Abstract: Systems and methods are provided for locating threats to an aircraft that are located on the ground. Associated bearings are determined from an aircraft for each of a plurality of detected shots from a threat at ground level. A plurality of pairs of bearings are selected, and a weight value is calculated for each selected pair of bearings. An estimated position for the threat is determined from each selected pair of bearings. An improved estimation of the position for the threat is calculated as a weighted combination of the estimated positions.

Abstract: A method including: receiving acoustic signals originating from an acoustic source at a first pair of microphone elements, arranged symmetrically about a detection point; calculating, with a processor device, a cross correlation of signals provided by the first pair of microphone elements, resulting in a first cross correlation signal; receiving the acoustic signals originating from the acoustic source at a second pair of microphone elements, arranged symmetrically about the detection point; calculating, with the processor device, a cross correlation of signals provided by the second pair of microphone elements, resulting in a second cross correlation signal; and calculating, with the processor device, a direction between the detection point and the acoustic source based on a convolution of the first cross correlation signal by the second cross correlation signal.

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.

Abstract: Directional microphone or microphones for position determination. One or multiple directional microphones are implemented in various locations to perform acoustic wave capture of acoustic waves associated with object (e.g., a player, a gaming object, a game controller, etc.). The generator of such acoustic waves may be co-located with the object (e.g., integrated into the object if the object is a device such as a gaming object, a game controller, etc., or integrated into clothing worn by a player such as on a hat, a jacket, etc.). The acoustic waves described herein may be generated by any number of means/devices including audio output devices, speakers, pulse wave generators, audio oscillators, etc. Moreover, such acoustic waves may be ultrasonic. A game module and/or processing module processes directional vectors associated with positions of the directional microphones when detecting relative maximum amplitude of an acoustic wave emits by an acoustic wave generator.

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: To enable precise calculation of a propagation time of a direct wave which arrives the earliest from an ultrasonic emission source without being affected by a reflected wave. A plurality of ultrasonic signals generated based on a plurality of M sequences different from each other are propagated from a transmission side to a reception side, whereby the reception side executes processing of correlation between each model waveform of the plurality of M sequences and a waveform of each ultrasonic signal and detects a subsidiary peak of a correlation value appearing when both waveforms partly coincide with each other to, starting with the smallest one of subsidiary peaks detected by all the correlation processing, determine a plurality of corresponding M sequences.

Abstract: An energy based technique to estimate the positions of people speaking from an ad hoc network of microphones. The present technique does not require accurate synchronization of the microphones. In addition, a technique to normalize the gains of the microphones based on people's speech is presented, which allows aggregation of various audio channels from the ad hoc microphone network into a single stream for audio conferencing. The technique is invariant of the speaker's volumes thus making the system easy to deploy in practice.

Abstract: The invention relates to a device for localizing acoustic sources and measuring their intensity comprising an antenna having at least two sub-antennas, each sub-antenna having at least two branches disposed in a cross or star shape, each branch being equipped with a plurality of microphones, and a system for processing the signals coming from the microphones, the device being designed to establish, for a frequency higher than a given value fc, an acoustic source hologram, i.e. a distribution of acoustic pressures or intensities at different computation points on a given surface.

Abstract: A method and apparatus for detecting an aircraft. The method is provided for wide area tracking of aircraft. An acoustic emission of the aircraft is detected from a plurality of locations. A position of the aircraft at a set of times is estimated by comparing a set of harmonically related Doppler shifted frequencies for the acoustic emission to an expected zero Doppler shifted frequency of the aircraft to form an estimated position. The position of the aircraft and a heading of the aircraft are tracked using the estimated position. The aircraft type is classified based on the corresponding set of zero Doppler frequencies at each acoustic sensor.

Abstract: A method and a system for detection and position determination of chips, which transmit ultrasound signals in a room. The system comprises electronic identification chips, which are attached to objects that have to be monitored. Each chip is equipped with a transmitter and a receiver. The signals are received by a plurality of detector units, which are connected to a detector base unit that registers and interprets the signals transmitted form the identification chips. Detector base units located in different rooms are interconnected in a network and transmit processed information to one or more central units for further interpretation and sorting. The special feature of the invention is that line interference is substantially removed, and it is possible to determine position even though the identification chips are in motion.

