What is RFID?
RFID is the next evolutionary step towards automated asset tracking, inventory and supply chain management. It's basic elements are tags (or transponders), readers (or interrogators) and the air interface. Radio Frequency Identification is commonly referred to as RFID.
In this brief article I wish to examine the following key concepts:
• Building blocks
• RFID versus bar codes
• Radio Waves & Air Interface
• Singulation
• Basic RFID Categories: Passive, Battery Assisted Passive and Active
• Points of Distinction
Building Blocks
Tags are the devices to uniquely identify an item. We physically attach a tag to an item of interest. Readers are the transceivers used to automatically identify the tags and record their unique serial number. The air interface is the medium that the radio waves travel through to facilitate communications between the tag and the reader and vice versa.
RFID versus Bar Codes
Unlike its bar-coding precursor, RFID provides a unique identifier for each item tagged. This difference offers significant financial and operational advantages. For example, a product recall can be very specific using RFID. It allows for a certain batch made from a defined work cell by a specific employee on a specified day. Not so with a bar code! There is no need to conduct a blanket recall because you lack the ability to easily identify everything at the individual item level. This and many other advantages are allowing RFID to leap frog bar codes as the preferred Auto ID technology of choice.
Radio Waves & Air Interface
RFID is the automated process of retrieving stored data from the memory of an integrated circuit using radio waves. Radio frequency communication, aka wireless, is the basis for moving data from the memory of an RFID transponder or tag to an RFID interrogator or reader. This movement is through the air interface. Transmission range is generally determined by radio frequency, antenna size, power, and items creating path loss in the communications channel. An RF engineer refers to this as the link budget and can analyze and optimize each stage to yield best practices performance.
Every radio wave has two critical modes of operation known as far field and near field which is based on the wavelength of the frequency being used for the wireless RFID communications. In non-engineering terms this affects whether you are using the magnetic or electric component of the radio wave. Magnetic waves are better at penetrating most items but have dramatically reduced read range then the electrical wave.
Singulation
Under the EPCglobal or ISO 18000-6C specification the information stored in the tags memory is its 96 bit electronic product code or (EPC). It is this information that is transmitted via radio waves from the tag to the reader during singulation.
Singulation is the method by which an RFID system recognizes a tag with a unique identification number from multiple tags present in the system.
Basic RFID Categories
The three fundamental categories of RFID are:
1) Passive
2) Battery Assisted Passive (BAP)
3) Active
Let's take a look at how the basic categories operate.
Passive RFID systems function when a tag enters the field of view or read zone of an RFID reader. The tag becomes energized by the electromagnetic radio waves emitted by the reader. The tag uses this energy to modify the RF waves and reflect them back. The antennas of the reader then receive the modified RF transmission. The reader then uses hardware and software to interpret the changes. The key deliverable from this stage is the EPC information stored on the tag.
A passive RFID system typically includes:
A passive tag consisting of an integrated circuit, memory and one or more antenna element(s) which reflects energy radiated by a reader.
An RFID reader, comprised in part of one or more antennas, which energize the passive tag and capture the response.
An active RFID system typically includes:
An active RFID system still utilizes radio frequency communication; however the effective radiated power budget is different from passive systems. Active RFID systems typically have greater read ranges than passive RFID systems due to increased power. Active tags utilize a battery which helps the tag's transmitter to better broadcast the data stored within the tags memory to the air interface and subsequently to the reader.
Points of Distinction
Radio frequency communication does not require line of sight between devices. Thus, RFID tags can be read through packaging, shipping containers, and many other common materials. End user's should be aware that metals reflect radio waves and other materials which absorb radio waves provide the exception and create hurdles for RFID to perform.
Specialty tags are available which attempt to compensate for these difficult materials and thereby deliver acceptable performance.
Even under RF hostile conditions, RFID far exceeds conventional counting methods such as bar-coding in terms of survivability, speed and accuracy. For applications requiring heightened security, the radio frequency communication can be encrypted to ensure the integrity of the data passing between the tag and reader.
