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73-569: Once the applicant is approved, they are issued a Radio Frequency Identification ( RFID ) card identifying their status in the CBP database when arriving at U.S. land and sea ports of entry (POE). SENTRI users have access to dedicated lanes into the United States. Unlike NEXUS , which is a joint program between United States and Canadian immigration authorities, SENTRI is solely a CBP program and only applies to customs and immigration inspections into

146-545: A terahertz frequency identification (TFID) tag that is barely 1 square millimeter in size. The devices are essentially a piece of silicon that are inexpensive, small, and function like larger RFID tags. Because of the small size, manufacturers could tag any product and track logistics information for minimal cost. An RFID tag can be affixed to an object and used to track tools, equipment, inventory, assets, people, or other objects. RFID offers advantages over manual systems or use of barcodes . The tag can be read if passed near

219-512: A battery and thus can be read at a greater range from the RFID reader, up to hundreds of meters. Unlike a barcode , the tag does not need to be within the line of sight of the reader, so it may be embedded in the tracked object. RFID is one method of automatic identification and data capture (AIDC). RFID tags are used in many industries. For example, an RFID tag attached to an automobile during production can be used to track its progress through

292-560: A certain distance of the reader to authenticate the holder. Tags can also be placed on vehicles, which can be read at a distance, to allow entrance to controlled areas without having to stop the vehicle and present a card or enter an access code. In 2010, Vail Resorts began using UHF Passive RFID tags in ski passes. Facebook is using RFID cards at most of their live events to allow guests to automatically capture and post photos. Automotive brands have adopted RFID for social media product placement more quickly than other industries. Mercedes

365-792: A changing magnetic dipole . This type of dipole field near sources is called an electromagnetic near-field . Changing electric dipole fields, as such, are used commercially as near-fields mainly as a source of dielectric heating . Otherwise, they appear parasitically around conductors which absorb EMR, and around antennas which have the purpose of generating EMR at greater distances. Changing magnetic dipole fields (i.e., magnetic near-fields) are used commercially for many types of magnetic induction devices. These include motors and electrical transformers at low frequencies, and devices such as RFID tags, metal detectors , and MRI scanner coils at higher frequencies. The potential effects of electromagnetic fields on human health vary widely depending on

438-494: A different inertial frame using a combination of electric and magnetic fields. Analogously, a phenomenon that one observer describes using only a magnetic field will be, in a relatively moving reference frame, described by a combination of fields. The rules for relating the fields required in different reference frames are the Lorentz transformations of the fields . Thus, electrostatics and magnetostatics are now seen as studies of

511-402: A force along the direction of the field, and a charge moving through a magnetic field feels a force that is perpendicular both to the magnetic field and to its direction of motion. The electromagnetic field is described by classical electrodynamics , an example of a classical field theory . This theory describes many macroscopic physical phenomena accurately. However, it was unable to explain

584-408: A function of time and position. Inside a linear material, Maxwell's equations change by switching the permeability and permittivity of free space with the permeability and permittivity of the linear material in question. Inside other materials which possess more complex responses to electromagnetic fields, these terms are often represented by complex numbers, or tensors. The Lorentz force law governs

657-445: A greater whole—the electromagnetic field. In 1820, Hans Christian Ørsted showed that an electric current can deflect a nearby compass needle, establishing that electricity and magnetism are closely related phenomena. Faraday then made the seminal observation that time-varying magnetic fields could induce electric currents in 1831. In 1861, James Clerk Maxwell synthesized all the work to date on electrical and magnetic phenomena into

730-412: A long straight wire that carries an electrical current. In the frame of reference where the laboratory is at rest, the wire is motionless and electrically neutral: the current, composed of negatively charged electrons, moves against a background of positively charged ions, and the densities of positive and negative charges cancel each other out. A test charge near the wire would feel no electrical force from

