296 results about "Hydrophone array" patented technology

A fiber splice tray for connecting optical fibers between hydrophone modules, allowing each module to be independently assembled. The tray houses the optical fiber in a small space envelope, and allows positioning of a spliced fiber along a straight portion of an internal groove. The internal groove has alternate paths for housing the fiber. The internal groove comprises two opposing parallel sections and two arcs at both ends of the parallel sections, making two continuous looped alternative fiber paths. The internal groove may further comprise two sections that are alternatives to the parallel sections and that cross each other in the middle of the tray. The various alternative fiber paths make it possible to position a splinted optical fiber splice or splice sleeve, which cannot tolerate a bend in the path, in a straight section of the groove.

A fiber transition segment for transitioning an optical fiber from a hydrophone module to the central axis of the module. The segment comprises a conical, elongated element and a cylindrical portion of reduced diameter that protrudes longitudinally from the wide end of the conical element. The cylindrical portion is reciprocally mounted within an interconnect spring at the end of the hydrophone assembly. The fiber transition segment has a helical internal groove for receiving the optical fiber from the interconnect spring. The groove is aligned with and approximately matches the pitch of the groove in the interconnect spring to provide a smooth transition to the fiber transition segment and then to the central axis of the module.

A termination assembly for use in an optical hydrophone module, comprising a module oil seal and an optical fiber seal. The termination assembly is used at the ends of modules and provides a means for filling individual modules with fill fluid. A module oil seal comprises a cylindrical wall defining a cavity, with one end substantially closed and the other end open. An annular face plate on the open end makes a seal dividing a coupling and a clevis. A check valve is mounted to an orifice that passes through the substantially closed end of the module oil seal. Optical fibers pass through the substantially closed end and the optical fiber seal is provided around the optical fiber that passes therethrough. The fiber seal fits snugly in a module oil seal opening. Both components serve to provide a seal that can withstand high pressures and maintain optical fiber integrity.

A woven fiber protection cable assembly for use in an optical fiber hydrophone module. The assembly comprises an elastic woven fiber strap with at least one tube attached to one or more sides of the strap in a sinusoidal pattern. The strap at a first end and longitudinal middle portion is substantially aligned with the central axis of the hydrophone module. Two layers of the strap are fastened together in the longitudinal middle portion, and the first end of the strap comprises a loop. The two layers at the second end of the strap are spatially separated and on opposite sides overlap a fiber transition segment, around which one end of the tube is coiled. The elongation of the strap causes the period of the sinusoidal pattern to increase without imparting damaging stress to the optical fiber.

The invention provides an SINS/LBL (strapdown inertial navigation systems/long base line) tight combination based AUV (autonomous underwater vehicle) underwater navigation positioning method. The SINS/LBL tight combination based AUV underwater navigation positioning method is characterized by comprising three major parts, namely an SINS mounted on an AUV, an LBL underwater sound positioning system laid on the seabed, and a data processing unit. The method comprises the following specific steps: firstly performing a strapdown algorithm on IMU (inertial measurement unit) data to obtain AUV position information, and representing the position information by using earth rectangular coordinates; secondly reckoning an SINS slant-range difference according to the AUV position information provided by the SINS and hydrophone array position coordinates; and thirdly establishing an LBL slant-range difference model according to LBL positioning characteristics, and correcting SINS navigation positioning information according to filter estimation compensation by taking the difference value between the SINS slant-distance difference and the LBL slant-distance difference as an observed quantity of a kalman filter. According to the SINS/LBL tight combination based AUV underwater navigation positioning method, the use of GPS and other radio positioning systems is avoided at the same, and the AUV underwater operation efficiency is improved.

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. By the acoustic transmission and sharing of information, as needed, about the known depths of the systems, the known geophysical position of the base system, and the range between the systems, sufficient data is gathered at one or both systems and used to determine the geophysical position of the autonomous system.

The invention belongs to the field of marine environment detection equipment, and particularly relates to a real-time transmission multivariate vector hydrophone array subsurface buoy system which acquires and stores marine environment noise of different depths. The real-time transmission multivariate vector hydrophone array subsurface buoy system comprises a vector hydrophone array, a watertight electronic storehouse, a communication cable, a buoy, an acoustic releaser and an anchor block. The vector hydrophone array is vertically arranged, the tail part is in the free state and the number of the array elements is freely adjusted according to the depth. The vector hydrophone array can simultaneously measure the marine environment information of different depths. As for the real-time performance, the acquired data can be uploaded to a shore station in real time to be processed with no requirement for waiting for recycling equipment to perform data recycling processing.

