51results about How to "Self noise reduction" patented technology

Disclosed is a satellite communication timing synchronization error detection method based on full-digital receiving. In view of wide application of a Gardner algorithm in a timing synchronization loop and the limitation of the Gardner algorithm to band-limited signals, when polarity jump happens to two adjacent symbols, after two adjacent code elements are utilized for cosine roll-off forming filtering, the relation between samples of two best sampling points and the sample of a middle point of the two best sampling points is utilized, the effect of different adjacent symbols to the middle value is firstly taken into consideration and the effect value is calculated according to the minimum mean-square error criterion, and is then eliminated; when polarity jump does not happen to the adjacent symbols, how to reduce self noise generated by the situation that timing information can not be acquired is taken into consideration. A sign function sign (.) in an E-Gardner algorithm is utilized to solve the problem. Under the satellite channel environment, the enhancing algorithm is simple in structure, under the condition of a small roll-off coefficient, the performance of QPSK modulating signal clock capturing and error detection is improved, and the satellite communication timing synchronization error detection method based on full-digital receiving can effectively eliminate self-noise and reduce system resource consumption.

A partial optical fiber discharge detecting system comprises a light source, an acoustic-optic modulation device, a sensing light path and a demodulating system. Frequency shifting and delaying are carried out on light emitted by the light source through the acoustic-optic modulation device, and only two paths of light with the same optical path can interfere in the sensing light path and a reference light path. When partial discharge signals occur outside, the generated sound waves act on the sensing light path, the phase position of the interference signals changes, and the related information (intensity, position and the like) of outside partial discharge signals can be obtained by demodulating the variable quantity. Compared with traditional electromagnetic sensing and piezoelectric sensing, optical fiber sensing is insulated from electromagnetism essentially, the sensing optical fiber can be arranged in insulating oil of a transformer, the sensitivity for detecting the partial discharge signals is further improved, multiplexing can be formed easily, and the partial discharge signals can be precisely positioned.

The invention provides a water surface rainfall intensity measurement method based on rain sound spectrum and a device thereof, relates to water surface rainfall intensity measurement, and specifically provides a water surface rainfall intensity measurement device which is based on a DSP digital acquisition system and has the advantages of high anti-interference, low self noise, high reliability, high bandwidth and data mass memory as well as a method. The device is provided with a gas-tight silo, a gas-tight silo float, a hydrophone, a hydrophone float and a circuit. In the measurement method, frequency range division and shape of underwater rain sound spectrum are adopted in combination with the least square method and the non-linear method to invert water surface rainfall intensity; according to log-linear change principle of the sound spectrum at the frequency range ranging from 15kHz to 30kHz, rainfall is divided into 3 types: no rain, light rain and heavy rain; an S-type growth model is adopted to study the sound spectrum principle in the process of the light rain and quantize rainfall intensity in the process of light rainfall; a log-linear model is adopted to study the sound spectrum principle in the process of heavy rainfall and the low frequency range of 2-10KHz of the rain sound spectrum and parameter value of the log-log model are adopted to quantize the rainfall intensity in the process of the heavy rainfall.

The invention discloses an oceanic capacitive electrode and is applied to ocean electric field measurement in the field of geophysical exploration. The oceanic capacitive electrode mainly comprises a capacitive electrode body made of metal materials and a protecting structure, and an insulating layer is arranged on the surface of the capacitive electrode body and is high in insulating property and corrosion resistance. The oceanic capacitive electrode has the advantages that direct contact between the capacitive electrode body and external environment media is avoided by the insulating layer, the electrode body and external electrolyte form a capacitor, and an external electric field is measured by means of capacitive coupling; in the presence of the insulating layer, chemical reaction between the electrode and ions in seawater is avoided, electrochemical noise generated during the chemical reaction is further avoided, and the electrode can achieve lower noise level; meanwhile, stabilization time for the electrode to establish balance is shortened, and continuous consumption during electrode use is avoided.

