Abstract: A PWM signal generator is operable to generate a first pulse signal and a second pulse signal at least one of before and after generating the first pulse signal. A duty ratio of the second pulse signal is gradually changed. A low-pass filter is operable to convert the first pulse signal output from the PWM signal generator into an analog acoustic signal. The low-pass filter is operable to convert the second pulse signal output from the PWM signal generator into the analog acoustic signal having an inaudible frequency.

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 microwave oscillating portion 30 has an output oscillator function that is capable of adjusting automatically a frequency of microwaves radiated from an electrically conductive member made of an outer panel 11-14 as an antenna at a specific frequency of a sufficiently short wavelength in relation to a size of the electrically conductive member made of the outer panel 11-14. The microwave oscillating portion 30 can detect a human and an object of a detection object 27 in a detection area 11A-14A set at an outside of the outer panel 11-14 that is integrally or separably mounted on a vehicle 1.

Abstract: Embodiments of the present invention include methods and apparatus for the detection of objects using acoustic imaging. Vibrational resonance characteristics of man-made objects may be significantly different from those of the surrounding natural materials, allowing an acoustic image to highlight the position of the object, even if the object is concealed from visual imaging.

Abstract: In a radar device installed in a vehicle for detecting a target around the vehicle, a transmitter transmits a plurality of radio signals at intervals. A scanning mechanism is arranged such that each of the plurality of radio signals is individually entered thereto. The scanning mechanism is swingable relative to the transmitter to change a direction of each of the plurality of radio signals entered thereto, thus scanning each of the plurality of radio signals over an angular scanning field. The angular scanning field is located around the vehicle. A receiver receives a plurality of reflected signals to detect intensities of the plurality of received reflected signals. At least some of the plurality of reflected signals are generated based on reflection of at least some of the plurality of radio signals from the target.

Abstract: Methods for mitigating errors in velocity estimates obtained from correlation SONARs when the SONARs are operated over irregular ocean-bottom terrain are disclosed.

Abstract: An ultrasonic sensor includes: a first vibrator for transmitting an ultrasonic wave; multiple second vibrators for outputting a reception signal of a reflection wave; a casing having a bottom for accommodating the vibrators, an outer surface of the bottom providing a vibrating surface; and multiple tubes for guiding the ultrasonic wave. Each tube has a first opening coupled with an outside of a mobile body. An area of the first opening is smaller than an area of the vibrating surface. A distance between two adjacent first openings is smaller than a distance between two adjacent vibrating surfaces. The length of the tubes is determined to equalize a phase difference of the reflection waves at the first openings is equal to that at the vibrating surfaces.

Abstract: A controlled acoustic beam generator system comprising: an array of acoustic transmitters; a signal generator, amplifier for amplifying the acoustic signal; multi-channels signal processor, for processing the acoustic signal, distributing corresponding processed acoustic signals, into the array of acoustic transmitters; steering for steering an acoustic beam which is the resultant of transmitted processed signals by the array of acoustic transmitters; and a control unit, for the operation of the system, by controlling the signal generator, the multi-channel signal processor, and the steering.

Abstract: An ultrasonic sensor has a sensor body and a bezel having a metal spring attached on a side wall thereof for installation on a vehicle component. A free end of the metal spring is positioned to protrude from a through hole of the side wall, is pressed by a portion of the sensor body that is inserted in a hollow space of the bezel, and is pushed back by an opening face of the sensor body. In this manner, the bezel is firmly attached on the component and the sensor body is firmly attached on the bezel.

Abstract: A radar that detects whether spike noise due to an interference with a transmission signal from an object vehicle is superimposed on a beat signal obtained from the transmission signal and a reception signal. When the spike noise is detected, a threshold for extracting a peak from a frequency spectrum is temporarily increased. Normally, a threshold (TH0) is set not so as to extract background noise as a target peak. When the spike noise is detected, a noise floor level (NFL) of the frequency spectrum is determined on the basis of the maximum absolute value of the spike noise, and a threshold (TH1) higher by a predetermined amount ?L than the threshold TH0 is set. This allows a proper target peak to be accurately extracted without mistakenly extracting many peaks caused by the noise as the target peaks.

Abstract: An obstacle detection system has multiple ultrasonic sonars. When a threshold value used for determining an existence of an obstacle is compared with a receiving signal having been amplified at a predetermined gain, the sonar having a receiving mode is provided with the gain which is higher than that of the sonar having a sending/receiving mode. Thus, the sensitivity of the sonar having the receiving mode can be improved so that a continuous sound field of the sonar is broadened. Accordingly, the distance of the border of the continuous sound field of the obstacle detection system from the vehicle can become substantially even.

