What is Radio Frequency Identification (RFID) ?

RFID or Radio Frequency Identification is a technology that provides wireless identification of people or assets. A RFID tag is attached to an object and contains information about that object. The basic units of any RFID based systems are small RF “tags” – devices which emit RF signals either at periodic intervals (active RFID technology) or when they come in close proximity to an RFID reader (passive RFID technology).

For active RFID solutions, the sensors are mounted at regular intervals throughout a facility, blanketing the entire region in a “sensory network” which can pick up the location of a tag anywhere in the system. When the tagged object passes within range of an RFID reader (line of sight is not required), the reader will pick up the wireless signal from the tag and the information can then be transferred to a computer system for processing.

This makes it possible to track objects within a controlled environment, which may be a warehouse, a hospital, a high-security building, or wherever important valuable assets need to be tracked closely. Processes can be automated by including item specific information or instructions within the tag.

RFID Application by Indosoft:

Indosoft RFID Tags :

Pallet RFID Tag

·Operating Mode: Read/Write, RTF (Reader Talk First)
·Memory: 64 bits ID number, 216 bytes of user memory
·Frequency Range: 902~928MHz
·Air Interface: ISO18000-6B
·R/W Range: 0～10m (depend on the antenna used)
·Operating Temperature: -20～70C
·Moving Speed: 0～60km/h
·Feature: Suited for systems comprising single or multiple tags, and moving tags
·Dimension: 137×94×30mm
·Installation: Insert into the aperture of the plastic pallet
·Application: Plastic pallet tracking, product line automation

RFID Thick card

·Operating Mode: Read/Write, RTF (Reader Talk First)
·Memory: 64 bits ID number, 216 bytes of user memory
·Frequency Range: 902~928MHz
·Air Interface: ISO18000-6B
·R/W Range: 0～10m (depend on the antenna used)
·Operating Temperature: -20℃～70℃
·Moving Speed: 0～60km/h
·Feature: Suited for systems comprising single or multiple tags, and moving tags
·Demension: ISO thick card, 85.6×54×1.9mm
·Installation: Used in glass substrate
·Application: High way non-stop toll, parking lot management and other vehicle management applications

RFID Vehicle Tag

·Operating Mode: Read/Write, RTF (Reader Talk First)
·Memory: 64 bits ID number, 216 bytes of user memory
·Frequency Range: 902~928MHz
·Air Interface: ISO18000-6B
·R/W Range: 0～10m (depend on the antenna used)
·Operating Temperature: -20℃～70℃
·Moving Speed: 0～60km/h
·Feature: Suited for systems comprising single or multiple tags, and moving tags
·Dimension: 226×38×23.6mm
·Installation: Use magnet on it to affix itself to the metal surface
·Application: Vehicle identification, container management and other metal objects identification and management applications

RFID Logistic Tag

·Operating Mode: Read/Write, RTF (Reader Talk First)
·Memory: 64 bits ID number, 216 bytes of user memory
·Frequency Range: 902~928MHz
·Air Interface: ISO18000-6B
·R/W Range: 0～10m (depend on the antenna used)
·Operating Temperature: -20℃～70℃
·Moving Speed: 0～60km/h
·Feature: Suited for systems comprising single or multiple tags, and moving tags
·Dimension: 160×3×0.1mm (can be customized)
·Installation: Adhere to the surface of objects to be identified
·Application: Logistics

RFID Access Card

·Operating Mode: Read/Write, RTF (Reader Talk First)
·Memory: 64 bits ID number, 216 bytes of user memory
·Frequency Range: 902~928MHz
·Air Interface: ISO18000-6B
·R/W Range: 0～10m (depend on the antenna used)
·Operating Temperature: -20℃～70℃
·Moving Speed: 0～60km/h
·Feature: Suited for systems comprising single or multiple tags, and moving tags
·Dimension: ISO thick card, 85.6×54×1.9mm
·Installation: Used in air
·Application: Access control

What is RFID Tag:

An RFID tag is a uniquely identified (or identifiable) object, that can be embedded (or attached) to any physical body to track it's position or location. Tags are of various kinds, covering the entire spectrum the passive tags powered in the presence of a reader, to a continuously signal-emitting active tag.