The invention discloses a phase modulation and demodulation device based on a fiber grating hydrophone array. A fiber grating is used as a component of a hydrophone, and a reflection phase modulator with a Faraday rotating mirror is adopted, which makes the structure simpler and reduces the cost. Meanwhile, a PI/2 phase modulation method is adopted, two orthogonal signals can be directly separatedby sampling, and there is no need for general reference signal mixing and filtering. Thus, the complexity of the algorithm is simplified, the phase noise is reduced, and the system is more applicable.

The invention provides an acoustic monitoring system and method based on ambient sea noise. The method comprises the following steps: enabling an acoustic monitoring system to drift with the ocean current in the form of a buoy; under the control of an internal control computer, receiving ambient sea noise and carrying out filtering, gain amplification and sampling, and storing the sampled ambient sea noise data; and finally, carrying out hydrophone formation correction and inversion of seabed water depth and layered structure information. The system comprises the internal control computer connected with a receiving unit, a clock synchronization unit and an upper computer; and the receiving unit is connected with a hydrophone array comprising 3-16 hydrophones. The method is simple in steps, convenient to implement, high in measurement efficiency and reliable in monitoring result; and the monitoring system has the advantages of simple structure, low cost, and convenient use, and has a wide application value.

A hydrophone stave comprises a tubular member, a braided cord (or similar flexible structure), cylindrical hydrophones, pins, two plugs and two couplings. The hose (made of a thermoplastic material) is corrugated or convoluted, and is cuffed at both ends to permit a plug to engage at each end. Each coupling includes a wire rope (or similar flexible structure). Each hydrophone has a longitudinal through-aperture (through which the braided cord passes) and a perpendicularly transverse through-aperture (through which a pin passes while also passing through a void created between strands of the braided cord). The stave is suitable for incorporation into a hydrophone array assembly providing for a selected arrayal of hydrophones, e.g., an assembly including two opposite frames united therebetween by numerous congruous parallel staves, each stave including equally spaced hydrophones, each coupling linking a plug with a frame so that the staves are selectively arranged.

The invention pertains to sonar receive arrays. More particularly, the invention pertains to a process for calibrating the amplitude, position and phase angle of an array of underwater receive hydrophones with respect to one another. The process requires projecting an acoustic test signal at a known frequency from a towed underwater acoustic projector toward an array of towed, underwater, interconnected, receive hydrophones; detecting and determining the response of the receive hydrophones to said test signal by signal processing means; and calibrating at least one parameter for the operation of the receive hydrophones resulting from the response. Calibrated parameters include the amplitude, position and phase angle of the receive hydrophones relative to one another.

The invention discloses a measurement system and method for detecting the orientation and the size of an underwater target on the basis of a laser sound source. According to the measurement system and method, the sound source is generated through lasers, laser energy is converted into sound wave energy, an acousto-optical coupling interference type optical fiber hydrophone array serves as a receiving sensor, the defects that in the optical measurement process, optical waves which are used are large in attenuation and the measuring distance is short are overcome, the defects of a sonar sensor in traditional acoustics detection are overcome, and the advantages that mobility and flexibility are high are achieved. Meanwhile, a sound source signal is generated through a laser-induced sound system, and generated sound signals have the advantages of being high in sound pressure level, wide in frequency spectrum, capable of conducting non-contact type control, and the like. An acousto-optical coupling interference type optical fiber hydrophone is used as the acoustic signal sensor, and the acoustic signal sensor has the advantages of being capable of detecting underwater acoustic signals in the non-contact mode, high in mobility, small in size, flexible in structural design, and the like.

A novel packaging structure for a fiber optic hydrophone probe and a fiber optic hydrophone array comprise an outer shell, polyurea composite material, an armored cable, a pressure plate connector, a transition connecting sleeve, a Kevlar rope, an acoustic sensor and the like. The outer shell is packaged under pressure through the acoustic sensor with pressure resistance and sound transmission of the probe considered; the polyurea composite material is watertight packaging material with excellent hydrophobic and sound transmission properties; the armored cable is used for connecting and packaging when a plurality of probes form an array and fibers among the probes are protected with good watertight and mechanical properties. Both ends of the acoustic sensor are connected with the armored cable through the pressure plate connector; an external sleeve of the pressure plate connector is sealed through a transition connected sleeve; a plurality of fixing holes are formed on the connected sleeve to fix the Kevlar rope and improve tensile strength of an arraying probe cable. Compared with the prior art, the packaging structure has high structural reliability, good water tightness and strong deepwater pressure capacity. Furthermore, engineering and mass assembly are easy to realize.

