Abstract: A system and method for activating vehicle sensors which are based on inductive loops. A voltage controlled oscillator is scanned throughout the required frequency range while a balanced mixer, low-pass filter, and detector are arranged to show the presence of a signal from an inductive loop by the amplitude of the resultant signal at a difference frequency. The voltage controlled oscillator is then made to dwell at or near the frequency of the sensor loop by adjusting so as to keep the amplitude of that low-frequency difference as high as possible.

Abstract: An improved system and method for protecting sensitive electronic equipment or components against unauthorized access, by detecting and also reacting to unauthorized intrusions into the enclosures for the sensitive electronic equipment or components is disclosed. For example, a protective system for protecting sensitive electronic equipment or components against unauthorized access is disclosed that includes a fiber optic cable mesh or network attached to, or embedded in, the walls of the enclosure for the electronic equipment or components. A continuous signal or burst is applied to the fiber optic cable, which is coupled to an optical signal detection device. Thus, any attempt to remove or penetrate the walls of the enclosure interrupts the signal in the fiber optic cable, and the interruption of the signal is detected by the optical signal detection device.

Abstract: A method for detecting threatening objects in a security screening system. The method includes a step of classifying unique features of magnetic data as representing a threatening object. Another step includes acquiring magnetic data. Another step includes determining if the acquired magnetic data comprises a unique feature.

Abstract: The present invention is a technique for locating and identifying a failed filter/arrester in an underground conveyance such as a fiber optic cable. A sensor is installed in the filter/arrester housing to sense grounding of a cable locating frequency. The sensor will monitor the cable locating signal that is normally on the cable and blocked by the filter arrester to ground. A small radio frequency oscillator (85 to 88 Hz), also installed inside the filter housing, is activated by the sensor. The RF signal is detected above ground with standard cable locating equipment. A warning indicator such as an indicator light may also be installed on the outside of the filter housing. The indicator is also activated by the sensor. In that way, the particular failed filter can be identified if multiple filters are installed at that location. The power that will be required to operate the RF transmitter and indicator will be obtained from the voltage passing through the cable.

Abstract: The present application describes a monitoring circuit for an aircraft. The monitoring circuit comprises an inductive system, wherein the inductive system comprises a multitude of air core inductors and capacitors. Depending on the distance between a target and the inductive system the frequency response of the inductive system is changed. The change in the frequency response is detected and displayed in a display unit. The monitoring circuit can be used to improve door monitoring in an aircraft.

Abstract: An apparatus for detecting a potentially dangerous ferromagnetic object carried inadvertently by a person approaching the magnet of a magnetic resonance imaging system (14) uses the fringe field (16) of the magnet and provides guide members (11) defining a path along which the person is prescribed to pass. The path (11) is generally or approximately parallel to the field the path. At least one sense coil and generally two sets of sense coils (12, 13) are located on respective sides of the path (11) s the movement of the ferromagnetic object in the field of the magnet causes a voltage to be generated in the sense coil.

Abstract: This application describes a system for contraband and weapons detection. The system comprises a coplanar sensor array, electronic drive circuitry, a data acquisition circuit, a video frame grabber, a video camera, and a computer control unit with a control module installed. Properly constructed and aligned, the system allows for the detection of very small magnetic moments, which surround ferromagnetic materials. This ferromagnetic detection allows users to screen personnel for contraband electronic devices and concealed weapons.

Abstract: The invention relates to a method for the control of a monitored zone, in particular at transport devices for objects, wherein the monitored zone is scanned by means of at least one spatially resolving sensor, in particular a laser scanner and/or a camera system, the positions of object points in the monitored zone are determined and a contour search is carried out in at least a sub-set of the determined positions in that these positions are mathematically examined as to whether the respective object points lie on at least one model line pre-determined with respect to shape and/or length within a pre-determinable tolerance, said model line corresponding to at least a part of a contour of a permitted object in the monitored zone, with the contour search being carried out independently of the location of the positions relative to the sensor.

Abstract: At least one time-varying signal is applied to a plurality of coil elements in cooperative relationship with and spanning different portions of a vehicle. The coil elements generate an associated plurality of magnetic field components that interact with the vehicle. At least one detection circuit generates a detected signal responsive to signal components from the coil elements so as to provide for detecting a change in a magnetic condition of the vehicle.