Both active as well as passive RFID tags consist of a small microchip that contains a unique ID encoded within it. The rest of the tag consists of a mechanism to transmit this unique ID to an “Interrogator” or a reader that can identify this tag.

In the case of a passive RFID tag, the construction consists of an antenna that serves a dual purpose - it acts as a “coil” that generates enough electric current when placed within an electromagnetic field (i.e. Close to a passive reader) to “power” the microchip. The unique ID encoded within the microchip is then transmitted in an elecromagnetic pulse, that uses the antenna to broadcast the pulse back to the reader.

In the case of an Active tag, an internal power source (battery) is used to power the transmission - which broadcasts the tag's unique ID to all sensors/receivers that are listening on the specified frequency. The signals are non-directional, and may be received by one or more sensors. These signals then need to be interpreted by the system to determine the location of the tag within a facility.

Both active as well as passive tags fall within a range of frequencies that are used according to the international ISO specifications for air interface (ISO-18000 2-7). Some of these specified frequencies are more suitable to passive operation (i.e. Shorter range, larger bandwidth, lower power) while some are more suitable to active RFID technology. Passive tags in the HF range are commonly found in the 125Khz and the 13.56 Mhz range. Some of the newer tags are also available in the UHF range, with larger bandwidth, read speeds, as well as larger read ranges. However, these technologies also require higher power readers than those with correspondingly lower frequencies.

Most active RFID badges usually work between 420 - 450 Mhz. Some of the tags (e.g from Versus technologies) also work between the 63.57 Mhz frequency range, which compensate for the lower range (90m) with much longer battery life, which is a very practical consideration for an actual deployment.

Features

• All tags use some kind of FM modulation in order to transmit the tag's unique ID to the Interrogator
• Interrogated remotely via RF/inductive signals (passive) and direct broadcast (active)
• Long life - can withstand mechanical shocks, dirt etc.
• Non-directional, with non line-of-sight functioning that enables complete automation of RFID enabled (or supported) systems and processes.
• Non-contacting (tamperproof) and non-obtrusive (transparent to user)
• Robust protocol - fault tolerant transmission, inherently engineered for error-handling and recovery
• Flexible with minimal interference
• Unique identification number allows stronger authentication of personnel and systems.

Comparison of Active vs. Passive Tags

Applications of Tags:

Active Tags

Active tags are a subset of RFID tags that allow real-time tracking of any object they are attached to. They are typically used for applications like:
· Tracking very mobile objects - including personnel in a facility, objects that are very mobile (like warehouse loading equipment etc.), that need to be actively tracked and monitored all the time.· Tracking objects of very high value, that need “ubiquitous” security without necessarily having personnel watching over it all the time. An Active RFID solution is much better than traditional CCTV solutions, primarily because the system can be configured to trigger events in the case of any anomalous behaviour, e.g. On any movement. 

Technology 

Active tags are self-powered - usually by a permanent voltage source like an in-built battery. Other power sources like solar powered (for outdoor use) tags are currently in developmet at Indosoft, for a variety of innovative uses. The voltage source is used to periodically send out active RF signals, broadcasting the ID of the tag to all available receivers, from where it can be picked up by the (software) system to “track” the tag. 
Some of the newer tags have an in-built motion detector, that broadcasts signals only when the tag is in motion - which helps to extend the battery life for those tags very significantly. Although tags usually broadcast their ID's, they can also be designed to broadcast other useful information. For example, some tags can have a temperature or pressure sensor built-in, and can broadcast this information to RF sensors for “active” control.
The RFID tags utilize electro magnetic energy to send signals to program the transponder by switching the electro magnetic field on and off. The duration of the on or off-phase defines whether a low-bit or high-bit of information is being transmitted. This technique of data transfer is called Pulse Width Modulation.

Programming an Active Tag

Active tags are programmable, allowing you to change information stored on them. However, in most cases, their ID's are fixed during manufacture, and software is used to track the item/object that each tag is attached to. However, since the transponder can be updated with new information on the fly, this permits applications for product tracking and reusing tags.
An RFID tag stores the ID in an EEPROM. A writer can 'program' a tag directly by means of a special signal (which is usually of higher power than the usual communication signal power) or in the presence of a special field (UV) that allows the EEPROM to be written. The programmed data is stored into the transponder's EEPROM. 
The transponder also contains a lock feature that allows the user to lock the data permanently on the tag that can't be modified. Every transponder contains a unique factory code that allows for tag trace ability and can't 
be duplicated by the manufacturer.

