Abstract: A method of installing a security system includes activating a security device. An air-borne identification signal is transmitted from the device in response to the activation. The identification signal identifies the activated device. The identification signal is used to ascertain a type of the device. The device is automatically wirelessly configured dependent upon the type of the device.

Abstract: The present invention relates to a system and method for detecting bats from a remote location. In one aspect the invention provides a bat detection system comprising an upper detection unit connected to a base computer unit. The upper detection unit can be positioned on a vertical structure, and a second lower detection unit, or additional detection units, can also be positioned on the vertical structure. Each detection unit comprises a housing which is connected to, and contains, an audio detector. The base computer unit is enclosed by a housing and comprises a data processor, a data storage device, and a remote communication interface device. The data processor is operatively connected to the data storage device, remote communication interface device, and the audio detectors of any detection units positioned on the vertical structure. The base computer unit communicates with a remote computer transferring information regarding the bat sounds detected by the detection units.

Abstract: A measurement system and method combine an audio announcement system with a plurality of spaced apart sensors to evaluate intelligibility of audio output from loudspeakers of the audio announcement system. Processing can take place at some or all of the sensors as well as at a common control element. Evaluations can be based on use of an appropriate speech intelligibility index method.

Abstract: A method of detecting a human, that includes (a) measuring the ultrasonic signal emitted from human footsteps; (b) measuring the human body motion Doppler signature; reviewing the measurements of steps (a) and (b); and (d) determining the presence of a human.

Abstract: A dual-modality sensor for detecting a presence of a human intruder within a secure setting includes a seismic sensor for acquiring a seismic signature of a disturbance, and includes an active acoustic sensor to acquire an acoustic signature of the disturbance. A system processor is electrically connected to the seismic and active acoustic sensors to receive and process the seismic and acoustic signatures, and generate an alarm signal when the disturbance is determined to come from a human intruder. Also included is an antenna and/or hard-wire connection arranged for communicating the alarm signal. The dual-modality sensor is arranged in a sensor housing constructed to contact a surface of the secure setting. The sensor may include a battery or other means for providing electrical power.

Abstract: An acoustic collision detection system that enables an aircraft to detect an approaching target, recognize the potential for collision and change course to maintain a safe separation distance, with or without operator invention. The acoustic collision detection system consists of an array of acoustic probes and a digital signal processor which receives acoustic data from the approaching target. The digital signal processor is configured to receive acoustic data from the array of acoustic probes; filter out noise and its own acoustic signals; extract the acoustic signals emanating from the approaching target; calculate the intensity, the bearing and the bearing angle rate of change of the approaching target, and determine whether the aircraft and the approaching target are on a potential collision course.

Abstract: A telemetry system is described in which a plurality of channels are coupled to a bus. A control subsystem controls the channels so that one of the channels presents to the bus during its designated time period a channel characteristic. The control subsystem interrogates in the analog domain each of the channels during its designated time period, and forms a signal representative of the channel characteristic. The control subsystem may combine one or more of the signals into a digital packet, and transmit the same via transceiver over a wireless network. The channels may be contained within a submersible enclosure and displaced at intervals along the bus, thereby forming an array for monitoring waterborne threats. The array may lie along an ocean floor, may be towed by a marine vehicle, or may suspended from a deployable buoy containing the control subsystem, transceiver, and a remote power source. The array may further comprise a defensive countermeasure deployable responsive to detecting a threat.

Abstract: Described are embodiments that detect attempts at malicious action against an installation under surveillance based on signals detected by a plurality of sensors distributed near an installation.

Abstract: A dual-modality sensor for detecting a presence of a human intruder within a secure setting includes a seismic sensor for acquiring a seismic signature of a disturbance, and includes an active acoustic sensor to acquire an acoustic signature of the disturbance. A system processor is electrically connected to the seismic and active acoustic sensors to receive and process the seismic and acoustic signatures, and generate an alarm signal when the disturbance is determined to come from a human intruder. Also included is an antenna and/or hard-wire connection arranged for communicating the alarm signal. The dual-modality sensor is arranged in a sensor housing constructed to contact a surface of the secure setting. The sensor may include a battery or other means for providing electrical power.

