Abstract: A sensor and sensing method are provided in which a ghost which significantly occurs when only higher frequencies are present can be reduced, and a high directivity which is not obtained when only lower frequencies are present can be obtained. A sensor 100 for detecting a direction of an object to be sensed (target), includes a sensing section 102 configured to sense wave motions having a plurality of frequencies which come from the target 2, an information acquisition section 106 configured to acquire information about incoming directions of the wave motions, and a determination section configured to determine the direction of the target 2. The sensing section 102 senses at least a first wave motion having a first one of the plurality of frequencies and a second wave motion having a second one of the plurality of frequencies.

Abstract: An ultrasonic distance-measuring sensor assembly and an ultrasonic distance-measuring sensor thereof are disclosed. The ultrasonic distance-measuring sensor includes at least two piezoelectric actuators and a member. The member includes a side wall, at least two vibration generating/receiving surfaces and a partition. The vibration generating/receiving surfaces accommodate the piezoelectric actuators as sources. The side wall surrounds the vibration generating/receiving surfaces. The partition is disposed between the vibration generating/receiving surfaces and includes a slot. The slot is disposed between the vibration sending/receiving surfaces.

Abstract: A position detection method, system, and computer readable article of manufacture tangibly embodying computer readable instructions for executing the method for detecting the position of a sound source using at least two microphones. The method includes the steps of: emitting a reproduced sound from the sound source; observing the reproduced sound and an observed sound at the microphones; converting the reproduced sound and the observed sound into electrical signals; transforming the signals of the reproduced sound and of the observed sound into frequency spectra by a frequency spectrum transformer apparatus; calculating Crosspower Spectrum Phase (CSP) coefficients of the frequency spectra of the signals by a CSP coefficient calculator apparatus; and calculating distances between the position of the sound source and the positions of the microphones based on the calculated CSP coefficients by a distance calculating apparatus, thereby detecting the position of the sound source.

Abstract: A computer-implemented method of discriminating a surface from a subsurface sound-generating target in the water includes identifying an arrival angle of sound generated by the sound-generating target and received by a sound receiver at a known depth in the water. The method also includes generating a probability density function about the measured arrival angle having a corresponding plurality sound arrival angles and mapping the probability density function about the measured arrival angle to a probability density function of vertex depths. The method also includes calculating a probability that the depth of the sound-generating target is greater than a threshold depth by integrating the probability density function of vertex depth. A computer readable storage medium has instructions for implementing the above method and a system has modules for implementing the above method.

Abstract: An apparatus and method for providing indoor detection, location, position, or track determination of object devices using building information and/or powerlines. An object device may determine the dimensions of the interior of a building and compare it to known information about the dimensions of the building to determine that it's indoors and/or also determine its exact location or position in the building. An object device may also determine dimensions in an enclosure in order to identify if it is in an automobile, aircraft, or any other conveyance.

Abstract: A system for estimating a location of the source of a projectile includes a radar system for transmitting a wave and detecting and providing an indication of a wave reflection from the projectile, an acoustic detection system for detecting and providing an indication of at least one sound associated with the projectile, and circuitry for estimating the location in response to the indication of a wave reflection and the indication of at least one sound.

Abstract: A system for determining loudspeaker position estimates comprises motion sensors (201, 203, 205) arranged to determine motion data for a user movable unit where the motion data characterizes movement of the user moveable unit. A user input (207, 209) receives user activations which indicate that at least one of a current position and orientation of the user movable unit is associated with a loudspeaker position when the user activation is received. The user activation may for example result from a user pressing a button. An analyzing processor (211) then generates loudspeaker position estimates in response to the motion data and the user activations. The system may e.g. allow a speaker position estimation to be based on a handheld device, such as a remote control, being pointed towards or positioned on a speaker.

Abstract: A sound direction estimation apparatus includes a sound source model storage unit that stores likelihood of a sound source class in correspondence with a sound feature quantity, a sound signal input unit that receives a sound signal, a sound source identification unit that identifies a sound source class of the sound signal input from the sound signal input unit with reference to the sound source model storage unit based on the sound feature quantity of the sound signal, and a first sound source localization unit that estimates a sound direction of the sound signal of the sound source class identified by the sound source identification unit.