Abstract: A fabrication process produces markers for a magnetomechanical electronic article surveillance system. The marker includes a magnetomechanical element comprising one or more resonator strips of magnetostrictive amorphous metal alloy; a housing having a cavity sized and shaped to accommodate the resonator strips for free mechanical vibration therewithin; and a non-deactivatable bias magnet adapted to magnetically bias the magnetomechanical element. The process employs adaptive control of the cut length of the resonator strips, correction of the length being based on deviation of the actual marker resonant frequency from a preselected, target marker frequency. Use of adaptive, feedback control advantageously results in a much tighter distribution of actual resonant frequencies. Also provided is a web-fed press for continuously producing such markers with adaptive control of the resonator strip length.

Abstract: This application describes a system for contraband and weapons detection. The system comprises a coplanar sensor array, electronic drive circuitry, a data acquisition circuit, a video frame grabber, a video camera, and a computer control unit with a control module installed. Properly constructed and aligned, the system allows for the detection of very small magnetic moments, which surround ferromagnetic materials. This ferromagnetic detection allows users to screen personnel for contraband electronic devices and concealed weapons.

Abstract: A surface tracker includes a tubular marker body having an interior electronic marker and a visual indicator attached to an upper end of the marker body which extends away from the marker body. When deployed, the marker body is mostly underground and the visual indictor extends upwardly from the ground level to provide above-ground visual recognition. The electronic marker may be a passive electronic marker that includes a ferrite core assembly having a longitudinal axis which is generally parallel to a longitudinal axis of the marker body. The visual indicator may be a plurality of resilient filaments which pass through a hole in a tab portion of the marker body at the upper end thereof, the filaments being folded about the tab portion and secured to the tab portion using a heat-shrink tube. In an exemplary embodiment, the filaments extend about six inches from the marker body and are brightly colored. Multiple trackers can be used to mark the path of a buried utility.

Abstract: Methods for detecting and locating ferromagnetic objects in a security screening system. One method includes a step of acquiring magnetic data that includes magnetic field gradients detected during a period of time. Another step includes representing the magnetic data as a function of the period of time. Another step includes converting the magnetic data to being represented as a function of frequency. Another method includes a step of sensing a magnetic field for a period of time. Another step includes detecting a gradient within the magnetic field during the period of time. Another step includes identifying a peak value of the gradient detected during the period of time. Another step includes identifying a portion of time within the period of time that represents when the peak value occurs. Another step includes configuring the portion of time over the period of time to represent a ratio.

Abstract: A metal detector (1) used for identifying contaminants (35) in products (35). The detector (1) includes an oscillator coil assembly (10) that may be formed as a combination of pairs of series wound coils (15, 18) and pairs of parallel wound coils (16, 17). A pair of input coils (13, 14) defines the boundaries of a region (39) within which the oscillator coil assembly (10) resides. A first signal (8) is generated by the first input coil (13) in response to the presence of a metallic object (35) while a second signal (24) is generated by the second input coil (14) in response to the presence of the metallic object (35). By measuring the ratio of the first signal (8) to the second signal (24) the physical location of a metal object within the metal detector cavity (7) can be determined.

Abstract: A system and method is disclosed to the elimination of cross talk between inductive loop detector units in a security system. The system includes appropriate devices for assigning different operational frequencies of each loop detector circuit to avoid cross talk. In a further aspect it provides a system and method for determining actual operational frequencies of various loop detector circuits in a security system and for changing the resonant frequencies to eliminate cross talk.

Abstract: A magnetic screening system including an arrangement of gradiometers each including at least three magnetometers, a gradiometer processor in communication with the magnetometers that scales outputs from the magnetometers with unequal weights and combines the scaled outputs to orient a direction of sensitivity of the respective gradiometer toward a volume of interest and at least one arrangement processor in communication with the arrangement of gradiometers that uses the gradiometers in a collective manner to detect a target object.

Abstract: A radio frequency identification (“RFID”) tags that are useful on metal or other conductive surface and to methods for manufacturing the same. In one embodiment, the radio frequency identification tag includes: a substrate including a first major surface and a second major surface opposite the first major surface; a radio frequency identification antenna attached to the first major surface of the substrate; an integrated circuit attached to the antenna; and a first composite layer.

