Intrusion detection system and method thereof

An intrusion detection system and method utilizing a power transmission cable connected to a source of radio frequency signals. A data transmission cable is associated with the power transmission cable and is provided with a plurality of radio frequency identification chips. The power transmission cable would induce an electromagnetic field within the data transmission cable allowing each of the RFID chips to transmit a signal during normal operation. However, if an intrusion occurs or the power transmission cable or data transmission cable is severed, the system according to the present invention, would be able to determine the exact point of intrusion based upon the signals received or not received from the RFID chips.

FIELD OF THE INVENTION

The present invention relates generally to systems and devices for providing security to a particular area or structure.

BACKGROUND OF THE INVENTION

The field of protecting an individual's personal property as well as industrial/commercial real estate has mushroomed in the last 20 or 25 years from a multi-million to a multi-billion dollar industry. Initially, this industry concerned itself with protecting structures, such as homes or businesses from intrusion, particularly by thieves or other nefarious individuals. Generally, entry points to the particular structure, such as doors or windows were wired in a manner such as to produce a signal if the door or windows were opened without shutting off an alarm. Similarly, if a window is broken, an alarm would be emitted and/or transmitted to a remote location such as a police station or a monitoring agency.

Unfortunately, valuable personal property such as audio/visual components, computers and the like were provided with sensors such that if the item or personal property was either moved without permission or transported across a threshold, such as the perimeter of the individual's residence or place of business, an alarm would be sounded as well as alerting the police or the monitoring agency.

Additionally, during the last several years, we have witnessed an alarmingly large increase in the amount of domestic as well as international terrorism being perpetrated on innocent individuals. Although a large amount of time, effort and money has been budgeted for developing different devices, systems and methods of protecting both individuals as well as their personal property, this increase in terrorism has not abated. This is partly due to the fact that access control devices supervise access at perimeter doors, but fail to detect vandalism or terrorist threats to the exterior and the immediate vicinity of a structure or area to be protected.

Prior art security protection intrusion devices consist of a single wire cable attached to a fence or similar structure to sense vibration, noise or the actual cutting of the cable.

A number of U.S. patents have issued in the security field. For example, U.S. Pat. No. 4,213,122, issued to Rotman et al describes an intrusion detection system for protecting a metallic structure, such as an airplane, trailer, hangar or other metallic object or housing. The purpose of this patent was to secure the physical integrity of the metallic structures by detecting any attempts to penetrate through a zone or protection surrounding the metallic structures. As shown inFIGS. 1aand1b,a radio frequency source11,21would be connected to the particular metallic structure10,20to be protected. The metallic structure would be surrounded by ground wires12,22which in turn would be themselves surrounded by receiver wires14,24. The metallic structure becomes one part of a radiating antenna system producing electromagnetic fields in the surrounding receiving wires. These fields are monitored by radio frequency pickup devices which would detect any changes from a quiescent or undisturbed state. These changes would be produced by an individual crossing the receiving wires into the protective zone surrounding the metallic structures. However, as can be appreciated, directly connecting the radio frequency sources to the metallic structures could potentially cause problems to various electronic components provided in the metallic structures. Additionally, while the patent to Rotman et al would be able to sense a disturbance in the electromagnetic field surrounding the metallic structures, it would not be able to pinpoint the exact spot of this disturbance. This is particularly important when a rather large area is to be protected.

U.S. Pat. No. 4,588,988, issued to Karas describes a system for the protection of a particular secure area from intruders by sensing the deformation of a physical barrier surrounding the secure area, such as a barbed wire fence or fences shown inFIGS. 1 and 2. One or more ported coaxial cables are disposed in relation to the barbed wire fence or fences. Radio frequency sources would be connected to the coaxial cables and would be used as a source of radio frequency energy as well as for receiving reflection produced by disturbances of the electromagnetic field produced by an intruder. However, as was true with respect to the patent to Rotman et al, while the patent to Karas would sense the presence of an intruder, it could not make a determination of the exact point of entry of the intruder into the secured area. Additionally, since the radio frequencies are induced into barbed wire coils to produce the electromagnetic field, this particular configuration could not be utilized as a direct attachment to solid walls constructed from concrete, glass or brick. Even if the coaxial cables shown in the Karas patent were utilized in a manner to surround the secured area, as indicated previously, it would be ineffective to locate the point of intrusion.