Abstract: A system includes a receive line array that generates one or more receive line array signals, a processor operatively connected to the receive line array to process the receive line array signals and to generate detonation signals based upon the processed receive line array signal, and a modem operatively connected to the processor that transmits the detonation signals to one or more explosive line arrays, the explosive line arrays having at least one explosive charge coupled thereto that is detonated upon receipt of the detonation signals. The receive line array may include multiple sensors and multiple hydrophones. The sensors may be magnetic field, electric field, or electromagnetic sensors. The explosive line arrays may be detection line arrays or disruption line arrays. The modem may be configured to receive and transmit one or more user-initiated detonation signals to the disruption line arrays to detonate the disruption line arrays.

Abstract: Methods and apparatus determine if an underwater intruder passes under a protective boundary. A sonar sensor system comprises a plurality of sonar sensor modules that are spaced on a protective boundary. A sonar sensor module comprises a sonar transducer (sonar array) that is characterized by an omni-directional radiation pattern that may overlap an omni-directional radiation pattern of an adjacent sonar sensor module transducer. The sonar sensor module collects sonar data such as range information of the target in relation to time. A central processor obtains the sonar data from each sonar module through a telemetry link. The central processor processes the sonar data from the plurality of sonar sensor modules in order to determine an estimated path of the target and may determine if the target should be considered as a threatening underwater intruder from a calculated threat level estimate based on this data.

Abstract: Methods and apparatus determine if an intruder passes into a security zone that is associated with a waterfront asset. An embodiment of the invention provides a harbor fence system that is designed to be deployed in water around ships or other waterfront assets to serve as a line-of-demarcation in order to provide protection. The harbor fence system comprises a series of spars that protrude above the water surface and that are connected with an electrical computer with a telemetry subsystem. Each spar contains electronic sensors, e.g. water immersion sensors and accelerometers, and circuitry to detect an intrusion and to communicate the location of the intrusion to a computer control station. The embodiment also facilitates deploying and retrieving the harbor fence system. Additionally, the embodiment may also determine whether an underwater intruder is passing under a protective boundary, in which the harbor fence system interfaces to an underwater sonar sensor subsystem.

Abstract: A break-in detection system includes a detection sensor of an FBG type for detecting an intruder trying to climb over a fence around a premises, and a detection sensor of an OTDR type for detecting an intruder trying to demolish the fence. A fiber optic cable used as a detection sensor has a sensor core wire and a LAN transmission core wire arranged in parallel to form a LAN transmission channel. The LAN transmission core wire transmits videotaped image signals from ITV cameras and image control signals two ways between a monitoring room and an ITV control device. The LAN transmission channel is available for connection by IP telephone sets, a LAN terminal, a wireless LAN terminal, and an IP-BOX for internet communication. The system has excellent reliability and maintenance-free characteristics.

Abstract: A pool monitoring system includes a hydrophone configured to generate an electrical signal in response to receiving a pressure wave in the liquid of a pool, and a processor configured to receive the electrical signal and generate a trigger signal, when the electrical signal includes a characteristic signature over a time period within a predetermined range of time periods.

Abstract: Methods and apparatus determine if an intruder passes into a security zone that is associated with a waterfront asset. An embodiment of the invention provides a harbor fence system that is designed to be deployed in water around ships or other waterfront assets to serve as a line-of-demarcation in order to provide protection. The harbor fence system comprises a series of spars that protrude above the water surface and that communicate with a computer with a telemetry subsystem. Each spar contains electronic sensors, e.g. water immersion sensors and accelerometers, and circuitry to detect an intrusion and to communicate the location of the intrusion to a computer control station. Spars may communicate wirelessly and may also be solar powered. Additionally, the embodiment may also determine whether an underwater intruder is passing under a protective boundary, in which the harbor fence system interfaces to an underwater sonar sensor subsystem.

Abstract: A pool monitoring system includes a hydrophone configured to generate an electrical signal in response to receiving a pressure wave in the liquid of a pool, and a processor configured to receive the electrical signal and generate a trigger signal, when the electrical signal includes a characteristic signature over a time period within a predetermined range of time periods.

