Introduction
Automatic Identification (Auto-ID) systems have become common place in access control and security applications, in industries requiring the tracking of products through the supply chain or manufacturing process, and in industries requiring the identification of products at the point of sale or point of service. Perhaps the most widely recognized Auto-ID system is the bar code system developed during the early 1970’s. More recently, Radio-Frequency Identification (RFID) systems have begun to find greater use in automatic identification applications.
RFID (Radio Frequency ID) is a varied collection of technical approaches for many applications across a wide range of industries. It is much simpler than its predecessor, the bar code, and is primarily used in automatic data capture.
Radio frequency identification is one of today’s most rapidly expanding technologies and is viewed as a profitable venture for many upstart enterprises.
Chapter 1
Introduction to RFID
1-1) What is RFID?
In general terms, RFID (Radio Frequency Identification) is a means of identifying a person or object using a radio frequency transmission. The technology can be used to identify, track, sort or detect a wide variety of objects. Communication takes place between a reader (interrogator) and a transponder (Silicon Chip connected to an antenna) often called a tag.
Tags can either be active (powered by battery) or passive (powered by the reader field), and come in various forms including Smart cards, Tags, Labels, watches and even embedded in mobile phones. The communication frequencies used depends to a large extent on the application, and range from 125KHz to 2.45 GHz. Regulations are imposed by most countries (grouped into 3 Regions) to control emissions and prevent interference with other Industrial, Scientific and Medical equipment (ISM).
Radio frequency Identification (RFID) provides for “sightless” or no line of sight identification of items. It can either replace bar codes for tasks such as check out, check in, inventory holds, lists, and mis-shelved items. RFID can prove to be very efficient when compared to traditional bar codes.
RFID is a combination of radio -frequency-based technology and microchip technology. The information contained on microchips in the tags is read using radio frequency technology regardless of item orientation or alignment (i.e., the technology does not require line-of-sight or a fixed plane to read tags as do traditional theft detection systems) and distance from the item is not a critical factor except in the case of extra-wide exit gates.
1-2) Why RFID:
The tasks of receiving, transporting, sorting and shelving material has exploded in recent years while circulation and materials management continues to grow. RFID provides a solution to automate much of this handling.
The use of RFID reduces the amount of time required to perform many operations. The most significant time saving is attributable to the fact that information can be read from RFID tags much faster than from bar codes and that several items in a stack can be read at the same time.
1-3) How RFID works:
Each RFID tag has a non power radio antenna which can be communicated to by a powered antenna belonging to a tag reader on a scanner or security gate. Although it is not necessary that the two antennas " see" each other as is needed with the traditional bar code, it is necessary that they be relatively close to one another since the power used by the powered antenna is very low for health and safety reasons The RFID reader sends out electromagnetic waves and the tag antenna is enabled to receive these waves. “When the tag antenna enters the RF (radio frequency) field, the tag's microchip circuit are powered by signals from this RF field created by the reader. The chip then modulates the waves and the tag sends them back to the reader. The reader converts the signals received from the tag into digital data and sends it to a computer.
1-3-1) Anti-collision:
If many tags are present then they will all reply at the same time, which at the reader end is seen as a signal collision and an indication of multiple tags. The reader manages this problem by using an anti-collision algorithm designed to allow tags to be sorted and individually selected. There are many different types of algorithms (Binary Tree, Aloha....) which are defined as part of the protocol standards. The number of tags that can be identified depends on the frequency and protocol used, and can typically range from 50 tags/s for HF and up to 200 tags/s for UHF. Once a tag is selected, the reader is able to perform a number of operations such as read the tags identifier number, or in the case of a read/write tag write information to it. After finishing dialoging with the tag, the reader can then either remove it from the list, or put it on standby until a later time. This process continues under control of the anti collision algorithm
1-4) Components of an RFID System:
A comprehensive RFID system has three components:
(1) RFID tags that are electronically programmed with unique information.
(2) Readers or sensors to interrogate the tags.
(3) A server or docking station on which the software that interfaces with the system is loaded. It is also possible to distribute the software among the readers and sensors.
1-4-1) Tags:
Active and passive tagsvv;
The first basic choice when considering a tag is between either passive, or active.
