Patent Publication Number: US-2006002461-A1

Title: External perimeter monitoring system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is a continuation of prior application Ser. No. 09/522,087, filed Mar. 10, 2000, now U.S. Pat. No. 6,937,647. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
      Not Applicable  
     BACKGROUND OF THE INVENTION  
      1. Field of Invention  
      This invention relates to a system for monitoring an outdoor perimeter. More particularly, this invention relates to a system for monitoring activity along a wire bounded perimeter.  
      2. Description of the Related Art  
      Residential and light commercial security systems have become an increasingly popular addition to many homes and businesses. These systems are typically based on the electronic detection of a breach in the perimeter of the structure. A breach is detected at either the perimeter itself or the interior of the structure. The perimeter is generally defined as the entrance/egress points to a structure such as doors and windows. Perimeter breaches are generally detected by magnetic sensors which monitor the opening and closing of doors and windows and by frequency sensors attuned to the sound of glass breakage. Interior breaches are generally detected by heat and motion detectors which monitor moving objects having a temperature greater than the ambient temperature. While providing a warning of intrusion, both the detection of perimeter and interior breaches occur after damage to the structure or entry has been obtained.  
      Similarly, motion sensors are used to turn on outdoor lighting thereby providing a deterrent to intrusion onto the property. However, these sensors are indiscriminate in that they may be triggered by small animals, children, or other moving objects which are not considered security risks. Further, because of the difficulty in accurately setting the range of each sensor, the limited sensor range, and the arcuate detection zone of each sensor, setting up a comprehensive coverage area limited to the boundaries of one&#39;s property is difficult at best. Finally, it should be noted that while the external sensors could be connected to a central alarm system, the inability to discriminate between legitimate security risks and stray animals and the difficulty in defining the protection area render such a system unreliable.  
      Ideally, a monitoring system could identify and announce activity along the monitored perimeter. Accordingly, there is a need for a monitoring system which allows a boundary of protection to be easily defined. Further, there is a need for a monitoring system capable of identifying potential threats to security so as to avoid false alarms.  
      Therefore, it is an object of the present invention to provide a monitoring system which permits a fixed protection boundary to be defined.  
      It is another object of the present invention to provide a monitoring system which detects activity along the borders of the protection area.  
      Yet another object of the present invention is to provide a monitoring system which discriminates between various types of activity.  
      It is a further object of the present invention to provide a monitoring system which can be integrated with an existing residential and light commercial security system.  
      A still further object of the present invention is to provide a monitoring system which can be added into an existing pet containment system.  
      Yet a still further object of the present invention to provide a monitoring system which defines the protected area using a single wire.  
     BRIEF SUMMARY OF THE INVENTION  
      A system for detecting activity along a wire-bounded perimeter is provided. The system includes a single-conductor wire which bounds an area defined as the protected area. Electrically connected to the wire at predetermined locations is a series of sensors and a transponder.  
      The transponder serves as the controller for the system. Each of the sensors is provided with a unique identification, or address, allowing the transponder to communicate with a selected sensor. Communication is accomplished using an addressable data packet transmitted along the wire using a frequency shift keying technique.  
      The sensors of the present invention each include a communication interface, a transceiver, a DC power source, and an activity measuring device. There are two general types of sensors used in the present invention. First are the wired sensors wherein the communication interface is a transformer physically coupled to the wire. Next are the mobile sensors which operate without actual physical connection to the wire. The communication interface of the mobile sensors is a single-turn, inductive antenna placed near, but not directly over, the wire and oriented in a substantially vertical orientation with respect to the wire, thereby creating a mutual inductive coupling allowing bidirectional communication. The signal transmitted through the wire generally includes a power signal, or carrier, to which a modulated data signal is attached. The timing of the data signals is controlled by the transponder.  
      Each of the sensors is provided with a unique identification, or address, allowing the transponder to communicate with a particular sensor. Communication is accomplished using a data packet having a header containing at least a frame synchronization code, at least one command character, at least one address character, and a security code. The command packet is transmitted through the wire using any appropriate modulation scheme.  