The invention relates to a distributed optical fiber sound sensing and positioning system, which performs optical fiber sound detection by means of a Mach-Zehnder interference and phase-sensitive optical time domain reflection mixed structure, combines an MZI interference type optical fiber sound sensing system and a phi-OTDR optical fiber vibration positioning system, and realizes restoration andpositioning of external sound signals simultaneously. Compared with an existing distributed optical fiber vibration measurement technology, the distributed optical fiber sound sensing and positioningsystem has the advantages of low cost, high reliability, high real-time monitoring capacity, long monitoring distance and high resolution, can realize restoration and positioning of vibration sound signals simultaneously, and has huge application potential in long-distance safety detection of natural gas, petroleum pipelines and the like. In addition, a chaotic light source used in an MZI opticalpath of the distributed optical fiber sound sensing and positioning system has the advantages of wide spectrum, more carried information, good autocorrelation and low autocorrelation noise, and can suppress scattering noise in the optical path and increase the signal-to-noise ratio, thereby improving the response sensitivity of the device.

The invention provides a low-noise vector hydrophone. The low-noise vector hydrophone comprises an underwater sensitive probe (1), a lead wire (3), a sealing housing (4), an installation pedestal (6), a conditioning chamber (7), a conditioning circuit (8) and a cable (9), wherein the underwater sensitive probe (1) is connected with the sealing housing (4) through an internal vibration damping structure (2), a first sealing ring (5) is arranged between the sealing housing (4) and the installation pedestal (6), the conditioning circuit (8) is installed in the conditioning chamber (7), a second sealing ring is arranged between the conditioning chamber (7) and the installation pedestal (6), and signals subjected to amplification filtering conditioning through the conditioning circuit are transmitted via the cable (9). According to the invention, self-noise from the inside of the vector hydrophone is effectively reduced, the capability of resisting interference from external vibration and electricity, electromagnetism and sound is improved, the equivalent self-noise acceleration spectrum level is of the low-noise vector hydrophone is enabled to reach lowest level, and the pick-up demand of underwater sound field weak signals can be satisfied.

This invention provides a system apparatus and method for ship-towed deployment of a non-linear volumetric array of hydrophones, allowing line-intersect or line-transect sampling of marine mammal populations through passive acoustic monitoring, enabling unambiguous real-time three-dimensional localization of single sounds received through a low-cost, modular, robust, stable, small, light, neutrally to slightly negatively buoyant volumetric array having low self-noise and low flow noise, that avoids putting high tension on the tow cable and that is compatible with standard hydrophones, instrumentation, cabling, and analytical software.

The invention relates to an anechoic tile based on a composite material, in particular to an anechoic tile made of a foam metal material and a rare-earth supermagnetostrictive material, and belongs to the technical field of anechoic. It is composed of foamed metal material sheet with certain radian and thickness, rare earth super magnetostrictive material sheet, and synthetic rubber sheet which is vulcanized and packaged into an integral structure after they are bonded to each other. The shapes of the metal foam material sheet and the rare earth super magnetostrictive material sheet are consistent, and their radians are consistent with the surface radian of the underwater moving body. After being encapsulated by a synthetic rubber sheet, they jointly form an anechoic tile. The invention can not only absorb the sound waves of the active sonar, significantly reduce the reflection intensity of the sound waves of the active sonar, but also suppress the vibration generated by the underwater moving body itself, isolate the machine noise in the underwater moving body from radiating to the underwater moving body, and significantly reduce the Self-noise of underwater moving bodies, reducing the passive sonar range of the detection side, etc.

The invention discloses a real-time processing system of modularized array acoustic signals, and belongs to the technical field of ocean acoustic signal collection. The system comprises a mounting base, and data collection modules, a signal processing module, a storage module, a clock module, a control module and a power supply module mounted on the mounting base; the data collection modules receive analog electric signals output by an acoustic sensor, and process the analog electric signals; the signal processing module makes data interaction with the data collection module, and carries out time-frequency conversion, weak signal detection and target signal identification on data; the control module is used for synchronous management of the data collection modules and communication among the modules; the power supply module supplies power for the modules; and the data collection module, the signal processing module, the storage module, the clock module, the control module and the powersupply module are integrated on PCBs respectively, and each PCB is provided with the same data input and output ports. Thus, the signal to noise ratio as well as the collection consistency of an underwater acoustic signal collection array circuit can be improved.