Abstract: Provided is a rotary type distance estimation apparatus. The rotary type distance estimation apparatus includes: a signal transmission unit transmitting a signal for measuring a distance to an obstacle; a signal reception unit receiving the signal reflected by the obstacle; a distance calculation unit calculating the distance to the obstacle by processing the received signal; a rotation unit rotating a direction of the signal transmitted from the signal transmission unit; and a determination unit determining the direction of the signal within a predetermined angle range according to what number of times the received signal matches based on a rotation angle per sampling of the signal.

Abstract: An acoustic treatment apparatus obtains a first output signal by performing filtering for forming a directivity in a first direction for received sound signals of sound receivers, obtains a second output signal by performing filtering for forming a directivity in a second direction different from the first direction for received sound signals of sound receivers, obtains a strength ratio between a strength of the first output signal and a strength of the second output signal, and estimates a sound source direction on the basis of the strength ratio.

Abstract: A method for localizing the range and bearing of a distant underwater object includes firing a preselected number of supercavitating projectiles sequentially from a firing location such that each projectile tracks along substantially the same trajectory. Supercavitating pellets are dispersed from a projectile at a pre-selected range. Acoustic signals are sensed to detect acoustic signals caused by supercavitating pellet impact with an object. These signals can be processed to determine the range and bearing to the object. In further steps the range and bearing can be used to aim the projectiles.

Abstract: User-wearable sensor arrays for use with projectile-detection systems, and methods of detecting a projectile with user-wearable sensor arrays.

Abstract: In accordance with some embodiments of the present disclosure, a process for determining a direction vector of a sound source is described. The process may be implemented to detect, by a first sound sensor, a first sound pressure of a sound wave propagated from the sound source, and detect, by a second sound sensor, a second sound pressure of the sound wave. The process may further be implemented to determine, by a processor, the direction vector of the sound source relative to the first sound sensor and second sound sensor, wherein the direction vector is based on the first sound pressure, the second sound pressure, and a first distance between a first physical location of the first sound sensor and a second physical location of the second sound sensor.

Abstract: An autonomous sonar system and method provide an arrangement capable of beamforming in three dimensions, detecting loud targets, adaptively beamforming in three dimensions to avoid the loud targets, detecting quiet targets, localizing the loud or quiet targets in range, bearing, and depth, detecting modulation of noise associated with propellers of the loud or quiet targets, generating three dimensional tracks of the loud or quiet targets in bearing, range and depth, making classification of the loud or quiet targets, assigning probabilities to the classifications, and generating classification reports according to the classifications for communication to a receiving station, all without human assistance.

Abstract: A method for short range alignment using ultrasonic sensing is provided. The method includes shaping an ultrasonic pulse on a first device to produce a pulse shaped signal and transmitting the pulse shaped signal from the first device to a second device, receiving the pulse shaped signal and determining an arrival time of the pulse shaped, identifying a relative phase of the pulse shaped signal with respect to a previously received pulse shaped signal, identifying a pointing location of the first device from the arrival time and the relative phase, determining positional information of the pointing location of the first device, and reporting an alignment of three or more points in three-dimensional space. Other embodiments are disclosed.

Abstract: Localization of remote devices by: the emission of pulses from acoustic transmitters, whose wavefronts propagate in the space region occupied by the remote devices and finally reach them; the emission of radiofrequency pulses from each remote device at the time of detection of the wavefront by an on-board microphone; the acquisition, by a radio base, of the radiofrequency signals propagating from the remote devices, to evaluate the arrival time delays proportional to the distance between the i-th acoustic source and the j-th remote device; the formation of a reception vector for each emission by the i-th source, this vector having a maximum length M equal to the number of remote devices and consisting of the sequence of distances obtained as the product of the reception times and the estimated sound velocity. These steps are repeated for all acoustic sources, to form N+1 reception vectors, to calculate the position of the device by solving derived matrix equations.

Abstract: Described is modeling a room to obtain estimates for walls and a ceiling, and using the model to improve sound source localization by incorporating reflection (reverberation) data into the location estimation computations. In a calibration step, reflections of a known sound are detected at a microphone array, with their corresponding signals processed to estimate wall (and ceiling) locations. In a sound source localization step, when an actual sound (including reverberations) is detected, the signals are processed into hypotheses that include reflection data predictions based upon possible locations, given the room model. The location corresponding to the hypothesis that matches (maximum likelihood) the actual sound data is the estimated location of the sound source.