Abstract: A tesla coil security system for proactively and effectively deterring unauthorized individuals from entering an opening in a non-lethal manner. The tesla coil security system includes a tesla coil, a length of wire electrically connected to the tesla coil for surrounding an opening to be protected, and a plurality of charge dissipaters electrically extending from the wire for facilitating the discharge of electrical charge thereby creating an electrical visual effect for deterring entry through the opening. A control unit is in communication with the tesla coil for controlling the operation of the tesla coil and a sensor is in communication with the control unit for determining the presence of an individual, whereby detection by the sensor of the presence of an individual causes the tesla coil to be activated.

Abstract: An operation section 2 is provided to a proximity sensor including: a detection section having an oscillation circuit 10; and an amplification section 2 having a function detecting a metal body using an oscillation amplitude of the oscillation circuit 10. In a set mode, when an operation to set an adjustment value for a sensitivity adjustment (a sensitivity adjustment value) is conducted in an operation section 22, CPU 20 generates a sensitivity adjustment signal in digital quantity indicating the sensitivity adjustment value and outputs the signal to a D/A converter 25. The sensitivity adjustment signal digital-to-analog converted by the D/A converter 25 is given to a feedback circuit 13 through a voltage adjustment circuit 26. Since the feedback circuit 13 is designed so as to change a feedback current quantity according to an applied voltage, a current with a magnitude matching a value the sensitivity adjustment signal is fed back to a resonance circuit 11 to thereby control an oscillation amplitude.

Abstract: An electronic ferrous metal detector with an alarm includes a non-ferrous core positioned circumferentially about an opening in an object, such as a hole in a garbage can lid. A pick-up coil having a sufficient number of windings is wound about the non-ferrous core for detecting magnetized objects passing therethrough and generating a voltage. The voltage is passed through an op-amp and into a comparator/detector, where a preset reference point is compared to the voltage from the op-amp. Once the voltage passes the preset reference point, the comparator goes to a high output and powers a switch, such as a SCR or Triac, which is gated on and carries the current and feeds the voltage to an alarm that provides an audible or visual signal that a magnetized piece of ferrous material has passed through the metal detector.

Abstract: A ferromagnetic detection pillar having one or more applied magnetic field sources and one or more magnetic field sensors, with the magnets and sensors arranged and adapted to detect a ferromagnetic threat object on one side of the pillar. A detection device, such as a motion detector or infrared detector, is also provided, to detect the presence of an object on a selected side of the pillar. A single free-standing pillar can be used, or two or more free-standing pillars can be arranged to constitute a variable aperture detection portal. Single sensors or multiple-sensor configurations can be used.

Abstract: A magnetic field sensor is provided alongside a roadway in order to detect vehicles.

Abstract: A surveillance system is provided. The system includes at least one target detection sensor, a plurality of adjustable identification sensors and a system controller. The syste controller is coupled to the at least one target detection sensor and the plurality of adjustable identification sensors. The system controller processes data from the plurality of target detection sensors, applies threat criteria, and, when a target is identified as a threat, the system controller selects at least one of the plurality of adjustable identification sensors and adjusts a sensing input of the selected one of the plurality of adjustable identification sensors to capture information on the identified target. The system also includes a monitoring station that is adapted to receive signals from the selected one of the adjustable identification sensors and to display the captured information.

Abstract: An alarm system sensor (10) monitoring movement of an object (D) and placing the system into alarm when the object moves more than a predetermined distance from a predetermined position. First and second reed switches (16, 18) are located in a predetermined orientation relative to each other and in tandem to the object. Bias magnets (24, 26) are used with the reed switches. A magnet (20) is movable with the object and produces a force simultaneously sensed by both reed switches. This force maintains both reed switches in a state keeping the alarm system in a non-alarm condition so long as the object substantially remains in its predetermined position. The object, when it moves, moves toward one of the reed switches and away from the other reed switch. Movement of the object more than the predetermined distance results in the force sensed by one of the reed switches increasing and the force sensed by the other reed switch decreasing.

Abstract: Disclosed is one method and one apparatus which teach improved techniques in equipping an RFID with security measure. Conventionally an RFID is employed basically to replace the usage of an infrared bar-code label thereby to supply electronic or digital signature and identification. In this sense, the traditional RFID technology is in lack of security and an RFID can be tampered with in an arbitrary manner not to cause an alert. This is no longer true if an RFID is endowed with security. In this invention an RFID, either an active or a passive device, has the ability to memorize its original spatial position so that if the position is changed without authority, an alarm signal is generated.

