RFID in 902mhz-928mhz questions and answers

• Author: fonkan
• Source: fonkan
• Date: 2018-09-05
• Views: 708Times

1. Electromagnetic compatibility of products

 

Currently working in 902 MHZ to 928 MHZ band wireless devices including GSM mobile communication equipment, RFID uhf wireless telephone equipment, as well as some of the equipment used in industry, scientific research and medical purposes (international, called ISM frequency band), 890 MHZ to 915 MHZ in the spectrum used for GSM uplink transmission in the system, i.e. mobile phone from the base station sends a message in this band, base station in receiving this band;935mhz-960mhz is used for the base station to send messages to the mobile phone, which receives them.There is a 20MHz gap between the two frequency bands, that is, the 20MHz at 915mhz-935mhz is allocated for RFID use, so it will not cause interference between each other.

 

 

 

2. Description of product interference by other 902mhz-928mhz readers

 

RFID read-write device adopt advanced "fh" (that is, to read and write device operating frequency can be "random" change within the whole work frequency band) way of anti-interference, dozens of ms change every working frequency, and according to the random function in the frequency band to change its frequency, avoid affected by accidental emergency (in "electronic warfare" this technique is often used against external interference).In the multiple experiments of electromagnetic compatibility with GSM mobile phones, the reader interference has never occurred.

 

 

 

3. Description of the effect of the product on human body and interference of other 902mhz-928mhz readers

 

Legibility of the output power of 1 W (test), after the consideration of antenna gain is about 6 W, just phone about twice as large as the output power of 3.2 W, but phone calls with the distance is only a few centimeters of the brain, have proved that did not pose a threat to the health of human body, in contrast, legibility of the distance of antenna and the owner is far more.

 

In addition, the reader is manufactured in accordance with the technical specifications of DSRC (short range radio communication), with an effective range of 10 meters (less than the effective range of cordless telephone);In addition, this system is aimed at small area launch (within a dozen cubic meters), which is substantially different from the full-direction launch of mobile phones. The direction of energy transmission is towards the ground, and it will not spread to the air.At the same time, frequency hopping technology is adopted to spread the energy spectrum to the whole working frequency band and further significantly weaken the impact on other systems.Thus, the possibility of reader interference with other electronic devices is basically non-existent.

 

Based on the above two factors, the product has excellent electromagnetic compatibility, which cannot be compared with the earlier 902mhz-928mhz frequency band RFID system.

 

 

 

4.902 mhz-928mhz system application

 

Passive RFID systems only use the allocated radio spectrum resources in a very narrow space and a very small area, which is greatly different from the omnidirectional and full-duplex active mobile line communication.With proper design and installation, ETC charges can be completed on many lanes at the same time with only one frequency point without interference.In contrast, mobile radio communications systems assign different radio channels to each mobile phone user in the service area to avoid interference from each other.From this perspective, the RFID system is a special system that should not be subject to the radio management system. For this reason, the RFID product specifications of many manufacturers have claimed that the equipment can be used without the permission of the radio management department.

 

In addition, because the 902mhz-928mhz frequency band RFID system adopts the passive working mode, its frequency points occupy only in the microwave communication area of ETC lane. Therefore, the number of vehicles increases, and the working point frequency of the RFID system can meet the needs of capacity expansion.

 

The T6 standard used in our products is the technical specification submitted to the U.S. national information technology commission for approval in 1999.In the United States, 902mhz-928mhz frequency band RFID products have been used for more than 10 years, which has solved the problem of mutual adaptation between RFID and radio communication services.In the United States alone, 20 million UHF tags and 30,000 readers are sold, of which 915MHz is widely used in the United States.

 

The 902mhz-928mhz frequency band RFID products of the ministry of railways of China have obtained the license issued by the state commission of non-leadership.

 

The promotion of electronic charging and the development of intelligent transportation (ITS) information industry based on automatic vehicle identification cannot take China's national conditions into consideration.Our product is a kind of product with high performance and price, which can be widely used and recognized by the market, so it has strong vitality.

 

 

 

5. Accuracy, reliability and maintainability of the system

 

According to the technical data provided by the product supplier, the correct card reading rate of the system will be higher than 99.99%.