Abstract: To assess the effectiveness of advertising campaigns and channels, a portable user appliance is provided to each of a plurality of panel members. Each device includes a scanning module for scanning and storing a UPC code for each product purchased by a corresponding panel member, a processor, a memory, a user-interface, and a communication interface operative to transfer information stored in memory to a central facility. Each device further includes a microphone and is operative to monitor an audio portion of at least one of a radio broadcast and a television broadcast. UPC codes and information corresponding to purchases made by each respective panel member are received from the portable user appliances, as are transmissions from which the identities of advertisements included in monitored audio portions can be determined.

Abstract: Provided are an apparatus allowing a moving robot to localize a user, or localizing the moving robot from a fixed location, and a method and medium thereof. The apparatus includes a motion controller to control the moving robot such that the sensor passes a plurality of measurement points by rotating the moving robot, a distance measuring unit, which includes the sensor that senses predetermined waves generated from the transmitter, to measure distances between the sensor and the transmitter at the plurality of measurement points, a rotational angle measuring unit to measure rotational angles of the moving robot at the measurement points, and a location calculator to calculate relative locations using input values of the measured distances, the measured rotational angles, and the radius of a circle determined by the sensor resulting from the rotation of the moving robot.

Abstract: A ballistic-acoustic transducer system includes a processor and one or more acoustic sensors. The sensors are positioned in a body of water and are in communication with the processor. The system is configured such that acoustic energy generated by a non-explosive projectile as it impacts the water, enters the water, and sinks through the water, is sensed by the one or more acoustic sensors, and the processor is configured to process the acoustic energy sensed by the one or more acoustic sensors.

Abstract: The invention relates to a method for determining the location of an impact on a surface of an object based on the analysis of an acoustic signal generated by the impact. This method further comprises a signal treatment step of weighting the acoustic signal to take into account spurious contributions in particular due to reflections at the border of the object.

Abstract: A distance sensor equipped with a mount for mounting the sensor in a mount hole of a bumper of a vehicle. The mount includes a casing with a sensor holder, a bezel, and a resin-made retainer. The bezel is made up of a cylindrical member joined to the sensor holder and a flange having an outer diameter greater than an inner diameter of the mount hole. The retainer includes an annular base joined to the bezel, a plurality of arms, and a plurality of protrusions. The protrusions extend from ends of the arms radially outward of the base and serve to establish a snap-fit on a peripheral edge of the mount hole, thereby nipping a wall of the bumper between the protrusions and the flange tightly to secure the distance sensor to the bumper.

Abstract: A handsfree communication system includes microphones, a beamformer, and filters. The microphones are spaced apart and are capable of receiving acoustic signals. The beamformer compensates for propagation delays between the direct and reflected acoustic signals. The filters are configured to a predetermined susceptibility level. The filter process the output of the beamformer to enhance the quality of the received signals.

Abstract: A system for an adaptable aperture planar array for maintaining source resolution is provided. The system includes a first nested array defining a first aperture responsive to a first range of frequencies. The first aperture is sized based on an angle between the array and the source, and includes a first subset of sensor elements. The system includes a second nested array defining a second aperture responsive to a second range of frequencies that is less than the first range of frequencies. The second aperture is sized based on the angle between the array and the source, and includes a second subset of sensor elements. The first aperture and second aperture change in size as the angle changes, which results in a change in the sensor elements within the first subset and the second subset to maintain the source resolution for the array.

Abstract: A novel beamforming post-processor technique with enhanced noise suppression capability. The present beam forming post-processor technique is a non-linear post-processing technique for sensor arrays (e.g., microphone arrays) which improves the directivity and signal separation capabilities. The technique works in so-called instantaneous direction of arrival space, estimates the probability for sound coming from a given incident angle or look-up direction and applies a time-varying, gain based, spatio-temporal filter for suppressing sounds coming from directions other than the sound source direction resulting in minimal artifacts and musical noise.

Abstract: A novel adaptive beamforming technique with enhanced noise suppression capability. The technique incorporates the sound-source presence probability into an adaptive blocking matrix. In one embodiment the sound-source presence probability is estimated based on the instantaneous direction of arrival of the input signals and voice activity detection. The technique guarantees robustness to steering vector errors without imposing ad hoc constraints on the adaptive filter coefficients. It can provide good suppression performance for both directional interference signals as well as isotropic ambient noise.

Abstract: An underwater device receives underwater signals from a pair of beacon units. Based on these signals, a processing circuit in the device determines a distance and a direction to each beacon unit. The underwater device also measures a depth for the device, and an angle of arrival of one or both of the incoming signals. Based on the distances to the two beacon units, the depth of the device, and the measured angle of arrival, the processing circuit can determine a current underwater location for the device.

