Foliage penetrating sensor array for intrusion detection

• US 20100026490A1
• Filed: 07/29/2008
• Published: 02/04/2010
• Est. Priority Date: 07/29/2008
• Status: Active Grant

• Current Assignee: FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Original Assignee: FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Inventors: Bjornholt, John Edward, Butler, Walker
• Granted Patent: US 8,542,109 B2
• Time in Patent Office: Days
• US Class Current: 340/552
• CPC Class Codes: G08B 13/2494 by interference with electro-magnetic field distribution combined with other electrical sensor means, e.g. microwave detectors combined with other sensor means

Abstract

An intrusion detection system that is capable of foliage penetration is disclosed employing an array of field disturbance transceivers operating at UHF frequencies. The array of transceivers generate a multiplicity of RF fields between nearby units and detect the presence of intruders by detecting disturbances in these fields. The emitted UHF signals used to generate the RF fields are also used to provide a communication link between transceivers in the array and to a control station. The control station facilitates the operation of the array from a remote monitoring site. A method of array deployment provides multiple opportunities to detect an intruder and secondarily provides redundant communication links in case of a sensor failure. Automatic means of setting detection thresholds based on environmental conditions assures a high probability of detection along with a low false alarm rate.

Claims

1. An apparatus for detection of any intruder passing through a protected area, comprising:

multiple sensors, each sensor including;

a first means for generating and modulating electromagnetic energy during a defined individual transmit period (time slot) with each of said multiple sensors assigned a different defined time slot, said electromagnetic energy generated in a portion of the electromagnetic spectrum that enables both penetration of foliage and detection of intruder presence;

a second means coupled to said first means for emitting said electromagnetic energy into said protected area, and for collecting electromagnetic energy existent within said protected area;

a third means coupled to said second means for collecting a portion of said electromagnetic energy existent within said protected area emitted from a plurality of nearby sensors;

a fourth means, coupled to said third means, capable of determining the identity and location of each of said plurality of nearby sensors, analyzing the amplitudes over time of said electromagnetic energy from said plurality of nearby sensors, and capable of detecting a physical presence of said intruder within the electromagnetic field existent between each said nearby sensor and said second means, said detection based on variations in the amplitude of said electromagnetic field greater than a computed threshold;

a fifth means, coupled to said first means, to said third means and to said fourth means, capable of controlling said generation of said electromagnetic energy during said defined time slot, capable of directing said third means to collect said electromagnetic wave energy from specific said nearby sensors, capable of responding to commands contained within the modulation of said collected electromagnetic energy from said nearby sensors, and capable of formulating the information content of said modulation of said first means including sensor identification, relay of commands to other said sensors, reports of the status of individual said sensors, and said detections of intruders;

an ordered array of said multiple sensors establishing said protected area and comprising;

two or more rows of said sensors having approximately constant distance between said rows, substantially equal spacing between said sensors along each of said rows, and any two of said sensors in one of said rows forming the base of an isosceles triangle with a said sensor in the other said row located at the peak of said triangle;

each of said multiple sensors possessing a unique identification number, with the left most of said multiple sensors at the proximal end of said array being designated sensor one and the right most of said multiple sensors at the distal end of said ordered array being designated as sensor N, with N being the total number of said multiple sensors in said array;

said first means of each of said sensors being commanded by said fifth means to generate electromagnetic energy, modulated by said information content, during said defined time slot in accordance with said unique identification number; and

a control means located near said ordered array that is capable of;

programming the internal memory of each of said multiple sensors at the time of deployment;

commanding said sensor one to begin said generation of electromagnetic energy during said first defined time slot;

receiving the emission from sensor N that may include sensor identification, said relay of commands to other said sensors, said reports of status of individual said sensors, and said detections of intruders; and

evaluating the data received from said ordered array, determining the status of said ordered array, generating declarations of said detections of intruders, and relaying detection information to appropriate controlling authorities.

