Radio Frequency Identification Technology (1)-concepts and classifications

In modern society, smart cards have penetrated into all aspects of life. There are countless bus cards, attendance cards, ID cards, and mobile phone cards.

When using a smart card, whether or not it is in contact with a card reader can be divided into a contact type smart card and a non-contact type smart card. The contact type smart card has 6-8 contacts, which are inserted in the card seat during use, such as a mobile phone card and a previous public phone card. Non-contact smart cards have no contacts, and there is no power on the card. They obtain energy through the electromagnetic field generated by the card reader and exchange information with the reader. Due to the absence of source and contact-free features of non-contact smart cards, the service life and security of cards are greatly improved. Currently, they are widely used.

Based on the security level, smart cards can be divided into memory cards, logical encryption cards, and CPU cards. A memory card is like an unattended warehouse with an open door. Anyone can access data in the card at will. A logical Encryption Card adds a lock to the warehouse and only has a key (password) can be opened for use. The CPU card is like a dedicated guard warehouse with a CPU chip in it, and the password for storing data needs to be verified. Different applications may have different passwords, so data access is more strictly controlled, the highest security.

Non-contact IC cards use magnetic fields to obtain energy from the reader and exchange data. The magnetic field here is usually called the radio frequency field, so this card is also called the RF card. This technology is called the radio frequency identification (RFID) technology. No matter what the name is, the essence is the same. It is radio communication, which is essentially no different from radio, television, and mobile communication.

Very few useful signals are directly transmitted in radio communication. modulation and demodulation technology is usually used to modulated useful signals on a carrier at a certain frequency. After receiving the modulation signal, the receiver can demodulated the useful signals. The common carrier frequencies of non-contact IC cards include 125 Khz, 134.2 kHz, 13.56 MHz, and GHz. Generally, the higher the carrier frequency, the higher the data transmission rate, and the more complicated the technology.

Although they are free of contact, the effective operation distance between different cards is different. Some card numbers are called contact-free, but the reading distance is very short, only 0-2 cm. These cards are called CICC cards (close-couple ICC) and are generally translated into password-coupled cards; some cards are far away from each other and can reach 10 cm. These cards are called PICC cards (proximity ).
ICC), we call it close to the card. There is also a further way that can reach at least half meters or farther. This type of card is called the vicinity ICC, which is called the sparse coupling card in Chinese.

There are also some unwritten naming conventions in the industry. Generally, card operations are master-slave, that is, the card reader sends commands as the active party, and the card responds after receiving the command. This card is called an IC card. There is a simple type of card that stores only one identification number. Generally, when entering the RF field to obtain energy, the card will not stop sending this identification number. This type of card is often called an idcard. Of course, these names are just habits. In fact, IC is the meaning of Integrated Circuits. All the above cards should be called IC cards, but the power of habit is often very large and takes a long time, this is also accepted.

I will discuss the radio frequency identification technology in a series of "mantalk ". The so-called "mantalk" is informal. I wrote neither a technical document nor a teaching material, but I had some experience in developing RFID cards over the past decade and expressed it in a less rigorous language. In addition, I am familiar with 125 Khz, 134.2khz, and 13.56mhz, and have developed related RF cards. Therefore, the subsequent radio frequency identification technology is based on these three frequencies.