Patent Publication Number: US-2005129294-A1

Title: Device and method for detecting localization, monitoring, and identification of living organisms in structures

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      The present application is a continuation-in-part application of co-pending U.S. patent application Ser. No. 10/934,089, filed Sep. 3, 2004, which is a continuation application of U.S. patent application Ser. No. 10/309,489, filed Dec. 3, 2002, issued as U.S. Pat. No. 6,801,131, which is a continuation-in-part of U.S. patent application Ser. No. 09/873,118, filed Jun. 1, 2001, abandoned. 
    
    
     FIELD OF THE INVENTION  
      The present invention relates to a device and method for detecting living organisms, for example insects in or behind a structure and, more particularly, to a device and method for detection, localization, monitoring and identification of living organisms such as insects, animals, humans in or behind a structure or behind wall and other partitions, using interrogating signals, such as microwave or radio-frequency (RF) radiation, or acoustic broadcasting.  
     BACKGROUND OF THE INVENTION  
      An ability to detect, localize, and identify living organisms and monitor their activities has many uses. Biological attacks caused by wood destroying fungus, borers, termites, carpenter ants and the like are a major problem for structures made wholly or partially of wood. Such attacks can cause considerable damage to wooden structures. The detection and localization of active infestation of termites, ants, and other insects could substantially improve treatment outcome. The detection and monitoring of human activities gives the invention utility as a potential rescue system when it is used in the search for unconscious subjects who may be injured. The invention can also be used as intrusion and stowaway detection; it can help military forces clear a building when people may be concealed in interior hiding places. The invention will enable Special Weapons and Tactics (SWAT) or Special Operations Response Team (SORT) team commanders to better visualize hostage situations. Another equally important use of the invention is in law enforcement including police enforcement and management of correction institutions to detect and monitor offenders through structural walls.  
      Commonly used methods for detection of living organisms are mostly based on visual observations using human eyes or optical cameras. However if a partition obstructs the view visual approach does not work. Microwave, RF or acoustic signals can penetrate through a structure or partition thus offering an opportunity to detect living organisms within or behind it. This approach is known as Though Wall Sensing, or TWS. The sensing of living organisms&#39; activities is based on their motion. The microwave, RF or acoustic TWS system is capable of detecting extremely small motions allowing for detection of living (moving) organisms in otherwise static environment. Conversely with the detection of insects in a wall, in the case where the invention is used to detect living organisms behind a structure or partition, the signals can be filtered to eliminate indications within a wall or structure to show the presence of living organisms on the other side of the structure or wall.  
      Prior art relevant to TWS are utilizing effects of Doppler or phase fluctuation due to motion of a target or echo-location of a target coupled with monitoring of target&#39;s position.  
      U.S. Pat. No. 3,754,254 to Jinman (the “Jinman &#39;254 patent) discloses a device for detecting moving targets by the Doppler shift of radiation reflected or scattered by a target that is illuminated by transmitted radiation. The Jinman &#39;254 patent focused on the problem of an interfering signal having a frequency difference from the transmitted radiation lying in the range of the expected Doppler shift, which would give a false target indication. The Jinman &#39;254 patent discloses that modulating the frequency of the transmitted radiation can mitigate such problem, so that the scattered or reflected radiation has a coherence with the transmitted radiation. The Jinman &#39;254 patent further discloses that a device performing the aforesaid function is particularly applicable to intruder alarm systems.  
      U.S. Pat. No. 6,313,643 to Tirkel (the “Tirkel &#39; 643 . Patent”) has been distinguished from the invention disclosed by the Jinman &#39;254 patent on the basis that the termite detection system disclosed therein includes a transmitter adapted to transmit a “near field” microwave signal into a structure and a receiver adapted to receive reflected signals that are indicative of the presence of insects in the “near field” of the microwave signal. However, the Tirkel &#39;643 patent does not disclose that the termite detection system is able to detect the presence of termites within the “far field” of the signal generated thereby. As a result, the termite detection system&#39;s function is substantially constrained. In addition, the Tirkel &#39;643 patent does not disclose whether the termite detection system is able to distinguish output signals indicative of the presence of termites in a structure and output signals caused by movement of the termite detection system itself. As a result, it would be difficult for an operator of the termite detection system disclosed by the Tirkel &#39;643 patent to distinguish false indications of the presence of insects in a structure from the actual presence of insects therein and, therefore, could lead to increased time and costs for testing a structure and/or inaccurate test results.  