 

About reliability

 

The product meets the ANSI standards of the national bureau of standards and the quality of the product produced under such standards should be trustworthy.The whole identification tag card has been integrated into one integrated block, eliminating the fault source in the past caused by poor contact between circuit board and component joint and failure of individual components.In addition, the integrated block is powered by radio waves emitted by the card reader as energy, which does not require a battery and avoids frequent failures caused by poor contact or insufficient power supply.

 

 

 

6. On maintainability

 

A number of complete machines are used for full system backup. If the maintenance staff of the fault passes the fault detection, tracking, and is determining its fault point, the whole machine causing the fault is replaced, so that the lane is re-opened in the shortest time and put into service.

 

 

 

7. Information security measures for products

 

Each tag has a unique identification number in the world and is locked before delivery, preventing tampering.The sensitive data in the readable area of the toll station in the electronic tag can be locked and cannot be modified after being locked.

 

Configure a code password for a particular owner that is placed in the system area of the card to ensure that no organization or user can rewrite the data in the card issued by a particular owner.

 

The encryption of sensitive data can be further strengthened by using DES (data encryption standard) algorithm.

 

 

 

8. Whether there are mature standards to rely on

 

902mhz-928mhz products comply with ISO/ 18000-6c international standard and American ANSINCITS256 standard.2.45ghz products are manufactured to the FCC/ITS standards approved by the federal communications commission (FCC).Three frequency band technologies are widely used in the world.

 

 

 

9. About system security

 

The 902mhz-928mhz system USES the locked and non-tamable global unique ID code in the electronic tag to index the central data to obtain relevant information of the vehicle owner. No information related to the user needs to be recorded in the tag, and the confidentiality and information security are very high.In fact, this method has been used for many years in the United States. More than 27 million electronic tags that have been issued in the United States all use this mode, because they do not need to pay attention to the content of the user data area in the electronic tags, nor do they need to encrypt the data in the tags to ensure information security.Taking advantage of the uniqueness of the lock ID number in each tag (once locked, it cannot be unlocked), it is the most effective and efficient way to secure the information.Because it is safest to store all user accounts and personal information that cannot be modified with a unique ID number in the data center.

 

By contrast, the 902mhz-928mhz system is easy to implement and the measure is reliable, simple and effective, while the 5.8ghz system is limited by the physical structure of the label, so it is difficult to completely solve the requirement of the defense.In addition, the 5.8GHz system needs to encrypt all sensitive data in the card through the digital addition algorithm (DES), which greatly increases the system overhead.

 

 

 

10. About anti-interference

 

The 5.8ghz band is monopolized by ETC, and of course will not interfere with other devices.However, this is a waste of resources, and with the rapid development of information technology, it is difficult to guarantee that the frequency band does not overlap with other devices.

 

The frequency band is mainly used for mobile communication.The widely used 915MHz products, which are based on ISO/ 18000-6c and t-6 standards, have been comprehensively tested in the electromagnetic laboratory authorized by China, and their results meet the requirements of the national standard for radiation-interference experiment (gb6833.10-87) in the electromagnetic compatibility experiment specification and the regulations for electromagnetic radiation protection (gb8702-88).The former is to verify whether the product will cause interference to other electronic products in the same frequency band, while the latter is the ability of the system to tolerate interference from other electronic products in the same frequency band.The results all pass the test, and there is margin.

 

Field interference simulation testing has to two GSM mobile phone in the car with the two other cell phone near the antenna located in, speaking, reading and writing at the same time, in including dialing the entire communication process, read and write device for phone calls without interference, even if the GSM mobile phone with the identification card is very close to launch, also do not affect the accuracy and stability of the RFID system.

 

The 890-902mhz-928mhz frequency band in the GSM frequency band is used for mobile phone transmission and base station reception, while the 935-960mhz frequency band is used for mobile phone reception and base station transmission. The frequency band of 915.5mhz-934.5 MHz is selected, that is, the so-called industrial, scientific and medical frequency band is a "window" outside the GSM communication frequency band.This is based on the above two national standards of electromagnetic compatibility (electromagnetic compatibility experiments are conducted under the condition of the same frequency band as other electronic equipment) to further improve the interference protection through frequency isolation.