803-451: A loop creates a magnetic field through the loop". Thus, this law can be applied to generate a magnetic field and run an electric motor . Maxwell's equations can be combined to derive wave equations . The solutions of these equations take the form of an electromagnetic wave . In a volume of space not containing charges or currents ( free space ) – that is, where ρ {\displaystyle \rho } and J are zero,

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876-411: A nonzero electric field and thus a nonzero force. In the rest frame of the laboratory, there is no electric field to explain the test charge being pulled towards or pushed away from the wire. So, an observer in the laboratory rest frame concludes that a magnetic field must be present. In general, a situation that one observer describes using only an electric field will be described by an observer in

949-409: A particular product. Often more than one tag will respond to a tag reader. For example, many individual products with tags may be shipped in a common box or on a common pallet. Collision detection is important to allow reading of data. Two different types of protocols are used to "singulate" a particular tag, allowing its data to be read in the midst of many similar tags. In a slotted Aloha system,

1022-723: A reader, even if it is covered by the object or not visible. The tag can be read inside a case, carton, box or other container, and unlike barcodes, RFID tags can be read hundreds at a time; barcodes can only be read one at a time using current devices. Some RFID tags, such as battery-assisted passive tags, are also able to monitor temperature and humidity. In 2011, the cost of passive tags started at US$ 0.09 each; special tags, meant to be mounted on metal or withstand gamma sterilization, could cost up to US$ 5. Active tags for tracking containers, medical assets, or monitoring environmental conditions in data centers started at US$ 50 and could be over US$ 100 each. Battery-Assisted Passive (BAP) tags were in

1095-499: A risk assessment conducted by the Mexican government. US citizens who are SENTRI members may use TSA PreCheck on all participating airlines by entering their Customs and Border Protection ID number or PASS ID/KTN (Known Traveler Number) from their SENTRI card into their flight reservation information or into their frequent flyer account. The same privileges extend to NEXUS and Global Entry members. Note that such Trusted Travelers have

1168-465: A single mathematical theory, from which he then deduced that light is an electromagnetic wave. Maxwell's continuous field theory was very successful until evidence supporting the atomic model of matter emerged. Beginning in 1877, Hendrik Lorentz developed an atomic model of electromagnetism and in 1897 J. J. Thomson completed experiments that defined the electron . The Lorentz theory works for free charges in electromagnetic fields, but fails to predict

1241-510: A special tool or deactivated electronically when payment is made. On leaving the shop, customers have to pass near an RFID detector; if they have items with active RFID tags, an alarm sounds, both indicating an unpaid-for item, and identifying what it is. Casinos can use RFID to authenticate poker chips , and can selectively invalidate any chips known to be stolen. RFID tags are widely used in identification badges , replacing earlier magnetic stripe cards. These badges need only be held within

1314-436: A tiny radio transponder called a tag, a radio receiver , and a transmitter . When triggered by an electromagnetic interrogation pulse from a nearby RFID reader device, the tag transmits digital data, usually an identifying inventory number , back to the reader. This number can be used to track inventory goods. Passive tags are powered by energy from the RFID reader's interrogating radio waves . Active tags are powered by

1387-433: A transfer hose can read an RFID tag affixed to the tank, positively identifying it. At least one company has introduced RFID to identify and locate underground infrastructure assets such as gas pipelines , sewer lines , electrical cables, communication cables, etc. Electromagnetic field An electromagnetic field (also EM field ) is a physical field , mathematical functions of position and time, representing

1460-747: A very high probability of receiving PreCheck, it is not guaranteed: TSA still uses random procedures for all passengers. This said, Global Entry participants have the absolute highest priority/likelihood for receiving PreCheck (per CBP documents, including a note that it’s included—not “may” receive—with GE). Enrollment centers are located in Douglas , Nogales , and San Luis , Arizona; Calexico , Otay Mesa , and San Ysidro , California; and Brownsville , El Paso , Hidalgo , and Laredo , Texas. RFID Radio-frequency identification ( RFID ) uses electromagnetic fields to automatically identify and track tags attached to objects. An RFID system consists of