Abstract: A device for acoustic display of a position of an object in a reproduction space, a plurality of loudspeakers being arranged in the reproduction space at spatially different positions such that different spatial positions may be represented acoustically by differently driving the loudspeakers, includes a signal associater and a loudspeaker driver. The signal associater is configured to associate an acoustic signal to the object. The loudspeaker driver is configured to establish one or several loudspeaker signals for the plurality of loudspeakers, wherein the one or several loudspeaker signals by which the position of the object is displayed are based on the acoustic signal associated to the object by the signal associater. The one or several loudspeaker signals may be established such that, when reproducing the one or several loudspeaker signals, the position of the object in the reproduction space is displayed acoustically.

Abstract: A high velocity acoustic signal producing underwater shotgun system for dispersing a plurality of relatively small supercavitating projectiles over a wide spatial field at long range using the dynamics of cavity collapse for better target localization in underwater mine clearance. A typical supercavitating projectile design is enhanced to produce a two-staged projectile in order to accomplish this innovation. The first stage of the two stage design allows for the long range firing underwater typical of a supercavitating projectile while the second stage permits the coverage of a wide area with a plurality of small supercavitating projectiles just as the first stage projectile reaches its fixed range. A distinctive feature of the radiated noise from a supercavitating projectile contacting a solid object is used in conjunction with the two stage projectile design to provide a system for underwater mine clearance verification.

Abstract: A system for localizing an acoustic source is provided. This system includes a microphone apparatus, an audio processing apparatus, a photographing apparatus, and a decision apparatus. The microphone apparatus receives an acoustic signal and generates at least one received audio signal. The audio processing apparatus generates first location information based on the at least one received audio signal. The decision apparatus generates depth information based on at least one image captured by the photographing apparatus. According to the first location information, the at least one captured image, and the depth information, the decision apparatus determines a location corresponding to the source of the acoustic signal.

Abstract: The adaptive beamformer unit (191) comprises: a filtered sum beamformer (107) arranged to process input audio signals (u 1, u2) from an array of respective microphones (101, 103), and arranged to yield as an output a first audio signal (z) predominantly corresponding to sound from a desired audio source (160) by filtering with a first adaptive filter (f1(-t)) a first one of the input audio signals (u1) and with a second adaptive filter (f2(-t)) a second one of the input audio signals (u2), the coefficients of the first filter (f1(-t)) and the second filter (f2(-t)) being adaptable with a first step size (a1) and a second step size ((x2) respectively; noise measure derivation means (111) arranged to derive from the input audio signals (u1, u2) a first noise measure (x1) and a second noise measure (x2); and an updating unit (192) arranged to determine the first and second step size (a1, (x2) with an equation comprising in a denominator the first noise measure (x1) for the first step size (a1), respectively the

Abstract: An obstacle avoidance system having an ultrasonic sensor is provided. The system includes an ultrasonic sensor array having at least one ultrasonic sensor for measuring a distance to an obstacle using an ultrasonic wave, an orientation tracker for tracking a proceeding direction, an controller for receiving distance data and orientation data from the ultrasonic sensor array and the orientation tracker, respectively, and for determining an avoidance orientation based on the distance data and the orientation data, and an avoidance orientation guiding unit for informing the pedestrian of the avoidance orientation determined by the controller. The controller stores distance data for a certain number of previous frames and, if the controller determines that distance data of a first frame is noise, the distance data of the first frame is replaced with an average between the distance data of a frame prior to the first frame and the distance data of a frame after the first frame.

Abstract: A computer-implemented method of discriminating a surface from a subsurface sound-generating target in the water includes identifying an arrival angle of sound generated by the sound-generating target and received by a sound receiver at a known depth in the water. The method also includes generating a probability density function about the measured arrival angle having a corresponding plurality sound arrival angles and mapping the probability density function about the measured arrival angle to a probability density function of vertex depths. The method also includes calculating a probability that the depth of the sound-generating target is greater than a threshold depth by integrating the probability density function of vertex depth. A computer readable storage medium has instructions for implementing the above method and a system has modules for implementing the above method.