Deployment

Read range for Active Tags are generally between 30 meters to 300 meters, depending upon the technology of the tag, and the frequecy used for transmission. Higher frequencies
(420 Mhz) offer substantially larger read ranges, but also consume more power, leading to shorter battery life for tags. 
For any deployment, the sensor configuration is decided based upon a number of factors, including 
1.The topography of the area in which the RFID system is to be deployed. For outdoor use, this needs to be decided taking into account the land topography (which determines any signal 'shadow' areas), natural obstacles like trees or rocks, and other features of the terrain. For indoor use, the different floors, including any open spaces, need to be considered and analyzed separately to determine the optimal deployment configuraiton of sensors.
2.The elecromagnetic quality of the deployment area. Several features, including the existing communication equipment, as well as available spectrum need to be considered while deciding the technology to be used for the deployment.

Passive tags

Passive tags are a subset of RFID tags, that use an external power source to 'trigger' their operation, and to allow tracking. These tags are suitable for the following purposes:
· For tracking items within a facility - without having to necessarily know exactly where they are at any point of time (which would require 'active' technology). This requirement falls within the realm of “Access Control and Management”, and is usually accomplished by protecting all entry and exits in the facility with readers, which capture movement of tags in and out of the facility.· For automated inventory management, including expiration tracking/notification, ad-hoc operations (e.g. The “Smart Shelf” concept where the system should track when items are taken off or put back on the shelf without any human intervention), and for fast and efficient (and automated) tracking of material movement and placement within a facility. 

Technology  

Passive tags operate on principle of parasitic power transfer through electromagnetic induction. The core RFID chip on a passive tag contains a unique ID, and also necessary circuits to power (and operate) this chip when any current flows through the circuit. 
The power is provided by the external reader to the passive RFID tag through electromagnetic induction, as the copper loop in the tag generates a current as it travels through the electromagnetic field created by the reader. Since the electromagnetic field power falls off as the square of the distance, hence passive RFID systems are limited in the distance of operation - often operating between only 2 to 5 centimetres. 
Each tag has a unique ID that is set during manufacture, and cannot be changed. When the RFID chip is triggered, it uses the copper loop as an antena, and broadcasts it's unique ID, which is picked up by the RFID reader, thus triggering a “tag read”. This tag read can then be transmitted to an Enterprise information system, and processed accordingly.

Programming a Passive Tag

Passive tags are usually pre-programmed with a unique ID from the manufacturer. However many of the newer tags still contain some additional memory that is user-writable. This space can be used to store an electronic record of the item or object being tagged, which can lead to the creation of “self-aware” systems, which recognize objects by reading the tag.
In a number of the tags available in the market now, it is possible to write details of the item/object to which the tag is attached. Tags can be “written” by a reader, by a special “command set” that involves a higher power transmission level by the reader to function as a “writer” also. The data broadcast in a certain, pre-specified format at the higher power level, causes the information to be written to the tag. 
Passive tags may be reused, although (in the case of large supply chains), they may become effectively unavailable as they travel outside your “control boundary”, which comprises your factory/production unit, or warehouse. In such cases, important internal information may be deleted from the tag, or the tag destroyed through a special control/command sequence from the RFID writer, that renders it unusable thereafter.

Deployment

Read range for Passive Tags are generally between 2 cm to 1 meter, depending upon the technology of the tag. The lower frequency tags (125Khz) have the shortest range, but are also the cheapest. The higher frequency passive tags (13.56Mhz and higher) have larger read ranges and are more suitable for supply-chain automation, but are also more expensive. 
Thus the 125Khz tags may be used in order to minimally automate existing bar-code processes, to achieve better efficiency, as well as better control over automated processes like inventory checking, tracking, and maintenance of material in a facility. The higher frequency tags may be used for complete supply-chain or production/assembly line automation, but require the proper back-end systems to enable you to really achieve the production and process efficiencies to take the best advantage of the RFID infrastructure.

FAQs:

Is RF signal harmful for human beings and the environment?