The invention discloses a wide-band high-sensitivity planar optical fiber vector hydrophone. The wide-band high-sensitivity planar optical fiber vector hydrophone mainly comprises optical fiber acceleration sensing units; four optical fiber acceleration sensing units are connected in series so as to form the hydrophone; a 2*2 coupler and Faraday rotation mirrors are fixed in an interferometer box; the acceleration sensing units and the interferometer box are fixed on a polyurethane foam board; fixing screws are distributed at four corners of the polyurethane foam board; the input and output optical fibers of the hydrophone are led out by an optical cable; the outermost layer of the hydrophone is sealed through filling a polyurethane adhesive layer; the optical fiber acceleration sensing unit is mainly composed of optical fiber discs, a sensitizing structure and shells, wherein two optical fiber discs are bonded at the upper surface and lower surface of the sensitizing structure, and the sensitizing structure is bonded to the upper shell and the lower shell through an epoxy adhesive. As for the requirements of work bandwidth and high sensitivity of a conformal array hydrophone, the acceleration sensing units are adopted, and the optical path and structure of the hydrophone of the invention are optimized, and therefore, technical problems in corresponding process implementation and assembly can be solved.

This invention provides a system apparatus and method for ship-towed deployment of a non-linear volumetric array of hydrophones, allowing line-intersect or line-transect sampling of marine mammal populations through passive acoustic monitoring, enabling unambiguous real-time three-dimensional localization of single sounds received through a low-cost, modular, robust, stable, small, light, neutrally to slightly negatively buoyant volumetric array having low self-noise and low flow noise, that avoids putting high tension on the tow cable and that is compatible with standard hydrophones, instrumentation, cabling, and analytical software.

The invention discloses a low self-noise stainless steel wire. The diameter of the low self-noise stainless steel wire is 5.9-6.1 mm. The low self-noise stainless steel wire comprises, by mass percentage, 0.01-0.03% of carbon, 13-17% of chromium, 4-8% of nickel, 0.1-0.12 % of copper, 0.4-0.5 % of magnesium, 1-1.2% of manganese, and the balance iron. The prepared low self-noise stainless steel wire greatly improves the abrasion resistance and corrosion resistance performance, is easy to machine and form, has certain vibration reducing performance, is low in self-noise, better solves the problems that steel wires are likely to be corroded, rusted and abraded and large in noise, and prolongs the service life.

The invention discloses a high-sensitivity carbon fiber electric field sensor. The sensor has high-sensitivity response to an electric field signal in water. According to the sensor, carbon fibers aretaken as an electrode material; grafting and modifying are performed through a polyamine molecular substance; cutting and fixing, lead leading out and sealing are performed, so that the sensor can beprepared. The surfaces of the carbon fibers contain rich active nitrogen-containing groups, and surface double-electric-layer change caused by external electric field change can be converted into electric signals. The carbon fiber electric field sensor has the advantages of high sensitivity, small potential drift and low noise, and can be effectively used for measuring low-frequency weak electricfield signals in waters such as oceans or rivers.

The invention relates to a sound eliminating tile made of a piezoelectric material. An arc-shaped piezoelectric material block is vulcanized and encapsulated into novel synthetic rubber and used for underwater moving body shell surface and bridge surface. According to the basic principle that the density of piezoelectric material surface charge is in proportion to applied stress, an active sound eliminating tile for a hollow cavity type or a filler type underwater moving body shell surface is designed. By using the piezoelectric material as a core, the invention reduces the reflecting strength of a sound wave of an active sonar, inhibits vibration generated by an underwater moving body, isolates machine noise in the underwater moving body from being radiated to an underwater moving body and can obviously reduce the reflecting strength of the sound wave of the active sonar and the radiating noise and self noise of the underwater moving body and provide basis for the design of hidden and silent type underwater moving bodies.