1533-441: Is a fuzzy method for process support. From the perspective of cost and effect, bulk reading is not reported as an economical approach to secure process control in logistics. RFID tags are easy to conceal or incorporate in other items. For example, in 2009 researchers at Bristol University successfully glued RFID micro-transponders to live ants in order to study their behavior. This trend towards increasingly miniaturized RFIDs

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1606-460: Is a strategy for interrogating multiple tags at the same time, but lacks sufficient precision for inventory control. A group of objects, all of them RFID tagged, are read completely from one single reader position at one time. However, as tags respond strictly sequentially, the time needed for bulk reading grows linearly with the number of labels to be read. This means it takes at least twice as long to read twice as many labels. Due to collision effects,

1679-466: Is expected to rise from US$ 12.08 billion in 2020 to US$ 16.23 billion by 2029. In 1945, Leon Theremin invented the "Thing", a listening device for the Soviet Union which retransmitted incident radio waves with the added audio information. Sound waves vibrated a diaphragm which slightly altered the shape of the resonator , which modulated the reflected radio frequency. Even though this device

1752-507: Is likely to continue as technology advances. Hitachi holds the record for the smallest RFID chip, at 0.05 mm × 0.05 mm. This is 1/64th the size of the previous record holder, the mu-chip. Manufacture is enabled by using the silicon-on-insulator (SOI) process. These dust-sized chips can store 38-digit numbers using 128-bit Read Only Memory (ROM). A major challenge is the attachment of antennas, thus limiting read range to only millimeters. In early 2020, MIT researchers demonstrated

1825-408: Is not reliable. Bulk reading can be a rough guide for logistics decisions, but due to a high proportion of reading failures, it is not (yet) suitable for inventory management. However, when a single RFID tag might be seen as not guaranteeing a proper read, multiple RFID tags, where at least one will respond, may be a safer approach for detecting a known grouping of objects. In this respect, bulk reading

1898-526: Is only a single actual field involved which is simply being observed differently. The two Maxwell equations, Faraday's Law and the Ampère–Maxwell Law, illustrate a very practical feature of the electromagnetic field. Faraday's Law may be stated roughly as "a changing magnetic field inside a loop creates an electric voltage around the loop". This is the principle behind the electric generator . Ampere's Law roughly states that "an electrical current around

1971-438: Is the landmark 1948 paper by Harry Stockman, who predicted that "Considerable research and development work has to be done before the remaining basic problems in reflected-power communication are solved, and before the field of useful applications is explored." Mario Cardullo 's device, patented on January 23, 1973, was the first true ancestor of modern RFID, as it was a passive radio transponder with memory. The initial device

2044-428: Is used in intelligent transportation systems . In New York City , RFID readers are deployed at intersections to track E-ZPass tags as a means for monitoring the traffic flow. The data is fed through the broadband wireless infrastructure to the traffic management center to be used in adaptive traffic control of the traffic lights. Where ship, rail, or highway tanks are being loaded, a fixed RFID antenna contained in

2117-663: The Immigration and Naturalization Service (INS), U.S. Customs Service , and five other Federal stakeholder agencies was formed and established a technical concept, engineering design, and relevant policies. The first SENTRI lane was deployed at the Otay Mesa Port of Entry in San Diego, California , where the concept and design were refined. Additional technology tests, including in-vehicle biometrics and laneside facial recognition, were conducted at this site. In 1998,

2190-407: The assembly line , RFID-tagged pharmaceuticals can be tracked through warehouses, and implanting RFID microchips in livestock and pets enables positive identification of animals. Tags can also be used in shops to expedite checkout, and to prevent theft by customers and employees. Since RFID tags can be attached to physical money, clothing, and possessions, or implanted in animals and people,

2263-400: The electric field . An electric field is produced when the charge is stationary with respect to an observer measuring the properties of the charge, and a magnetic field as well as an electric field are produced when the charge moves, creating an electric current with respect to this observer. Over time, it was realized that the electric and magnetic fields are better thought of as two parts of

