Tuesday, January 11, 2011
Weak current College】 【RFID basic specifications】.
<br> <br> Can be used to measure frequency identification system of technical parameters, such as the system uses the frequency, protocol standards, recognition distance, recognition, data transfer speed, storage capacity, performance and anti-collision RFID packaging standards, .etc. The interplay of these technical parameters and constraints. <br> <br> Among them, the reader's technical parameters are: reader working frequency, output power, reader reader data transfer speeds, the reader output port and reader are adjustable; electronic tag .technology parameters are: electronic label energy requirements and capacity requirements for electronic labels, RFID frequency, RFID tag data transfer speeds, RFID read / write speed, electronic label package, RFID tag data security, and so on. <br> <br> ( .1) operating frequency <br> <br> Operating frequency is radio frequency identification system is the most basic technological parameters. Work frequency selections largely determine the application of RFID system, the scope of technical feasibility and cost of the system. Essentially, radio frequency .identification system is radio communication system, must occupy a certain amount of wireless communication channel. In the wireless communication channel, RF signal only electromagnetic coupling or, in the form of electromagnetic wave propagation. Therefore, radio frequency identification system of work performance must be subject .to electromagnetic wave transmission properties of space. <br> <br> From the physical properties of electromagnetic waves, reading distance, penetrating power and other characteristics, different radio frequency electromagnetic waves of a large difference. Especially in low frequency and high frequency two frequency .bands. Low-frequency electromagnetic wave has a strong penetrating ability to penetrate the water, metal, animals and other conductor materials, but propagation distance compared to the past. In addition, because of the low frequencies, you can use frequency bands narrow, relatively .low data transfer rate, low-noise comparison, is susceptible to interference. <br> <br> Compared to low-frequency electromagnetic waves, to get the same transmission effects, high-frequency systems transmitting power is smaller, the equipment is relatively simple ., the cost is relatively low. High-frequency electromagnetic wave of data transfer rate is high, no low-frequency limitations of signal to noise ratio. However, high-frequency electromagnetic waves penetrating ability is poor, it is easy to be water absorbed by .conducting media, trapped in this regard, the high-frequency electromagnetic waves on obstructions, the sensitivity of the strong. <br> <br> (2) distance <br> <br> Radio frequency identification system for distance refers to the system of .effective recognition distance. Influence the reader identify electronic labels effective distance for a number of factors, including the following factors: the reader of the transmitting power, the system of working frequency and electronic label package, etc. <br> <br> Other things .being equal, the identification of low-frequency system, followed by the nearest high frequency system, microwave systems, microwave systems of recognition the farthest distance. As long as the reader's frequency is changed, the system frequency to be changed. <br> < .br> Radio frequency identification system for effective recognition and the reader's RF transmitter power proportional. The transmitting power, the greater the recognition distance farther away also. But the electromagnetic radiation over a certain range, it will have on the environment and human health effects of .harmful. Therefore, in terms of electromagnetic power must adhere to certain standards of power. <br> <br> Electronic label package also affect the system to recognize the distance. The larger the tag antenna, electronic labels through the reader's role in the region ., the greater of flux, the stored energy is also bigger. <br> <br> Application of the project required distance depends on several factors: the electronic label positioning accuracy; practical application for multiple electronic label the minimum distance between; in Reader work .area, the movement of the electronic label. <br> <br> Usually in RFID applications, select the appropriate antenna, you can adapt to the needs of long distance, reading and writing. For example, FastTrack carousel design pattern antenna is installed in .between the conveyer rollers, REID carrier is installed in the bottom of the pallet or products, to ensure that the carrier directly from the antenna. <br> <br> (3) data transfer rate <br> <br> For most data acquisition .system, the speed is very important factor. Because today's shrinking product production cycle, requires read and update the RFID carrier time shorter and shorter. <br> <br> ① read-only rate <br> <br> RFID read-only system .of data transfer rate depends on the length of the code, carrier data send rate, reading distance, carrier and carrier frequency between the antenna and the data transfer of modulation techniques and other factors. The transfer rate with the practical application of product categories. < .br> <br> ② passive read and write rates <br> <br> Passive read-write REID system of data transfer rate decision factors and read-only system, but in addition to read data from carriers, but also to write data carriers .. Transfer rates with practical application in product description. <br> <br> ③ Active read / write rate <br> <br> Active read / write RFID system of data transfer rate decision factors and passive system, different is passive systems need to .activate the capacitance charging carriers to communicate. It is important that a typical low-frequency read-write systems work rate may only 100 bytes / s or / s 200 bytes. In this way, since a site may have several hundred bytes of data need .to be delivered, data transfer time will take a few seconds, which may be smaller than the entire machinery operation time is long. EMS Company has adopted a number of unique and proprietary technology to design a low-frequency system, its rate higher than most .Microwave System. <br> <br> (4) security requirements <br> <br> Safety requirements, generally refers to the encryption and authentication. On a scheme of radio frequency identification system should make its security requirements are very precise assessment, so .as to exclude from the outset at the application stage may occur in a variety of dangerous attacks. To do this, analysis system in a variety of security vulnerabilities, attack possibilities, etc.BR> <br> (5) storage capacity <br> .<br> Data carrier storage of different sizes, the price of the system. Data carrier price tag primarily by electronic storage capacity. <br> <br> For price-sensitive, onsite needs little application, you should choose a fixed encoding of read .-only data carriers. If you want to write information in the electronic label, you need to use EEPROM or RAM storage technology RFID tag, the system costs be increased. <br> <br> Based on the storage system has a basic rule, .that is the storage capacity is not enough. No doubt, expand system storage capacity will expand the areas of application. Read-only vector of storage capacity of up to 20 bit, active read / write vector storage capacity from 64B to 32KB, which means .that you can read and write to the carrier can store several pages of text, this is enough to load cargo manifests and test data, and allow for system expansion. Passive read-write medium storage space from 48B onto 736B, it has many active read ./ write system does not have properties. <br> <br> (6) RFID system connectivity <br> <br> As automation system development branch, RFID technology must be able to integrate existing and developing automation technology. Importantly, REID system should .be able to direct and personal computers, programmable logic controllers or industrial network interface module (field bus), thereby reducing the installation costs. Connectivity that RFID technology can provide flexible functionality, ease of integration into a wide range of industrial applications. <br> .<br> (7) number of simultaneous reading of RFID <br> <br> Since the system may need at the same time on multiple electronic label identification, therefore, the reader provides many labels to read also need to consider. This causes the .performance of the reader, electronic tags mobile speed, etc. <br> <br> (8) the electronic label package <br> <br> In response to different working environments, the electronic label size, format determines the RFID installation and performance .of the electronic label packaging forms is also one of the parameters need to be considered. Electronic label package not only affects the system performance, but also affect the system's safety performance and appearance. <br> <br> On radio frequency identification system performance indicators .to assess complex, affecting the overall performance of the RFID system a number of factors, including the product factors, market factors, as well as environmental factors, etc. <br> <br> <br> <br> <br> <br .> <br>.