the power output of this frequency band is uniformly defined (defined as 4W in the United States and 500mW in Europe).
Maybe the limit of Europe will rise to 2W EIRP.
3.VHF radio waves cannot pass through many substances, especially suspended particulate substances such as water, dust and fog.
Compared with high-frequency electronic tags, electronic tags in this frequency band do not need to be separated from metals.
4. The antenna of electronic tag is usually long and tag-shaped.
The antenna has linear polarization and circular polarization design to meet the needs of different applications.
5. This frequency band has a good reading distance, but it is difficult to define the reading area.
6. It has a high data transmission rate and can read a large number of electronic tags in a short time.
Main applications:
Management and application in supply chain
2. Management and application of production line automation
3. Management and application of air parcels
4. Management and application of containers
5. Management and application of railway parcels
6. The application of logistics management system
Meet international standards:
A) ISO/IEC 18000-6 defines the physical layer and communication protocol of VHF; The air interface defines two parts: type A and type B; Supports both readable and writable operations.
B) EPCglobal defines the structure of electronic article coding, VHF air interface and communication protocol.
For example: class 0, 1 class, UHF Gen2.
C) Ubiquitous ID Japan organization, which defines UID coding structure and communication management protocol.
We have no doubt that VHF products will be widely used in the future.
For example, Wal-Mart, Tesco, U.S. Department of Defense and Metro Supermarket all applied RFID technology in their supply chains.
Radio Frequency Identification (RFID)
What is RFID?
RFID is the abbreviation of radio frequency identification, namely radio frequency identification, commonly known as electronic tag.
What is RFID technology?
RFID radio frequency identification is a non-contact automatic identification technology, which can automatically identify the target object and obtain relevant data through radio frequency signals, and can work in various harsh environments without manual intervention.
RFID technology can identify high-speed moving objects and multiple tags at the same time, which is quick and convenient to operate.
RFID is a simple wireless system with only two basic devices, which is used to control, detect and track objects.
The system consists of an interrogator (or reader) and many transponders (or tags).
What are the basic components of RFID?
Tag: It is composed of coupling elements and chips, and each tag has a unique electronic code, which is attached to the object to identify the target object;
Reader: a device for reading (sometimes writing) tag information, which can be designed as a handheld or fixed device;
Antenna: It transmits radio frequency signals between the tag and the reader.
What is the basic working principle of RFID technology?
The basic working principle of RFID technology is not complicated: after the tag enters the magnetic field, it receives the RF signal sent by the reader, and uses the energy obtained by the induced current to send out the product information stored in the chip (passive tag, passive tag), or actively sends out a signal with a certain frequency (active tag, active tag or active tag); The reader reads and decodes the information and sends it to the central information system for data processing.
A complete RFID system consists of reader, electronic tag, so-called transponder and application software system. Its working principle is that the reader sends radio wave energy of specific frequency to the transponder, which drives the transponder circuit to send internal data. At this point, the reader sequentially receives the interpreted data and sends it to the application for corresponding processing.
As far as communication and energy induction between RFID reader and electronic tag are concerned, they can be roughly divided into two types: inductive coupling and backscattering coupling. Generally, the first type is used for low-frequency RFID, while the second type is used for high-frequency RFID.
The reader can be a reading or reading/writing device according to the used structure and technology, and it is the information control and processing center of RFID system.
The reader usually includes a coupling module, a transceiver module, a control module and an interface unit.
Generally, half-duplex communication is used to exchange information between reader and transponder, and the reader provides energy and time sequence to passive transponder through coupling.
In practical application, management functions such as collection, processing and remote transmission of object identification information can also be realized through Ethernet or WLAN.
Transponder is the information carrier of RFID system. At present, most transponders are passive units composed of coupling elements (coils, microstrip antennas, etc.). ) and microchips.
What makes retailers admire RFID so much?
According to the retail analyst of Sanford C. Bernstein, Wal-Mart can save $8.35 billion a year by adopting RFID, most of which is due to the labor cost saved by not having to manually check the bar codes of purchased goods.
Although other analysts think that the figure of $8 billion is too optimistic, there is no doubt that RFID can help solve the two biggest problems in the retail industry: commodity shortage and loss (products lost due to theft and supply chain interruption). Now, Wal-Mart loses almost $2 billion a year. If a legitimate enterprise can reach this figure, it can rank 694th in the ranking of the largest enterprises in the United States 1000.
Research institutions estimate that this RFID technology can help reduce theft and inventory levels by 25%.
What is the typical application of RFID technology?
Logistics and supply management
Manufacturing and assembly
Air baggage handling
Mail/express parcel handling
Document tracking/library management
Animal identification
Motion timing
Access control/electronic tickets
Road automatic toll collection
RFID reading and writing equipment
Only with reading and writing equipment can RFID play a role.
RFID reading and writing equipment includes RFID card reader, RFID reading and writing module, etc. At present, there are YW-20 1, YW-60 1U and YW-60 1R on the market.
These devices can read or write RFID data and do a good job of encryption.