Abstract: System and method for tracking of a head comprising generating and radiating at least one acoustical test signal; receiving the radiated acoustical test signal(s) at two locations at the head under investigation and generating electrical measurement signals therefrom; and evaluating the two measurement signals for determining the position and/or angle of rotation ? from the measurement signals; the evaluation step comprises a cross power spectrum operation of the test signal(s) and the signals from the receivers in the frequency domain.

Abstract: The invention describes a method of determining the distance (d12) between two loudspeakers (L1, L2), wherein the method comprises the steps of providing a test signal (N), combining the test signal (N) with a sound signal (S) to give a combined signal (SN) in which the test signal is imperceptible to a listener (4), and issuing the combined signal (SN) by means of a first loudspeaker (L1). The combined signal (SN) is detected by a detecting means (M2) associated with the second loudspeaker (L2) and processed to obtain an acoustic impulse response (IR), which is used to determine the distance (d1,2) between the first loudspeaker (L1) and the second loudspeaker (L2). The invention further describes a system (1) for determining the distance (d1,2) between two loudspeakers (L1, L2) and an acoustic sound system, comprising a number of loudspeakers (L1, L2, . . . , Lk) for reproduction of multi-channel sound, and a system (1) for determining the distances (d1,2, d2,3, . . .

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: Apparatus (100), systems (110), and methods may operate to generate acoustic emissions from within at least a first borehole (120), receive the acoustic emissions within a second borehole (136), and process the acoustic emissions to locate a borehole bit (132) in formational space as the borehole bit is steered along a path within one of the first borehole or the second borehole. The acoustic emissions may be received by a plurality of acoustic receivers arranged in several ways, including linear and planar arrays. Additional apparatus, systems, and methods are disclosed.

Abstract: A computer implemented method for automatically detecting and classifying acoustic signatures across a set of recording conditions is disclosed. A first acoustic signature is received. The first acoustic signature is projected into a space of a minimal set of exemplars of acoustic signature types derived from a larger set of exemplars using a wrapper method. At least one vector distance is calculated between the projected acoustic signature and each exemplar of the minimal set of exemplars. An exemplar is selected from the minimal set of exemplars having the smallest vector distance to the projected acoustic signature as a class corresponding to and classifying the first acoustic signature. The first acoustic signature and the plurality of acoustic signatures may correspond to one of gunshots, musical instruments, songs, and speech. The minimal set of exemplars may correspond to a hierarchy of acoustic signature types.

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: A method for utilizing a matched field-processing algorithm employing a number of sensors wherein the sensor output is the measured acoustic data as the first input and is translated to a frequency by applying a Fourier transform to a set of time samples as a data vector output. A replica vector is the second data input as a predicted quantity which is computed by an acoustic model with an assumed acoustic location. The output is an ambiguity surface ranging between zero and one with the highest values indicating the likely position of an acoustic location. The matched field response is generalized by averaging the response over multiple frequencies. A response for an array may be computed by forming beams and then combining them by multiplying each by an eigenray factor before summing. The computation of the response may be further defined by voxel interpolation.

Abstract: A method, system, and apparatus are provided for focused ultrasonic acoustic imaging of objects within a body of water. A plurality of echo soundings are collected, the soundings produced by an ultrasonic transmitter and detected by an ultrasonic receiver. Spatial location information of the transmitter and receiver is collected and associated with each collected echo sounding. A focused signal spatial location is selected. One or more of the collected echo soundings are selected. An echo signal from each selected echo sounding is selected. The echo signal selection is determined by a calculation of which echo signal from the selected echo sounding corresponds to a focused signal occurring at the selected focused signal spatial location. The calculation is based on the selected focused signal spatial location and on the collected spatial information associated with the selected echo sounding. The selected echo signals are combined, whereby a focused echo signal is formed.

