Classification of RF technology:
Automatic identification technology
Automatic equipment identification technology is a new technology that is developing rapidly in the world at present. Its English name is Automatic Equipment Identification (AEI). The basic idea of this technology is to realize people's automatic identification and management of objects or equipment (people, goods) in different States (moving, static or harsh environment) by adopting some advanced technical means.
At present, the most widely used automatic identification technology can be roughly divided into two aspects: optical technology and radio technology. Among them, the products widely used in optical technology are: bar codes and cameras. These two products have been widely used in people's daily life and are widely known. For example, bar codes are used for commodity management, and cameras are used to capture illegal vehicles.
Radio frequency identification technology
Radio frequency identification technology can be divided into low-frequency system and high-frequency system according to the different frequencies it uses. According to whether the battery power supply is installed in the electronic tag, it can be divided into active system and passive system. The information injected by electronic tags can be divided into three categories: integrated circuit solidification type, field wired rewriting type and field wireless rewriting type; According to the technical means of reading electronic tag data, it can be divided into three categories: broadcast emission, frequency doubling and reflection modulation.
1. Generally speaking, the low-frequency system means that its working frequency is less than 30MHz, and the typical working frequencies are: 125KHz, 225KHz, 13.56MHz, etc. Radio frequency identification systems applied in these frequency points are usually supported by corresponding international standards. Its basic characteristics are low cost of electronic tags, less data stored in tags, short reading distance (in passive case, the typical reading distance is 10cm), various shapes of electronic tags (card shape, ring shape, button shape and pen shape), and weak directivity of reading antennas.
2. High-frequency system generally means that its working frequency is greater than 400MHz, and the typical working frequency bands are: 9 15MHz, 2450MHz, 5800MHz, etc. High frequency systems are also supported by many international standards in these frequency bands. The basic characteristics of high-frequency system are high cost of electronic tag and reader, large amount of data stored by tag, long reading distance (up to several meters to more than ten meters), good adaptability to high-speed movement of objects, generally card-shaped, and strong directivity of reading antenna and electronic tag antenna.
3. Active electronic tags are equipped with batteries, which generally have a long reading distance, but the disadvantage is that the battery life is limited (3~ 10 years); There is no battery in the passive electronic tag. After receiving the microwave signal from the reader (reading device), it converts part of the microwave energy into direct current for its own work, which is generally maintenance-free. Compared with active system, passive system has some limitations in reading distance and adapting to the moving speed of objects. ......