CH
EN
RFID (Radio Frequency Identification) is a general term, basically all of our positioning tags can be called RFID. The common interpretation is that radio signals are transmitted by electromagnetic fields tuned to radio frequencies from a tag attached to an item to automatically identify and track the item. Some labels can get energy from the electromagnetic field emitted by the identifier during identification, and do not need a battery; There are also tags that have their own power source and can actively emit radio waves (electromagnetic fields tuned to radio frequencies). The tags contain electronically stored information that can be identified within a few meters. Unlike bar codes, RF tags do not need to be in the line of sight of the identifier and can also be embedded in the object being tracked.
RFID is classified according to whether it is active, there can be three kinds, passive, semi-active, active.
Passive RFID, completely need external incentives, generate electricity, the data is sent out through the antenna, the most typical is our access card;
Semi-active, need to sense that the outside is reading it, and then work through its own battery, self-generated work and external transmission of the power supply does not rely on excitation, but is completely battery-powered, the most typical is ETC, ETC under normal circumstances is completely not working, when close to the gate, back by the driver wake up, and then start to work. NFC can also operate in semi-active mode;
Active tags generally work actively, such as our positioning tags.
RFID can work in different frequency bands, typical RFID has the following types:
The most typical RFID has three kinds, low frequency (125KHz), high frequency (13.56MHz), ultra-high frequency (850MHz ~ 910MHz), of which the high frequency is divided into general RFID and NFC two kinds of the following four typical to describe
125K RFID
The general operating frequency of the card reader used in low frequency ranges from 120KHz to 134KHz, and the TI operates at 134.2KHz. The wavelength of this band is about 2,500 meters. Due to its low operating frequency, the relative reading distance is further than that of 13.56MHz.
It is mainly used in animal husbandry management system, marathon running system application, etc., which follows international standards:
a) ISO 11784 RFID livestock applications - coding structures
b) ISO 11785 Applications of RFID in animal husbandry - Technical theory
c) ISO 14223-1 RFID applications for animal husbandry - Air interfaces
d) ISO 14223-2 Application of RFID in animal husbandry - Protocol definition
e) ISO 18000-2 defines the physical layer, collision prevention and communication protocols for low frequencies
f) DIN 30745 is mainly a European standard defined for waste management applications
13.56MHz RFID
13.56MHz RFID operates at 13.56MHz, and the wavelength of this frequency is about 22 meters. Is the most widely used passive RFID, our access card, reading library book label, due to its price of about 0.1 yuan, is widely used in logistics and other fields, for traceability and other work.
The main international standards are:
a) ISO/IEC 14443 near-coupled IC card with a maximum reading distance of 10cm.
b) ISO/IEC 15693 loosely coupled IC card with a maximum reading distance of 1m.
c) ISO/IEC 18000-3 This standard defines the physical layer, collision avoidance algorithm and communication protocol of the 13.56MHz system.
d) 13.56MHz ISM Band Class 1 Definition 13.56MHz complies with the interface definition of the EPC.
MiFare
The name MIFARE, derived from the MIkron FARE collection System, is a registered trademark for a range of contactless smart card and proximity card technologies owned by NXP Semiconductors.
MIFARE includes a range of proprietary contactless smart card solutions that utilize radio frequency identification (13.56MHz) in accordance with ISO/IEC 14443-A specifications. The technology was first developed by the Mikron Group in 1994 and resold to Philips Electronics in 1998 (renamed NXP Semiconductors in 2006).
Card reading process
When the card is close to the reader and enters the sensing range of the communication antenna (about 2.5 cm to 10 cm), the reader and reader will provide a small amount of electricity (about 2 volts after) to drive the circuit on the card.
At this time, the card and the machine encrypt the communication content with MANCHESTER Encoding and Miller encoding respectively, and then use Amplitude Shift Keying (Amplitude Shift Keying, amplitude shift keying, amplitude shift keying). ASK sends and receives radio wave signals through the modem to verify whether the card is correct. If the verification result is correct, the card machine will confirm the data storage block to be accessed, and perform password verification on the block. After the card and the machine are authenticated correctly, the actual working communication can be carried out through encryption.