The invention discloses a preparation method for a low-self-noise stainless steel wire. The diameter of the low-self-noise stainless steel wire is 5.9-6.1 mm. The low-self-noise stainless steel wire comprises, by mass, 0.01%-0.03% of carbon, 13%-17% of chrome, 4%-8% of nickel, 0.1%-0.12% of copper, 0.4%-0.5% of magnesium, 1%-1.2% of manganese and the balance iron. According to the low-self-noise stainless steel wire prepared through the preparation method, the abrasion resistance and the corrosion resistance of the stainless steel wire are greatly improved; machining and forming are easy; a certain damping performance is achieved; the self noise is low; the problems that a steel wire is prone to being corroded, rusted and abraded and large in noise are well solved; and the service life of the low-self-noise stainless steel wire is prolonged.

The invention, which relates to the deep-sea subsurface buoy positioning, provides a three-point type deep-sea subsurface buoy positioning method. Longitudes and latitudes at different positions within response distances of three releasers and corresponding ranging values are obtained; data are introduced into a designed geometric model; and calculation is carried out by a calculation program to obtain calculation values and sketch maps of a longitude, a latitude, and a depth of a weight block. A scientific and effective method that can be implemented simply and conveniently is provided for positioning work in deep-sea subsurface buoy recycling; and only with the three-point positioning, the actual position of the subsurface buoy in water is obtained and then recycling is carried out, so that time needed by recycling is saved to the great extent and the risk of subsurface buoy losing is reduced.

The invention provides a sandwich type acoustic window structure form of a ship dome. A main body is of a sandwich structure and comprises an inner constraint surface layer, an outer constraint surface layer and a sandwich, wherein the material of the constraint surface layers is a fiber enhanced resin-based composite material or a titanium alloy; the material of a core layer is a viscoelastic material; the constraint surface layers are tightly stuck with the core layer. According to the sandwich type acoustic transmission window structure form provided by the invention, requirements of the structure in the aspects of strength and acoustic characteristics are comprehensively considered; after the structure strength is met, the sandwich type acoustic window structure form has good sound transmission performance, small insertion loss, great damping factors and high specific strength; self noise generated under the excitation of surface turbulent fluctuation are reduced so that signal interference, caused by flow noises, on a sonar antenna is reduced.

The invention provides a pipeline internal detection system which comprises a receiving and transmitting system and a detector, the receiving and transmitting system is arranged at the position of an inlet and outlet metal hose of an oil depot tank, and the detector is a spherical detector and is put and recycled through the receiving and transmitting system. The receiving and transmitting system comprises a receiving and transmitting ball cylinder and a main pipeline, the main pipeline is the inlet and outlet metal hose pipeline of the oil depot tank, the receiving and transmitting ball cylinder communicates with the two ends of the pipeline, and the detector is received and transmitted through the receiving and transmitting ball cylinder. The ratio of the diameter of the detector to the pipe diameter is (0.7-0.8): 1. The pipeline spherical internal detector adopts equipment special for putting and recycling, and system operation is safe and simple. The capacitive micro machining ultrasonic sensor is adopted to well overcome many defects of a piezoelectric sensor, and has the advantages of high sensitivity, wide bandwidth, easiness in manufacturing, small size, low noise, wide working temperature range and easiness in electronic integration. The spherical internal detector has the advantages of simple mechanical structure design and flexible movement.