Abstract: Noise discrimination in signals from a plurality of sensors is conducted by enhancing the phase difference in the signals such that off-axis pick-up is suppressed while on-axis pick-up is enhanced. Alternatively, attenuation/expansion are applied to the signals in a phase difference dependent manner, consistent with suppression of off-axis pick-up and on-axis enhancement. Nulls between sensitivity lobes are widened, effectively narrowing the sensitivity lobes and improving directionality and noise discrimination.

Abstract: The invention relates to a method for localizing and tracking acoustic sources (101) in a multi-source environment, comprising the steps of recording audio-signals (103) of at least one acoustic source (101) with at least two recording means (104, 105), creating a two- or multi-channel recording signal, partitioning said recording signal into frames of predefined length (N), calculating for each frame a cross-correlation function as a function of discrete time-lag values (?) for channel pairs (106, 107) of the recording signal, evaluating the cross-correlation function by calculating a sampling function depending on a pitch parameter (f0) and at least one spatial parameter (?0), the sampling function assigning a value to every point of a multidimensional space being spanned by the pitch-parameter and the spatial parameters, and identifying peaks in said multidimensional space with respective acoustic sources in the multi-source environment.

Abstract: The invention describes a method of determining the distance (d12) between two loudspeakers (L1, L2), wherein the method comprises the steps of providing a test signal (N), combining the test signal (N) with a sound signal (S) to give a combined signal (SN) in which the test signal is imperceptible to a listener (4), and issuing the combined signal (SN) by means of a first loudspeaker (L1). The combined signal (SN) is detected by a detecting means (M2) associated with the second loudspeaker (L2) and processed to obtain an acoustic impulse response (IR), which is used to determine the distance (d1,2) between the first loudspeaker (L1) and the second loudspeaker (L2). The invention further describes a system (1) for determining the distance (d1,2) between two loudspeakers (L1, L2) and an acoustic sound system, comprising a number of loudspeakers (L1, L2, . . . , Lk) for reproduction of multi-channel sound, and a system (1) for determining the distances (d1,2, d2,3, . . .

Abstract: An apparatus and method of voice activity detection (VAD) are disclosed. To detect a target sound, a target sound detecting apparatus calculates the phase difference corresponding to each frequency component from a plurality of sound signals converted in frequency domain, calculates a characteristic value indicating possibility that the phase difference of the frequency component is within an allowable phase difference range of target sound calculated based on a direction angle of the target sound, and detects the presence and/or absence of target sound using the characteristic value.

Abstract: Systems and methods for locating the shooter of supersonic projectiles are described. The system uses at least five, preferably seven, spaced acoustic sensors. Sensor signals are detected for shockwaves and muzzle blast, wherein muzzle blast detection can be either incomplete coming from less than 4 sensor channels, or inconclusive due to lack of signal strength. Shooter range can be determined by an iterative computation and/or a genetic algorithm by minimizing a cost function that includes timing information from both shockwave and muzzle signal channels. Disambiguation is significantly improved over shockwave-only measurements.

Abstract: A method and apparatus for measuring a distance to a sound source. The method includes combining sound source signals input through at least two microphones and generating at least two microphone output signals, and performing an operation on the generated microphone output signals and calculating a distance to a sound source by using the relationship between a result of the operation and a frequency of the input sound source signals. Accordingly, regardless of the strength of a sound source, the distance to a sound source can be measured.

Abstract: A system for small space positioning comprises a transmitting device, movable within an approximate range, configured for transmitting a modulated continuous wave, wherein the modulated continuous wave includes a carrier signal and a base-band signal, and a receiving unit configured for receiving signal (s) transmitted by the transmitting device and for determining a position of the transmitting device within the approximate range based on analysis of both the carrier signal and the base-band signal received from the transmitting device.

Abstract: A standard non-destructive testing probe (4) may be coupled with a localization system (10) according to the invention so as to determine the position of the apparatus (4) on the surface to be analyzed (1) at any moment. The localization system (10) comprises an ultrasonic emitter (12) and two ultrasonic receivers (14, 16) coupled with means for determining the distance between the emitter (12) and the receivers (14, 16), each of the components being able to be moved freely relative to each other. The coupling between the emitter (12) and the probe (4) allows the position of the latter to be determined by triangulation. A localization and mapping method is also described.