U.S. Pat. No. 5,446,446 issued to Harman describes a device that uses a cable with a center conductor and one or two sense wires. Although this cable can detect the point of intrusion, it depends upon vibration and is best attached to a chain link fence. It is not effective on solid structures such as brick, block or concrete walls or similarly constructed buildings. Additionally, since this system operates on a sensed vibration, many false positive outputs could occur.

SUMMARY OF THE INVENTION

The deficiencies of the prior art are addressed by the present invention which, in its preferred embodiment, includes a cable, such as a coaxial cable, designated as a power transmission cable, in direct communication with a device for producing a radio frequency signal, such as an oscillator. A second cable, such as a coaxial cable, designated as a data cable, would be spaced from the first cable and substantially parallel to that first cable or concentric with that first cable. A plurality of radio frequency identification (RFID) chips would be attached to or incorporated into the data cable at discrete locations. Although the present invention need not operate in this manner, generally, the RFID chips would be equally spaced from one another. An electromagnetic field would be created by the power transmission cable and induced into the data cable. Each of the RFID chips would be provided with a unique address which would be continuously or intermittently transmitted to a system controller provided at one end of the data cable. If there is no interference to the electromagnetic field, all of the RFID chips would transmit its unique address to the system controller on a regular basis. However, if there is interference to the electromagnetic field caused by an intruder between the power transmission cable and the data cable, or if the power or data cable has been completely severed, one or more of the RFID chips would cease producing a signal along the data cable or while producing such a signal, it would not be received by the system controller. Therefore, based upon the information received, or not received by the system controller, the exact position of the intruder would be determined.

Other embodiments of the present invention would utilize the technology of the present invention but would provide frequency sources at both ends of the power cable as well as system controllers at both ends of the data cable. A further embodiment would utilize the teachings of the present invention by creating a closed loop configuration of both the power transmission cable as well as the data cable.

A further embodiment of the present invention would incorporate both the power cable and the data cable into a single pad of various widths, and lengths, allowing for a quick and efficient manner of deploying the intrusion detection device.

A still further embodiment of the present invention would be used to count the passage of various items on a conveyor belt or individuals passing a certain point at various events, such as a sporting contest.

Yet a further embodiment of the present invention would determine if unauthorized individuals were climbing or scaling various structures, such as trees, bridges, monuments, building walls or roofs.

A further embodiment of the present invention would utilize the power transmission cable/data cable combination to protect an area or structure by burying the cable combination underground or under water.

Yet a further embodiment of the present invention would embed the power transmission cable/data cable combination to concrete, glass, wood or other material.

Still a further embodiment of the present invention would include a data cable substantially or completely encircling an object or objects to be protected. The data cable would include a plurality of RFID chips and an electromagnetic field would be created utilizing a single omni-directional radio frequency oscillator.

A further embodiment of the present invention would affix the data cable to the top a series of poles, thereby used as an invisible fence to detect intruders.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings,FIG. 1illustrates a first embodiment of the present invention used to protect against an intruder by determining whether a particular secure zone has been breached such as scaling a wall or entering into a protected environment, or by determining whether unauthorized activity is occurring on a particular object such as an individual climbing or scaling trees or structures such as bridges, monuments or the like. The invention10includes a power transmission cable12, such as a coaxial cable substantially parallel to a data cable14. The cables are separated from one another at a distance of approximately 6–24 inches or further apart depending on the frequency and power output allowed. However, it is noted that the exact space interval between the cables12,14is of little importance. What is important is that the spacing would allow an electromagnetic field created by the power transmission cable12to be induced into the data cable14. The data cable14has attached thereto or is incorporated therein with a plurality of radio frequency identification (RFID) chips16,18,20,22and23. Each of these chips are spaced apart from one another on the data cable14at particular intervals such as between 6 and 24 inches. However, as was true with respect to the spacing between the cables12and14, the exact spacing between the RFID chips would be unimportant to the teachings of the present invention. The power transmission cable12is connected to a radio frequency signal generator24for producing signals in the direction of arrow34. The transmitter24would generate an RF signal at various frequencies such as 125 MHz, 13.56 KHz, 900 MHz, 2.4 GHz or other frequencies allowed by the FCC for transmitting a signal through the power transmission cable12. The transmission of the radio frequency signal through the power transmission cable12would produce an electromagnetic field27, the intensity of which would be adjustable by varying the signal source24. Consequently, the strength of the electromagnetic field could be either extended or restricted.

