A short article to introduce you to RFID

Speaking of RFID, many friends have never heard of it or have heard of it but don't know what it is. When we check out at the supermarket, the cashier can identify the product with a wave of the barcode scanner; when we pass the highway toll station, the fee can be automatically deducted without stopping; when we borrow books from the library, the administrator can complete the registration with a light scan; these common moments all hide the same "invisible hero" - RFID.

RFID was actually born a long time ago, quietly serving all walks of life in every corner. RFID is the abbreviation of Radio Frequency Identification, and its Chinese name is wireless radio frequency identification. Simply put, it is a non-contact automatic identification technology that can realize information identification without human intervention.

Development of RFID

The application of RFID can be traced back to World War II, when the US military used it to identify Allied aircraft to avoid accidentally hitting friendly forces. It began to rise in the 1980s and gradually matured. In addition to the military, in many other industries, people have the need to identify various items. For this reason, many labels must be attached to the items, and a lot of information must be entered on the labels. This is a waste of time and manpower, and the data error rate is relatively high. So in order to save labor and free their hands, people began to look for a method that can automatically identify, and RFID came into being. It helps people solve many problems such as slow manual input speed, high error rate, high labor intensity, simple and repetitive work, etc., and also improves the real-time and accuracy of the information system, bringing great convenience to the work of various industries.

Composition of RFID

The composition of RFID is very simple, consisting of three components: electronic tag, antenna and reader. These are all indispensable parts of RFID to complete its work.

Electronic tag

The electronic tag is a micro device that stores target information (such as ID, attribute data), which is equivalent to a "wireless ID card". Its core function is to receive energy, parse instructions, and feedback data.

Antenna

The antenna is the physical transmission channel of energy and signals between the reader and the tag. Its main function is to transmit and receive signals.

 

Reader

The reader is a digital transceiver, responsible for initiating communication, processing signals, and managing data interaction, which is equivalent to a "wireless card reader".

 

Working principle of RFID

The working principle of RFID is not complicated. The language of communication between RFID and reader is electromagnetic waves. The reader, antenna and electronic tag realize energy transfer and data interaction through electromagnetic waves. The logical relationship can be summarized as follows: the reader sends instructions and receives the return signal of the tag under the control of the host, the antenna is responsible for the emission and reception of electromagnetic waves, and the electronic tag passively or actively responds and feedbacks information.

RFID Electronic tag

The electronic tag is equivalent to the "identity card" of RFID. It mainly has two storage areas - the ID area stores the world's unique "identity card number" (UID), which cannot be changed by anyone; the user data area is like a notepad, where you can write and draw at will, so that everyone can store the information they need. Antenna
The antenna is equivalent to the "mouth" and "ear" of RFID, responsible for sending and receiving electromagnetic wave signals, allowing RFID to "chat" with the reader. Reader
The reader is equivalent to the "translator" of RFID. The reader first sends a signal through the antenna. After receiving it, the RFID sends the information in the tag back to the reader through the antenna. Finally, the reader transmits the information to the host to complete the identification.

RFID frequency

RFID can be divided into four categories according to frequency: low frequency, high frequency, ultra-high frequency and microwave. Different frequencies have different characteristics and play unique roles in different scenarios.

 

Low-frequency (125KHz)

Like a slow-moving person, speaking softly, the reader must be within 1.2 meters to hear clearly. But it has strong penetration and cannot be blocked by obstacles other than metal, suitable for close-range scenes such as parking lots and access control.

High frequency (13.56MHz)

Like a "machine gun" with a fast speaking speed, but the transmission distance is also about 1.2 meters. It can often be seen in library book borrowing and medical logistics management.

Ultra-high frequency (860-960MHz)

Like a "loud voice + fast mouth", it can communicate even if it stands 4 meters away, and it has its own power supply (active), suitable for scenes that require rapid identification such as production lines and container management.
Microwave (2.45GHz, 5.8GHz)
Like a "long-distance running champion", it can transmit up to more than 100 meters, and mobile vehicle identification and remote access control rely on it.

Active and passive

The transmission distance of information does not only depend on the frequency, but also on many other factors. For example, the energy supply method to be introduced next is one of the determining factors. RFID is divided into two types according to the energy supply method, namely active RFID and passive RFID, which also correspond to the active method (active) and passive method (passive) in the communication method.