Abstract: A system and method for signal distribution within a sensor array uses a coaxial transmission line. Taps are affixed to the outer conductor of the coaxial transmission line and include field coupling portions extending into the internal field region of the coaxial transmission line. Electromagnetic energy propagating within the transmission line can be extracted to power the sensors. Sensor signals can be modulated onto radio frequency signals and propagated along the transmission line to distribute the sensor signals.

Abstract: A motion sensing transducer is disclosed that includes a case having an inner surface, a first cap that closes the case at a first end and a second cap that closes the case at a second end. The case inner surface, first cap and second cap define a space within the case. The apparatus further includes at least one inner plate member separating the space into at a first compartment and a second compartment within the case, a coil-magnet assembly that produces a signal when subjected to motion, the coil-magnet assembly disposed immediately within the case and in the first compartment, and an electronic circuit disposed within the second compartment that modifies the signal.

Abstract: A method for determining a fault in a seismic air gun includes comparing a near field seismic signal measured during operation of the air gun to a reference near field signal and determining the existence of a fault in the air gun when a difference between the measured near field signal and the reference near field signal exceeds a selected threshold.

Abstract: A wideband irregular signal is decomposed into respective frequency bands, the ratio of the highest to the lowest frequency within each band being in the ratio of approximately 3:1 and the total number of bands being 3 or 4. The wideband signal, or a re-constituted wideband signal formed by combining the decomposed components, is transmitted as a interrogating signal. A reflection of the interrogation signal is decomposed into respective frequency bands, and within each frequency bands the different components are compared. The results of the comparisons are combined to determine whether an object has been detected and, if so, its range. Decomposition of the wideband signal can be achieved by using a bank of low-pass filters in respective frequency bands, the output of each low-pass filter having subtracted there from the output from the filter with the next-lower frequency cut-off characteristic. Delay circuits are used within each channel so that the total delays in each individual channel are equal.

Abstract: A method for determining the position of an underwater device includes placement of a plurality of station keeping devices on or below the surface of the water in known positions. A device to locate is provided for placement below the surface of the water, and the device to locate and the station keeping devices are provided with a synchronized time base and a common acoustic pulse time schedule. Each station keeping device sends an acoustic pulse at a time according to the common acoustic pulse schedule. The device to locate receives pulses sent by the station keeping devices and calculates a distance between itself and each station keeping device based upon the time that the acoustic pulse is sent and the time that the pulse is received. The device to locate then calculates its position based upon the distances between the device to locate and the station keeping devices. Systems and devices are also disclosed.

Abstract: An acoustic method and apparatus for an acoustic system use a transceiver module, which can transmit to a transmit acoustic element of a transmit sonar array and receive from a receive acoustic element of a receive sonar array in accordance with a common transmit/receive control signal.

Abstract: In an ultrasound receive beamformer signals from two or more aperture elements are multiplexed at the input of each beamformer channel, stored in different portions of a delay memory, delayed and apodized in a time-multiplexed fashion, demultiplexed at the output of the channel, and summed in different summation units running at an upsampled rate. The partial sums are then time-aligned, summed to produce the total upsampled beam sum, filtered and decimated in an interpolation filter to produce the beamformed signal.

Abstract: A system and a method for conveying data using the vector components of the acoustic field, in addition to the scalar component is described. Receivers capable of determining the transmitted data values by measuring one or more parameters of an acoustic field are utilized. Measured parameters of the acoustic field may include both the scalar and vector components. The described system and method may optimize the conveyance of communications through a fluid.

Abstract: The present application provides a linear mechanism for optical-to-acoustic energy conversion for optoacoustic communication from an in-air platform to an undersea vehicle. Signals used in underwater acoustic telemetry applications are capable of being generated through the linear optoacoustic regime conversion process. A number of issues concerning linear optoacoustic communication is addressed that lead to a formulation of a linear regime optoacoustic communication scheme. The use of oblique laser bean incidence at an air-water interface to obtain considerable in-air range from the laser source to the vehicle is also addressed. The effect of oblique incidence on in-water range is addressed as well. Optimum and sub-optimum linear optoacoustic sound-generation techniques for selecting the optical wavelength and signal frequency for optimizing in-water range are identified.