Passive tags can be read at a distance of up to 4 - 5m using the UHF frequency band, whilst the other type of tags (active) can achieve much greater distances of up to several kilometers for Active. This large difference in communication performance can be explained by the following:
- Passive tags use the reader field as a source of energy for the chip and for communication from and to the reader. The available power from the reader field, not only reduces very rapidly with distance.
-Active tags are battery powered devices that have an active transmitter onboard. Unlike passive tags, active tags generate RF energy. This autonomy from the reader means that they can communicate at distances of over several kilometers.
Each paper-thin tag contains an etched antenna and a microchip with a capacity of at least 64 bits. There are three types:
a) - Read only tags:
"Read only" if the identification is encoded at the time of manufacture and not rewritable. This type of tag contains nothing more than item identification. It can be used for items acquired after the initial implementation of RFID. Such tags need not contain any more than 96 bits.
b) - Worm tags:
"WORM" (Write-Once-Read-Many)" tags are programmed by the using organization, but without the ability of rewriting them later. The main advantage over read only tags is that information in addition to the identification number can be added. However, it must be information that won’t need to be changed.
c) - Read / Write Tags:
"Read/write tags," which are chosen by most application, can have information changed or added.
1-4-2) Readers:
A typical system includes several different kinds of readers, also known as sensors. These are radio frequency devices designed to detect and read tags to obtain the information stored there on. The reader powers an antenna to generate an RF field. When a tag passes through the field, the information stored on the chip in the tag is decoded by the reader and sent to the server. While there is software in each reader to facilitate communication with the server, most of the software supplied by the RFID system vendor is on the server when one is included in the system. When there is no server, most of the software is on the readers.
Main Criteria for readers
- Operating Frequency (HF or UHF) – some companies are developing Multifrequency readers
- Protocol Agility – Support for different Tag Protocols (ISO, EPC, proprietary) – Most companies offer Multi- protocol support, but do not support all!
- Different regional regulations
- UHF frequency agility 902 – 930 MHz in the
- Power Regulations: 4 Watts in the
- Networking to host capability: Wireless LAN (802.11), Ethernet LAN
- Managing multiple antennas: Typically 4 antennas/reader
* Frequencies:
Based on the type of domain or application targeted, RFID systems are generally distinguished to three frequency ranges - Low, Intermediate and High. The following table summarizes these three frequency ranges, along with the typical system characteristics and examples of major areas of application:
| Frequency Band | Characteristics |
| Low
| Short to medium read range, inexpensive, low reading speed |
| Intermediate
| Short to medium read range, potentially inexpensive, medium reading speed |
| High
| Long read range, high reading speed, line of sight required, expensive |
1-4-3) Servers/Docking Station:
The server is the heart of some comprehensive RFID systems. It is the communications gateway among the various components. It receives the information from one or more of the readers and exchanges information with the circulation database.
1-5) The advantages of RFID when compared with Bar codes:
1- Simultaneous Identification:
Unlike other ID methods where items must be physically separated or read individually, RFID smart labels tags can be read simultaneously multiple labels, containers or items all at the same time as the pass a reading location or are read with a handheld scanner.
RFID is the only technology that can read individual items simultaneously.
2- Non Line Of-Sight:
RFID provides a contact free data link without the need for line of sight. With this technology, labels can be hidden or embedded in items, but still read. This isn't possible with other auto ID methods such as bar codes.
3- Data Storage:
RFID can store upwards of 30 times more data than bar codes allowing the tag to carry a range of real time information about an item. Mass serialization or the ability to store a unique serial number for each and every item is something that cannot be accomplished with bar codes.
4- Read / Write:
RFID tags act as data carrier. Information can be written to and update on the tag which is specific to an item, container or pallet in the supply chain. This information is then held with that item, acting as a traveling item history or self - contained data base.
5- Read Reliability:
First pass is important in much application, with RFID; the need for spending time scanning items multiple times is eliminated. Using other ID technology requiring line of sight , tags sometimes have to be run through the system a second time or multiple times to be read .