The invention belongs to the technical field of noise elimination, vibration reduction and noise reduction, and relates to a volcanic rock noise elimination tile, in particular to a noise elimination tile made from volcanic rocks and synthetic rubber. The volcanic rock noise elimination tile is composed of a natural volcanic rock hollow frame, multiple natural volcanic rock cones arranged in the natural volcanic rock hollow frame, and a synthetic rubber block for vulcanization and package of an assembled and combined body of the natural volcanic rock hollow frame and the multiple natural volcanic rock cones, wherein outer walls of both the upper surface board and the lower surface board of the natural volcanic rock hollow frame have certain radian; holes of the selected volcanic rocks are formed naturally in a non-uniform manner; the radian of the volcanic rock noise elimination tile is consistent with that of the surface of an underwater moving body; after packaged by the synthetic rubber, the volcanic rock hollow frame and the volcanic rock cones form the noise elimination tile together. The volcanic rock noise elimination tile can absorb sound waves of active sonar, remarkably reduce reflection strength of sound waves of the active sonar, suppress vibration generated by the underwater moving body itself, prevent machine noise inside the underwater moving body from radiating to the underwater moving body, remarkably lower self noise of the underwater moving body, reduce operating range of passive sonar of a detection side and the like.

The invention belongs to the field of signal detection, and provides a photovoltaic hybrid array detection system which is low in self-noise, high in sensitivity, large in dynamic range and strong in anti-interference capacity. According to the technical scheme, the photovoltaic hybrid array detection system comprises a data recording center, data transmission modules, data collecting modules, a light source module, a photovoltaic conversion module, fiber optic hydrophones and optical fibers. On the one hand, the data recording center is responsible for sending control commands to all the data transmission modules. On the other hand, the data recording center is responsible for receiving detection data transmitted by all the data transmission modules and carrying out storage and corresponding processing on the data. The signal collecting modules and the data transmission modules are in data communication through RS485 interfaces or SPI interfaces or in a level matching direct connection mode. The data transmission modules are connected in series in sequence, and the control commands sent by the data recording center are transferred to the data transmission module at the last end in sequence. The photovoltaic hybrid array detection system is mainly applied to gas detection.

The invention discloses a transmitter converting current to voltage. The transmitter comprises a current source circuit, a current converting circuit, and a voltage converting circuit. The current source circuit is used to provide stable direct current for the current converting circuit. The current converting circuit is used to convert an input first current range to a second current range. The voltage converting circuit is used to convert the second current range to a preset voltage range. The transmitter is a universal transmitter which can convert a standard 4-20 mA current signal output by a sensor to a 0-5 V voltage signal which meets input requirements of an analog-digital converter. The transmitter is suitable to be used in operation temperature of 25 DEG C to 85 DEG C, and is small in volume and high in converting precision.

The invention belongs to the technical field of noise elimination, vibration reduction and noise reduction, and relates to a combined-type anechoic tile, in particular to the anechoic tile made of conic vesuvianite, porous light-weight metal material and synthetic rubber. The anechoic tile is formed by the porous light-weight metal material block with certain radian and thickness, conic vesuvianite and the synthetic rubber block used for sulphurating and packaging the porous light-weight metal material block and the conic vesuvianite into an integral structure; the selected vesuvianite and vesuvianite holes are formed naturally, and are uneven; the radian of the porous light-weight metal material block is consistent with the surface radian of an underwater moving body; and the anechoic tile is formed after packaging of the synthetic rubber block. The anechoic tile can absorb acoustic waves of active sonar, remarkably reduces the reflection strength of acoustic waves of the active sonar, can further restraint vibration generated by the underwater moving body, isolates the noise of the machine, radiating to the underwater moving body, inside the underwater moving body, remarkably reduces the self noise of the underwater moving body, and reduces the operating range of passive sonar of the detection party.

The invention provides a high-performance piezoelectric accelerometer with a ring beam structure. The high-performance piezoelectric accelerometer comprises the ring beam structure, piezoelectric elements, an upper outer shell and a lower outer shell, wherein the ring beam structure comprises an annular beam, a plurality of elastic beam arms and a central base plate which are integrally arranged;the central base plate is arranged in the center of the annular beam; the plurality of elastic beam arms are uniformly arranged in the annular beam; the central base plate is a regular N-polygon baseplate; each side surface of the central base plate is matched with one elastic beam arm; the other end of each elastic beam is fixedly connected with the inner wall of the annular beam, the upper surface and the lower surface of the center base plate are matched with central mass blocks in the same shape respectively, piezoelectric elements are arranged on the upper surface and the lower surface of each elastic beam arm, a cavity for accommodating the ring beam structure is defined by the upper outer shell and the lower outer shell, and the upper outer shell and the lower outer shell clamp theannular beam. By utilizing the bending mode of the beam, the high-performance piezoelectric accelerometer enhances the sensitivity, increases the bandwidth without losing performance due to the highsymmetry, and further improves the torsion resistance and the anti-jamming capability.