2. An apparatus for detection of any intruder passing through a protected area, comprising:

multiple field disturbance transceivers, each including;

a transmitter for generating and modulating electromagnetic energy during a defined individual transmit period (time slot) with each of said multiple field disturbance transceivers assigned a different defined time slot, said electromagnetic energy generated in a portion of the electromagnetic spectrum that enables both penetration of foliage and detection of intruder presence;

an antenna coupled to said transmitter for emitting said electromagnetic energy into said protected area, and for collecting electromagnetic energy existent within said protected area;

a receiver coupled to said antenna for collecting a portion of said electromagnetic energy existent within said protected area emitted from a plurality of nearby said field disturbance transceivers;

a signal processor, coupled to said receiver, capable of determining the identity of each of said plurality of nearby field disturbance transceivers, analyzing the amplitudes over time of said electromagnetic energy from said plurality of nearby field disturbance transceivers, and capable of detecting a physical presence of said intruder within the electromagnetic field existent between each said nearby field disturbance transceiver and said antenna, said detection based on variations in the amplitude of said electromagnetic field greater than a computed threshold;

a timing and control function including computing functions and digital memory, coupled to said transmitter, to said receiver and to said signal processor, capable of controlling said generation of said electromagnetic energy during said defined time slot, capable of directing said receiver to collect said electromagnetic energy from specific said nearby field disturbance transceivers, capable of responding to commands contained within the modulation of said collected electromagnetic energy from said nearby field disturbance transceivers, and capable of formulating the information content of said modulation of said transmitter including own identification and status, relay of commands to other said field disturbance transceivers, reports of status of other said field disturbance transceivers, and said detections of intruders;

an ordered array of said multiple field disturbance transceivers establishing said protected area and characterized by;

two or more rows of said field disturbance transceivers having approximately constant distance between said rows, substantially equal spacing between said field disturbance transceivers along each of said rows, and approximate positioning so that any two of said transceivers in one of said rows forms the base of an isosceles triangle with a said transceiver in the other said row located at the peak of said triangle;

each of said multiple field disturbance transceivers possessing a unique identification number with the left most of said multiple field disturbance transceivers at the proximal end of said array being designated as transceiver one and the right most of said multiple field disturbance transceivers at the distal end of said ordered array being designated as transceiver N, with N being the total number of said multiple field disturbance transceivers in said array;

said transmitter of each of said field disturbance transceivers being commanded by said timing and control function to sequentially generate electromagnetic energy during said defined time slot in accordance with said unique identification number, thus forming a sequence of emissions with each said field disturbance transceiver emitting once during said sequence;

said spacing between said field disturbance transceivers and the power level of said generated electromagnetic energy sufficient to allow said receiver to receive the emissions from at least two said field disturbance transceivers having lower said identification numbers and from at least two said field disturbance transceivers having higher identification numbers;

said emissions from said antenna forming said electromagnetic fields with said antennas coupled to at least two said field disturbance transceivers having lower said identification numbers and from at least two said field disturbance transceivers having higher identification numbers, except for non-existent said identification numbers at the ends of said array;

passage of said intruder through said protected area requiring passage through multiple said electromagnetic fields with multiple said detections due to variations in the amplitude of said electromagnetic field greater than a computed threshold, and;

a control station located near said ordered array that is capable of;

programming the internal memory of each of said multiple field disturbance transceivers at the time of deployment;

commanding said transceiver one to begin said generation of said electromagnetic energy during said first defined time slot;

receiving the emission from transceiver N encoded with information including said field disturbance transceiver identification, said reports of status of individual said field disturbance transceivers, and said detections of intruders; and

evaluating the data received from said ordered array, determining the status of said ordered array, generating declarations of said detections of intruders, and relaying detection information to controlling authorities.

3. The apparatus as claimed in claim 2, wherein said portion of said electromagnetic spectrum includes the range from 150 to 1,000 MegaHertz, with preferred operation within the 900 to 930 MegaHertz band.

4. The apparatus as claimed in claim 2, wherein said antenna is a vertically deployed, non-directional, one-quarter wavelength element coupled to said transmitter and said receiver by a semi-rigid coaxial cable feed line.

5. The apparatus as claimed in claim 2, wherein said array comprising said two or more rows of said field disturbance transceivers:

may have said rows deployed in straight lines or in curved configurations as necessary to conform to the shape of a boundary or area to be protected;

has a preferred spacing of approximately 30 meters between said field disturbance transceivers along each said row, and a separation of some 25 meters between said rows; and

may have said field disturbance transceivers placed at lesser or irregular spacings to provide reliable detection of intruders in uneven terrain.

