Monday, December 27, 2010
【 Weak current College 】 RFID technical details 】
Electronic product code Auto-ID Center has introduced a new electronic product code, as a recognition of the next generation of products. Our goal is not to replace the existing bar code standards, we want to establish a migration path, and help them from existing barcode standard transition to the new electronic product code, in order to encourage this development, we have adopted the global trade in coding (GTIN) of the basic framework. We cannot guarantee that electronic product codes will in the world widely used but our proposal is to obtain the regulatory standards of the international barcode of the two institutions, which are uniform coding Committee and international EAN organizations. In addition, we are also working with other national and international trade groups and standards organizations have relationships. How is the electronic product code work? Electronic product code is a header encoding and three data set, composed of a number, as shown above. Head coding to identify the version number of the electronic product code, which makes future scalable electronic product codes are different for different length or type. The second part identifies the electronic product code, the most likely is the electronic product code representative of the manufacturer of the product, for example, the Coca-Cola company. The third part of the article category, refers to the exact category, products are usually in stock units, such as the 330 ml cans of Coca-Cola Park, United States. The fourth part is the serial number of each item are not the same, the concrete representation of our refers to what a can of Coca-Cola Park. This allows to quickly find out about expired products possible. Electronic product codes category Auto-ID Centre a 64 bit and 96 bit two electronic product code, the end may also be more. One of the 96-bit electronic product code is we believe that one of the most commonly used. We are sure that all products have a unique code and reduce the cost of the label was made by the trade-offs between them, thus choosing a 96-bit. The 96-bit electronic product code can 2.68 home manufacturer identification code to each producer can have 1600 000 product categories, each category can have 680 million product serial number, enough for the next few years the world-wide production of all products. Because there is no need for so many of the serial number, so we made a 64-bit encoding as a transitional period. Small bits of code to ensure adequate provision of unique electronic product codes at the same time, you can keep the RFID chip prices lower. The basic principles of a RFID tag RFID label consists of one attached to the antenna on the microchip. In different applications, there are different types of tags, in this section we will introduce the content. The RFID can track a single commodity play a role in one of the key is to significantly reduce the cost of the label. In this section, the following section describes how to plan implementation. Active and passive active RFID tags have a battery, the battery to operate micro-chip circuit to provide power and to send a signal to a reader (cellular phone base station transmits a signal to the same principle). Passive tags without batteries, on the contrary, it receive power from the reader. Reader sent the electromagnetic wave, in the tag antenna in a current. Semi-active label with a battery to Microchip's operation provides electric energy, but send signal and reception of signals are obtained from the reader. Active and semi-active tags in the track high-value of merchandise are useful because they need the scanning distance, for example, in the train on the tracks, but that tag consumes 1 USD or more, which makes him unfit to low-cost commodity. Auto-ID centers are concentrated on passive tags, now it costs have been reduced to less than 1 dollar. Their scanning distance is not like Active label so far, usually less than 10 feet, and active tags can reach 100 feet, but they are cheaper than active tags, and requires no maintenance. In addition, we also develop other kinds of label types, our system may use them. Read-write and read-only in the RFID tag chip can be read/write or read-only. Use read-write chip, when the label in the reader or the Finder scope of read and write, you can add information to the label or cover up the original information. Read and write tags in some special applications is useful, but because it is read-only chips much more expensive, so it is used to track the price of goods is not practical. Some read-only microchip contains in the production process the stored information, such information is always on the chip cannot be changed. Another method is to use electrical erasable programmable read only memory, EEPROM, use of, or a special electronic procedures, the data can be overwritten. Auto-ID Center Description: we're going to create RFID tags, or even to tell suppliers what type should be label production. Our only concern is that the label contains an electronic product code information to an open, standardized way to exchange information, and meet some minimum performance requirements, so that it can be in any location to read information from the reader. However, because of the low cost label is a key component of the system, we are already committed to chip design, the aim is to design and production costs after about 5 cents, and be at least 4 feet wide read