The process takes about 0.1 seconds to complete. If multiple cards enter the sensing range of the card reader at the same time, the card reader will number the cards and select one card for verification until all cards are verified (called anti-collision mechanism) or leave the sensing range.
Card/machine triple authentication steps:
1. The card generates a random number RB and sends it to the card reader;
2. The card reader will send the received random number RB to the TokenAB value encoded by the formula and sent back to the card;
3. After receiving TokenAB, the card will interpret the encrypted part and then compare parameter B and random number RB. At the same time, according to the random number RA received, the formula is encoded to generate TokenBA and send back to the card reader
4. After receiving TokenBA, the card reader interprets the encrypted part, compares the random number RB, RA and the RB and RA solved in TokenBA, and the correct one can complete the instruction (charge, open the door lock or register other matters).
IC/ID/CPU:
IC Card full name Integrated Circuit Card (Integrated Circuit Card), also known as Smart card (Smart Card). Read and write, large capacity, encryption function, reliable data record, more convenient to use, such as card system, consumption system, etc., the main PHILIPS Mifare series cards.
ID Card full name Identification card (Identification Card), is a non-writable induction card, including a fixed number, mainly Taiwan SYRIS EM format, the United States HID,TI,MOTOROLA and other ID cards.
The ID card is only a card number inside, the card reader read, you can decide whether to release the card or not, but also by the background server to decide how to perform the action; IC card has a chip, divided into memory cards, such as mifare1 card, there are storage sectors, through different levels of keys for reading and writing; A cpu card, equivalent to a computer, has processing power. The ID card is the cheapest and the CPU card is the most expensive. The CPU card has the highest security level
UHF card
UHF is a ultra-high frequency card, because its read and write distance is generally more than one meter, widely used in the field of materials, production and manufacturing.
Comply with air standard: ISO 18000-6, GB/T 29768-2013
Test standard (ISO 18046)
Support multi-coding block read and write, provide high temperature resistant coding block (1024 bytes), ProfiNet, TCP/IP and other series versions
UHF uses different frequency bands around the world
NFC
NFC technology is in line with ISO18092, ISO21481 standards, compatible with ISO14443, ISO15693 RF standards.
ISO 14443 and ISO15693 both use 13.56MHz alternating signal as the carrier frequency: ISO15693 read and write distance is longer, of course, this is also related to the antenna shape and transmission power of the application system;
ISO14443 defines two types of protocols: TYPE A and TYPE B. The communication rate is 106kbits/s, and the difference between them is mainly the modulation depth of the carrier and the encoding method of the bits. The following table compares the two protocols. You need to consider which protocol to use in specific application scenarios.
NFC labels are classified into five types
Type-1
Comply with ISO/IEC 14443A specification. It is read-write capable and can be configured by the user to be read-only. The memory size ranges from 93 bytes to 2 kilobytes, and the communication speed or data rate is 106 kilobits per second. The conflict prevention mechanism is not supported.
Type-2
Comply with ISO/IEC 14443A specification. It is read-write capable and can be configured by the user to be read-only. The memory size ranges from 48 bytes to 2 kilobytes, and the communication speed or data rate is 106 kilobits per second. Support conflict prevention mechanism.
Type-3
The label complies with ISO/IEC 18092 and JIS X 6319-4 standards with data rates of 212 kbit/s or 424 kbit/s. Support collision avoidance mechanism.
Type-4
Both A and B versions of the ISO/IEC 14443 Type-4 label contain 32 kilobytes of memory, support data rates of 106 kbit/s, 212 kbit/s and 424 kbit/s, and a collision avoidance mechanism.
Type-5
Tag (NFC-v) It relies on the ISO/IEC 15693 standard, contains up to 8 kilobytes of memory, supports a data rate of 26.48 kilobits per second and a collision avoidance mechanism.
RFID location
RFID positioning is mainly through the RFID Reader to read the ID, if it can be read, the identification and RFID binding target exists in the area of the Reader.
RFID positioning is mainly used for access control, production line logistics process monitoring and other fields.