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2336-495: The electromagnetic spectrum . An electromagnetic field very far from currents and charges (sources) is called electromagnetic radiation (EMR) since it radiates from the charges and currents in the source. Such radiation can occur across a wide range of frequencies called the electromagnetic spectrum , including radio waves , microwave , infrared , visible light , ultraviolet light , X-rays , and gamma rays . The many commercial applications of these radiations are discussed in

2409-547: The photoelectric effect and atomic absorption spectroscopy , experiments at the atomic scale. That required the use of quantum mechanics , specifically the quantization of the electromagnetic field and the development of quantum electrodynamics . The empirical investigation of electromagnetism is at least as old as the ancient Greek philosopher, mathematician and scientist Thales of Miletus , who around 600 BCE described his experiments rubbing fur of animals on various materials such as amber creating static electricity. By

2482-582: The railroad industry, RFID tags mounted on locomotives and rolling stock identify the owner, identification number and type of equipment and its characteristics. This can be used with a database to identify the type, origin, destination, etc. of the commodities being carried. In commercial aviation, RFID is used to support maintenance on commercial aircraft. RFID tags are used to identify baggage and cargo at several airports and airlines. Some countries are using RFID for vehicle registration and enforcement. RFID can help detect and retrieve stolen cars. RFID

2555-402: The 18th century, it was understood that objects can carry positive or negative electric charge , that two objects carrying charge of the same sign repel each other, that two objects carrying charges of opposite sign attract one another, and that the strength of this force falls off as the square of the distance between them. Michael Faraday visualized this in terms of the charges interacting via

2628-653: The French retailer Decathlon , customers perform self-checkout by either using a smartphone or putting items into a bin near the register that scans the tags without having to orient each one toward the scanner. Some stores use RFID-tagged items to trigger systems that provide customers with more information or suggestions, such as fitting rooms at Chanel and the "Color Bar" at Kendra Scott stores. Item tagging can also provide protection against theft by customers and employees by using electronic article surveillance (EAS). Tags of different types can be physically removed with

2701-615: The SENTRI team was disbanded, and SENTRI became a program office within INS. After INS was sunsetted on March 1, 2003, the SENTRI program office was absorbed by DHS Customs and Border Protection . Today, SENTRI Lanes can be found at the following ports of entry, from West to East: US citizens may use their SENTRI membership at US Customs and Border Protection Global Entry kiosks located in participating US airports. Mexican nationals who are SENTRI members may apply for Global Entry after passing

2774-509: The US$ 3–10 range. RFID can be used in a variety of applications, such as: In 2010, three factors drove a significant increase in RFID usage: decreased cost of equipment and tags, increased performance to a reliability of 99.9%, and a stable international standard around HF and UHF passive RFID. The adoption of these standards were driven by EPCglobal, a joint venture between GS1 and GS1 US , which were responsible for driving global adoption of

2847-444: The United States, not into Mexico. SENTRI members are permitted to utilize NEXUS lanes when entering the United States from Canada by land (but not vice versa). Global Entry allows registered users to enter their own SENTRI applications and approved members to edit their information. A valid SENTRI card is a Western Hemisphere Travel Initiative (WHTI) compliant document. SENTRI was conceived in 1995. A team of representatives from

2920-417: The advent of special relativity , physical laws became amenable to the formalism of tensors . Maxwell's equations can be written in tensor form, generally viewed by physicists as a more elegant means of expressing physical laws. The behavior of electric and magnetic fields, whether in cases of electrostatics, magnetostatics, or electrodynamics (electromagnetic fields), is governed by Maxwell's equations. In

2993-686: The barcode in the 1970s and 1980s. The EPCglobal Network was developed by the Auto-ID Center . RFID provides a way for organizations to identify and manage stock, tools and equipment ( asset tracking ), etc. without manual data entry. Manufactured products such as automobiles or garments can be tracked through the factory and through shipping to the customer. Automatic identification with RFID can be used for inventory systems. Many organisations require that their vendors place RFID tags on all shipments to improve supply chain management . Warehouse Management System incorporate this technology to speed up