The present invention relates to a system for sensing the curvature of a towed hydrophone array and a curvature sensor used in the system. The system has at least two curvature sensors positioned along the length of the array. Each of the curvature sensors comprises a bend member which bends as the array bends, at least one optical fiber within the bend member, and at least one detection device embedded within the at least one optical fiber to detect a change in the strain in the at least one optical fiber.

The invention discloses an underwater sound communication device and a method based on time reversal and orthogonal frequency division multiplexing (OFDM) combined treatment. The underwater sound communication device comprises a signal transmitter, a power amplifier, a transmitting transducer, a receiving hydrophone array, a signal receiver and a signal processor, wherein the signal processor comprises a broadband Doppler estimation and compensation module, a time reversal processing module, an OFDM demodulation module, a channel estimation and compensation module and a frequency deviation estimation and compensation module. In the underwater sound communication device, the space time focusing characteristics of the time reversal are utilized to eliminate the multipath influence of the channel; a pulse channel response length can be shortened by the time reversal so as to reduce the length of an OFDM symbol guard interval and improve the communication efficiency; and because the guard interval is reduced, the length of the OFDM symbol can be shortened so as to enlarge a subcarrier frequency interval. With the method disclosed by the invention, interference among subcarriers can be reduced, and the available rate of the OFDM underwater sound communication is further improved.

The invention provides a shallow sea target depth classification method based on a hydrophone array. Detection is performed by integrating information received by multiple hydrophones, a typical probability density function of energy field change produced by model-based deep and shallow sound sources is generated by acoustic propagation simulation, likelihood ratio test (LRT) is performed based on the probability density function to identify a received signal, prior knowledge is extracted according to the law of distribution of sound energy within the whole range of a sound field, and thus, depth classification is performed on the sound field target. The algorithm is easy to implement and high in environmental adaptability.

A structure and method for constructing a non-oil-filled towed array providing a single cable entry point for each channel irregardless of the number of hydrophones used to make up a hydrophone group or array is described. The method and apparatus enables uniform buoyancy of the hydrophone array and the primary cable around which the hydrophone array is wound. Uniform buoyancy is achieved through the addition of hollow micro-spheres into a Reaction Injection Molded (RIM) polyurethane material used to mold the hydrophones. Additional buoyancy may be desired adjacent heavier cable sections where connectors and telemetry modules are located. An embodiment enables precise adjustment of hydrophone cable buoyancy by providing precise adjustment of the concentration of hollow glass micro-spheres in areas where more or less buoyancy is desired.

The invention discloses an MIMO (multiple input multiple output) based high-resolution underwater target detection device and method. According to the invention, a potential target is actively detected through a plurality of mutually-orthogonal detection waveforms transmitted by a transmitting transducer array in a hydroacoustic environment, and a hydrophone-array received target echo is received. Through MIMO processing, a method for carrying out detection and estimation on an MIMO frame is established, and the extension of waveform diversity gains and virtual array apertures is obtained. By using the MIMO based underwater target detection method disclosed by the invention, in the process of carrying out hydroacoustic target detection, compared with conventional phase control, a higher detection resolution and higher parameter identification performance can be obtained.

The invention discloses a device for calibrating the lineup of a dragging linear array. The hardware of the device mainly comprises a calibration sound source, a receiving hydrophone array, a signal acquisition transmission module array and a data processing module. The lineup calibration process mainly comprises the following steps: (1) calibrating a sound source to transmit a calibrated submarine sound signal in a system synchronous clock; (2) according to the system synchronous clock, enabling the signal acquisition transmission module array to start work while the sound signal is transmitted, that is, a timer starts timing and hydrophones acquires data; (3) recording the timing time of the timer while the signal acquisition transmission module array acquires the transmitted calibrated submarine sound signal, and transmitting the timing time to the data processing module; (4) estimating the distances between the hydrophones and the calibrated sound source according to the timing time; (5) estimating the coordinates of hydrophones through the data processing unit according to the estimation results in combination with depth sensor data, thereby realizing lineup calibration. By adopting the device and the method, position calibration of array elements of a dragging array can be conveniently achieved.