      Recently developed TWS techniques to sense the location of a human subject inside of a room from the outside of that room is described in Hunt, A., Tillery, C., and Wild, N., “Through-the-Wall Surveillance Technologies,” Corrections Today, Vol. 63, No. 4, July 2001. Thus, Greneker, at.al. has developed so-called “RADAR Flashlight” which operates at X-band frequency range (near 10 GHz) and employs a CW homodyne radar configuration. (Greneker, E. F., “Radar Sensing of Heartbeat and Respiration at a Distance with Security Applications,” Proceedings of the SPIE, Radar Sensor Technology II, Volume 3066, April 1997; Geisheimer, J. L., Marshall, W. S., and Greneker, E. F. “A continuous-Wave CW Radar for Gait Analysis,” 35th IEEE Asilomar Conference on Signals, Systems and Computers, vol. 1, 2001, pp 834-838; Greneker, Geisheimer, J. “RADAR Flashlight Three Years Later: An Update on Developmental Progress,” Proceedings of the 34th Annual International Carnahan Conference on Security Technology, Ottawa, Canada, October 2000).  
      Other reported developments are based on wide-band (pulse) technology working similar to echo-locating radars there presence and position of the target based on intensity and time-of-flight of reflected RF pulses. McEwan, T. E.” Ultra-wideband radar motion sensor”, U.S. Pat. No. 5,361,0701, discloses motion sensor based on ultra-wideband (UWB) radar technology. UWB radar range is determined by a pulse-echo interval. For motion detection, the sensors operate by staring at a fixed range and then sensing any change in the averaged radar reflectivity at that range. A sampling gate is opened at a fixed delay after the emission of a transmit pulse. The resultant sampling gate output is averaged over repeated pulses. Changes in the averaged sampling gate output represent changes in the radar reflectivity at a particular range, and thus motion.  
      Other prior art, Barnes et al., “Wide area time domain radar array” U.S. Pat. No. 6,218,979, describes a system and method for high resolution radar imaging using a sparse synchronized array of time modulated ultra wideband (TM-UWB) radars. Two or more TM-UWB radars are arranged in a sparse array. Each TM-UWB radar transmits ultra wideband pulses that illuminate a target, and at least one receives the signal returns. The signal return data is processed according to the function being performed, such as imaging or motion detection.  
      There is other prior art that utilizes a synchronized array of transmitters and/or receivers for coherent processing of reflected signals, such as described by Geisheimer, et al., Phase-based sensing system, U.S. Pat. No. 6,489,917.  
      Although significant resources have been devoted to development of practical and commercially viable TWS systems, so far these efforts produced mostly demonstrational or experimental prototypes which are difficult and impractical to employ for real world applications. One of the reasons is that none of the referred prior art is able to distinguish one type of living organism from another: for example to distinguish termite related activity in a wall from moving people that pass behind the same wall. The prior art can&#39;t differentiate between insect and human.  
      In addition, there is no known living organisms detection device that is able to distinguish motion signals indicative of the presence of living organisms in a structure and signals caused by movement of the device itself. Since electronic insect detection devices typically contain sensitive components designed to detect the movement of insects, any movement of these devices can lead to the false indication of the presence of living organisms in a structure. For instance, hand tremors of an operator holding a living organism detection device cause significant movement thereof. In addition, if a living organism detection device is placed against a structure to be tested, structural vibrations caused by wind, appliances or nearby moving vehicles can lead to the movement of the detection device. Also, moving vehicles that pass behind a structure undergoing testing can cause motion signals that can lead to false indications of the presence of living organisms in a structure. As a result, it would be difficult for an operator of a living organism detection device to distinguish false indications of the presence of living organisms in a structure from the actual presence of living organisms therein.  
      Accordingly, what would be desirable, but has not yet been developed, is a reliable practical device and method for detecting, localization, monitoring, and differentiating living organisms inside structures, within or behind walls and other partitions.  
     SUMMARY OF THE INVENTION  
      In accordance with the present invention, a living organism detection, localization, monitoring, and identification device and method employ a plurality of transceivers, each of which generate separate and distinct interrogating signals and receives separate and distinct signals reflected from a structure being tested for presence of living organisms. The reflected signals received by each of the transceivers are processed, for instance by a microprocessor, so as to provide output signals that indicate the presence or absence of living organisms in the structure being tested.  
      It is another object of the present invention to provide a method and apparatus for the detection, localization, monitoring, and identification of living organisms in dwellings, other structures, and behind walls, doors, or other partitions while being outside of the structures or on the other side of a partition.  
      It is yet another object of the present invention to provide a method for detection, localization, monitoring, and identification of living organisms in dwellings, other structures, and behind walls, doors, or other partitions with high sensitivity and a low rate of false alarms.  
      It is an additional object of the present invention to provide a method and apparatus for detection, localization, monitoring, and identification of living organisms in dwellings, other structures, and behind walls, doors, or other partitions while being outside of the structures without being in close proximity to the structure or partition.  