Abstract: A set of seismic detectors is distributed throughout a defense zone in communication with a set of attack or other controllable devices. A seismic signal source controlled by a zone defense coordinator communicates at scheduled times to the seismic detectors and through them to the associated devices to convey mission critical information. The seismic detectors and the attack devices are controlled singularly and/or collectively by self-contained processors. The seismic source may be at a fixed site and is substantially repeatable as well as controllable. The system may be specially adapted to a wide range of terrains including land and water; and from very shallow to very deep water. Targets may be characterized in terms of their typical seismic signatures and the same hardware system used for seismic communication may be also programmed for target detection and device activation.

Abstract: Manatee vocalizations are detected by performing a variety of frequency domain processing operations on sound signals detected in an underwater region. Overlapping time windowed portions of digitized sound data are converted to the frequency domain where power spectrums therefor are estimated. Each such power spectrum is then normalized with each resulting normalized spectrum value indicative of broadband noise having a value that is less than a normalized spectrum value indicative of narrowband tones. Normalized spectrum values indicative of narrowband tones that occur (i) in windows of frequency bins encompassing frequencies lower and higher than each of a lowest resonant frequency (associated with manatee vocalizations) and its harmonics and (ii) with a specified degree of variance with respect to frequency separation therebetween, are filtered out. Remaining normalized spectrum values indicative of narrowband tones are assigned to a frequency based harmonic set.

Abstract: Methods and apparatus determine if an underwater intruder passes under a protective boundary. A sonar sensor system comprises a plurality of sonar sensor modules that are spaced on a protective boundary. A sonar sensor module comprises a sonar transducer (sonar array) that is characterized by an omni-directional radiation pattern that may overlap an omni-directional radiation pattern of an adjacent sonar sensor module transducer. The sonar sensor module collects sonar data such as range information of the target in relation to time. A central processor obtains the sonar data from each sonar module through a telemetry link. The central processor processes the sonar data from the plurality of sonar sensor modules in order to determine an estimated path of the target and may determine if the target should be considered as a threatening underwater intruder from a calculated threat level estimate based on this data.

Abstract: Methods and apparatus determine if an intruder passes into a security zone that is associated with a waterfront asset. An embodiment of the invention provides a harbor fence system that is designed to be deployed in water around ships or other waterfront assets to serve as a line-of-demarcation in order to provide protection. The harbor fence system comprises a series of spars that protrude above the water surface and that are connected with an electrical computer with a telemetry subsystem. Each spar contains electronic sensors, e.g. water immersion sensors and accelerometers, and circuitry to detect an intrusion and to communicate the location of the intrusion to a computer control station. The embodiment also facilitates deploying and retrieving the harbor fence system. Additionally, the embodiment may also determine whether an underwater intruder is passing under a protective boundary, in which the harbor fence system interfaces to an underwater sonar sensor subsystem.

Abstract: Methods and apparatus determine if an intruder passes into a security zone that is associated with a waterfront asset. An embodiment of the invention provides a harbor fence system that is designed to be deployed in water around ships or other waterfront assets to serve as a line-of-demarcation in order to provide protection. The harbor fence system comprises a series of spars that protrude above the water surface and that are connected with an electrical computer with a telemetry subsystem. Each spar contains electronic sensors, e.g. water immersion sensors and accelerometers, and circuitry to detect an intrusion and to communicate the location of the intrusion to a computer control station. The embodiment also facilitates deploying and retrieving the harbor fence system. Additionally, the embodiment may also determine whether an underwater intruder is passing under a protective boundary, in which the harbor fence system interfaces to an underwater sonar sensor subsystem.

Abstract: The object of the present invention is to provide an individual authentication method and apparatus that use no bulky apparatuses, are insusceptible to forgery, and use an auditory organ which is almost independent of health condition and aging, is little subject to physiological rejection, and exists in everyone.