Abstract: An expendable metal detector system for facilitating the detection of improved explosive devices (IED) where the metal detector is launched toward the suspected IED and using either magnetic field sensors in a passive mode to detect magnetic anomalies or current pulses through a loop antenna in an active mode to detect eddy currents, or using both modes sequentially, detects the ferrous material in the IED. In the active mode, the loop antenna is deployed automatically after launch and impact. The signals are transmitted from the metal detector to the operator who can then take appropriate steps to neutralize the IED.

Abstract: An electronic bait station utilising the disruption of an electromagnetic field to detect the movement of insects or small animals within the station. The bait station consists of a housing, with at least one cavity having an electromagnetic radiation element generating an electromagnetic field in the cavity, and an electromagnetic receiving element detecting the electromagnetic field. Movement of an insect or small animal in the cavity causes a change in the electromagnetic field, which is detected. The preferred bait station comprises an outer cavity and a coaxial inner cavity, each with an electromagnetic field. This arrangement allows the direction of movement of insects and small animals to be determined and minimises the occurrence of spurious signals.

Abstract: The present technology involves a method and apparatus for detecting and reporting magnetic fields in the proximity of a utility meter as an approach to determining tampering of such meter. The sensitivity level of the magnetic field sensors may be adjustable allowing either remote or local sensitivity adjustments to a magnetic field sensor to compensate for variations in the electromagnetic environments of different meter installation sites. Alternatively, the output of each magnetic field sensor may be connected to the input of an adjustable threshold circuit. When the output voltage of the magnetic field exceeds a predetermined threshold voltage, a magnetic event signal is generated. Threshold adjustments to the adjustable threshold circuit may be performed locally at the meter site or remotely from a station. The output of each magnetic field sensor may be monitored by a locally or remotely programmable magnetic sensor output monitor.

Abstract: A human body detection sensor includes two oscillation circuits, a tuning circuit which connects equivalent points of the two oscillation circuits to each other, an antenna electrode which is connected to any one of the oscillation circuits so that a change in circuit state occurs upon approach of a human body, and a wave detector circuit for detecting a shift of oscillation between the two oscillation circuits.

Abstract: A system and method of interfacing a drilling machine with one of a number of different walk-over guidance systems involves receiving an ID signal from a particular walk-over guidance system selected for use with the drilling machine. A protocol library associated with the particular walk-over guidance system is accessed in response to the ID signal. The protocol library is used to effect communication between the particular walk-over guidance system and a control system of the drilling machine during cooperative use of the particular walk-over guidance system and drilling machine. Using the protocol library involves converting, as prescribed by the protocol library, locator signals received from the particular walk-over guidance system from a locator protocol to a common protocol used by the control system of the drilling machine. Locator and drilling machine data of various types can be presented to a drilling machine operator via an on-board display.

Abstract: A portable walk through metal detector with interchangeable sensor panels and other structural members that can be quickly assembled, or disassembled and transported. The device includes two structural base members to anchor the archway, multiple sensor panels with which the sides of the archway are constructed, and a top cross-member to join and support the walls of the archway. In addition, the top cross-member provides a vehicle platform for moving a disassembled unit with built-in wheels, a handle, and stacking structures to support the other members.

Abstract: A detection apparatus determines the type of an object approaching a vehicle. The detection apparatus is provided on a bumper of the vehicle, and comprises a coil as well as electrode lines to serve as the electrodes of a capacitor for detecting a human body. The detection apparatus is capable of differentiating a metallic body and a human body from each other based on variations in output voltage, which are caused by changes in their impedance.

Abstract: A method is provided for at least one of detecting and tracking an object within a wide-area. The method including: deploying three or more sensors within the wide-area, each of the sensors having one or more polarized radio frequency waveguides; transmitting polarized radio frequency radiation from at least one source; detecting a reflection of the transmitted polarized radio frequency radiation; and calculating one of a detection or position of an object within the wide-area based on the detected reflection. At least one of the three or more sensors and at least one source can be a mobile platform, which can be manned or unmanned. The three or more sensors can be deployed manually or remotely, such as from a projectile.