      The method and the apparatus of the present invention are comprised of one or a plurality of independent interrogating sensors. The sensors can be standalone, i.e. performing interrogation, data acquisition, processing and displaying, or could be wired or wirelessly communicating with one or a plurality of independent communication modules, a signal processor for extracting information relevant to a living organisms&#39; (targets) activities and suppressing unrelated interfering signals, and a data processing/displaying module for displaying information about targets&#39; activities and their location as well as controlling sensors&#39; operation. Among the information that may be extracted is information regarding the vital signs of the target.  
      A wireless link between sensor and data processing/displaying module allows the ability to provide a safe stand-off distance for an operator, create light weight, low cost reusable or even disposable sensors requiring minimum battery power. Another benefit of wireless connectivity is an ability to deploy various sensor delivery means, so sensor could be easily placed or attached with adhesives on wall surface, thrown with a hand or mechanical means as projectile, or delivered with a robotic device. Yet another extremely important benefit of the wireless connectivity is elimination of sensor motion caused by operator hand or body tremor.  
      By providing a plurality of sensors, the present invention allows a user to determine the position of a target using triangulation or observing signal intensity changes from sensor to sensor as a target moves inside a structure. A plurality of sensors also helps to eliminate certain types of false indications of the presence of living organisms in a structure. For example, structural vibrations could cause all sensors attached to the structure to indicate presence of motion approximately the same intensity, which unlikely to take place if sensor&#39;s motion signal outputs are caused by a living organism situated at different distances and/or angles with respect to different sensors. A plurality of sensors allow for implementation of more sophisticated signal processing algorithms so the data from various independent sensors could be processed collectively further reducing false indication of living organisms presence and their activities.  
      The various configurations of the system provide the following advantages: 
          Eliminates self-motion effects because of fixed position of the interrogating sensors     Provides freedom of motion and safe distance/location for an operator such as soldier, policeman, or rescuer     Allows for ample time for safe data gathering and reliable detection     Provides simultaneous detection at multiple locations (eventually covering the entire structure)     Enables advanced multi-channel processing algorithms for elimination of false alarms     Allows for information shearing between soldiers, commanders, etc.     The system operates in various modes providing flexibility and affordability for various users.        

      Further features and advantages of the invention will appear more clearly on a reading of the detailed description of the exemplary embodiments of the invention, which are given below by way of example only with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      For a better understanding of the present invention, reference is made to the following detailed description of the exemplary embodiments considered in conjunction with the accompanying drawings, in which:  
       FIG. 1  is a block diagram of a living organism and damage detection device in accordance with an exemplary embodiment of the present invention.  
       FIG. 2  is a graph of an output signal of the living organism and damage detection device shown in  FIG. 1 , which shows both the absence and presence of live organisms.  
       FIG. 3  is a block diagram of a living organism and damage detection device in accordance with a second exemplary embodiment of the present invention.  
       FIG. 4  is a block diagram of a living organism and damage detection device in accordance with a third exemplary embodiment of the present invention.  
       FIG. 5   a  is a graph of an output signal of the living organism detection device shown in  FIG. 4 , which shows the absence of insects in a structure.  
       FIG. 5   b  is a graph of an output signal of the insect detection device shown in  FIG. 4 , which shows the presence of insects in a structure.  
       FIG. 6  is a block diagram of a living organism and damage detection device in accordance with a fourth exemplary embodiment of the present invention  
       FIG. 7  is a block diagram of a living organism and damage detection device in accordance with a fifth exemplary embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
      The present invention relates to a device and method for nondestructive detection, localization, identification, and monitoring of living organisms inside structures, within or behind walls and other partitions using penetrating interrogating signals such as microwave, RF or acoustic radiation. By structures it is meant any structure, including, but not limited to, houses, buildings, containers, compartments, bridges, other wooden, concrete or metal structures, wooden or metal frames, utility poles, piles, etc. The detection of living organisms is based on their reflectivity and/or constant motion. For example, all living organisms are comprised of electrolyte (conductive) material while many construction materials such as wood, sheetrock, and others are dielectric. This creates high contrast reflectivity for microwave and RF radiation. Living organisms are made out of water and other substances much denser than air thus creating high reflectivity for acoustic waves propagating in air. Also, all living organisms are in constant motion. The present invention detects very small movements (fraction of mm per second), thus allowing for detection of living (moving) organisms in static material.  
      As can be seen in  FIG. 1 , the apparatus of the present invention, generally indicated as  10 , includes a microwave or RF generator  20 , a receiver  30 , an antenna  40  for sending and receiving signals, a signal processor  50  for processing the received signals and a display  60 . Preferably, the apparatus is hand-held and is moved along the wooden structure  8  being tested. Microwave or RF signals (i.e., radiation) are generated by the generator  20 . The generator  20  does not have to be particularly strong; for example, in testing it was found that a 10 mW generator was sufficient. The generated signal is constantly sent by the antenna  40 , which also constantly receives a reflected signal. The signals are received by the receiver  30  and processed by the signal processor  50 . Optionally, the apparatus  10  can include the display  60  for displaying the results. Alternatively, the apparatus  10  could merely emit an audio or visual alarm indicating the presence of live organism. Alternatively, the generator  20  may generate acoustic signals having power level of a few watts.  