Abstract: Disclosed herein is a signal processing apparatus and method for removing a reflected wave generated by a robot platform. The signal processing apparatus includes a transfer function measuring unit for measuring an inter-channel transfer function (IcTF) from signals of a plurality of channels; an impulse response obtaining unit for obtaining an inter-channel impulse response (IcIR) from the IcTF measured by the transfer function measuring unit; and reflected wave removing unit for removing the reflected wave by differentiating a direct wave directly generated by a sound source and the reflected wave with a time delay from the IcIR obtained by the impulse response obtaining unit. The signal processing method of removing a reflected wave includes measuring an IcTF from signals of a plurality of channels; obtaining an IcIR from the measured IcTF; and removing the reflected wave by differentiating a direct wave directly generated by a sound source and a the reflected wave with a time delay from the obtained IcIR.

Abstract: Method of multi-parameter direction finding of several sources in an array of N sensors, comprising at least the following steps: a) choosing a parameter to be determined, or parameter of interest, b) expressing the direction vector in the form of a linear relation between the parameter of interest chosen and the secondary parameters b0(?, ?0)=U0(?) ?0(?0), c) applying a MUSIC-type direction finding step by factorizing the criterion serving for the determination of the angles of incidence so as to determine at least the incidence parameter, d) on the basis of the incidence value, determining the vector representative of the secondary parameters and expressing this vector in the form of a linear relation between a chosen parameter to be determined and the other secondary parameters, e) applying a MUSIC-type direction finding step by factorizing the criterion serving in the determination of the chosen parameter, f) repeating steps d) to e) so as to determine the majority or the whole set of secondary parameters

Abstract: A method for tracking motion using an audio compass is disclosed. The method comprises receiving motion sensor data indicating seismic activity recorded by at least two seismic sensors, and converting the received motion sensor data into audio signals for interpretation at an audio compass. The method uses the audio compass to determine a current distance to the seismic activity based on an interpreted signal intensity of the audio signals. The method further uses the audio compass to identify a current position of the audio compass relative to the seismic activity.

Abstract: A rehabilitation device includes a moving body, a motor, a control system and a sensor module. The moving body has a housing and a moving mechanism. The motor, disposed in the housing, connects to the moving mechanism and drives the moving mechanism. The control system is disposed in the housing and coupled to the motor. The sensor module is disposed on the moving body and coupled to the control module. The control system controls the operation of the motor to move the moving body according to information detected by the sensor module.

Abstract: A method and apparatus for detecting the launch position of a projectile is described. The apparatus includes at least one wideband microphone array positioned so as to be responsive to acoustic emissions generated by the launch and flight of a projectile. The apparatus includes signal processing means, for processing the signals generated by the microphone array or arrays, the output of which provides an estimate of launch position and kinematic information relating to the projectile.

Abstract: A method and an apparatus for passive determination of target parameters by directionally selective reception of sound waves emitted or transmitted from a target, by an arrangement (24) of underwater sound sensors of a sonar receiving installation from estimated bearing angles determined from estimated positions of the target, and bearing angles measured at the measurement point by the arrangement (24). A bearing angle difference between measured and estimated bearing angles is iteratively minimized and, when the minimum is reached, the target parameters are used for an optimized solution for outputting target position, course, range and/or velocity and they are updated during each processing cycle in a series of successive processing cycles.

Abstract: The subject matter disclosed herein relates to determining a distance from a mobile device to a remote object or a size of the remote object.

Abstract: A high velocity acoustic signal producing underwater shotgun system for dispersing a plurality of relatively small supercavitating projectiles over a wide spatial field at long range using the dynamics of cavity collapse for better target localization in underwater mine clearance. A typical supercavitating projectile design is enhanced to produce a two-staged projectile in order to accomplish this innovation. The first stage of the two stage design allows for the long range firing underwater typical of a supercavitating projectile while the second stage permits the coverage of a wide area with a plurality of small supercavitating projectiles just as the first stage projectile reaches its fixed range. A distinctive feature of the radiated noise from a supercavitating projectile contacting a solid object is used in conjunction with the two stage projectile design to provide a system for underwater mine clearance verification.

Abstract: A measuring method and a device are adapted for the positioning of a wheel for mash seam resistance welding in the butt-joining of steel strips on continuous processing lines. A rotary roller which is fastened to a movable frame is positioned in a measuring position. The measuring position is vertically below a reference wheel. The reference wheel is continuously vertically lowered so that its lower surface comes into contact with the rotary roller and produces a bearing force on the roller. The roller is continuously moved in the direction of lowering. A distance between an index, which is secured to a measuring arm of the frame, and an articulated column of the frame is repeatedly measured during the continuous movement. The distance is compared with a distance threshold for each of the repeated measurements until the wheel reaches a first operating position in which the distance is equal to a predefined factor of the distance threshold.