Abstract: A firearm discharge detection device and alarm system featuring a plurality of detector units placed inside a structure which communicate with a central monitoring unit. Each detection unit will detect the discharge of a firearm in its proximity from decibel levels and duration using on board filters and timers and thereon signal the central monitoring unit. A digitized embodiment may also be used to determine the sound of a firearm using a digitized fingerprint of the sound compared to an library of firearm sounds in onboard memory by a microprocessor. The central monitoring unit will thereupon communicate with all the other detection devices installed to sound an audible and/or visible alarm to occupants to exit. Concurrently the central monitoring unit will communicate the firearm discharge and location to police. An optional directional exit alarm or warning to hide may also be activated.

Abstract: A firearm discharge detection device and alarm system featuring a plurality of detector units placed inside a structure which communicate with a central monitoring unit. Each detection unit will detect the discharge of a firearm in its proximity from decibel levels and duration using on board filters and timers and thereon signal the central monitoring unit. A digitized embodiment may also be used to determine the sound of a firearm using a digitized fingerprint of the sound compared to an library of firearm sounds in onboard memory by a microprocessor. The central monitoring unit will thereupon communicate with all the other detection devices installed to sound an audible and/or visible alarm to occupants to exit. Concurrently the central monitoring unit will communicate the firearm discharge and location to police. An optional directional exit alarm or warning to hide may also be activated.

Abstract: A remote acoustic detection system includes at least one detection unit delivered to a remote or inaccessible location by a missile or other aircraft. The detection unit monitors acoustic events at the location such as aircraft takeoffs and landings and preferably is provided the capability of classifying the events, for example, as to the event or type of aircraft. A sleep mode can be provided to conserve power such that the unit is activated only in the presence of threshold acoustic levels. The unit also includes a wireless transceiver for relaying data to a central monitoring authority, which may be a passing or loitering aircraft. Each detection unit may be provided with an address for allowing monitoring of a network of detection units.

Abstract: A remote acoustic detection system includes at least one detection unit delivered to a remote or inaccessible location by a missile or other aircraft. The detection unit monitors acoustic events at the location such as aircraft takeoffs and landings and preferably is provided the capability of classifying the events, for example, as to the event or type of aircraft. A sleep mode can be provided to conserve power such that the unit is activated only in the presence of threshold acoustic levels. The unit also includes a wireless transceiver for relaying data to a central monitoring authority, which may be a passing or loitering aircraft. Each detection unit may be provided with an address for allowing monitoring of a network of detection units.

Abstract: Disclosed is a oscillation isolator having a oscillation-proof support means (2) for supporting a oscillation isolation platform (1), on which a device is mounted, on a pedestal (7) while oscillation of the oscillation isolation platform (1) is reduced. The oscillation isolator is provided with a displacement adjustment mechanism (3) between the oscillation-proof support means (2) and the oscillation isolation platform (1) or pedestal (7) for adjusting relative displacement. The displacement adjustment mechanism has a high rigidity and therefore will not produce significant oscillation in response to an externally applied force.

Abstract: An acoustic sensor system for the detection, location and classification of sound-generating targets, such as helicopters, from a ship includes a base station aboard the ship, having a radio transmitter/receiver (B-Tx/Rx) and a digital signal processor unit (DSP). A plurality of floating remote stations, which in use are positioned remotely from the ship, are each arranged to carry apparatus including an electrical power source, a radio transmitter/receiver (STx/Rx) suitable for two way communication with the B-Tx/Rx, a control unit, sound detectors, and a data processor (DP). The control unit is responsive to signals transmitted from the B-Tx/Rx and received by the S-Tx/Rx for controlling provision of electrical power for the apparatus. The DP is operative to classify electrical signals generated by the sound detectors in response to the reception thereby of sound signals, and to initiate, dependent upon classification, transmission of data from the S-Tx/Rx to the B-Tx/Rx appertaining to the sound signals.

Abstract: A passive target detection system for use with a moving platform which indes a module for postulating modeled target signals based upon a number of factors including at least one factor selected from the group consisting of signal beam pattern, frequency, non-linear signal progression and carrier movement; a receiver for receiving signals from a target; and a comparison unit for comparing the signals with the modeled target signals, for determining location of the target.