      When a request is received by the sensor, the activity measurement device is activated to detect local activity through one of a variety of detection methods. The activity measuring device is positioned and adjusted such that activity near or approaching the perimeter of the protected area from the outside is detected. The detected activity signal is then encoded by the microprocessor and transmitted to the transponder by the transceiver. The transponder comparison device compares the measured activity signal to exemplary activity profiles from selected activity sources, such as vehicles, animals, and humans. A result generated from the comparison is generated and interpreted by the transponder processing device. Should activity be detected, the transponder processing device then generates an alert which is transmitted to a user through the indicator and/or to an external conventional residential and light commercial security system through the external interface. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
      The above-mentioned features of the invention will become more clearly understood from the following detailed description of the invention read together with the drawings in which:  
       FIG. 1  is a block diagram of a system for monitoring a wire bounded perimeter showing various features of the transponder of the present invention;  
       FIG. 2  is a block diagram of a system for monitoring a wire bounded perimeter showing various embodiments of the sensors of the present invention;  
       FIG. 3  is a block diagram of a sensor showing various features of the present invention;  
       FIG. 4  is a block diagram of an alternate embodiment of the system of the present invention incorporating a pet containment transmitter to provide additional functionality; and  
       FIG. 5  is a block diagram of an alternate embodiment of the transponder of  FIG. 1  replacing the memory and comparison devices with a digital signal processor. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      A system for a monitoring a wire-bounded perimeter is illustrated generally at  10  in the figures. The system for monitoring a wire bounded perimeter, or monitoring system  10 , uses at least one sensor  14  located at a predetermined location around a protected area  13  to identify activity at the perimeter of the protected area  13 .  
       FIG. 1  illustrates a block diagram of the monitoring system  10  of the present invention. The monitoring system  10  includes a single-conductor wire  12  which bounds an area defined as the protected area  13 . Electrically connected to the wire  12  at predetermined locations are a series of sensors  14  and a transponder  16 . In the illustrated embodiment, the transponder  16  includes a processing device  18 , a gateway  20 , a comparison device  22 , a memory device  24 , an indicator  26 , an external interface  28 , and a power supply  30 . Corresponding elements of the monitoring system  10  are labeled with like numerals.  
      The transponder  16  serves as the controller for the monitoring system  10 . Specifically, the transponder  16  supplies power, receives data from the sensors  14 , processes the received data, displays information about the processed data, and communicates with external devices, such as a conventional residential and light commercial security system (not shown). The transponder processing device  18  sequences the operation of these functions. One skilled in the art will recognize that the processing device may be implemented in a variety of ways including discrete logical components (not shown) and a microprocessor (not shown). In the illustrated embodiment, the transponder processing device  18  is a microprocessor to allow the functionality of the transponder  16  to be varied, with minimal hardware changes, through the use of software. Typical functions of the transponder processing device  18  include providing timing to control signal traffic across the wire  12 , requesting information from the sensors  14 , and analyzing the information received from the sensors  14 . Additionally, the transponder processing device  18  generates an output which is sent to an external interface  24 . The external interface  24  translates the output into a form which is usable by a conventional residential and light commercial security system allowing the perimeter monitoring system  10  of the present invention to be integrated with an existing structural intrusion detection system. Such integration allows the perimeter monitoring system  10  to be monitored by an off-premises security monitoring company.  
      Many of these functions compete for transmission time across the single conductor wire  12 . The gateway  20  manages access to the wire  12 . One skilled in the art will recognize that a variety of electrical components can be used to implement the gateway  20  including switches, multiplexers, gates, and universal asymmetric receiver-transmitters (UARTs). In the illustrated embodiment the gateway  20  is a UART responsive to the transponder processing device  18 . Generally, the transponder processing device  18  directs the gateway  20  which of the various signals has the right-of-way on the wire  12 .  
      Among the signals competing for use of the wire  12  are information signals directed to one or more sensors  14  from the transponder processing device  18 , and information signals from one or more sensors  14  directed to the transponder processing device  18 . In general, the wire  12  carries a power signal from the power supply  30 . Data signals are encoded into the base signal by applying a modulation technique, such as frequency shift keying.  
      To monitor activity near the perimeter of the protected area  13 , the transponder  16  requests information from each sensor  14  by sending a data packet containing the appropriate command characters to the particular sensor  14 . When energized, each sensor  14  detects local activity and sends the detected activity signal to the transponder  16  for processing. The transponder  16  compares the detected activity to a variety of exemplary activity signals. Using the comparison result, the transponder then categorizes detected activity within one of the predetermined classes. One skilled in the art will recognize that various types of sensors  14  can be used depending upon the desired monitoring capabilities of the system, including, but not limited to, seismic, infrared, and audio sensors. Further, one skilled in the art will recognize that various levels of sophistication in the discrimination process can be used to provide more specific identification of the activity source.  