In this brief article I wish to examine the following key concepts:
• Building blocks
• RFID versus bar codes
• Radio Waves & Air Interface
• Singulation
• Basic RFID Categories: Passive, Battery Assisted Passive and Active
• Points of Distinction
Building Blocks
Tags are the devices to uniquely identify an item. We physically attach a tag to an item of interest. Readers are the transceivers used to automatically identify the tags and record their unique serial number. The air interface is the medium that the radio waves travel through to facilitate communications between the tag and the reader and vice versa.
RFID versus Bar Codes
Unlike its bar-coding precursor, RFID provides a unique identifier for each item tagged. This difference offers significant financial and operational advantages. For example, a product recall can be very specific using RFID. It allows for a certain batch made from a defined work cell by a specific employee on a specified day. Not so with a bar code! There is no need to conduct a blanket recall because you lack the ability to easily identify everything at the individual item level. This and many other advantages are allowing RFID to leap frog bar codes as the preferred Auto ID technology of choice.
Radio Waves & Air Interface
RFID is the automated process of retrieving stored data from the memory of an integrated circuit using radio waves. Radio frequency communication, aka wireless, is the basis for moving data from the memory of an RFID transponder or tag to an RFID interrogator or reader. This movement is through the air interface. Transmission range is generally determined by radio frequency, antenna size, power, and items creating path loss in the communications channel. An RF engineer refers to this as the link budget and can analyze and optimize each stage to yield best practices performance.
Every radio wave has two critical modes of operation known as far field and near field which is based on the wavelength of the frequency being used for the wireless RFID communications. In non-engineering terms this affects whether you are using the magnetic or electric component of the radio wave. Magnetic waves are better at penetrating most items but have dramatically reduced read range then the electrical wave.
Singulation
Under the EPCglobal or ISO 18000-6C specification the information stored in the tags memory is its 96 bit electronic product code or (EPC). It is this information that is transmitted via radio waves from the tag to the reader during singulation.
Singulation is the method by which an RFID system recognizes a tag with a unique identification number from multiple tags present in the system.
Basic RFID Categories
The three fundamental categories of RFID are:
1) Passive
2) Battery Assisted Passive (BAP)
3) Active
Let's take a look at how the basic categories operate.
Passive RFID systems function when a tag enters the field of view or read zone of an RFID reader. The tag becomes energized by the electromagnetic radio waves emitted by the reader. The tag uses this energy to modify the RF waves and reflect them back. The antennas of the reader then receive the modified RF transmission. The reader then uses hardware and software to interpret the changes. The key deliverable from this stage is the EPC information stored on the tag.
A passive RFID system typically includes:
A passive tag consisting of an integrated circuit, memory and one or more antenna element(s) which reflects energy radiated by a reader.
An RFID reader, comprised in part of one or more antennas, which energize the passive tag and capture the response.
An active RFID system typically includes:
An active RFID system still utilizes radio frequency communication; however the effective radiated power budget is different from passive systems. Active RFID systems typically have greater read ranges than passive RFID systems due to increased power. Active tags utilize a battery which helps the tag's transmitter to better broadcast the data stored within the tags memory to the air interface and subsequently to the reader.
Points of Distinction
Radio frequency communication does not require line of sight between devices. Thus, RFID tags can be read through packaging, shipping containers, and many other common materials. End user's should be aware that metals reflect radio waves and other materials which absorb radio waves provide the exception and create hurdles for RFID to perform.
Specialty tags are available which attempt to compensate for these difficult materials and thereby deliver acceptable performance.
Even under RF hostile conditions, RFID far exceeds conventional counting methods such as bar-coding in terms of survivability, speed and accuracy. For applications requiring heightened security, the radio frequency communication can be encrypted to ensure the integrity of the data passing between the tag and reader.
posted by Harold Clampitt at 5:16 PM
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