Abstract: A door system includes an antenna-based proximity sensor with a releasable electrical connector that enables the sensor to function with a breakaway feature of the door. The sensor includes a signal generator and a door-mounted antenna for sensing a body or an obstruction near the door. The signal generator (or oscillator) can be installed at various locations between a power source and the antenna. In some cases, the wiring between the antenna and the power source includes a rotatable feature to accommodate the rotation of a drum that carries a wrap-up, pliable door panel. The rotatable feature may be a rotatable electrical connector, or it may be a wire having sufficient length and flexibility to twist about itself within the hollow interior of the drum.

Abstract: This invention concerns a process and a device for producing strip elements for electronically securing articles and a corresponding produced strip element. The aim of the invention is to present a process, a device, and a strip element which can be economically produced according to said process. As for the process, the aim is achieved in that an endless strip of electronically detectable material is fed and is cut into individual segments of a defined length, in that the individual segments are advanced by means of a conveyor, the speed of which is greater than the speed at which the endless strip is fed, the relative velocity being adjusted to provide the desired interval between two consecutive strip segments, and in that the segments separated by intervals are given a coating on one or both sides.

Abstract: A test procedure and a metal detector having transmitting coils, receiving coils and an electronic processing circuit adapted to detect variations in the signals received by the receiving coils against a reference value. The metal detector, also includes a test module which has a selector able to detect a test request, and a controller, used when a test request is detected by the selector, able to compare the signals from the receiving coils during the subsequent passing of a known standard reference object with a predetermined response through the detector.

Abstract: A metal detection circuit that includes a power source and a connection to ground. At least one transmitter circuit is electrically coupled to the power source and ground and a transmit coil is electrically coiled to the transmitter circuit. At least one receiver coil has provided along with an amplifier to be electrically coupled to the receiver coil. An integrator is electrically coupled to the amplifier and a track/hold circuit is electrically to the integrator. A filter is electrically coupled to the track/hold circuit and an output. The circuit provides a high amplitude, low duty cycle excitation pulse, which allows for the sensitivity of a high level excitation signal with the power economy of a much lower energy excitation signal. The receiver circuit collects and conditions the signals resulting from the relatively short duration, large amplitude excitation pulse, and goes in to hold mode during the relatively long charge and idle periods.

Abstract: A method and apparatus to detect an external source are described.

Abstract: A detection system is provided which is configured to have a transmitter capable of interacting with an object by generating a field, and a multiplicity of receivers operative to measure changes in the environment caused by the object's response to the generated field and mounted to a closed-looped belt, which is displaceable in a proximity to the object.

Abstract: A method and device for activation of large quantities of security elements for the electronic article protection. The security elements are exposed to at lease one magnetic field produced by one or more coils carrying a line current subjected to sine oscillations. The coils are supplied with current pulses that are shorter than the sine oscillations. The amplitude of the current pulses diminishes as a function of time.

Abstract: A security system is described that includes an optical fiber net woven from an optical fiber wire. A light generator introduces an incident light signal into the optical fiber wire. A light receiver receives an exigent light signal from the optical fiber wire. An optical sensor wire is connected to the optical fiber net and is displaced when a force is applied to the optical fiber net. The optical sensor wire receives a patterned incident light signal that is altered upon application of the force applied to the optical fiber net, thereby producing an altered patterned exigent light signal. The light receiver initiates an alarm either (1) if the exigent light signal from the optical fiber wire terminates, or (2) after comparing the exigent patterned light signal with the incident patterned light signal in the optical sensor wire and establishing a deviation, if the deviation exceeds a predetermined threshold.

Abstract: A method for enrolling devices in a security system based upon RFID techniques. The method prevents unauthorized devices from engaging in communications by and between the various devices in the security system. While the security system may have long RF range during normal operation, the RFID readers of the security system reduce their read range during an enrollment operation. A user must be physically proximate to an RFID reader to enroll any device. The controller has an associated master key RFID transponder containing at least one code necessary for enabling enrollment of an RFID reader. This master key RFID transponder can only be read during enrollment. RFID transponders and RFID readers also exchange at least one code during the enrollment of RFID transponders. The codes can enable encrypted communications during normal system operation.

Abstract: A combination magnetic tag (10) is described comprising an optical part (20) and a magnetic part (30), the optical part including a plurality of optical elements for conveying an optical code and the magnetic part including a plurality of magnetic elements for conveying a magnetic code, the optical and magnetic codes being mutually complementary for verifying authenticity of the tag (10). Incorporation of both optical and magnetic codes into the tag is of advantage in that they are capable of rendering the tag less susceptible to copying. The tag (10) is relevant to appropriate to anti-counterfeiting applications.