The invention provides a lattice sandwich acoustic window structure of a ship dome and belongs to the technical field ship acoustics. The lattice sandwich acoustic window structure of the ship dome comprises an inner constraint surface layer, an outer constraint surface layer and a middle core layer, wherein the core layer is tightly stuck between the inner constraint surface layer and the outer constraint surface layer; the inner constraint surface layer and the outer constraint surface layer are made of carbon fiber enhanced composite materials; the core layer is a three-dimensional lattice layer body formed by integrating one layer or more layers of three-dimensional lattice structures; the material of the core layer is the same as the materials of the inner constraint surface layer and the outer constraint surface layer. An acoustic window and the dome are integrated, so that the lattice sandwich acoustic window structure is conveniently and integrally mounted and influences, caused by an installation structure of a splitting type acoustic window, on performance of an energy converter are avoided.

The invention belongs to the field of signal detection, and provides a photovoltaic hybrid array detection system which is low in self-noise, high in sensitivity, large in dynamic range and strong in anti-interference capacity. According to the technical scheme, the photovoltaic hybrid array detection system comprises a data recording center, data transmission modules, data collecting modules, a light source module, a photovoltaic conversion module, fiber optic hydrophones and optical fibers. On the one hand, the data recording center is responsible for sending control commands to all the data transmission modules. On the other hand, the data recording center is responsible for receiving detection data transmitted by all the data transmission modules and carrying out storage and corresponding processing on the data. The signal collecting modules and the data transmission modules are in data communication through RS485 interfaces or SPI interfaces or in a level matching direct connection mode. The data transmission modules are connected in series in sequence, and the control commands sent by the data recording center are transferred to the data transmission module at the last end in sequence. The photovoltaic hybrid array detection system is mainly applied to gas detection.

The invention discloses an inflatable water-jet propeller which comprises a pump shell, a nozzle is arranged at one end of the pump shell, an impeller and an inlet runner are arranged in the pump shell, the impeller is arranged between the nozzle and the inlet runner, the impeller is fixed on a shaft capable of driving the impeller to rotate. The inflatable water-jet propeller is characterized in that an inflating device is arranged in the inlet runner; and the inflation device is connected with an air storage device through an air supply pipeline. According to the inflatable water-jet propeller, the cavitation performance of the water-jet propeller is improved, and the cavitation noise of the water-jet propeller is reduced.

The invention provides low-self-noise special steel. The low-self-noise special steel comprises, by mass, 0.01%-0.03% of carbon, 13%-17% of chrome, 7%-8% of nickel, 0.1%-0.12% of copper, 0.4%-0.5% of magnesium, 0.1%-0.12% of manganese and the balance iron. The special steel provided by the invention can be applied to equipment parts resistant to nitric acid corrosion, cold phosphoric acid corrosion, organic acid corrosion, salt solution corrosion and alkali solution corrosion. The category of alloy materials is increased, and the proportion components of all the material elements are adjusted; the nickel, the chrome, the copper, the magnesium, the manganese and the like are added into the prepared material, so that the special steel contains the nickel, the chrome, the copper, the magnesium, the manganese and other elements which are all reasonable in proportion; thus, the abrasion resistance and the corrosion resistance of the special steel are greatly improved, the special steel is easy to machine and form and has certain vibration reducing performance, and the self noise is low; and the problems that the parts are prone to be abraded and rusted are solved, and the service life of the special steel is prolonged.