Abstract: A covert aircraft detection system for a submarine is described which inces an acoustic antenna array and a signal processor to process the acoustic signals to provide the location of the detected aircraft and to classify the detected aircraft. The acoustic antenna array is mounted on the submarine mast and includes a vertically extending rod having a microphone and connected thereto three or more folding legs having microphones connected thereto. The microphones detect the aircraft acoustic signals and these signals are transferred to the signal processor which provides the location of the aircraft and matches the acoustic signal with the database of aircraft acoustic signals to classify the type of aircraft. When the acoustic antenna array is connected to a rotatable mast, such as a periscope, a rotary encoder and mast bearing indicator are utilized to account for the rotation of the acoustic antenna array and the rotation of the mast, respectively.

Abstract: The present invention comprises a method for filling in missing data intels in a quantized time-dependent data signal that is generated by, e.g., an underwater acoustic sensing device. In accordance with one embodiment of the invention, this quantized time-dependent data signal is analyzed to determine the number and location of any intervals of missing data, i.e., gaps in the time series data signal caused by noise in the sensing equipment or the local environment. The quantized time-dependent data signal is also modified by a low pass filter to remove any undesirable high frequency noise components within the signal. A plurality of mathematical models are then individually tested to derive an optimum regression curve for that model, relative to a selected portion of the signal data immediately preceding each previously identified data gap.

Abstract: An alerting process is presented that uses the steps of first receiving at least a first signal from a signal source for a predetermined short interval. The first signal is analyzed over the predetermined short interval to obtain the spectral energy of the first signal within contiguous incremental frequency bands that extend over the frequency spectrum of interest. The energy value obtained for each incremental frequency band is then stored as a short term integrated value in a memory at an address location corresponding to the incremental frequency. Successive short term integrated values are then integrated over a predetermined long term interval to obtain a long term integrated value for each respective incremental frequency band. Each short term integrated value is then divided by the corresponding long term integrated value to obtain an enhanced STI frequency value for each incremental frequency band.

Abstract: A device and a method for locating and counting insects in agricultural commodities has been developed. Acoustic sensors pick up sounds emanating from adult and or larval insects. The electrical outputs of the sensors are amplified and analyzed to determine (1) the first sensor to detect the sound, (2) the second sensor to detect the sound and (3) the time difference between the first and second detection. These determinations are used to calculate the locations and numbers of insects in the agricultural commodity samples.

Abstract: A method and apparatus for processing a set of signals to identify narrow bandwidth features of the signals, and optionally to process the signals further to extract information about the identified narrow-band features. The invention processes a set of input signal frames (a multi-dimensional pixel array) to generate a narrow-band feature signal (also a multi-dimensional pixel array) from which narrow-band features of the input signal frames can be efficiently, automatically, and unambiguously identified. In a class of preferred embodiments, the input signal frames are the power spectra of a set of sequentially measured signals. Thus, the set of input signal frames is a "spectrogram," comprising rows and columns of pixels (with row indices representing time, and column indices representing frequency). Alternatively, the input signal frames represent a data array of another type, such as a correlogram or a sequence of images.

Abstract: This invention provides an apparatus including a plurality of omnidirectional hydrophone sensors in a particularly configured array comprised of ring members which are carried between a plurality of tensioned cables, the cables being tensioned by an anchor weight at the bottom end of the array and a capsule float at the top end, the configuration enabling simplified signal processing techniques to achieve sound source discrimination in both azimuth and elevation within an underwater environment.

Abstract: In the computer interpretation of seismic data, the critical first step is to identify the general class of an unknown event. For example, the classification might be: teleseismic, regional, local, vehicular, or noise. Self-organizing neural networks (SONNs) can be used for classifying such events. Both Kohonen and Adaptive Resonance Theory (ART) SONNs are useful for this purpose. Given the detection of a seismic event and the corresponding signal, computation is made of: the time-frequency distribution, its binary representation, and finally a shift-invariant representation, which is the magnitude of the two-dimensional Fourier transform (2-D FFT) of the binary time-frequency distribution. This pre-processed input is fed into the SONNs. These neural networks are able to group events that look similar. The ART SONN has an advantage in classifying the event because the types of cluster groups do not need to be pre-defined.

