RFID Technology And System

- Oct 11, 2018-

1. What is RFID technology?

RFID radio frequency identification is a non-contact automatic identification technology. It automatically recognizes the target object and acquires relevant data through the radio frequency signal. The identification work can work in various harsh environments without manual intervention. RFID technology recognizes high-speed moving objects and recognizes multiple labels at the same time, making operation quick and easy. Short-range RF products are not afraid of harsh environments such as oil stains and dust pollution. Bar codes can be replaced in such environments, such as tracking objects on the assembly line of a factory. Long-range RF products are mostly used for transportation, and the recognition distance can reach more than ten meters, such as automatic charging or identification of vehicle identity.

2. What are the components of the RFID system?

The most basic RFID system consists of three parts: Tag: consists of coupling elements and chips, each tag has a globally unique electronic code, attached to the object to identify the target object; Reader: Read (in A device that can also write) tag information when reading and writing a card; Antenna: Transmits RF signals between the tag and the reader. 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 reader can read and recognize the electronic data stored in the electronic tag without contact, thereby achieving the purpose of automatically identifying the body. Usually the reader is connected to the computer, and the read tag information is transmitted to the computer for further processing.

3. What is the working principle of the RFID system?

The reader transmits a certain frequency of the radio frequency signal through the transmitting antenna, generates an induced current when the electronic tag enters the working area of the transmitting antenna, the energy obtained by the electronic tag is activated, and the information such as its own code is transmitted through the built-in transmitting antenna of the card; the receiving antenna of the system receives The carrier signal sent from the electronic tag is transmitted to the reader via the antenna adjuster, and the reader demodulates and decodes the received signal and sends it to the background main system for correlation processing; the main system determines the legality of the card according to the logic operation. Sexuality, corresponding processing and control for different settings, issuing command signals to control actuator actions.

4. In which frequency bands does the RFID system work?

Low-frequency systems generally refer to operating frequencies less than 30MHz. Typical operating frequencies are: 125KHz, 225KHz, 13.56M, etc. Radio frequency identification systems for these frequency applications are generally supported by corresponding international standards. The basic characteristics are that the cost of the electronic tag is low, the amount of data stored in the tag is small, the reading distance is short (passive case, the typical reading distance is 10 cm), and the electronic tag has various shapes (card shape, ring shape, button shape). , pen shape), reading antenna is not strong. High-frequency systems generally refer to operating frequencies greater than 400 MHz. Typical operating frequencies are: 915 MHz, 2450 MHz, 5800 MHz, and so on. High frequency systems are also supported by numerous international standards in these bands. The basic characteristics of the high-frequency system are that the amount of data stored in the tag is large and the reading distance is far (up to several meters to ten meters). The high-speed motion performance of the object is good, and the reading antenna and the electronic tag antenna have strong directivity.

5. Other 900MHz equipment interferes with product description Mulan Technology\RFID\Reader\Electronic Label\Smart Identification\RF Automatic Identification Reader adopts advanced “frequency hopping” (ie the reader's working frequency can be used throughout "Random" change in the working frequency band) Anti-interference mode, change the operating frequency every tens of ms, and change the frequency according to the "random function" in each frequency band to avoid accidental sudden influence (in "electronic warfare" This technique is often used to combat external interference). In the multiple electromagnetic compatibility experiments with GSM mobile phones, the reader has never been disturbed.

6. The impact of the product on the human body and the interference of other 900MHz devices indicates that the output power of the reader is 1W (test value), considering the gain of the antenna is about 6W, which is only about twice the output power of the mobile phone by 3.2W. The distance between the mobile phone and the human brain is only a few centimeters. It has been proven that it does not pose a threat to the health of the human body. In contrast, the antenna of the reader is farther away from the owner. In addition, the effective distance of the first reader is 10 meters (less than the effective range of the cordless phone); plus the system is directed to small area launch (in the range of more than ten cubic meters), with the full mobile phone There is an essential difference in directional emission. The direction of energy emission is towards the ground and will not spread into the air. At the same time, frequency hopping technology is used to spread the energy spectrum to the entire working frequency band, further greatly reducing the impact on other systems. Therefore, the possibility of the reader's interference with other electronic devices is basically absent. Based on the above two factors, the electromagnetic compatibility of the product is very good, which is unmatched by the RFID system of the early fixed frequency 915MHz band.

7. 915MHz system application The passive RFID system uses allocated radio spectrum resources only in a very narrow airspace and a small range, which is greatly different from omnidirectional and geographically active full-duplex mobile line communication. . As long as the correct design and installation, only the same frequency point can be used to complete ETC charges in many lanes without interference. In contrast, mobile radio communication systems need to assign different radio channels to each mobile phone user participating in the communication in the service area to avoid mutual interference. From this point of view, the RFID system is a special system that should not be constrained by the radio management system. For this reason, many manufacturers' RFID product specifications have claimed that they can be used without the permission of the radio management department. In addition, since the 915MHz band RFID system adopts the passive working mode, its frequency occupancy range is only in the ETC lane microwave communication area, so the number of vehicles increases, and the RFID system working point frequency can meet the needs of capacity expansion. The T6 standard used in our products was submitted to the National Information Technology Council for approval in 1999. In the United States, using the 915MHz band RFID products for more than ten years, it is a good solution to the problem of mutual adaptation of RFID and line communication services. In the United States alone, 20 million electronic tags and 30,000 readers in the UHF band have been sold, and the 915 MHz part has a wide range of applications in the United States.

 8. What are the advantages of RFID technology compared to Barcode technology?

* Barcode is a very widely used automatic identification technology, but the advantages of RFID are obvious:

* No need for light source, even read data through external materials; Long service life, can work in harsh environments; Can be easily embedded or attached to different shapes and types of products;

* Read distances farther; can handle multiple tags at the same time;

* Can write and access data, writing time is less than printing barcodes;

* The content of the tag can be changed dynamically;

* The data access of the tag is password protected and the security is higher; * The object attached to the RFID tag can be tracked and positioned.