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3066-408: The basic equations of electrostatics , which focuses on situations where electrical charges do not move, and magnetostatics , the corresponding area of magnetic phenomena. Whether a physical effect is attributable to an electric field or to a magnetic field is dependent upon the observer, in a way that special relativity makes mathematically precise. For example, suppose that a laboratory contains

3139-403: The decision was made to expand SENTRI to El Paso, Texas . The aim was to relieve congestion at the busy Paso del Norte International Bridge . However, this bridge was not wide enough to set aside one lane as a dedicated commuter lane. Therefore, the nearby Stanton Street bridge, which had been a southbound-only bridge, was chosen as the best place to deploy SENTRI. A new port of entry facility

3212-424: The electric and magnetic fields satisfy these electromagnetic wave equations : James Clerk Maxwell was the first to obtain this relationship by his completion of Maxwell's equations with the addition of a displacement current term to Ampere's circuital law . This unified the physical understanding of electricity, magnetism, and light: visible light is but one portion of the full range of electromagnetic waves,

3285-436: The electric field ( E ) is non-zero, and is constant in time, the field is said to be an electrostatic field . Similarly, if only the magnetic field ( B ) is non-zero and is constant in time, the field is said to be a magnetostatic field . However, if either the electric or magnetic field has a time-dependence, then both fields must be considered together as a coupled electromagnetic field using Maxwell's equations . With

3358-684: The electric field, ∇ ⋅ E = ρ ϵ 0 {\displaystyle \nabla \cdot \mathbf {E} ={\frac {\rho }{\epsilon _{0}}}} and ∇ × E = 0 , {\displaystyle \nabla \times \mathbf {E} =0,} along with two formulae that involve the magnetic field: ∇ ⋅ B = 0 {\displaystyle \nabla \cdot \mathbf {B} =0} and ∇ × B = μ 0 J . {\displaystyle \nabla \times \mathbf {B} =\mu _{0}\mathbf {J} .} These expressions are

3431-411: The electromagnetic field is described by Maxwell's equations and the Lorentz force law . Maxwell's equations detail how the electric field converges towards or diverges away from electric charges, how the magnetic field curls around electrical currents, and how changes in the electric and magnetic fields influence each other. The Lorentz force law states that a charge subject to an electric field feels

3504-412: The electromagnetic field. The first one views the electric and magnetic fields as three-dimensional vector fields . These vector fields each have a value defined at every point of space and time and are thus often regarded as functions of the space and time coordinates. As such, they are often written as E ( x , y , z , t ) ( electric field ) and B ( x , y , z , t ) ( magnetic field ). If only

3577-484: The energy spectrum for bound charges in atoms and molecules. For that problem, quantum mechanics is needed, ultimately leading to the theory of quantum electrodynamics . Practical applications of the new understanding of electromagnetic fields emerged in the late 1800s. The electrical generator and motor were invented using only the empirical findings like Faraday's and Ampere's laws combined with practical experience. There are different mathematical ways of representing

3650-437: The field produced by the reader by changing the electrical loading the tag represents. By switching between lower and higher relative loads, the tag produces a change that the reader can detect. At UHF and higher frequencies, the tag is more than one radio wavelength away from the reader, requiring a different approach. The tag can backscatter a signal. Active tags may contain functionally separated transmitters and receivers, and

3723-526: The influences on and due to electric charges . The field at any point in space and time can be regarded as a combination of an electric field and a magnetic field . Because of the interrelationship between the fields, a disturbance in the electric field can create a disturbance in the magnetic field which in turn affects the electric field, leading to an oscillation that propagates through space, known as an electromagnetic wave . The way in which charges and currents (i.e. streams of charges) interact with