6. The apparatus as claimed in claim 2, wherein said total number of said multiple field disturbance transceivers in said array is equal to or less than 99, and said sequence of emissions occur during a one second period with each time slot having a duration of ten (10) milliseconds.

7. The apparatus as claimed in claim 2, wherein said control station can be located at a distance exceeding 1,200 meters from said transceiver one and from said transceiver N when equipped with a directional antenna, a low-noise receiver, and a transmitter of adequate power.

8. The apparatus as claimed in claim 2, wherein said control station is not required to establish said first defined time interval, and said transceiver one is capable of determining the appropriate times to begin said first defined time slot and begin said generation of said electromagnetic energy without receiving commands from said control station, said transceiver one thus having a difference from other said field disturbance transceivers in said array.

9. A field disturbance transceiver for deployment in an array for detection of any intruder passing through a protected area, comprising:

a transmitter for generating and modulating electromagnetic energy during a defined individual transmit period (time slot) at a continuous and constant power level of approximately one milliwatt, said electromagnetic energy generated in a portion of the electromagnetic spectrum that enables both penetration of foliage and detection of intruder presence, said modulating of said electromagnetic energy enabling the communication of data to other said field disturbance transceivers while said electromagnetic energy generates electromagnetic fields for said detection of intruder presence;

an antenna coupled to said transmitter for emitting said electromagnetic energy into said protected area, and for collecting electromagnetic energy existent within said protected area, said antenna being a vertically deployed, non-directional element;

a receiver coupled to said antenna for collecting a portion of said electromagnetic energy existent within said protected area emitted from a plurality of nearby said field disturbance transceivers;

a signal processor, coupled to said receiver, capable of determining the identity of each of said plurality of nearby field disturbance transceivers, capable of analyzing the amplitudes over time of said electromagnetic fields from said plurality of nearby field disturbance transceivers, and capable of detecting a physical presence of said intruder within said electromagnetic field existent between each said nearby field disturbance transceiver and said antenna, said detection based on variations in the amplitude of said electromagnetic field greater than a computed threshold;

a timing and control function including computing functions and digital memory, coupled to said transmitter, to said receiver and to said signal processor, capable of;

receiving data and commands from a control station during deployment of said field disturbance transceiver in said array, including transceiver identification number and associated said defined time slot, frequency of operation, global positioning system (GPS) location, detection threshold parameters, and other data specific to the particular said array,

determining a position of said defined time slot within sequence of time slots defined for all said field disturbance transceivers in said array, the number of said field disturbance transceivers in said array being equal to or less than 99 and said sequence of time slots occurring during a period of one (1) second,

recognizing if said emissions from said nearby field disturbance transceivers with lower said defined time slots fail to occur and respond by commanding said transmitter to generate said electromagnetic energy at appropriate said defined time slot with modulation containing most current data available;

controlling said generation of said electromagnetic energy during said defined time slot, each said defined time slot being limited to ten (10) milliseconds, said generation of electromagnetic energy during said defined time slot requiring 8.33 milliseconds thus providing a duty cycle of said emission of less than one percent and average power output of less than ten (10) microwatts,

directing said receiver to collect said electromagnetic energy from specific said nearby field disturbance transceivers, capable of responding to commands contained within the modulation of said collected electromagnetic energy from said nearby field disturbance transceivers, and capable of formulating the information content of said modulation of said transmitter including own transceiver identification number and status, relay of commands to other said field disturbance transceivers, reports of status of other said field disturbance transceivers, and said detections of intruders, and;

a housing capable of containing all said field disturbance transceiver circuitry and components including a battery providing continuous unattended operation for a minimum of two years, capable of protecting contained circuitry and components from the deployment environment of said array, capable of being buried below ground surface to a total depth of approximately twice the length of said housing, and capable of supporting said antenna with said antenna protruding above said ground surface.

10. The field disturbance transceiver as claimed in claim 9, wherein said portion of said electromagnetic spectrum includes the range from 150 to 1,000 MegaHertz, with preferred operation within the 900 to 930 MegaHertz band.