Abstract: A sonar system for detecting underwater acoustic signals includes a plurality of hydrophone units capable of converting acoustic impulses to electrical signals, the hydrophone units being substantially vertically oriented when deployed in a body of water, and the hydrophone units occupying at least some of the positions of an M×N horizontal array. Two-dimensional Chebyshev mathematical weighting is applied to the electrical signals from the individual hydrophone units such that each individual signal from each hydrophone unit is assigned a respective weighting number and a numerical value is assigned to each individual signal corresponding to the strength of the electrical signal as adjusted by the respective weighting number.

Abstract: A sound source localizer is provided which includes a receiver (41) composed of a plurality of highly versatile microphones (10) each having a predetermined directivity D, a data base (12) which is to calculate a difference in directional sensitivity between one of the microphones (10) of the receiver (41) pointed in one direction and the other directed at an angle of 180 deg. to the one direction and has pre-stored therein information used for determination of an arrival direction and angle of a sound source, and a calculator (11) for calculating differences in level between signals received by the receiver (41) in different directions to determine the arrival direction, angle and sound level of the sound source with reference to the information stored in the data base (12).

Abstract: The invention is directed to a method comprising receiving input signals emanating from at least two microphone arrays each comprising at least two microphones, processing the input signals of each microphone array by a beamformer to determine temporal and spatial information about the input signals of each microphone array.

Abstract: An acoustical positioning system for positioning a portable electronic device including a loudspeaker system including three or more loudspeakers and a control unit operable according to a first time reference wherein the control unit controls the transmission of a series of audio beacons from the loudspeakers, wherein a first beacon is transmitted at a first time of the first time reference from a first speaker, a second beacon is transmitted at a second time of the first time reference from a second speaker, and a third beacon is transmitted at a third time of the first time reference from a third speaker; at least one portable electronic device operable according to a second time reference and including a synchronizer for synchronising the second time reference to the first time reference; a microphone for receiving the transmitted series of audio beacons; a detector for detecting the time according to the second time reference at which an audio beacon is received and for identifying the origin of the rece

Abstract: In a building environment, a distance associated with a building automation device is determined as a function of an interval or an inserted time delay between a wireless transmission of a signal and wireless reception of another signal. For example, a two-way communication is provided with an automatic interval or a desired time delay inserted before responding to a received transmission. By using two-way transmissions, the building automation devices may be free of clock synchronization. Acoustic signals may be used in a building environment to determine a distance. The building automation device may also use radio frequency information for communicating with other devices.

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: Method for determining the location and/or speed of at least one swimmer, swimming through water, comprising: —sending acoustic signals through the water, using stationary acoustic transmitter means (AT) having a stationary position, or using mobile acoustic transmitter means (AT?) being carried by said swimmer (S); —receiving the acoustic signals using mobile acoustic receiver means (AR) being carried by said swimmer (S), or using stationary acoustic receiver means (AR?) respectively; —determining the time difference between the time of sending and the time of receiving each acoustic signal; —determining a location and/or speed of said swimmer (S) with respect to said stationary transmitter means (AT) or stationary receiver means (AR?), using said time differences and a predetermined propagation speed of the acoustic signal through the water.

Abstract: A method and a system for detection and position determination of chips, which transmit ultrasound signals in a room. The system comprises electronic identification chips, which are attached to objects that have to be monitored. Each chip is equipped with a transmitter and a receiver. The signals are received by a plurality of detector units, which are connected to a detector base unit that registers and interprets the signals transmitted form the identification chips. Detector base units located in different rooms are interconnected in a network and transmit processed information to one or more central units for further interpretation and sorting. The special feature of the invention is that line interference is substantially removed, and it is possible to determine position even though the identification chips are in motion.

Abstract: Described is a system and method for detection using an ultrasonic wave. The system may include a first arrangement and a second arrangement. The first arrangement may include a transmitter and a receiver. The transmitter transmits an ultrasonic wave along a surface on which items are to be stored and the receiver receives the wave after it has passed over the surface. The second arrangement receives from the first arrangement data corresponding to properties of the received wave. The second arrangement compares the properties of the received wave to properties of the transmitted wave to generate current condition value. The second arrangement determines based on the current condition value and calibration data a current condition state corresponding to a degree of the surface currently occupied by the items. The calibration data includes at least one calibration value and a corresponding calibration condition state.