       FIG. 2  illustrates a block diagram of the present invention with emphasis on the various embodiments of the sensors  14 . The sensors  14  each include a communication interface  32 , a transceiver  34 , a DC power source  36 , and an activity measuring device  38 . There are two general types of sensors  14  used in the present invention. First are the wired sensors  14 A,  14 B,  14 C. In each of the wired sensors  14 A,  14 B,  14 C, the communication interface  32  is a transformer physically coupled to the wire  12 . Next is the mobile sensor  14 D which operates without actual physical connection to the wire  12 . The communication interface  32  of the mobile sensor  14 D is a single-turn, inductive antenna placed near, but not directly over, the wire  12  and oriented in a substantially vertical orientation with respect to the wire  12 , thereby creating a mutual inductive coupling allowing bidirectional communication. In the illustrated embodiment, a variety of DC power sources  36  are shown. First is a power conditioning in-line zener diode  36 A connected to wire  12  for generating a DC voltage drop used to power the sensor  34 . Next is a DC transformer  36 B for converting the AC voltage traveling through wire  12  into a DC voltage. Finally, an independent power source  36 C,  36 D is shown. The independent power source  36 C,  36 D can be a battery or a solar cell. One skilled in the art will recognize that the independent power source  36 D provides the greatest benefit when used in a mobile sensor  14 D such that it can be readily moved without the need for connection to an external power source.  
      Each of the sensors  14  is provided with a unique identification, or address, allowing the transponder  16  to communicate with a particular sensor  14 . Communication is accomplished using a data packet having a header containing at least a frame synchronization code, at least one command character, at least one address character, and a security code. One skilled in the art will recognize that other information may be included including, but not limited to, packet size and checksum information. In the illustrated embodiment, the data packet is transmitted using an RS-232 data format. The frame synchronization code is made up of sixteen (16) consecutive logical one bits coupled with no more than four (4) stop bits between the characters in the data packet. The command packet is transmitted through the wire  12  using any appropriate modulation scheme. The preferred embodiment utilizes frequency shift keying (FSK) for transmitting the data packet. One method for implementing a FSK transmission is to use a higher frequency, such as 18 kHz, to transmit a logical one and a lower frequency, such as 14 kHz, to transmit a logical zero.  
       FIG. 3  illustrates the sensor  14  of the present invention. The transceiver  34  includes a sensor processing device  40 , a limiting amplifier  42 , a driving amplifier  44 , and a frequency tuner  46  in communication with a tightly wound ferrite core antenna  48  for monitoring an electromagnetic field for disruptions and for communicating with the transponder  16 . In the illustrated embodiment, the frequency tuner  46  is a capacitor selected to tune the transceiver to the frequency having the desired sensitivity. In the stand-by, or receiver, mode, the driving amplifier  44  is turned off allowing the ferrite core antenna  48  to pick up the signal being carried through the wire  12 . The limiting amplifier  42  amplifies the received signals into logical ones and zeros and presented to the sensor processing device  40  for period measurement using a frequency discrimination technique suited for a small microprocessor. In the illustrated embodiment, frequency discrimination is achieved by comparing the measured period to a predetermined threshold level. Conversely, in transmitter mode, the driving amplifier  44  is activated and the desired transmission frequency generated by the sensor processing device  40  for the current response character is impressed on the input to the driving amplifier  44  and broadcast by the ferrite core antenna  48 .  