6- Durability:
Without concern about harsh or dirty environments that restrict other ID technologies, the durability of RFID technology is especially suited to fit the needs of warehousing applications. RFID smart labels can be read through dirt, soiled packaging or other materials.
| Features | RFID Tags | Bar codes |
| Read more than one item at a time | √ | X |
| Read while item is moving | √ | X |
| Programmable | √ | X |
| Line of site read not required | √ | X |
| Lifetime guarantee ( 100,000 reads ) | √ | X |
| Read in dirty environment (dust, wet,) | √ | X |
| Able to resist water damage | √ | X |
| Built in Security | √ | X |
| Read items without handling items | √ | X |
1-6) Advantages:
1- Sightless identification which provide that more than one item can be read at the same time .Also provide that items can be placed on the reader without careful placement required with the line of sight reading .
2- Read items without handling item which give faster process and also the ability to locate specific items and protect staff from many materials handling related injuries.
3- Saves processing time as tags are guaranteed for the life of the item.
4-Memory and data storage , an RF tags data storage are available in many different memory size from 96 bits up to 8K bytes , which extend the applications and also enable a mobile data base .
5- Flexibility and modularity as it provide the ability to manage the expenses over a number of years and give the ability to add newer product and features
6- Low cost of Tags which helps extend the range of applications.
7-Tags can be read despite dust, moisture...
8- Maintenance free and resistance to ageing.
9- Rewritable.
1-7) Frequently Asked Questions:
1- Can tags be used with other RFID readers?
While ISO-18000-3 establishes a standard for RFID, it is a general technology standard, not an application standard. In theory, this means that all tags and readers that adhere to the standard will be capable of reading each other's tags.
2- What is the read range of the tag?
while the security gate are capable of reading information within 91 cm the other readers used with the system can read from a distance of no more than 15 cm . And there is a special type of tags which is used in locating its range can be extended to 2 KM.
3-Should a protective cover be placed over each RFID tag?
Using a protective covers is cost effective and provide additional protection but it is not necessary.
4- Are there any materials to which an RFID tag cannot be applied?
RFID tags should not be placed inside of metallic materials.
5- How long does it take to program a tag?
It only takes a second or two to program a tag and this increase its flexibility.
6- Are there any health risks associated with RFID?
No, the system is not harmful to persons.
7- Does RFID have any effect on magnetic media?
RFID Applications:
RFID (Radio Frequency ID) is a varied collection of technical approaches for many applications across a wide range of industries. RFID is far simpler than its predecessor, the optically read barcode and is primarily used for automated data capture.
Radio frequency identification is one of today’s most rapidly expanding technologies, especially for newly established enterprises to whom the promise of lower operating costs is particularly attractive. RFID’s ability to allow more accurate product and asset information had led organizations to introduce RF technologies in the supply chain to improve asset tracking, optimize stock levels, enforce tighter security and comply with new industry regulations.
Applications fall into two principal categories:
1- Short range applications, where the reader and tag must be in close proximity, usually just a few inches. This is generally associated with manufacturing industries, where it is required to track a product along an assembly line for example.
2- Medium to long range applications, where range of the system extends to a few feet and is associated with logistical applications as well as item and personnel location.
The main advantages of RFID, as mentioned before, are:
- Non – LOS scanning.
- More cost-effective on the long run.
- More reliable and accurate.
The aim of this chapter is to further elaborate the many advantages of implementing RFID in our daily routines, in industry and in business corporations through the following real-life applications.
1- Tracking Material Movement in and out of a Warehouse:
2- At the Retail Store:
As soon as new products arrive, the retail system updates the entire inventory database. In this way, stores can locate any of their products automatically, accurately and at low cost. Reader-enabled ¨smart shelves¨ can automatically order more products from the system and therefore maintain stock at cost-effective and efficient levels.
3- Vehicle Control:
Equipping tractors and other equipment with RFID tags, accompanied with readers placed at fueling stations, gates and other access points, enables access to these facilities as well as recording the exact time at which a particular truck and container entered or left a terminal.
RFID employee badges can be used to validate that the right driver has the right vehicle and load. Tags on vehicles or RFID badges can be used to unlock fuel pumps and record fuel usage.
4- Passports:
Biometric passports are documents combining paper and electronics to authenticate the citizenship and identity of travelers. A traveler’s critical information will be stored on a small imbedded RFID chip. Such information will usually include biometric data such as finger prints, iris scans, and facial recognition data. This system provides for virtually impregnable security. To address various privacy concerns, the passports will incorporate a thin metal lining to make it more difficult for unauthorized readers to "skim" information when the passport is closed.