information of the chip. We developed the first label is the ultra high frequency, the frequency with which to 915MHZ, using EEPROM. So the company can in commodity production and packing in the label is written to the electronic product code, but can also use other storage technologies. Reduce tag cost RFID tags in high-cost has become the technology of mass promotion of one of the biggest obstacles. Currently, the cheapest RFID tags for mass production also takes 50 cents. In the Centre, we aim to Auto-ID will each tag cost reduced to 5 cents, to achieve that goal has been to design multiple policies. Simple is the best in the Centre of scheme Auto-ID, a 96-bit or 64-bit electronic product code is stored in the RFID tag's unique information. This is because the storage of small, low-cost chip. Imagine a single silicon circuit door — Microchip's basic structure, cost about thousandths cents.Auto-ID Center members a year more than 5000 million units of the product, so the label on each additional switch is going to cost them more than the cost of $ 5 million. Reduce chip reduces passive and read-only label cost of a key that is used by the size of the micro-chip. 8-inch silicon wafer price relatively stable, but the chip are cut into small pieces, each small piece prices are relatively low. At present, most of the chip is made of diamond cut, this approach can produce up to 15000 block microchip, 1 flat on mm. There is another method called erosion cutting, it can produce up to 25 million chip, probably the square microns 150 per chip, or perhaps is the width of human hair. This process is the acidic liquid onto the chip, then corrosion cut wafers. Smaller chip compared to the traditional micro-chip is much cheaper, but with these devices tend to have a problem. Even with mechanical robots to handle most of the silicon chip, and it cannot cope with such little chip. Auto-ID Center supporters Alien technology, has developed a manufacturing process, called fluid self-Assembly, the chip is mounted on a base, and antenna can add up. Because of the acidic liquid causes corrosion of silicon wafer, chip has a slanted edges. Alien build a base, there are some holes that appear these chips in the stencil, and then thousands of tiny chip on it. Alien will they called "nanoblocks" base above special liquid flows, some will automatically fall into the hole, the remaining will be collected and used again. Base metal sheet cutting strips, so that the antenna can be assembled on the chip, made into a label. Antenna and chips are two sandwich made with a complete label. When the Alien's new production facility in full operation, it will produce 800 million chips. Other methods of assembling a small chip is also in development, they are also the improvement of existing methods. A very promising approach is to shock Assembly, it is by MIT and Auto-ID Center of PHILIPS Semiconductor research. New antenna another low-cost key label is to reduce the cost of the antenna. Auto-ID Center of a supporter of Rafsec, is developing a new type of antenna, it will be used to add Alien chip production label, the label in mass production, it may take around 5 cents. Currently, most RFID antenna is the use of acid removal of copper and aluminum conductor elements in metal, forging forming. Rafsec is the world's largest paper manufacturer and one of Finland UPM-Kymmenc subsidiary of a company, it has created a high speed plating technology, antenna using conductor ink drawing, and then add a layer of metal printed on top of it. Use of this technology, the Rafsec in high-volume production of antennas, antenna cost control can be in the 1 cent, roughly the same as with the existing technology of production of ordinary antenna 5 to 15 cents sharp contrast of the cost. In addition, there are other production low cost antennas innovative approach by other Auto-ID Center supporters. Silicon substitutes several companies are independent of the Centre for research on the use of Auto-ID to cheap alternatives to the production of Silicon RFID tag technology, or even simply using magnetic "no chip label". This effort is likely to be successful, the Centre also supports Auto-ID. We are in the development of this system does not exclude these technologies or any other technology. Our vision is a kaleidoscopic world, where any tag, as long as you use the correct language, meet basic performance requirements, regardless of silicon or other material, are able to work with any reader information exchange. Use of artificial polymers or special chip making chips may be cheaper than silicon chips, and they may have some other applications, such as monitoring temperature and vibration sensor. Through the establishment of a global network, the company can use it to identify the product, we can also create a new market, where such innovations will prosper. On radio waves to understand labels use radio waves to communicate with the reader, we began to introduce reader works, it is necessary to introduce a bit of knowledge of radio waves and their properties. Radio waves are part of the electromagnetic spectrum, and the electromagnetic spectrum is a very broad definition, scientists use it to indicate wave form divergence of all frequency energy. One end of the spectrum is low frequency waves, such as the am radio and sea vessel communication system using radio waves. Is the frequency of high-end x-ray and gamma ray. The Government requires that Governments around the world provides a lot of the