      The method includes generating and sending a microwave, RF or acoustic signal, receiving a reflected signal, and processing and evaluating the received signal. It has been found that a generated microwave or RF signal having a frequency of between 0.5 and 50 Ghz is suitable; acoustic signal having frequency of between 1 KHz-200 kHz is suitable for TWS. The method could be employed with a hand-held unit wherein the unit is moved about a structure to be tested. Alternatively, the apparatus could be stationary and allowed to operate for a given time to cover a given area. In such a case, the apparatus could be attached to the wooden structure being tested for a short period of time, or left attached for a longer time for long term monitoring.  
      The apparatus  10  could additionally include a stimulator for stimulating living organisms&#39; movement to make detection easier (not shown in  FIG. 1 ). The stimulator could be based on vibration, ultrasound, electromagnetic radiation, heating, etc. Preferably, a stimulator would be used prior to or during the application of the probing device.  
      An exemplary application of the invention was conducted. In the example, tests were performed with live ants contained within a plastic box and dead ants which were attached to an adhesive. The ants were placed beneath a wooden board.  
      As shown in  FIG. 2 , where there is no motion, i.e. dead ants, there is basically no output signal from the probe. However, slight motion of live insects resulted in appreciable output signals.  
      In another exemplary case, live termites were put into a plastic container and one-inch wood board was used to separate the probe from the container. A significant output, similar to that shown in  FIG. 2  (but not shown in the Figures), was achieved for live termites as opposed to the absence of termites.  
       FIG. 3  shows another embodiment of the present invention generally indicated as  110 . The device includes an antenna  140  having a transmitting portion  142  and a receiving portion  144 . The transmitting and receiving portions  142 ,  144  can be interconnected with a circulator (not shown in  FIG. 3 ). Alternatively, two separate transmitting and receiving antennas can be utilized. The transmitting portion  142  of the antenna  140  radiates the tested structure  8  with probing microwave, RF or acoustic energy. The transmitted energy penetrates into/through the tested structure  8  via matching media  146  having similar properties to stranture&#39;s dielectric or acoustic properties. Inhomogeneties in and behind the structure, such as insects or other living organisms, cause reflection of the interrogating signal back to the receiving portion  144  of antenna  140 . The received signal is processed for moving living organism detection. A tunable signal generator  120  is controlled by a microprocessor  170 . The tunable signal generator  120  interconnects with a power amplifier  122  to deliver a signal to the antenna  140 . The receiving portion  144  of antenna  140  outputs a signal to an amplitude and phase discriminator  132  that is interconnected with the tunable generator  120 . The signal is then sent to a gain and offset control  134  which is interconnected with the microprocessor  170  and then sent to an analog-to-digital converter  136  and then to the microprocessor  170 . Finally, the output is displayed on a display  160 .  
      In the calibration mode, the microprocessor  170  sweeps the frequency range of the generator  120  to find a frequency with maximum (strongest) received signal. In the detection mode, the microprocessor  170  sets the fixed frequency of the generator  120 . This frequency corresponds to the maximum received signal, for greatest sensitivity. If there are moving reflectors (i.e., living organisms) the received signal contains amplitude and phase variations due to the motion. These variations are extracted with the amplitude-phase discriminator  132  and sent to the gain and offset control device  134 , which adjusts amplification and offset voltage for optimum evaluation of the signal sent to the microprocessor  170 . The microprocessor  170  calculates the standard deviation of the received signal. When deviation exceeds a threshold level, predetermined during sensor calibration, the microprocessor  170  sends a live insect message to the display  160 . The display can be a simple indicator, i.e. a red, green indicator, a sound indicator, or a more sophisticated LED or LCD display.  
      Another exemplary embodiment of the present invention is illustrated in  FIG. 4 , wherein a living organism detection device  200  includes a rectangular-shaped housing  202  having an end  204 , a microprocessor  206  and eight (8) transceivers  208  that are positioned proximate to the end  204  of the housing  202 . The housing  202  supports and houses the other components of the living organism detection device  200 , and is preferably rectangular in shape, but it can consist of other shapes and sizes. The living organism detection device  200  preferably includes the eight transceivers  208 , but it may include a greater or lesser number than eight. Furthermore, the transceivers  208  are preferably positioned linearly proximate to the end  204  of the housing  202  (as shown in  FIG. 4 ), but other configurations of the positioning of the transceivers  208  may be utilized. For example, as shown in  FIG. 6 , the transceivers  308  may be separated from the main housing  302  and connected to the main housing  302  by a cable or bus  304 . The transceivers  208  are sometimes collectively referred to herein as “channels” and each individually as a “channel.” The functions of the microprocessor  206  and the transceivers  208  shall be described hereinafter.  