In the preferred embodiment, each of the RFID chips would be passive in nature and would be powered by the electromagnetic field26. Therefore, each of the RFID chips need not include or be connected to an independent source of power. Consequently, the chips would be “sleeping” until “activated” by the electromagnetic field26. Each of these chips, as will be later explained, would be provided with its own unique address. According to the teachings of the present invention, if there is no disturbance to the electromagnetic field, each of the RFID chips would generate a signal including its specific chip address in the direction of the arrow36to be received by a system controller26. However, if there is a disturbance to the electromagnetic field created by severing either of the cables12or14or by an individual or other object coming between the cables12and14at a particular spot, the system controller26would not receive signals from any of the RFID chips or would receive signals from only a certain number of the RFID chips.

The system controller26is connected to a microprocessor such as embodied in a personal computer (PC)28. Software, hardware or firmware, included in the system controller26and/or the PC28would be used to locate the spot of intrusion. For example, if the data cable14was severed at a point between RFID chip18and RFID20, the system controller26would receive data signals from only RFID chips16and18. The determination of the location of this point of severing would be ascertained by the fact that address information was received from only the RFID chips16and18and that since RFID chip18was furthest from the system controller26, the point of intrusion must be between RFID chip18and RFID chip20. The system controller26or the PC28would contain information allowing the exact physical location of the break or disturbance to the electromagnetic field, i.e., at a point 100 ft. from the system controller, to be determined. This would be true in the instance in which cable12as well as cable14were not severed but the electromagnetic field was disturbed between RFID chip18and RFID chip20by the presence of an unauthorized individual.

Alternatively, the spot of intrusion would be determined by the time it would take for the system controller to receive a signal from the most remote RFID chip reporter, such as chip18in the description of this first example. This would be accomplished since the radio frequency transmitter24would be in communication with the system controller26thereby allowing the system controller to become aware of when particular signals were being transmitted over the power cable12, thereby creating the electromagnetic field27, which would power each of the RFID chips. It is noted that the transmitter24would transmit either a continuous signal or an intermittent signal.

The PC28would contain or be connected to a particular display30which could illustrate the exact point of intrusion. The display30could be connected to an alarm32showing the specific point of intrusion within a specific zone. This alarm32could sound an audio alarm as well as produce a visual alarm as well as automatically informing particular individuals, such as individuals located at a security company of the occurrence as well as location of an intrusion. Based upon the information received by the system controller26as well as the PC28, the exact time, date, location and duration of an intrusion would be determined and maintained in the memory of the system controller26or the PC28.

The electromagnetic field created by transmitting radio frequencies through the power transmission cable12would allow the electromagnetic field to be created in the data cable14through the air as well as through various materials, such as wood, concrete, brick and glass allowing both the power transmission cable12and the data cable14to be placed behind or embedded within these or other materials, thereby protecting their integrity as well as the cable becoming less intrusive. A system according to the present invention would operate to adjust the field intensity, alarm thresholds, duration and frequency of intrusions based upon various parameters included in the microprocessor of the PC28as well as any microprocessor associated with the system controller26. The filtering of parameters would allow for analog or digital reports and graphic user displays to be produced.

FIG. 2illustrates an alternate embodiment of the present invention and is similar in many respects toFIG. 1. A major difference betweenFIG. 1andFIG. 2is the utilization of signal transmitters24and40provided at both ends of the cable12. Furthermore, along with the system controller26, PC28, display30and alarm32provided at one end of the data cable14a similar system controller46, PC48, display50and alarm52are provided at the second end of the cable14. In this manner, radio frequency waves would be created by both of the transmitters24and40as well as the signals produced by the RFID chips16,18,20and22being received by one or both of the system controllers26and46. This is illustrated by showing the RF signals being transmitted in the direction of both arrows34and42and signals being received by both of the system controllers in the direction of arrows36and44. Additionally, signal direction could be alternated.