electromagnetic spectrum of uses. For example, in the United States, FM radio, radio frequency must be between the 88 to 108MHZ (if you listen to 91.5FM, means you have FM radios to receive per second repeat 9.15 Jessica radio waves). One problem with using RFID is the world's countries have different bands are divided into different uses, ISM-band reserved for industrial, scientific, medical purposes, in addition to this special band, world each place almost all already have without the use of the band. This means that one in a State to label 915MHZ work in another country may not be read because in this country, the band has been used for other purposes. A single frequency can not meet all application even in the spectrum of a band in the world, no country can not be used, by limiting the RFID tags, only the band seems to be able to meet the requirement, but it still may produce undesirable results. Because different frequencies have different characteristics, so that they are used for different applications. For example, low-frequency tags than UHF labels, use less energy and better through non-metallic substances. They are in close range scan rich water of substances is desirable, such as fruit. UHF frequency usually wider and faster data transfer rate, but they consume more energy and less likely to penetrate the body. Because the UHF frequency more directional, they require in the tag and Reader have aClear channel. UHF labels might scan through discharge door to warehouse the goods better effect. Water and metal, many people know that radio waves can be absorbed by water, twisted metal, making RFID Tracking is rich in water and metal containers and packaging of the product is useless. This really makes tracking metal products or products containing moisture becomes a big problem, but we've found a good system design and engineering to overcome these shortcomings of RFID. This is why our method does not restrict the supplier or the user has only one frequency system. Our goal is to establish a system, in this system, any label as long as it contains electronic product codes, we have established basic Exchange standard, it can be used to identify a product. Reader RFID reader use many ways to interact with the label information, proximity read passive tag information of the most common way is inductive coupling. As long as close to the reader of the coiled antenna and coiled antenna of the label with respect to form a magnetic field. Label is the use of the magnetic field of the electromagnetic energy is sent back to the reader. The return of electromagnetic waves are converted to the data information, the label of electronic product code. Affordable sensitive reader at present, a reader cost about $ 1000 USD or more, but most can only read a single frequency chip information. Auto-ID Center has designed the sensitive interpretation for detailed specifications of reference, the reader can read different frequency chip information. In this way, companies can take advantage of the different circumstances of different kinds of label, and not for each frequency labels have to purchase a reader. Because the company will need to purchase many reader to cover all areas of their operations, so the reader price must be acceptable for them. Our specifications will enable producers in the mass production of the produce cost approximately $ sensitive reader. Avoid conflicts use RFID reader reader encounters a problem is, from an encoder signals may and another coverage overlap encoder signals interfere with each other. This phenomenon is called an encoder conflicts, Auto-ID Center uses something called time division multiple access (TDMA) mechanism to avoid conflicts. In short, the reader is directed at different times of the read information, but not at the same time attempting to read information, this ensures that they do not interfere with each other. But this means that two reader overlapping areas of any RFID tags will be read twice, so we have developed a set of removing redundant information system. Avoid label collisions another reader encountered problem is in the same range to read many chip information at the same time, when more than one chip to the reader returns a signal so that the label conflict occurs, it makes the reader cannot clear judging information. Auto-ID Centre has adopted a standardized method to solve the problem. Reader only requires the first digit meet it required an interpretation of the response to the label. Essentially speaking, that is, the reader request: "electronic product code to 0 at the beginning of the label in response to the reader. "If more than one response, the reader continues to ask:" electronic product code to the beginning of the label response 00 reader. "This operation until only one label response. This process is very fast, a reader in 1 seconds can read 50 label information. Read distance range read information depends on the interpretation of the energy and the reader and the tag is used to Exchange frequency. Generally speaking, the high-frequency tags have more reading distance, but they need the reader output energy of electromagnetic waves. A typical low-frequency tags must be read within a foot and a UHF labels can be 10 to 20 feet of distance is read. In certain application cases, reading distance is one of the key issues to consider, for example when trains under the track time to tell them you will need a longer read range. But long reading distance is not necessarily benefits, if