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3796-442: The interaction of the electromagnetic field with charged matter. When a field travels across to different media, the behavior of the field changes according to the properties of the media. The Maxwell equations simplify when the charge density at each point in space does not change over time and all electric currents likewise remain constant. All of the time derivatives vanish from the equations, leaving two expressions that involve

3869-457: The named and linked articles. A notable application of visible light is that this type of energy from the Sun powers all life on Earth that either makes or uses oxygen. A changing electromagnetic field which is physically close to currents and charges (see near and far field for a definition of "close") will have a dipole characteristic that is dominated by either a changing electric dipole , or

3942-456: The organization number is assigned by the EPCGlobal consortium. The next 24 bits are an object class, identifying the kind of product. The last 36 bits are a unique serial number for a particular tag. These last two fields are set by the organization that issued the tag. Rather like a URL , the total electronic product code number can be used as a key into a global database to uniquely identify

4015-473: The possibility of reading personally-linked information without consent has raised serious privacy concerns. These concerns resulted in standard specifications development addressing privacy and security issues. In 2014, the world RFID market was worth US$ 8.89 billion , up from US$ 7.77 billion in 2013 and US$ 6.96 billion in 2012. This figure includes tags, readers, and software/services for RFID cards, labels, fobs, and all other form factors. The market value

4088-528: The radio energy transmitted by the reader. However, to operate a passive tag, it must be illuminated with a power level roughly a thousand times stronger than an active tag for signal transmission. Tags may either be read-only, having a factory-assigned serial number that is used as a key into a database, or may be read/write, where object-specific data can be written into the tag by the system user. Field programmable tags may be write-once, read-multiple; "blank" tags may be written with an electronic product code by

4161-423: The range of the RFID reader and read them simultaneously. RFID systems can be classified by the type of tag and reader. There are 3 types: Fixed readers are set up to create a specific interrogation zone which can be tightly controlled. This allows a highly defined reading area for when tags go in and out of the interrogation zone. Mobile readers may be handheld or mounted on carts or vehicles. Signaling between

4234-410: The reader and the tag is done in several different incompatible ways, depending on the frequency band used by the tag. Tags operating on LF and HF bands are, in terms of radio wavelength, very close to the reader antenna because they are only a small percentage of a wavelength away. In this near field region, the tag is closely coupled electrically with the transmitter in the reader. The tag can modulate

4307-484: The reader broadcasts an initialization command and a parameter that the tags individually use to pseudo-randomly delay their responses. When using an "adaptive binary tree" protocol, the reader sends an initialization symbol and then transmits one bit of ID data at a time; only tags with matching bits respond, and eventually only one tag matches the complete ID string. Both methods have drawbacks when used with many tags or with multiple overlapping readers. "Bulk reading"

4380-425: The receiving and delivery of the products and reduce the cost of labor needed in their warehouses. RFID is used for item-level tagging in retail stores. This can enable more accurate and lower-labor-cost supply chain and store inventory tracking, as is done at Lululemon , though physically locating items in stores requires more expensive technology. RFID tags can be used at checkout; for example, at some stores of

4453-401: The static EM field when a particular frame has been selected to suppress the other type of field, and since an EM field with both electric and magnetic will appear in any other frame, these "simpler" effects are merely a consequence of different frames of measurement. The fact that the two field variations can be reproduced just by changing the motion of the observer is further evidence that there

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4526-414: The tag need not respond on a frequency related to the reader's interrogation signal. An Electronic Product Code (EPC) is one common type of data stored in a tag. When written into the tag by an RFID printer, the tag contains a 96-bit string of data. The first eight bits are a header which identifies the version of the protocol. The next 28 bits identify the organization that manages the data for this tag;

4599-572: The time required is greater. A group of tags has to be illuminated by the interrogating signal just like a single tag. This is not a challenge concerning energy, but with respect to visibility; if any of the tags are shielded by other tags, they might not be sufficiently illuminated to return a sufficient response. The response conditions for inductively coupled HF RFID tags and coil antennas in magnetic fields appear better than for UHF or SHF dipole fields, but then distance limits apply and may prevent success. Under operational conditions, bulk reading