Abstract: Each of multiple probability distribution outputting units computes a probability distribution of a data value detected by the corresponding sensor or algorithm in an image recognition processing or the like. The respective probability distributions of the multiple probability distribution outputting units are given as outputs to a synthetic determination processing unit. Data formats of the outputs to the synthetic determination processing unit can be thereby standardized. Hence, the synthetic determination processing unit is exempted from considering which type of sensor or algorithm each of the outputs is based upon. Even when a sensor or algorithm is added or changed, the same data-fusing algorithm in the synthetic determination processing unit can be uniformly used.

Abstract: In a positional information detecting device, a tone-burst signal propagating unit causes a tone-burst signal to propagate through a path. The tone-burst signal is composed of a continuous wave train, the continuous wave train including a plurality of cycles of a constant frequency. A detecting unit detects, at a predetermined position in the path, the tone-burst signal propagating through the path every one cycle of the tone-burst signal to measure a propagation delay time based on the detected signal. The propagation delay time represents a period for which the tone-burst signal has propagated through the path. A phase obtaining unit obtains a phase of the detected signal. A positional information obtaining unit obtains positional information associated with the predetermined position based on the measured propagation delay time and the obtained phase of the detected signal.

Abstract: The delay between two signals is determined by obtaining zero crossings from each signal, and using each crossing to trigger the sampling of the other signal. Two samples are taken in response to each zero crossing, and the difference between those two samples is calculated. This difference is summed for each event and both signals to derive a value. The process is repeated for different delays between the first and second signals. The values are examined to determine the delay which corresponds to the greatest coincidence between the signals.

Abstract: An apparatus for range-estimating a noise source including a first passive, vertical hydrophone array of at least two receivers at a first distance from the noise source. The apparatus includes a second passive, vertical hydrophone array of at least two receivers at a second distance from the noise source. The apparatus also includes a processor communicating with the first passive, vertical hydrophone array and the second passive, vertical hydrophone array to determine a ratio of the first distance to the second distance.

Abstract: A device for measuring the radius of curvature of a surface comprises a main body that is held above the surface being measured; and a non-contact sensor mounted to the main body that measures a distance between the surface being measured and the sensor, the device calculating the radius of curvature of the surface based on the measured distance. The device can further include a display mounted to the main body that displays the calculated radius of curvature. The non-contact sensor can be, for example, an acoustical distance sensor or an optical distance sensor. In one embodiment, the device includes two arms extending from the main body of the device and being substantially symmetric about the non-contact sensor, the arms terminating in contact points that make contact with the surface being measured.

Abstract: A system and method for detecting, identifying, and fixing the location of the source of an acoustic event. The inventive system includes: a plurality of sensors dispersed at somewhat regular intervals throughout a monitored area; a communication network adapted to deliver information from the sensors to a host processor; and a process within the host processor for determining, from the absolute times of arrival of an event at two or more sensors, a position of the source of the event. Acoustic events are detected and analyzed at each sensor so that the sensor transmits over the network: an identifier for the sensor; an identifier for the type of event; and a precise absolute time of arrival of the event at the sensor. In a preferred embodiment, the system also identifies the type of weapon firing a gunshot.

Abstract: A system and method for archiving and retrieving information from an array of remote sensors. In a preferred embodiment the invention is incorporated in a gunshot detection and location system to preserve audio information surrounding a gunshot event for later review or analysis. In a preferred embodiment the system includes a plurality of acoustic sensors deployed in an array, a computer for processing gunshot information from the sensors, and a mass storage device for temporary archival of audio information. When a gunshot event is detected, the location of the audio information of the data within the spool is stored in an index to facilitate later retrieval of the information.

Abstract: Systems and methods for determining and disambiguating the location of the shooter of supersonic projectiles based on shockwave-only signals are described. Using several spaced sensors, an initial portion of the shockwave-only signals is sensed to determine Time-Differences-Of-Arrival (TDOA) for the sensor pairs. The resulting TDOAs are used to determine the gradient of curvature of the shockwave wavefront on the sensors. The gradient of curvature is then used to determine the disambiguated projectile trajectory.