A third embodiment of the present invention is illustrated inFIG. 3showing the device according to the present invention in a continuous loop. The embodiments shown inFIGS. 1 and 2are primarily used to protect a structure, such as a wall which extends in a generally straight line. The embodiments illustrated with respect toFIG. 3are primarily used to protect an enclosed area from intruders penetrating the periphery of the enclosed area as well as monitoring individuals, such as prisoners or people suffering from Alzheimer's disease or similar affiliations from leaving the enclosed area. In this embodiment, a power transmission cable60would be powered by a radio frequency generator74similar to the generator previously described. Radio frequencies would travel in the direction shown by arrows84and85. The data cable62would be also provided in a loop. Although the data cable62is shown to surround the power transmission cable60, the opposite could be true with the power transmission cable surrounding the data transmission cable. What is important is that the power transmission cable60at the data cable62be separated by distance to induce a current within the data cable62. As shown by arrow86, information from each of the RFID chips66,68,70and72would be transmitted to the system controller76which in turn is connected to a PC or similar device78. The PC78is connected to or included with a display80and as was true with respect to the embodiment shown inFIGS. 1 and 2, an alarm82would also be included. As was true with respect to the embodiments shown inFIGS. 1 and 2, the radio frequency transmitter74would produce either a continuous signal or an intermittent signal creating the electromagnetic field64, powering each of the RFID chips.

A power transmission cable100according to the teachings of the present invention is illustrated inFIG. 4. This cable would include an outer insulated sheath102totally covering the cable100as well as a foil protective layer104having a window or slit107running the length of the cable, thereby allowing the RF signal a restricted path and concentrating the field in one direction toward the data cable. As illustrated inFIG. 4, a conductor106would be provided within the protective layer104, and would be connected to a radio frequency signal source allowing an electromagnetic field to be directed through the window107. Alternatively, the window or slit would be provided at regular intervals along the cable at positions related to the RFID chips provided in the data cable.

FIG. 5shows a data cable108according to the teachings of the present invention. The data cable108is also provided with an insulated sheath110completely covering the cable as well as a foil protective layer112also provided with a slit116running the length of the cable, thereby allowing a data bus114to transmit information from the RFID chips to the system controller or controllers.

FIG. 6illustrates a situation in which power transmission cables120and140are parallel to one another. A first data transmission cable130is provided parallel between the two power transmission cables120and140. A second data transmission cable150is provided next to and parallel to the second transmission cable140. In this instance, when a radio frequency signal is produced by a suitable source, or sources, electromagnetic fields121,131and141would be produced inducing RFID chips in the data transmission cables120and150to produce the appropriate signals to be transmitted to their respective system controller. Each of the cables120,130,140and150would be surrounded by its respective insulated sheath124,132,142and152. The power transmission cable120would be provided with a conductor122and the power transmission cable140would be provided with a conductor144through both of which an RF signal is conducted. The data transmission cable130would include a foil sheaths136,138producing windows or slits133,135running the length of the cable. Similarly, the data transmission cable150would be provided with a conductor156as well as the protective foil covering154leaving an opening or window158allowing an electromagnetic current to be induced within the data cable. The power transmission cable140would be provided with the protective foils146,148, running the length of the cable140, thereby provided with windows143and145, through each of which an electromagnetic field would be directed.

A typical RFID chip200is shown inFIG. 7. This chip would be passive in nature and would be powered by the electromagnetic field generated by one of the power transmission cables. An antenna210would receive the electromagnetic field and power would be directed to the receiver212. Control logic206would control the operation of the RFID chip200thereby transmitting information, such as the RFID address contained in memory204to a transmitter202which would transmit this information through the data transmission cable acting as the antenna210.

A fourth embodiment of the present invention220is illustrated with respect toFIGS. 8 and 9. A data cable222would be provided with a plurality of RFID chips228,230,232and234. Similar to the previously described embodiments, the exact number of RFID chips is unimportant. What is important is that they be provided along at least a portion of the data cable222. The purpose of this embodiment is to protect objects from being improperly removed. These objects could include paintings or similar artwork hanging on a wall or objects, such as jewelry or antiques resting on a table. In this embodiment, the data cable222will surround the object or objects to be protected. In the case of protecting an object hanging on a wall, the data cable could be placed behind or embedded in the wall or placed underneath or embedded into a counter or tabletop.

A transmitter of RF frequency224located in the center of the data cable22would also be embedded in a or attached to a planar surface such as the wall or table. The transmitter224would radiate an RF signal producing the electromagnetic field226. It is noted that the signal transmitter would broadcast a 360° pattern, thereby encompassing the RFID chips228,230,232and234of the data cable222. Similar to the previously-described embodiments, each of the RFID chips would include a unique identification address to a system controller238. The system controller is in communication with a personal computer240incorporating a display242or connected to a separate display. The system controller238and the PC240are, in turn, connected to an alarm244. Any attempt to remove or disturb the protected object (not shown) would interfere with the electromagnetic field27, and cause one or more of the RFID chips to fail to report to the system controller238, thereby causing an alarm to be activated. AlthoughFIG. 8shows a hard-wired connection between the RFID chips228,230,232and234with the system controller noted that a wireless connection between the RFID chips and the system controller could also be utilized. In addition, similar to the previously described embodiments, the RFID chips are powered by the electromagnetic field226produced by the transmitter224. When the transmitter224is not producing the electromagnetic field226, the RFID chips would be in the “sleep” mode.