4672-403: The transmission and sensor data, respectively. RFID tags can be either passive, active or battery-assisted passive. An active tag has an on-board battery and periodically transmits its ID signal. A battery-assisted passive tag has a small battery on board and is activated when in the presence of an RFID reader. A passive tag is cheaper and smaller because it has no battery; instead, the tag uses

4745-410: The user. The RFID tag receives the message and then responds with its identification and other information. This may be only a unique tag serial number, or may be product-related information such as a stock number, lot or batch number, production date, or other specific information. Since tags have individual serial numbers, the RFID system design can discriminate among several tags that might be within

4818-431: The vector field formalism, these are: where ρ {\displaystyle \rho } is the charge density, which is a function of time and position, ε 0 {\displaystyle \varepsilon _{0}} is the vacuum permittivity , μ 0 {\displaystyle \mu _{0}} is the vacuum permeability , and J is the current density vector, also

4891-408: The wire. However, if the test charge is in motion parallel to the current, the situation changes. In the rest frame of the test charge, the positive and negative charges in the wire are moving at different speeds, and so the positive and negative charge distributions are Lorentz-contracted by different amounts. Consequently, the wire has a nonzero net charge density, and the test charge must experience

4964-650: Was a covert listening device , rather than an identification tag, it is considered to be a predecessor of RFID because it was passive, being energised and activated by waves from an outside source. Similar technology, such as the Identification friend or foe transponder , was routinely used by the Allies and Germany in World War II to identify aircraft as friendly or hostile. Transponders are still used by most powered aircraft. An early work exploring RFID

5037-554: Was an early adopter in 2011 at the PGA Golf Championships , and by the 2013 Geneva Motor Show many of the larger brands were using RFID for social media marketing. To prevent retailers diverting products, manufacturers are exploring the use of RFID tags on promoted merchandise so that they can track exactly which product has sold through the supply chain at fully discounted prices. Yard management, shipping and freight and distribution centers use RFID tracking. In

5110-527: Was built, and the SENTRI lane opened in September 1999. Next, the SENTRI team elected to deploy a system at the busiest single border crossing in the world, San Ysidro, California . The congested nature of Tijuana , near the border crossing, made it difficult to identify a place to put the dedicated lane, but with the cooperation of many organizations on both sides of the border, a lane was segregated, and SENTRI opened at San Ysidro in 2000, after which point

5183-484: Was granted to David Everett, John Frech, Theodore Wright, and Kelly Rodriguez. A radio-frequency identification system uses tags , or labels attached to the objects to be identified. Two-way radio transmitter-receivers called interrogators or readers send a signal to the tag and read its response. RFID tags are made out of three pieces: The tag information is stored in a non-volatile memory. The RFID tag includes either fixed or programmable logic for processing

5256-939: Was passive, powered by the interrogating signal, and was demonstrated in 1971 to the New York Port Authority and other potential users. It consisted of a transponder with 16 bit memory for use as a toll device . The basic Cardullo patent covers the use of radio frequency (RF), sound and light as transmission carriers. The original business plan presented to investors in 1969 showed uses in transportation (automotive vehicle identification, automatic toll system, electronic license plate , electronic manifest, vehicle routing, vehicle performance monitoring), banking (electronic chequebook, electronic credit card), security (personnel identification, automatic gates, surveillance) and medical (identification, patient history). In 1973, an early demonstration of reflected power (modulated backscatter) RFID tags, both passive and semi-passive,

5329-532: Was performed by Steven Depp, Alfred Koelle and Robert Freyman at the Los Alamos National Laboratory . The portable system operated at 915 MHz and used 12-bit tags. This technique is used by the majority of today's UHFID and microwave RFID tags. In 1983, the first patent to be associated with the abbreviation RFID was granted to Charles Walton . In 1996, the first patent for a batteryless RFID passive tag with limited interference

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