Abstract: An ultrasonic imaging system for displaying color flow images includes a receiver which demodulates ultrasonic echo signals received by a transducer array and dynamically focuses the baseband echo signals. A color flow processor includes a time domain adaptive wall filter which automatically adjusts to changes in frequency and bandwidth of the wall signal components in the focused baseband echo signals. The mean frequency of the resulting filtered baseband echo signals is used to indicate velocity of flowing reflectors and to control color in the displayed image.

Abstract: A sensor for detecting acoustic energy emitted by a target is disclosed. The sensor comprises a housing including a plurality of transducers for receiving acoustic energy. The transducers are randomly deployed within a predetermined area around the housing, forming an array and a self-survey technique is utilized to determine the positions of the sensors. Beamforming techniques are utilized to analyze the acoustic energy detected by the transducers to provide the azimuth of a target and a class estimate of the target. A plurality of sensors may be utilized to provide target location, course and velocity.

Abstract: A swimming pool alarm responsive to wave motion that will produce a signal when two waves exceeding a threshold level of amplitude are sensed within a preset duration of time. A transducer senses air or water pressure changes and produces electrical signals corresponding to the changes. A comparator system, connected to the transducer, receives the transducer signals and, if the signals exceed a preset threshold level, transmits a signal to the discriminator system. The discriminator times the signals received from the comparator and when two signals are received within a specified period of time, a third signal is generated. A warning device such as an alarm is connected to the discriminator and will be activated by the third signal.

Abstract: A method and apparatus for processing a set of signals to identify narrow bandwidth features of the signals, and optionally to process the signals further to extract information about the identified narrow-band features. The invention processes a set of input signal frames (a two-dimensional pixel array) to generate a narrow-band feature signal (also a two-dimensional pixel array) from which narrow-band features of the input signal frames can be efficiently, automatically, and unambiguously identified. In a class of preferred embodiments, the input signal frames are the power spectra of a set of sequentially measured signals. Thus, the set of input signal frames is a "spectrogram," comprising rows and columns of pixels (with row indices representing time, and column indices representing frequency). Alternatively, the input signal frames represent a data array of another type, such as a correlogram or a sequence of images.

Abstract: A new method for measurement of the directional spectra of surface gravity (water) waves. Measurements are made at a single point by orthogonally mounted seismometers buried below the seabed surface and a pressure sensor resting on the seafloor or buried below the seabed. The maximum entropy principle is used to find the directional distribution function for the waves traveling through the sediments as measured by the seismometers. This function is combined with the frequency spectra of the ocean surface waves to form the directional spectra of the surface gravity waves. The method produced high directional resolution for instruments that were adequately coupled with the seabed. The method is also capable of detecting objects moving through water, such as surface ships and submarines.

Abstract: A system and method of indirect underwater acoustic ocean surveillance is sclosed requiring at least two sonar platforms, usually ships, travelling some distance apart. At least one of the platforms transmits sonar pulses, portions of which are scattered off the ocean floor to at least one companion sonar receiver platform. The receiver platform is provided with means to analyze the received scattered sonic pulses to determine if a submerged object such as a submarine is obstructing a portion of the pulse, thus casting an acoustic shadow. With accurate positioning information supplied by a navigation information system such as the NAVSTAR GLOBAL POSITIONING SYSTEM (GPS), and by combining pulse measurements over several positions the system will be able to locate, identify, and track the obstructing object by analyzing these acoustic shadows or silhouettes. Geometric silhouette reconstruction techniques and other mathematical techniques may be employed to construct an image of the submerged object.

Abstract: A firing circuit for use in booby traps providing four different operatio modes. A capacitor stores energy which is discharged through an electrical detonator upon the activation of a silicon controlled rectifier. The silicon controlled rectifier is activated by transistor circuitry in the event of supply voltage depletion or the physical parting of a break-wire by a target. It is also activated by a delay-timer for timed self-destruction and by circuitry responsive to vibrations in the firing circuit generated by the target.