      Still referring to  FIG. 4 , each of the transceivers  208  has a corresponding antenna  210  connected thereto and whose function shall be described hereinafter. In the case that the living organism detection device  200  is intended to detect living organisms very close to the device, for example insects in a wall, it is important that each of the antennas  210  is located at a specifically selected distance “d” from the end  204  of the housing  202  (as shown in  FIG. 4 ), whereby the distance “d” is greater than the “near field” of the signals transmitted by the antenna  210 . The near field of the signal transmitted by each of the antennas  210  is defined as a distance equal to or lesser than twice the square of its aperture width divided by the wavelength of the signal transmitted thereby, i.e., near field # 2a 2 /λ, whereby “a” is the aperture width of the antenna  210  (as shown in  FIG. 4 ) and λ is the wavelength of its transmitted signal. Each of the antennas  210  is preferably a horn antenna, but any or all of the antennas  210  can consist of a microstrip antenna, a dish antenna, or any other type of suitable antenna. Each of the antennas  210  and its corresponding transceiver  208  are flanked by rectangular-shaped partitions  212  (only one of which is labeled in  FIG. 4  with reference number  212 ) whose functions shall be described hereinafter. Each of the partitions  212  is preferably rectangular in shape and manufactured from a conductive material such as aluminum, but they can consist of other shapes and sizes and/or manufactured from other materials. The living organism detection device  200  can include a rectangular-shaped covering (not shown in  FIG. 4 ), preferably manufactured from a conductive material such as aluminum, that covers the top of the partitions  212 , and which, together with the partitions  212 , substantially enclose each of the antennas  210 .  
      The living organism detection device  200  can also be used to detect living organism targets  230  on the other side or at a distance from the other side of a structure, wall or partition. In this case, because the living organism target  230  is not so close to the antennas  210 , the distance “d” is not as critical because the living organism target  230  most likely will be in the far field of the signal transmitted by antennas  210 . Therefore, in an embodiment intended to detect living organism targets  230  through a structure, wall or partition, rather that within it, the antennas  210  can be positioned at any distance from the end  204 .  
      Still referring to  FIG. 4 , the living organism detection device  200  further includes a demultiplexer  214  and a multiplexer  216 , each of which are electrically connected to and controlled by the microprocessor  206  and whose functions shall be described hereinafter. The transceivers  208  are electrically connected to the demultiplexer  214  in parallel. Similarly, the transceivers  208  are electrically connected to the multiplexer  216  in parallel. The living organism detection device  200  further includes an amplifier/digitizer  218  that is electrically connected to the multiplexer  216  and the microprocessor  206  and whose function shall be described hereinafter. A control interface  220 , a visual display  222 , an audio speaker  224  and a communication port  226  are each electrically connected to the microprocessor  206 , and the functions of which shall be described hereinafter. A power supply  228  provides electrical power to all of the aforesaid electronic components of the living organism detection device  200 .  
      It is noteworthy that the microprocessor  206  is preferably manufactured by Amtel Corporation and having a model number of ATMega-16AC, while each of the transceivers  208  is preferably manufactured by Microwave Device Technology Corporation and has a model number of MO9061. In addition, each of the antennas  210  is preferably manufactured by Microwave Device Technology Corporation and has a model number of MHA4137. The demultiplexer  214  and multiplexer  216  are each preferably manufactured by Texas Instruments, each having a model number of CD4051. Alternatively, the aforesaid components may be manufactured by other entities and/or different models of such components may be utilized.  
      Still referring to  FIG. 4 , the living organism detection device  200  operates in the following manner. Each of the transceivers  208  generates microwave, RF or acoustic signals that are separate and distinct from the signals generated by each of the other transceivers  208 . The signals generated by each transceiver  208  are transmitted by its corresponding antenna  210  into a portion of a structure S to be tested (as shown in  FIG. 4 ) such as a wall, ceiling, floor, etc. Each of the antennas  210  and, in turn, its corresponding transceiver  208 , receives reflected signals from the structure S. The reflected signals received by each of the antennas  210  and its corresponding transceiver  208  are separate and distinct from the reflected signals received by each of the other antennas  210  and its corresponding transceiver  208 . It is preferable that each of the transceivers  208  has a single corresponding antenna  210  connected thereto that both transmits interrogating signals generated by the transceiver  208  and receives reflected signals to be received by the transceiver  208 . Alternatively, each of the transceivers  208  may have a pair of corresponding antennas connected thereto, whereby one antenna transmits the signals generated by the transceiver  208 , while the other antenna receives the reflected signals to be received by the transceiver  208 .  