you're a soccer field in such a big warehouse has two reader, you probably know what stock, but the reader cannot help you determine a specific location of a product. For supply chain, it is best to have a network patterns of many reader in the warehouse, they are able to accurately identify a the label of the exact location. Auto-ID centered design is a 4-foot distance can read labels sensitive reader. SAVANT if every article in the world has an RFID tag, the reader will collect continuous electronic product code information, how to manage and transmit all such information is a challenge, and in order to make the Global RFID network more useful, the difficulties must be overcome. Auto-ID Center has designed a software technology known as Savant, it will act as a whole network of nervous system. Savant distributed structure is different from the majority of enterprise management software, it is not an arched structure of the application. He is using a distributed architecture, are organized in a hierarchical, managing the flow of data. Savant will be used in stores, distribution centers, regional offices, factories, it is even possible in trucks or freight aircraft application. Each level of Savant systems will collect, store and process information, and other exchanges of Savant systems. For example, one at the store running Savant systems you may want to notify distribution centre need more products in the distribution centre run by Savant systems may notify shop Savant systems a consignment is in a specific time for delivery. The following is a Savant systems you need to complete some task. Data in the network on the edge of the plain Savant systems, direct and interpretation for the exchange of information, they will conduct data and shearing. Not every label each time is read, and sometimes a label of information may be read errors, using an algorithm, Savant systems capable of correcting thisSome errors. Reader coordination if from two overlapping areas of reader or signal, they may read the same tag information, generate the same and unwanted electronic product code. Savant's task is to analyze the information read and delete these redundant product coding. Data transfer in each level, Savant systems must decide what information you need in the supply chain on upload or passed down. For example, in cold storage plant of Savant systems may only need to transfer it to the store's merchandise temperature information. Data stored in existing database cannot be in a second transaction processing more than a few hundred, Savant systems another task is to maintain real-time storage event database (RIED). Essentially, the system will obtain real-time generation of electronic product codes and intelligent data storage, so that other business management application has permissions to access this information, and ensure that the database does not overload. Task management whether Savant systems in the hierarchy is level, all Savant systems has a unique task management system (TMS), this system allows them to implement user-defined tasks for data management and data monitoring. For example, a store of Savant systems may write procedures for some functions, when the shelf products down to a certain level, will alert you to the storage administrator. The object name service Auto-ID Center for an open, global tracking articles network concept needs some special network structure. Because only the electronic product code is stored in the tag, the computer will also need some matches the electronic product code to the appropriate product information. This role by the object name service (ONS) play, it is an automatic network service system, a bit similar to the domain name service (DNS), the DNS is a computer, navigate to the World Wide Web to a specific location. When a reader reads a RFID tag information, the electronic product code is passed to the Savant systems (see above). Savant systems and then in the LAN or the Internet using the object name service to find the product information stored location. The object name service to Savant systems specify a server, the product files stored on this server. Then this file can be found at Savant systems, and in this file for information on this product will be delivered to the company's inventory and supply chain applications. Special requirements for object name service will process than on the world wide web domain name resolution service more requests, therefore, companies need to have a computer in LAN, ONS to access information faster. Therefore a computer manufacturers may be his current vendors ONS data stored in your local area network, instead of each time a shipment arrived at the Assembly plant, to the World Wide Web looking for information on this product. This system will have inherent redundancy. For example, when a certain product information server crashes, ONS will be able to boot Savant systems found on another server, the same stores this information on the product. Physical markup language-language electronic product code identification of a single product, but all useful information on products with a new standard computer language physical markup language (PML) writing, PML is based on a widely accepted Extensible annotation language (XML) development. Because it will be a description of all natural objects, processes and environment of uniform standards, PML's application will be very extensive, and access to all industries. Our goal is to a simple language, encourage the use