Abstract: A method for combating a submerged target object through the intermediary of an active body which is deployable in an airborne mode, and which picks up a sonar contact with the target object from a helically descending searching trajectory below the water level. Also disclosed is an arrangement for combating a submerged target object, especially a double-hulled submarine, through the intermediary of an active body deployable in an airborne mode which is equipped with a sonar installation and with guidance media for the traversing of a helical gliding search trajectory. Upon contacting a target through the intermediary of a searching sonar which is more simply constructed in comparison with a homing sonar, the active body launches an effector which is equipped with an extremely rapid drive into linear attacking trajectory tangentially to the searching trajectory, and wherein the effector will detonate a warhead upon impact against a target.

Abstract: An apparatus for detecting a person in a body of water includes a transmitter for generating an electrical swept frequency signal having a frequency that continuously varies between upper and lower limits, at least one pair of transducers disposed in a body of water including a transmitting transducer connected to receive the swept frequency signal for launching a beam of acoustical waves in response to the swept frequency signal in the body of water and a receiving transducer disposed opposite the transmitting transducer for receiving the acoustical waves and for converting received acoustical waves into an electrical received signal, and a receiver connected to the receiving transducer for producing a detected signal in response to the received signal, for producing a threshold signal in response to the detected signal, and for initiating an alarm when the detected signal falls below the threshold for at least a predetermined length of time.

Abstract: Intrusion detection apparatus for use in perimeter security systems and the like is provided with multiple channel signal processing. Each signal processor includes a bandpass filter whose passband is selectable. Each is respectively responsive to sensed movement including vibrations within the associated selected passband. An output affirmative signal is generated if the amplitude of the input signal constituent within the associated frequency range exceeds a threshold level for a predetermined period of time. A logic circuit receives the outputs of all of the signal processors and provides an output alarm signal when a predetermined combination of affirmative signals is received from the signal processors. Such logic circuit preferably works with digital signals obtained by analog-to-digital conversion.

Abstract: An alarm device is placed in the water of a swimming pool for monitoring the swimming pool by triggering an alarm in response to changes in water pressure or sound as a result of persons falling into the swimming pool. The device includes a switch element and wave detector, as well as an acoustic alarm. A covering device or shelf, placed below the water surface and above the detector device is an integral component of the alarm device. The covering device includes a parabolically designed wall which is placed around the detector and is in hydraulic connection with it.

Abstract: A method is disclosed in which the direction and range of sound generating targets (2) is determined solely by means of passive sensors (10, 11). In this connection it is proposed to employ a seismic sensor (10) in addition to the acoustic sensors (11) customarily required for a bearing angle determination. In this case, a line characteristic of the signal source of the target (2) is measured in the airborne sound spectrum as well as in the solid-borne sound spectrum and the radial target velocity (V.sub.z,r) is determined from the Doppler shift of these lines and the propagation velocity (C) of the corresponding waves and, under consideration of the bearing angle (.alpha.), the target range (r) is calculated therefrom.

Abstract: An underwater transducer system reproduces high-fidelity audio signals underwater, and detects and monitors low levels of sound activity, both adjacent to a body of water such as a swimming pool, and in the water. The system includes an underwater housing for a diaphragm that directly contacts the water, a coil assembly movable within the housing and rigidly connected to the center of the diaphragm by a tubular member of the coil assembly engaging a cylindrical boss portion of the diaphragm. The housing can be suspended by an elongated cord member from a wall coping, or mounted within a wall fixture structure. The system can have a source of illumination, a conduit from the source terminating in the housing on the coil axis proximate the diaphragm, and an optical element sealingly protrudes the diaphragm for transmitting light-amplified illumination into the water.

Abstract: A system for detecting the approach of a vehicle toward the line of sight an antenna comprises an alerter for receiving an acoustic noise signal from the vehicle and determining whether the signal is increasing or decreasing. The increase of a noise signal indicates the approach of a vehicle and is used to activate a power supply to supply power to a digital signal processor. The digital signal processor receives the acoustic signal and performs a comparison to determine whether the signal in fact is noise produced by a vehicle. If so, the digital signal processor activates a radar based primary sensor which more accurately detects the approach of the vehicle and determines the instant at which the vehicle passes an antanna of the sensor. When the vehicle passes the antenna, the digital processor receives data and produces an output signal that can be used to activate a counter to count the passage of vehicles, surveillance equipment or to fuse a mine if the vehicle is assumed to be hostile.