Wednesday, January 5, 2011

【 Weak current College 】 RFID classification 】

Radio technology in automatic identification applications in more specific technical name for RFID, Radio Frequency Identification English, also known as RFID. Radio frequency identification system is composed of at least generally consists of two parts: (1) the electronic label, the English name for the Tag; (2) reader, the English name for the Reader. Electronic label General save agreed format for electronic data, in practice, the electronic label attached to the question to identify objects on the surface. Readers also known as the readout device, contactless and RFID reading and recognition in the electronic data, so as to achieve the purpose of automatic recognition of objects. Further through the computer and computer network object recognition information collection, processing and remote transmission and other management functions. Classification of radio frequency identification RFID technology in its use of the frequency of different can be divided into low-frequency systems and high-frequency systems, two categories; according to the e-tag fitted battery as its power, and it can be divided into active and passive system two categories; from electronic tags to save information into the ways it can be a sub-IC curing, on-site wired overwrite-and field-wireless; three class to override the read RFID tag data technology means that it can be divided into radio emission, multiplier and reflection modulated three categories. 1. the low-frequency systems generally refers to the operating frequency of less than 30MHz, typical operating frequency: 125KHz, 225KHz, 13.56M, based on the frequency of radio frequency identification systems generally have corresponding to international standards. Its basic features are the RFID tag is less expensive, labels, the amount of data saved in the smaller, reading distance is shorter (passive, typical reading distance 10cm), various electronic label shape (card shaped, rings, buttons, a pen), read antenna directivity is not strong, and so on. 2. the high-frequency systems generally refers to its operating frequency greater than 400MHz, typical working frequency: 2450MHz, 5800MHz 915MHz, etc. High-frequency systems in these bands, as well as a host of international standards to support it. The basic characteristics of high-frequency system is an electronic tag and reader costs are relatively high, labels, the amount of data saved in the larger, reading distance (up to a few meters to several meters), to adapt objects high-speed movement of good performance, outline General card, read the antenna and the RFID tag antennas are strong direction. 3. active RFID tag contains a battery, generally has a more distant reading distance, deficiencies is the battery life limited (3 to 10 years); passive RFID tag without the battery, it receives reader (readout device) issued by the microwave signal, will be part of microwave energy to DC for their work, can usually be done free of maintenance. Compared to active systems, passive system at reading distance and object movement speed is slightly restricted. 4. integrated curing type information in the electronic tags in IC production generally forthcoming information to ROM process mode injection, their saved information is immutable; spot wired overwrite-electronic label General will tag saved information is written to the internal storage of E2 in overwrite requires dedicated programmer or writer, the overwrite process must be powered; on-site wireless rewrite-electronic label generally applies to active electronic tags that have specific override directive, electronic tags saved information is also located in the storage area of E2. Generally override tag data is much larger than the time needed to read RFID tag data to the desired time. Typically, override the time required for the second level, the level of reading time in milliseconds. 5. radio emission of radio frequency identification systems to implement the simplest. Electronic label must be in Active mode, and live their store identification information to broadcast, the reader is equivalent to one only of the receiver. The disadvantage of this system is the electronic label due shall be kept to launch information, electricity, and electromagnetic pollution to the environment, and the system does not have security confidentiality. Multiplier-radio frequency identification systems to achieve up to a certain degree of difficulty. In General, a reader sent the signal RF, RFID tag query returns the signal carrier issued for the reader's RF frequency. Such work patterns on the readers receive treatment echo provides convenient, however, passive RFID tag, RFID will receive reader RF energy is converted to a harmonic echo carrier frequency, the lower the energy conversion efficiency, improve the conversion efficiency require higher microwave techniques, this means that the higher cost of electronic labels. At the same time, this system must take two working frequency, generally more difficult to obtain radio frequency management product application license. Reflex modulated radio frequency identification systems to achieve up to resolve the problem with frequency transceiver. System, reader emits microwaves query (energy) signal to the electronic label (passive) will be part of the received signal power microwave query as DC rectification within the tags for electronic circuit, another part of the microwave energy signals are electronic label in the saved data modem (ASK) is reflected back to the reader. The reader receives a reflection of amplitude modulation signals, to work out the electronic label the identifying data information. Systems work, reader emits microwave signal and reception reflection amplitude modulated signal simultaneously. Reflecting back on the signal strength is transmitting signals to weak much technical implementation difficulty on the same frequency.

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