Furthermore, it is noted that if the item or items to be protected are metallic in nature, such as jewelry or particular types of antiques, these metallic objects would affect the electromagnetic field by absorbing a portion of this field resulting in a diminished field. This adjusted response would establish a “baseline” at the system controller238. Therefore, the removal of that object would result in a change from the “baseline” and would result in an alarm. Consequently, in this situation, one or more of the RFID chips228,230,232and234, would report not only its unique address to the system controller238, but also the value of the electromagnetic field226. In this instance, an alarm condition would be reported even if all of the RFID chips would constantly report their own unique addresses, if the strength of the electromagnetic field is less than the baseline reading.

FIG. 9is a block diagram related to the embodiment shown inFIG. 8. The embodiment shown inFIG. 8illustrates a situation in which a single radio frequency source creates an electromagnetic field encompassing a single set of RFID chips provided in a single data cable used to protect one or more objects associated with the single data cable.FIG. 9illustrates the situation in which a single system controller262is used to supervise the operation of several data cables250,252and254protecting desparate articles or objects. Each of the data cables250,252and254would be provided with a plurality of RFID chips, each chip transmitting its own unique address to the system controller262when the chips are in the presence of an electromagnetic field. In this situation, separate radio frequency sources256,258and260would produce their own separate electromagnetic fields encompassing the objects to be protected as well as its own respective data cables250,252and254. Therefore, in the presence of an electromagnetic field, the RFID chips would transmit its own unique address to the single system controller262. This system controller would be in communication with a PC264, a display266, an alarm268similar to the system illustrated inFIG. 8. Since the system controller262and/or the PC264would be provided with a memory in which the location of each of the RFID chips will be located, the failure to receive one or more signals from the RFID chips would result an alarm condition being observed in one or more of the data cables. Similar to the embodiment shown inFIG. 8, the data cables250,252and254could be hardwired to the system controller262or, in the alternative, a wireless connection could be utilized.

Referring toFIG. 10, a fifth embodiment of the present invention would act as a “invisible” fence provided on the periphery of at least one side of a protected property. Alternatively, the “invisible” fence could completely surround the protected property. In this embodiment, a data cable270containing a plurality of RFID chips272,274and276would be attached to, or strung from, a plurality of vertical posts284,286,288,290and292. These posts would be provided on or near the periphery of at least one side of a protected property. These vertical posts could be in the form of telephone or other types of communication poles as well as light posts. The RFID chips would be similar in nature to the RFID chips previously described and illustrated with respect toFIG. 7.

A power transmission cable280is connected to a radio frequency signal generator282for producing signals creating an electromagnetic field281. The cable280could lie on the ground near the poles284,286,288,290and292. Alternatively, the cable280could be buried in the ground, thereby helping to hide its existence. The cable280could be formulated with a single window slit running the length of the cable or with a plurality of windows periodically arranged on the cable280. In both of these instances, the transmitted signal would be directed upward, thereby creating an electromagnetic field which would enclose the data cable270and the RFID chips270,272,274and276.

The data cable270, similar to the previously-described embodiments, would be connected to a systems controller294, which in turn would be connected to a PC296, a display298and an alarm system300.

The electromagnetic field281would awake the RFID chips from the “sleep” mode, allowing each of the RFID chips272,274and276to produce a unique address signal transmitted from the data cable270to the system controller294. It is noted that the data cable270could be directly hard-wired to the system controller294or a wireless communication could be created between the data cable270and the systems controller294. Normally, if there is no obstruction to the electromagnetic field281created by an intruder or intruders, each of the RFID chips272,274and276would continuously or intermittently transmit its unique identification code to the systems controller294. However, if one or more intruders would disrupt the electromagnetic field281beneath one or more of the RFID chips, it would interrupt the transmission of the unique address from one or more of the RFID chips to the system controller294. The appropriate lack of receipt of one or more of the unique chip addresses would result in the determination that an alarm situation has occurred as well as specify the location or locations of an intruder. Since this particular embodiment is designed to sense an intruder entering a protected piece of property between the poles284,286,288,290and292, it is noted that each of the RFID chips272,274and276are located between two of the poles. Although the exact dimensions are not crucial to the present invention, it is noted that the data cable including the RFID chips are attached to the top of the poles at approximately eight to ten feet from the ground with the poles spaced approximately 30 to 40 feet apart.