      When a request is received by the sensor  14 , the activity measurement device  38  is activated to detect local activity. The activity measuring device  38  is positioned and adjusted such that activity near to or approaching the perimeter of the protected area  13  from the outside are detected. The detected activity signal is then encoded by the microprocessor  32  and transmitted to the transponder  16 , of  FIG. 1 , by the transceiver  34 . Returning now to the illustrated embodiment of  FIG. 1 , a digital signal processing device  21  conditions the signal and the transponder comparison device  22  compares the detected activity signal to exemplary activity profiles from selected sources, such as vehicles, animals, and humans, which are stored in the transponder memory device  24 . A result generated from the comparison is generated and interpreted by the transponder processing device  18 . In the illustrated embodiment, the transponder processing device  18  is configured to generate one of four responses: vehicle, human, animal, or no activity, along with the identification of the sensor  14  where the response was generated. Should activity meeting determined characteristics be detected, the transponder processing device  18  then generates an alert which is transmitted to a user through the indicator  26  and/or to an external conventional residential and light commercial security system through the external interface  28 . One skilled in the art will recognize that the transponder processing device  18  can be configured to selectively transmit alert signals to the various outputs. For example, in one embodiment, when an animal is detected, the monitoring system  10  displays an alert at the indicator  26  but does not pass any information on through the external interface  28 . Similarly, where a human is detected, alerts are sent to both the indicator  26  and the external interface  28 . Further, one skilled in the art will recognize that the indicator  22  can vary depending upon the type and amount of information offered to the user. In the illustrated embodiment, the indicator  22  is a multi-line, alphanumeric display screen which can display the time, date, location, and type of activity. Other types of indications could be utilized, such as audio tones or light-emitting diodes representing a specific condition or location. Finally, one skilled in the art will recognize that other types of information can be communicated through the indicator  22  including, but not limited to, diagnostic information and system status.  
       FIG. 4  illustrates the monitoring system  10 ′ of the present Invention incorporating an electronic pet containment function known to those skilled in the art. To implement the pet containment function, the transponder  16 ′ additionally includes a signal generator  38 ′ and a transmitter  40 ′. The signal generator generates a radio frequency modulated electromagnetic signal of the type used in typical pet containment systems. The transmitter  40 ′ transmits the containment signal through the wire  12 ′. The pet  15 ′ to be confined wears a receiver  17 ′ configured to receive the containment signal and apply a corrective stimulus upon a predetermined trigger. Because the containment signal must coexist with the other information traveling along the wire  12 ′, the containment signal is routed through the gateway  20 ′ and the timing of the containment signal is controlled by the transponder processing device  18 ′.  
       FIG. 5  illustrates a block diagram of a transponder  12 ″ using an alternate method of classifying the detected activity signals. The transponder  12 ″ replaces the comparison device  22  and the memory device  24  with a digital signal processing device  25 ″. The digital signal processing device  25 ″ applies a digital filter to each detected activity signal. The filtered activity signal is then classified based on the response characteristics by the processing device  18 ″. The transponder  12 ″ incorporating the digital signal processing device  25 ″ is uniquely suited to use with a variety of sensor types. For example, the digital signal processing device  25 ″ can be configured to apply to differing digital filters to each detected activity signal based upon the sensor type, thereby allowing the processing device  18 ″ to identify activity in a number of differing forms and respond appropriately.  
      One skilled in the art will recognize that the ultimate function of the monitoring system  10  is to detect and categorize the activity prior to penetration of the protected area  13 . In this regard, various components of the system are interchangeably located without interfering with the objects of the present invention. Specifically, the signal processing device, the comparison device, the memory device, and the processing device may be located in each sensor  14  so that the transponder  16  simply collects the results and displays the information.  
      One skilled in the art will recognize that both the transponder  16  and the sensors  14  can include additional electronics, including modulators, demodulators, amplifiers, filters, etc., to enhance the basic function, accuracy, and reliability of the present invention without interfering with the objects of the present invention. Further, one skilled in the art will recognize that, within each of the transponder  16  and the sensors  14 , signals can be communicated between the various components using a variety of methods including the use of a bus.  
      What has been disclosed is an external perimeter monitoring system using strategically placed sensors connected to a transponder by a single conductor wire bus through which data signals and power signals are sequenced. Activity detected at the sensors is analyzed to classify the source of the activity and an alert is generated if necessary. The external perimeter monitoring system is capable of interfacing with a conventional residential or light commercial security system to allow off-premises monitoring. Further, an alternate embodiment of the external perimeter monitoring system is integrated with a conventional electronic pet confinement system allowing the single conductor wire bus to serve as a radio frequency antenna defining the confinement boundary with the confinement signal added to the data signal and power signal sequencing.  
      While a preferred embodiment has been shown and described, it will be understood that it is not intended to limit the disclosure, but rather it is intended to cover all modifications and alternate methods falling within the spirit and the scope of the invention as defined in the appended claims.  
      While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant&#39;s general inventive concept.