of new technologies. PML as time will evolve as the Internet's basic language like HTML, it has now evolved into more than just introduced is much more complex languages. Describes the items of standard PML will provide a common way to describe natural objects, it will be a wide range of hierarchy. For example, a can of Coca Cola can be described as carbonated drinks, which belong to a subclass of soft drinks, soft drinks and food categories below. Not all categories are so simple, in order to ensure the widespread acceptance of PML, a lot depends on the standards organization has done some work, such as the International Bureau of weights and measures, the United States National Institute of standards and technology. Types of PML data will not change except those product information (such as material composition), PML would include regular movements of data (dynamic data) and change over time (time series). In PML file in the dynamic data including shipping fruit of temperature, or a machine vibration level. Time series data throughout the lifecycle of objects, discrete and intermittently change, a typical example is the location of items. By making all of this information have PML file upper can be, the company will be able to type in a new innovative way to use those data. For example, a company can set up a trigger so that when the end of the validity period, the lower the price of the product. Third party logistics providers has the potential to provide service level contracts, that the goods in the transport process to always maintain a constant temperature. PML servers PML file will be stored in a PML servers, a dedicated computer will be configured for other computers they need. PML server maintenance by the manufacturer, and storage are the manufacturers of all goods information file. Control once the data over the network and Auto-ID corresponding PML information, the next most important issues is based on the information, determine the next step should be doing, and promote the running action may be affected. It is in the production phase, distribution, retail stage or family use phase adjust operational conditions in buildings meet the desired requirements is called control. For example, in production, this may mean robot uses the best methods to achieve optimal packaging line of packaging order. Auto-ID inHeart of vision is such an intelligent product in the world, without manual intervention can communicate with the machine, and therefore to influence it is production, movement, sale and use. For example, the future of intelligent washing machine can reads the joints in the shirt collar tag information, and get information from the Internet, see this shirt is made from fine fabrics, the washing machine will adjust the flow of circulation and decide the appropriate SOAP category and amount. Auto-ID will lead to a new highly distributed intelligent control system. However, in order to reach this day, you must have a formal process. Decision, of course, the first step is to computers and other machines to identify the goods. Our core technologies, including electronic product code, the object name service, material marking language files etc, make this possible. PML file may also contain some information on how to wash this shirt instructions or rules. However, you must have a series of agreements to follow, so that the shirt and the machine effectively "conversation". For example, a washing machine may not be able to implement a directive because it does not have this special feature, or at any other clothes are washed. Agreement to provide a series of steps to obtain a decision, even if necessary between machines in the shirt and provides a "consultation". This refers to the machine in an appropriate manner through a series of user-defined instructions. Recall earlier that the machines might at this point not only to wash a shirt. There are two basic factors influence the effectiveness of the implementation of control, they are physical control and physical action. Physical control means in the real world, computer hardware and implementation decisions required software, physical operations refers to the data directive into real-world action section. Physical operations can include warehouse transportation vehicle, factory robots and intelligent devices. Sacred mission Auto-ID Center at the University of Cambridge Research Group of control is committed to the basic problems concerning the control of, and is considering in inventory management, production control, home use, product distribution, and other aspects of the application to join the creative. The decision of creating some standard rules, protocols and guidelines that will enable software engineers developed a new type of enterprise management software, this software allows administrators to set some basic parameters, and allows the machine to be able to on the basis of these parameters automatically. System composition and working principle of most basic RFID system consists of three parts: 1. Tag (Tag, RF card): by coupling components and chips, the label contains built-in antenna for and communicate between RF antenna.
2. reader: read (read-write card can also write) label information.