      The microwave or RF signal generated by each of the transceivers  208  is not required to be powerful. For example, a 10 mW microwave/RF signal having a frequency within the range of 0.5 to 50 GHz is sufficient for the operation of the living organism detection device  200 . Alternatively, the transceivers  208  may generate acoustic signals to be transmitted by antennas  210 . A few watts acoustic signal generated within the frequency range 1 kHz to 200 KHz is sufficient for the operation of the detection device  200  transmitting acoustic energy. However, microwave, RF or acoustic signals generated with different levels of power and/or having different frequencies can be utilized. The demultiplexer  214 , which is controlled by the microprocessor  206 , sequentially activates and sequentially deactivates each of the transceivers  208 , whereby the transceivers  208  are activated and deactivated in succession. In other words, only one of the transceivers  208  generates signals and receives reflected signals from the structure S at a particular time. For example, the demultiplexer  214  activates one of the transceivers  208  (for instance, the transceiver  208  labeled as “Tx/Rx 1 ” in  FIG. 4 ), which generates signals and receives the reflected signals for a short period of time, while at the same time, the other seven transceivers  208  (labeled as “Tx/Rx 2 ” though “Tx/Rx 8 ” in  FIG. 4 ) remain deactivated. Next, the demultiplexer  214  simultaneously deactivates the activated transceiver  208  (i.e., the transceiver  208  labeled as “Tx/Rx 1 ” in  FIG. 4 ) and activates another one of the transceivers  208  (preferably the transceiver  208  that is next in line, which is labeled as “Tx/Rx 2 ” in  FIG. 4 ), which generates microwave signals and receives reflected signals for a short period of time. During this time, the other seven transceivers  208  (labeled as “Tx/Rx 1 ” and “Tx/Rx 3 ” though “Tx/Rx 8 ” in  FIG. 4 ) remain deactivated. The demultiplexer  214  activates and deactivates each of the transceivers  208  in succession and, thereafter, the cycle is repeated. Alternatively, all of the transceivers  208  may remain continuously activated.  
      Still referring to  FIG. 4 , the partitions  212  shield the antennas  210  from each other, thereby reducing any interference between the signals transmitted by the antennas  210  and between the reflected signals received thereby. The partitions  212  also shield the antennas  210  from signals that are reflected by portions of a structure that are not, at that particular time, subject to testing. For example, if a front wall of a structure is subject to testing, signals are reflected from the front wall as well as, for instance, sidewalls of the structure. Consequently, the signals reflected from the sidewalls of the structure can cause interference with the signals reflected from the front wall of the structure, i.e., the portion of the structure subject to testing. Thus, the partitions  212  shield the antennas  210  from signals reflected from the sidewalls of the structure being tested, thereby reducing or eliminating interference with the signals reflected from the front wall of the structure. Finally, the partitions  212  shield the antennas  210  from extraneous sources of electromagnetic radiation, e.g., television stations, radars, etc. As previously noted, the living organism detection device  200  can include a rectangular-shaped covering (not shown in  FIG. 4 ), preferably manufactured from a conductive material such as aluminum, that covers the top of the partitions  212 , which, together with the partitions  212 , substantially enclose the antennas  210 , and further shields the antennas  210  from each other, from signals that are reflected by portions of a structure that are not, at that particular time, subject to testing and from signals generated by extraneous sources.  
      The multiplexer  216 , which is controlled by the microprocessor  206 , receives and interrogates the reflected signals received by each of the transceivers  208 . The reflected signals received by the multiplexer  216  are then amplified and digitized by the amplifier/digitizer  218 , which allows for the reflected signals&#39; data to be processed and analyzed by the microprocessor  206  in order to provide output signals that indicate the presence or absence of living organisms in the structure S or behind the structure S, noted as target  230 .  
      When moving living organisms, such as termites, ants, human or others are present in or behind the structure S, their motion causes low frequency modulation of the reflected signals received by each of the antennas  210  its corresponding transceiver  208 . The modulating frequencies of the reflected signals are typically less than 10 Hz. The modulated, reflected signals and a portion of the transmitted signals are mixed within each of the transceivers  208  so as to produce low frequency difference signals, which are indicative of motion. Since the modulated frequency of the reflected signals (when living organisms are present) are typically less than 10 Hz, the reflected signals received by each of the transceivers  208  are sampled at a rate greater than 10 Hz, for example 256 Hz. The acquisition time “θ” to acquire a data sample for a channel (i.e., a single transceiver  208 ) is preferably less than or equal to 1/(N×F), where N is the number of channels (i.e., the number of transceivers  208 ) and F is the sampling rate in Hz. The reflected signals received by each channel is subsequently interrogated by the multiplexer  216  to produce data sample streams D n  (d nm ), where “n” is a channel number, “m” is a sample number and “d” is a single bit of data. The reflected signals have different characteristics, or “signatures”, depending on the living organism. For example, signals from insects are non-deterministic, that is, the output signals processed therefrom would be visualized as “noise.” Accordingly, the data processing and analysis conducted by the microprocessor  206  consists of calculating the moving average for each data stream D n  and determination of the signal deviation indicative of a positive motion signal. The deviation could be determined by the differentiation, the calculation of signal dispersion and other similar procedures known on the art of signal processing. The deviation is compared with a predetermined threshold. If the deviation exceeds the predetermined threshold, then the audio speaker  224  will issue an audible alarm. The greater the movement of insects, the greater the deviation and the higher the pitch of the sound generated by the audio speaker  224 .  