No. The power levels used for any RFID applications are well below the power levels that prove to have any harmful effects. RFID uses the low-end of the electromagnetic spectrum and is in compliance with the Federal Communications Commission(FCC) regulation.

Does RF signal pass through walls?

RF signals easily pass through walls. Tags can also be read through a variety of substances such as snow, fog, ice, paint, grease, oil, etc. and other visually and environmentally challenging conditions, where barcodes or other optically read technologies would be useless. The signal strength of RF falls off inversely to the distance travelled and is further degrade by passing through walls or reflecting off metal fixtures.

How does an Passive RFID system work?

The RFID system consists of an tag, which consists of a microch ip with a coiled antenna, and an interrogator/reader with an antenna. The reader emits electromagnetic waves that form a magnetic field when they "couple" with the antenna on the RFID tag. A passive RFID tag powers the microchip’s circuits by drawing the power from this magnetic field. The microchip then modulates the waves that the tag sends back to the reader and the reader converts the new waves into digital data.

Is RFID better than using bar codes? 

The two are different technologies which have some common applications. The biggest distinguishing factor between the two is bar codes are line-of-sight technology which require the bar code to be oriented towards the scanner for it to read.Radio frequency identification doesn’t require line of sight. RFID tags can be read as long as they are within range of a reader. Bar codes have several other shortcomings as well. If a label is ripped, soiled or falls off, there is no way to scan the item.Standard bar codes can identify only the manufacturer and product, they donot have a unique ID. The bar code on one medicine bottle is the same as every other, making it highly impossible to identify which one reaches its expiration date first.

Will RFID replace bar codes?

No. RFID and bar codes will have to coexist. 
How much does an RFID tag cost?The Passive tags cost a magnitude less than Active tags. The Passive tags can cost as little as 30 cents or even less if bought in bulk Active tags - those with a battery - can cost far more. Some Active tags even come with temperature or pressure sensors built in, which cost more than $100. 

Does RFID work around metal and water?

Radio waves cannot pass through metal,it bounces off metal and are absorbed by water at higher frequencies. This makes tracking metal products or those with high water content difficult, but with a good system design and engineering these problems can be easily overcomed. 

What is the difference between passive, semi-passive and active tags?

Active RFID tags have a battery, which is used to run the microchip's circuitry and to transmit a signal to a reader. Passive tags have no battery. They draw power from the reader, which sends out electromagnetic waves that induce a current in the tag's antenna. Semi-passive tags use a battery to run the chip's circuitry, but communicate by drawing power from the reader. Active and semi-passive tags are useful for tracking /location of high-value goods that need to be scanned over long ranges, but they are costly, making them very expensive to put on low-cost items. The read range for Passive tags is less than ten feet. In case of Active tags the read range is 100 feet or more. Passive tags are far less expensive than active tags and require no maintenance.

How much data can be stored in a tag?

It depends on the vendor and the application, but typically a tag would store around 2KB of data which is good enough to store some basic information about the item it is on. 

What is the difference between read-only and read/write tags?

Microchips in RF tags can be read-write or read-only. With read-write chips, information can be added to the tag or write over existing information when the tag is within range of a reader/interrogator. Since the Read-write tags are expensive they are used only in some specialized applications. Some read-only microchips have information stored on them during the manufacturing process. The information on such chips can never been changed. With a EEPROM(electrically erasable programmable read-only memory) the data can be overwritten using a special electronic process. 

How does tag collision occur?

Tag collision occurs when more than one tag sends back a signal at the same time, confusing the reader. Different vendors have developed different systems for having the tags respond to the reader one at a time. 

What are the different read ranges for a typical RFID tag?

The read range for a passive tag depends on a lot of factors i.e the frequency of operation, the power of the reader, interference from metal objects or other RF devices. In general, low-frequency tags are read from a foot or less. High frequency tags are read from about three feet and UHF tags are read from 10 to 20 feet. Where longer ranges are needed, active tags are used to boost read ranges to 300 feet or more.

Are there any standards for RFID?

Yes. There are number of standards that define the various aspects of operation of the RFID Technology.Some of them are:The Auto-ID standard set up by Uniform Code Council(UCC) and EAN International, and promoted by the Auto-ID consortium.At present, the UCC standards offer the most compatible technology for RFID systems, and are the de-facto standards for all commercial implementations