3. antenna: tag and reader between RF signal. Some systems also by readers of the RS232 or RS485 interface with an external computer (upper main system) connectivity, for data exchange. The basic workflow is: reader through emitting antenna to send certain frequency RF signal, when the RF card to enter the transmitting antenna when induced current in the work area, RF card access to energy is activated; RF card will own encoding information sent via the card built-in antenna sent; system receiving antenna to receive from the RF card to send to the carrier signal, the antenna controller transmitted to the reader, the reader on the received signal demodulation and decoding and then sent back to the primary system for processing; master system according to logical operations to determine the validity of the card, for different settings to make the appropriate handling and control, issued a directive signal control actuator. In coupling mode (inductance-electromagnetic), communication processes (HDX and FDX, SEQ), from the RF card to reader data transmission methods (load modulation, inverse scattering, high-harmonic), and frequency range wait connection, different non-contact transmission methods are fundamentally different from, but all the readers in the functional principle, as well as the design of this decision are similar on the structure, all readers can be simplified into high-frequency interface and control unit for two basic modules. High-frequency interface contains a transmitter and receiver, it features include: produce high-frequency transmitter power to start the RFID card and provides energy; to launch signal modulation, is used for data transfer to the RF card; receive and demodulation of the RF card from high-frequency signal. Different radio frequency identification system for high-frequency interface design has some differences. Reader control unit features include: and application software to communicate, and enforce application software from the command, control and RF card communicating process (master-slave principle); signal decoding. On some special system also performs anti-collision algorithm, the RF card reader to transfer data between the encryption and decryption, as well as RF card and reader of authentication, such as additional features. RFID system for the reading distance is a crucial parameter. Currently, long range RFID system price is also very expensive, so look for improving their reading distance is important. Effects of RF card read-write distance of factors including antenna operating frequency, reader's RF output power, readers receive sensitivity, RF card power, antenna and resonant circuit Q value, antenna and reader and RF card coupled ° RF card itself, as well as access to energy and the energy of sending information. Most of the system of reading distance and write distances are different, write to the distance is about 40% of the reading distance of ~ 80%. RF card standards and classifications are currently producing RFID products for many companies have adopted their own standards, international standards has not yet been unified. Currently, the available RF card using several standards ISO10536, ISO14443, ISO15693 and ISO18OOO. Apply the most iso14443 and ISO15693, these two criteria are determined by the physical characteristics, radio frequency power and signal interface, initialization and anti-collision and Transfer Protocol of four parts. Follow a different pattern, RF cards have the following categories: 1. According to the power supply is divided into active and passive card. Active means that the card has a battery provides power, which has the effect of distance, but life limited, large, costly, and not suitable for work under harsh environment; passive cardNo batteries, it leverages beam power supply technology receives the RF energy into the DC power supply for the internal card, which has the effect of distance relative short active cards, but long life and less demanding work environment. 2. press the carrier frequency is divided into low-frequency RF cards, medium-frequency RF cards and high-frequency RF cards. Low-frequency RF cards there are mainly two 125kHz and 134.2kHz, intermediate frequency RF cards mainly for high-frequency RF cards 13.56MHz, mainly for 433MHz, 915MHz, 5.8GHz 2.45GHz, etc. Low-frequency system is mainly used for short-distance, low-cost applications, such as the majority of access control, campus card, animal control, cargo tracking, etc. If the system is used for access control and need to transfer large amounts of data applications; high-frequency system to take longer to read and write distances and high read and write speed, its narrow antenna beam direction and higher prices, on the train control, highway toll system. 3. press the modulation method can be divided into active and passive. Active RF card with its own RF energy initiative to send data to the reader; passive RF card use modulation scattering mode emission data, it must use the reader of the carrier to your own signal, such techniques suitable for access control or traffic applications, as the reader can ensure that only activates a certain range of RF cards. In case of obstructions, with modulation scattering patterns, the reader of energy must go through the barrier twice. And active way of RF card emission signal only once through the barrier, the proactive approach of RF cards mainly for obstructions, distance farther (up to 30 meters). 4. press the range can be divided into tight coupling card (distance less than 1 cm), nearly coupling card (distance less than 15 cm), sparse coupling card (distance of about 1 meter) and distance card (distance from 1 m to 10 m and even further). 5. press the chip into only reader, reading and writing cards and CPU card.