5-Transport Fee Payment:
A transportation system can use RFID operated cards as a means for fare collection. The card can be charged at local convenience stores and gas stations and can be used in the underground, buses, parking lots and taxis. This can also be used to collect money from cars at highway toll stations. The car wouldn’t have to stop to pay the toll, while a reader placed in the station would scan the unique RFID tag attached to the car and send a bill to the owner’s home address. This application would help decrease congestion on major roads and highways.
This system can also be used to collect money from cars entering a restricted area of a city, such as entering
Figure: A main thoroughfare in
6- Automotive Customization:
A car can detect its RFID enabled key when it is approximately 3 feet away and so allow the driver to unlock and start the car with the key in his pocket. This would also allow for personal customizations, such as automatic driver seat position adjustments and other minor luxuries such as starting the air-conditioning or the sound system. These can be considered as advantageous options when incorporated into luxury cars.
7- Animal Identification:
Implanted RFID tags are also used in animal identification. RFID is currently being used in the cattle industry in hopes of helping identify the sources of potentially fatal diseases such as mad-cow disease. By implanting cattle with tags containing their medical histories, not only will it be easier to keep them healthy, it is also essential for automated farm management.
Practical circuits for RFID system
Radio Frequency Identification (RFID) systems use radio frequency to identify, locate and track people, assets and animals. Passive RFID systems are composed of three components – a reader (interrogator), passive tag and host computer. The tag is composed of an antenna coil and a silicon chip that includes basic modulation circuitry and non-volatile memory. The tag is energized by a time-varying electromagnetic radio frequency (RF) wave that is transmitted by the reader. This RF signal is called a carrier signal. When the RF field passes through an antenna coil, there is an AC voltage generated across the coil. This voltage is rectified to result in a DC voltage for the device operation. The device becomes functional when the DC voltage reaches a certain level. The information stored in the device is transmitted back to the reader. This is often called backscattering. By detecting the backscattering signal, the information stored in the device can be fully identified. There are two classes of RFID device depending on type of memory cell : (a) read only device and (b) read and write device. The memory cell can be made of EEPROM or FRAM. EEPROM is based on CMOS silicon and FRAM is based on ferroelectric memory. Since CMOS process technology has been matured, the EEPROM can be produced relatively at lower cost than the FRAM device. However, FRAM based RFID device consumes less power which is desirable for low power device. Therefore, it is known as a good candidate for the future RFID device, if its manufacturing cost becomes compatible to that of the CMOS technology .Because of its simplicity for use, the passive RFID system has been used for many years in various RF remote sensing applications. Specifically in access control and animal tracking applications
A small part of the emitted field penetrates the antenna coil of the transponder ,which is some distance away from the coil of the reader. A voltage Ui is generated in the transponder’s antenna coil by inductance. This voltage is rectified and serves as the power supply for the data-carrying device (microchip). A capacitor Cr is connected in parallel with the reader’s antenna coil, the capacitance of this capacitor being selected such that it works with the coil inductance of the antenna coil to form a parallel resonant circuit with a resonant frequency that corresponds with the transmission frequency of the reader. Very high currents are generated in the antenna coil of the reader by resonance step-up in the parallel resonant circuit, which can be used to generate the required field strengths for the operation of the remote transponder. The antenna coil of the transponder and the capacitor C1 form a resonant circuit tuned to the transmission frequency of the reader. The voltage U at the transponder coil reaches a maximum due to resonance step-up in the parallel resonant circuit. The layout of the two coils can also be interpreted as a transformer (transformer coupling), in which case there is only a very weak coupling between the two windings (Figure 3.14). The efficiency of power transfer between the antenna coil of the reader and the transponder is proportional to the operating frequency f , the number of windings n, the area A enclosed by the transponder coil, the angle of the two coils elative to each other and the distance between the two coils. As frequency f increases, the required coil inductance of the transponder coil, and thus the number of windings n decreases (135 kHz: typical 100–1000 windings, 13.56 MHz: typical 3–10 windings). Because the voltage induced in the transponder is still proportional frequency f (see Chapter 4), the reduced number of windings barely affects the efficiency of power transfer at higher frequencies.
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