Abstract: In a building environment, a distance associated with a building automation device is determined as a function of an inserted time delay between a wireless transmission of a signal and wireless reception of another signal. For example, a two-way communication is provided with a time delay inserted before responding to a received transmission. By using two-way transmissions, the building automation devices may be free of clock synchronization. Acoustic signals may be used in a building environment to determine a distance. The building automation device may also use radio frequency information for communicating with other devices. Communication between devices allows a controller to coordinate the determination of distances associated with different devices within a network, such as through transmission of a test signal and assigning distance measurement operations to devices that receive the test signal with sufficient strength or other characteristics.

Abstract: The present invention provides a system for identifying and locating an acoustic event. In a preferred embodiment a gunshot detection sensor includes an audio sensor which detects gunshots in combination with a GPS engine which provides location and timing in conjunction with a host system. This allows an acoustic sensing weapon locator which is integrated for size and portability. The inventive mobile military gunshot detector requires a battery or fuel cell at its heart to operate. By managing the power consumption, batteries can be down-sized and the time between changes or recharges can be dramatically extended allowing soldiers to carry less weight and transport fewer replacement batteries into a hostile environment.

Abstract: A system comprises a plurality of acoustic transmitters, mounted inside the streamers, adapted to transmit broadband signals having low cross-correlation between the signals of different transmitters; a plurality of acoustic receivers, mounted inside the streamers, adapted to receive the signals from the transmitters; at least one processor adapted to cross-correlate the signals received at the receivers with copies of transmitter signals to determine identities of the transmitters of the received signals and to determine travel times of the received signals; and a main processor adapted to convert the travel times to distances between the identified transmitters and the receivers and to determine relative positions of the streamers from the distances.

Abstract: System and method for determining a location of a first target. The sensor network comprises a first sensor cluster comprising a first plurality of bearing measuring sensors. A first gateway is operatively coupled to the first plurality of bearing measuring sensors. A second sensor cluster comprises a second plurality of bearing measuring sensors. A second gateway is operatively coupled to the second plurality of bearing measuring sensors. A central command node is operatively coupled to the first and the second gateways. A first limited set of pre-computed numbers representative of information for generating a global target location estimation is transmitted from the first gateway to the central command node. A second limited set of pre-computed numbers representative of information for generating the global target location estimation is transmitted from the second gateway to the central command node.

Abstract: This is an underwater acoustic ranging system for determining a range to a target object. An acoustic receiver is provided for detecting acoustic energy and determining an angle of arrival of said acoustic energy in at least one plane. An acoustic transmitter transmits an acoustic energy pulse. A receiver clock joined to the receiver, and a transmitter clock is joined to the transmitter. Acoustic energy is transmitted at a synchronized time. Range can be calculated based on the transmit time, the receive time and the reception angle. The system can also include a means for synchronizing the clocks.

Abstract: A method and apparatus for determining the geophysical position of an autonomous underwater system utilizing underwater acoustic modems that exchange broadband underwater acoustic signals. The method of the invention includes the steps of initiating an exchange of broadband acoustic signals between the autonomous system of unknown geophysical position and a base system of known geophysical position wherein the depths of both systems is known. A bearing calculation is made on one of the signals transmitted between the systems, preferably through the use of an array of hydrophones placed closely together at predetermined locations on either the autonomous or base system. Also, the range between the two systems is determined by measuring the time of travel of at least one signal.

Abstract: Systems and methods for locating the shooter of supersonic projectiles are described. The system uses at least five, preferably seven, spaced acoustic sensors. Sensor signals are detected for shockwaves and muzzle blast, wherein muzzle blast detection can be either incomplete coming from less than 4 sensor channels, or inconclusive due to lack of signal strength. Shooter range can be determined by an iterative computation and/or a genetic algorithm by minimizing a cost function that includes timing information from both shockwave and muzzle signal channels. Disambiguation is significantly improved over shockwave-only measurements.