      Very often, however, the signal deviation could be caused by motion of the detection device  200  itself. For instance, hand tremors of an operator holding the detection device  200  while testing the structure S, structural vibrations (caused by wind, appliances, etc.) or moving vehicles passing behind the structure S could cause motion signals, thereby resulting in a signal deviation that exceeds the predetermined threshold. This would lead to the false indication of the presence of insects in the structure S, i.e., non-insect motion, and, consequently, “false alarms” produced by the audio speaker  224  could occur. In this regard, the plurality of transceivers  208  plays a fundamental role to discriminate between the false indication of the presence of insects in the structure S (i.e., non-insect motion) and the actual presence of insects in the structure S. Since most insects, such as termites, ants, etc. move along narrow paths, only one or a couple of the transceivers  208  will detect the insects&#39; motion, while the remaining transceivers  208  will not detect the insects&#39; motion. If a condition that would trigger a false indication of the presence of insects in the structure S occurs (i.e., hand tremors, structural vibrations, moving vehicles etc.), all, or substantially all, of the transceivers  208  will receive a positive motion signal that indicates the possible presence of insects in the structure S, which is a false indication of the presence of insects in the structure S.  
      The microprocessor&#39;s  206  signal-processing algorithm is written to take into account the occurrence a false indication of the presence of insects in a structure. For example, if all or most of the transceivers  208  receive a positive signal (i.e., a motion signal) that indicates the possible presence of insects in the structure S, the microprocessor  206  will process these positive signals to determine whether they are substantially similar to each other. If the positive signals (i.e., motion signals) are substantially similar to each other, then the microprocessor  206  will extract the common positive signal received by the transceivers  208  and subtract such common positive signal from all of the signals received by the transceivers  208 , thereby generating residual signals. The residual signals are then analyzed to determine the presence of insects. Therefore, the insect detection device  200  is able to detect the presence of insects in the structure S despite the existence of motion signals caused by non-insect motion.  
      Similarly, if the living organism detection device  200  is intended to detect living organism targets  230  through a structure S, wall or partition. This situation is more relevant to detection of humans or animals. Signals, reflected from human or animals contain both noise-like (random motion) and deterministic (respiration, heartbeat) components. Still, these signals are non-stationary and nonlinear. As a result, conventional signal processing techniques such as Fourier transforms or statistical techniques such as described above are not very useful in differentiation between different “signatures”. The microprocessor&#39;s  206  signal processing algorithms can be programmed for more sophisticated algorithms such as empirical mode decomposition, adaptive filtering, and others known in art of advanced signal processing techniques to extract “signatures” relevant to various organisms. Here again the plurality of transceivers  208  plays an important role to avoid the false detection that may be generated by non-living organism motion of the structure S or transceivers themselves.  
      In order to eliminate movement caused by hand tremors, the living organism detection device  200  may be mounted to a stabilizing device such as a photographer&#39;s tripod, monopod, suction cap, adhesive tape, or a similar mounting and stabilizing device (not shown in the Figures). Alternatively, the detection device  200  can be slidably mounted to a linear bearing slide and rail device, such as that manufactured by 80/20, Inc. of Columbia City, Ind. (not shown in the Figures). This type of slide and rail device can be temporarily attached to a wall by, for instance, the use of suction cups. Such a configuration would allow a user to linearly move the living organism detection device  200  along the structure S being tested and take several readings. Although it is preferable that the mounting devices described above be utilized with the living organism detection device  200 , other mounting and stabilizing devices and means may be employed.  
      The visual display  222 , which is controlled by the microprocessor  206 , provides for a display of the output signals and/or data indicative of the absence or presence of living organism in a structure S, or on the other side of the structure S, wall or partition, as desired. The visual display  222  is preferably simple LED indicators (e.g., one indicator for each channel), but other visual display means, including, but not limited to, an LCD display, are available. Alternatively, the visual display  222  need not be utilized. The control interface  220 , which is controlled by the microprocessor, provides for an interface between an operator and the living organism detection device  200 . The control interface  220  may include, but is not limited to, a power switch, volume and sensitivity controls, and an earphone plug (not shown in  FIG. 4 ). The communication port  226 , which is controlled by the microprocessor  206 , allows for the signal data processed and analyzed by the living organism detection device  200  to be transferred to a personal computer or a personal digital assistant (PDA). The communication port  226  is preferably either a wired or wireless universal serial bus (USB) or an RS-232 serial port. Alternatively, other types of communication ports  226  may be utilized.  