A further adaptation of the present invention would mount a data cable including a plurality of RFID chips on the outside perimeter of a ship. The associated power transmission cable connected to a radio frequency source would create an electromagnetic field encompassing the ship and the data cable. This embodiment would detect the unauthorized boarding of the ship at any location of the ship.

Having described the intrusion detection system according to the present invention, the method of utilizing such a system to monitor either entry or exit from a particular secured environment as well as determining whether various structures or trees are being mounted or scaled will be described. When used to protect a particular structure such as a building, chemical storage tanks, gas lines, oil lines or other types of pipelines, a power transmission cable is embedded in the particular structure, pipeline or the like, or is buried parallel to the structure. The data transmission cable is embedded into the particular structure or buried in the ground parallel to the power transmission cable in a manner to provide a protected environment next to the structure or, in the case of a building or similar structure surrounding that building or similar structure. The data cable would be provided with a plurality of RFID chips along the entire length of the data cable or along at least one portion of the data cable. The data cable would be connected to the system controller which in turn would be connected to a PC having a display incorporated therein as well as possibly being connected to an alarm. A radio frequency generator such as an oscillator is connected to the power transmission cable and would produce either a continuous or intermittent signal. Particularly when an intermittent signal is produced, the radio frequency transmitter would be connected to the system controller allowing the system controller to monitor the location of the signals received by the system controller. Since each of the RFID chips is provided with an unique address, the system controller by itself or in conjunction with the PC would be able to determine whether there was an intrusion and the exact location of that intrusion.

If the system is operating properly, and there is no intrusion, the system controller should receive signals on a continuous or intermittent basis from all of the RFID chips. However, if an intrusion is sensed, or the power transmission cable or data cable would be severed, the system controller would not receive signals from any of the RFID chips beyond the location of the intrusion. The exact location of this intrusion would be pinpointed by the system controller either by being provided in its memory or its associated PC the exact physical location of each of the RFID chips or by determining this position utilizing the sensed time between transmitting an RF signal by the radio frequency transmitter and receiving a signal from the RFID chip immediately in front of the point of intrusion.

For ease of installation, the power transmission cable as well as the data cable would be incorporated into a single pad of various widths and lengths, these pads being either buried in the ground or embedded in various materials, such as glass, wood, concrete and other radio frequency acceptable materials. Similarly, if an area was to be protected, the power transmission/data cable combination would be embedded in or surround the entire area.

Along with its utilization in the field of intrusion detection and protection, the present invention could be utilized in various other environments. For example, the present invention could be utilized to count the number of individuals entering a certain area, such as a sporting event or a ship. In this instance, the power transmission cable would be provided on one side of a gate or gang plank and the data cable would be provided on the second side of the gate or gang plank. Thereafter, a continuous signal would be transmitted over the power transmission cable to induce an electromagnetic field between the power transmission cable and the data cable, thereby inducing a current in the data cable. The system controller and PC connected to the data cable would be able to count the number of interferences within the electromagnetic field, each interference due to an individual passing through the gate or gang plank.

Similarly, the present invention could be utilized in conjunction with a conveyor belt. For example, if the power transmission cable is provided on one side of the belt and the data cable is provided on the other side of the belt parallel to the power transmission cable, discrete items being transported on the conveyor belt could be counted. Additionally, with respect to a continuous item being transported on the conveyor belt, the sensing of a signal produced by one of the RFID chips would indicate the complete passage of that continuous item.

Additionally, the present invention could be utilized in conjunction with determining whether a particular portable item such as an electrical appliance or a firearm would interfere with the electromagnetic field in a manner to decrease the intensity of the field, thereby resulting in an alarm to be produced.

It is to be understood that the above-described embodiment of the invention are illustrative only, and that modifications thereof may occur to those skilled in the art. For example, although the present invention is illustrated in the drawings is provided with a separate system controller and PC, these two devices could be incorporated into a single entity. Accordingly, this invention is not to be regarded as limited to the embodiments disclosed herein.