Abstract: An apparatus for detecting ferromagnetic objects in the vicinity of a magnetic resonance imaging scanner. The apparatus comprises primary sensor means adapted to measure a magnetic field, arranged in communication with signal processing means configured to identify temporal variations in the measured magnetic field due to the movement of a ferromagnetic object within an ambient magnetic field and to provide an output indicative of the presence of a ferromagnetic object in the vicinity of the primary sensor means. The apparatus further comprises secondary, non-magnetic, sensor means adapted to detect the movement of objects in the vicinity of the primary sensor means in order to reduce false alarms. The output from the signal processing means may be used to operate an audible alarm, a visual alarm, an automatic door lock or a physical barrier.

Abstract: An improved security checkpoint separates certain individuals into a secure, enclosed wanding station for additional security screening. The wanding station may be constructed using glass (or other strong, visually transparent substance) and metallic (such as aluminum or steel) posts so that people may be securely enclosed in the wanding station but still have a direct line of sight to personal items being screened at another location. The size of the wanding station may vary according to the needs of the checkpoint but preferably has room to screen three people simultaneously. The wanding station may include an entry area in which people form a queue, optimally of six people, for entering the wanding station. Two or more personal and item screening areas may share a wanding station to form a double lane module. The security module is configured so that most people pass straight through the checkpoint, and people leaving the wanding station can easily obtain their items without delaying others.

Abstract: A method for identifying a buried metal object using a three-dimensional steerable magnetic field (3DSMF) system. The method comprises generating a magnetic field vector (MFV) at a first MFV position above the buried metal object; measuring a time decay response at the first MFV position; generating a MFV at a next MFV position above the buried metal object; measuring a time decay response at the next MFV position; repeating the above steps until a complete 360-degree measurement of time decay responses of the buried metal object is completed; processing all measured time decay responses with a target search algorithm to determine a magnetic polarizability tensor of the buried metal object; and identifying the buried metal object by matching the magnetic polarizability tensor of the buried metal object to a known magnetic polarizability tensor of an object.

Abstract: A Mobile Security Unit (MSU) has a security checkpoint and a transport. The security checkpoint has an item screening area and a personal screening area. The checkpoint is configured as needed to fit within the transport. The MSU may further separate certain individuals into a secure, enclosed wanding station for additional security screening. The wanding station may be constructed using glass (or other strong, visually transparent substance) and metallic (such as aluminum or steel) posts so that people may be securely enclosed in the wanding station but still have a direct line of sight to personal items being screened at another location. The MSU is configured so that most people pass straight through the checkpoint, and people leaving the wanding station can easily obtain their items without delaying others.

Abstract: A device for detecting a prohibited object in a zone with protected access includes a supporting base designed to receive a single foot wearing a shoe of an individual to be inspected. The device further includes a detector to detect a target material and a position-identifier suitable for imposing accurate positioning of the foot of the individual being inspected relative to the detector.

Abstract: A method and a system for monitoring access of a person from an exterior to an interior of a partition via a passage having an openable closed opening, using a detection device and supervision of an operator. A monitoring unit is coupled to both the detection device on the exterior, for handling in manual self-scanning procedure, and an input/output unit on the interior, for use by the operator. The monitored person handles the detection device, which transmits at least a first type handling signal, and at least a second type recognition signal to the monitoring unit. The operator rates the monitored person and transmits a third type rating signal to the monitoring unit, indicating crossing permission or crossing denial. The monitoring unit then derives an access signal from the three types of signals received from at least two sensors to allow or to deny access via the passage.

Abstract: A marker for remote detection of articles has an elongated sensor element with magnetic and electric properties. The elongated sensor element provides an electromagnetic reply signal when receiving an electromagnetic input signal. The elongated sensor element modulates the electromagnetic reply signal in response to an external magnetic modulating field. The marker also has means positioned in a vicinity of the elongated sensor element in the marker. The means is adapted to influence either the magnetic or the electric properties of the elongated sensor element in response to incident electromagnetic or magnetic energy, so that either the electromagnetic reply signal itself or the modulation thereof is substantially changed from an active state to a deactivated state.