      Referring to  FIGS. 5   a  and  5   b , an experimental application of the insect detection device  200  was conducted at a residence infested with live termites. The aperture width of each of the antennas  210  was 12.25 mm, while the frequency of each signal generated by each of the transceivers  208  and transmitted by each of the antennas  210  was 24.5 GHz. Therefore, the near field of the signals transmitted by each of the antennas  210  is calculated as approximately 25 mm. The living organism detection device  200  was positioned approximately 30 mm from a wall of the residence, which is clearly outside the near field of the signals transmitted by the antennas  210 . A portion of the wall that was known not to contain termites was first tested. In the absence of termites, the output signal generated by the living organism detection device  200  has virtually no amplitude, as shown in  FIG. 5   a . Next, a portion of the wall that was known to contain live termites was tested. The motion of the termites resulted in output signals having appreciable amplitudes, as shown in  FIG. 5   b.    
      The living organism detection device  200  can include a stimulator for stimulating insect movement so as to promote easier detection of insects (not shown in  FIG. 4 ). The stimulator could emit vibrations, ultrasound, heat and/or electromagnetic radiation. Preferably, the stimulator would be used prior to or during the insect detection process.  
      The living organism detection device  200  may be specifically designed to detect insects in a structure being tested by performing the following steps. First, a plurality of transceivers (such as the transceivers  208 ) is provided for generating microwave signals and receiving reflected signals from a portion of the structure being tested. Next, each of the transceivers is provided with an antenna (such as the antennas  210 ) adapted to transmit microwave signals generated by its corresponding transceiver and to receive the reflected signals to be received by its corresponding transceiver. The transceivers are then positioned a pre-selected distance from the portion of the structure being tested, the distance being specifically selected such that the portion of the structure being tested lies within each of the antennas&#39; far field. Next, the transceivers are sequentially activated and sequentially deactivated such that the transceivers are activated and deactivated in succession. The reflected signals received by the transceivers are then processed (for instance, by the microprocessor  206 ) in order to identify a positive signal that is indicative of the possible presence of insects in the portion of the structure being tested. Finally, all of the reflected signals received by the transceivers are compared to each other in order to determine whether all, or substantially all, of the transceivers have received signals substantially similar to the positive signal to thereby indicate the false presence of insects in the portion of the structure being tested.  
      As previously referred to,  FIG. 6  shows an alternative embodiment where the transceivers  308  and their antennas  310  are enclosed in separate transceiver housings  332  from the living organism detector housing  302 . The transceiver housings  332  are connected to the living organism detector housing  302  by one or more cables or a bus  304  that connect the transceivers  308  to the multiplexer  316  and the demultiplexer  314 . By separating the transceiver housings  332  from the main living organism detector housing  302 , the problems caused by a user handling or shaking the living organism detection device  300  while in operation is eliminated because the transceiver housings  332  can be separately secured to a structure, wall or partition.  
      Alternatively, as shown in  FIG. 7 , the transceiver housings  432  can be connected to the main living organism detection device  400  by wireless links. The transceiver housing  432  includes a wireless receiver/transmitter  434  connected to the transceiver  408  which communicates with a wireless receiver/transmitter in the main living organism detector housing  402 . Any of known wireless transmission methods may be used, including, but not limited to 802.11x, Bluetooth or analog methods. If a digital transmission method such as 802.11x or Bluetooth is used, an analog-to-digital converter  436  should be used between the transceiver  408  and the wireless receiver/transmitter  434 . By using a wireless communication method, the transceiver housings can be attached to a structure, partition or wall using many methods including, but not limited to, manual placement, shot as a projectile, throwing, etc. The wireless communication method is further advantageous because a plurality of transceiver housings  432  can be placed at intervals determined by a user for a particular application. For example, referring to  FIG. 8 , the transceiver housings  432  can be placed by a police officer at various locations throughout a building to determine the location of an intruder or hostage taker.  
      A further advantage of using a wireless communication method is that multiple main living organism detection devices  400  can communicate with the transceiver housings  432  at the same time. For example, in the case of police officers isolating an intruder, multiple officers could each have a handheld unit that replicates the main living organism detection device  400 . Alternatively, satellite units could simply include a display screen and a wireless receiver such that the main living organism detection device  400  transmits data to the satellite units for display. The use of simple satellite units is an economical solution due to the simplicity of the satellite units.  
      It should be understood that the embodiments described herein are merely exemplary and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the invention. Accordingly, all such variations and modifications are intended to be included within the scope of the invention as defined in the appended claims.