Abstract: A system and method for selecting an object from a plurality of objects in a physical environment is disclosed. The method may include analyzing acoustic data received by a plurality of acoustic sensors, detecting a snapping sound in the acoustic data, determining the direction of the snapping sound, estimating the distance to an object based on loudness measurements of the snapping sound detected in the acoustic data, and determining the location of the object relative to the system based at least in part on the determined direction, the estimated distance to the object and the location of the system. The method may further include identifying the selected object based on its geolocation, collecting and merging data about the identified object from a plurality of data sources, and displaying the collected and merged data.

Abstract: Systems and methods are provided for automatically detecting sonar contacts. The system comprises a data analyzer that integrates the raw data from a plurality of sonar detectors over a predetermined period of time, thereby providing integrated data characterizing a sonar image on a sonar display. A Hough transform module is configured to employ a Hough transform algorithm that transforms at least a portion of the integrated data to detect a substantially straight line in the sonar image.

Abstract: A method of providing assistance to a driver for parking a vehicle includes detection of a space and a location of the vehicle for vehicle parking. The method determines a feasibility for parking the vehicle into the space based on the space; calculates a parking path based on the space and the location; generates a constant target position of a steering wheel based on the parking path; generates a first human machine interface (HMI) signal that instructs the driver to turn the steering wheel based on the target position, wherein the first HMI signal is generated when the vehicle is not moving; monitors a steering wheel angle of the vehicle including comparing the steering wheel angle with the constant target position, and detecting that the steering wheel angle reaches a proximity of the target position.

Abstract: A temperature sensing device for remotely detecting the temperature of a subject having an identifying feature and a target zone in a fixed relationship to the identifying feature comprising: a distance sensor which measures the distance between the subject and the distance sensor; a temperature sensor for measuring a temperature difference in a sensing zone; a digital image capture device for capturing a digital image of the subject; a means of tilting at least the temperature sensor along at least one axis, and preferably tilting and panning along two axes; a controller that actuates the tilting means; and a support for supporting the distance sensor, the temperature sensor and the digital image capture device; wherein the controller tilts the distance sensor using the tilting means to reduce the distance between the target zone and the sensing zone; and a temperature sensor that measures a temperature difference proximate to the target zone, to detect elevated temperature illness in humans or animals.

Abstract: The presently claimed technology relates generally to audio-based, location-related methods. One claim recites a method in which a microphone in a user's portable device captures ambient sound, and corresponding data is then processed to determine location information about the user's location. Action is then taken involving the determined location information. By such arrangement, location information is determined by reference to ambient sound captured by a user-carried portable device. A great number of other features and arrangements are also detailed.

Abstract: Various embodiments of the present invention are directed to systems and methods for multimodal object localization using one or more depth sensors and two or more microphones. In one aspect, a method comprises capturing three-dimensional images of a region of space wherein the object is located. The images comprise three-dimensional depth sensor observations. The method collects ambient audio generated by the object, providing acoustic observation regarding the ambient audio time difference of arrival at the audio sensors. The method determines a coordinate location of the object corresponding to the maximum of a joint probability distribution characterizing the probability of the acoustic observations emanating from each coordinate location in the region of space and the probability of each coordinate location in the region of space given depth sensor observations.

Abstract: A method for determining whether a user having a communications device has encountered a perilous situation includes detecting a sound with the communications device and determining whether the sound is indicative of the perilous situation. The method generates a query with the communications device for the user when the sound is determined to be indicative of the perilous situation and waits for a response from the user via the communications device. The response or lack thereof is capable of confirming the perilous situation or a false alarm.

Abstract: A surveillance system is configured to detect a rotary-wing aircraft approaching a fixed facility and provide a warning upon detection. The system includes acoustic processing nodes that receive acoustic signals from the environment surrounding the fixed facility. As the nodes receive the acoustic signals, the nodes perform a spectral analysis of the signals to detect if the source of the acoustic signals is a rotary-wing aircraft. Additionally, based upon the acoustic signals, the nodes detect an altitude of the rotary-wing aircraft and a distance between the rotary-wing aircraft and the fixed facility. In the case where the system identifies the rotary-wing aircraft as encroaching a predefined geographical area outside of the facility, based upon the altitude and distance between the rotary-wing aircraft and the facility, the system generates a warning to allow security forces to intercept the rotary-wing aircraft prior to its arrival at the facility.