 

Low frequency

Low frequency is generally passive. Passive electronic tags do not have their own power supply and lack energy supply. They cannot speak actively. They need the reader to transmit radio waves to them. They use the received induced current to tell their information to the reader. They belong to the passive family. Although low frequency speaks slowly and quietly, their voices have strong penetration. General obstacles except metal cannot block the communication between them and the reader. However, due to their limited communication distance, they are usually active in pet management, sports equestrian event management, etc., which do not require high distance.

 

High frequency

High frequency is generally passive. In addition to metal, the signal can also pass through most materials, but these obstacles will reduce the distance of their sound propagation. They are used in automatic parking lot charging, hotel and community access control, library management and other places.

 

UHF

UHF is generally passive, and UHF signals cannot penetrate metal. Metal has a significant and strong impact on RFID UHF signals, and is one of the most common sources of interference in UHF RFID applications. UHF is generally used in production line automation, aviation package management, container management, railway package management and other places with high transmission speed requirements.

 

The simplest way to distinguish between active and passive is to see whether the electronic tag has its own power supply. Tags with their own power supply are active, while tags without power supply are passive

 

Microwaves

Microwaves are generally active, and microwave electronic tags have their own power supply. In order to achieve a relatively high frequency speaking rate, they need to have their own power supply to provide energy. It is also because of their own power supply that they can actively send radio frequency signals to the reader, and their own power supply can allow their signals to be transmitted farther. Microwave RFID is more widely used in the identification of mobile vehicles, electronic remote control, and other places where there are high requirements for transmission speed and transmission distance. Take the automatic toll collection of high-speed ETC vehicles as an example. Since the vehicle moves faster when it is moving, a microwave RFID with a faster speaking speed is needed. The owner sticks the microwave electronic tag in the car. The microwave electronic tag has its own power supply and emits electromagnetic waves through the antenna at any time to mark its location. When the vehicle passes through the toll station, the reader sends a signal through its antenna to obtain the vehicle information. The microwave electronic tag transmits the vehicle information to the reader. The reader receives the information and calculates the fees to be paid according to the vehicle model and distance, and then transmits the processed information (toll) back to the microwave electronic tag. Then the vehicle can pass after the owner pays the fee. The whole process is as fast as 2 seconds, which is very efficient.

RFID Applications

All walks of life have benefited greatly from the popularization and application of RFID technology. For example, the traditional retail industry relies on barcodes for inventory management, which requires manual scanning of each item. Not only is it inefficient (a 1,000 square meter large supermarket inventory may take several hours or even 1 day), but it is also easy to distort inventory data due to missed or wrong scanning, which in turn causes "out of stock" or "backlog" problems. After adopting RFID technology, RFID tags can record the entire life cycle data of goods such as warehousing, shelving, sales, and returns, and the system updates the inventory status in real time. Stores can accurately grasp "which goods are on the shelves, which are in the warehouse, and which are about to be sold out", avoiding "false out of stock" (goods are actually in the warehouse but not on the shelves) or excessive stockpiling due to information lags, and improving inventory turnover efficiency by 20%-50%.

 

In the warehousing and logistics industry, the entry and exit of goods in the past required manual counting and registration forms, which not only consumed a lot of manpower and time. Now that RFID technology has been adopted, forklifts can quickly read cargo information between insertion and unloading, and transmit cargo entry and exit information back to the big data visualization board. Factory warehouse managers can see the warehouse operation status at a glance through the board data.
RFID technology is applied to logistics management and warehouse management systems, and the accuracy and accuracy have reached or even exceeded 99%, which is much higher than the accuracy of previous manual visual management, reducing the cost waste of enterprises and the phenomenon of package delivery errors. All commodity logistics are automatically recorded and documents are generated, which makes it easier to further optimize tracking and identification.

 

In fact, RFID is everywhere in our lives. When you use the access card to open the door when you stay in a hotel, when you use the employee card to punch in at the company, when you swipe the card to borrow books from the library, and when you enter and exit the parking lot automatically, this magical RFID is at work. After reading the above introduction, do you have a deeper understanding of RFID?

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