56results about How to "Suppress low frequency noise" patented technology

A circuit and method for reducing noise in video imagers which takes advantage of the fact that the same image information is present in the drain current in a reset transistor used to reset a photodiode in a pixel as is present in the readout current. The noise is reduced by passing the multiplexed output voltage from the source follower output transistor in an APS imager system through a high pass filter to reduce the low frequency noise from the source follower. The drain current in the reset transistor used to reset the APS is passed through a low pass filter. The low pass filter output and the high pass filter output are then combined. Since the drain current in the reset transistor contains the same image information as the voltage output of the source follower output transistor the image information can be obtained by combining the output of the low pass filter and the output of the high pass filter. Since the low frequency noise components of the source follower output transistor have been suppressed combined outputs of the low pass filter and high pass filter will provide the image information with greatly suppressed low frequency noise.

A staggered grid 3D seismic prestack reverse time migration imaging method based on GPU small storage capacity is a very important technology for 3D prestack depth migration imaging of complex structures. The reverse time migration method based on the two-way wave equation has been realized, which can accurately image the rotary wave and the large-angle reflected wave, and at the same time solve the problem of the large amount of calculation of this method. Utilizing parallel computing technology based on GPU hardware, staggered grid difference format, checkpoint storage and other technologies, and relying on Laplace imaging conditions, the pre-stack reverse time migration imaging of 3D seismic data is realized, which greatly shortens the computing time. The efficiency has been increased hundreds of times, and the imaging accuracy has been significantly improved.

The invention discloses a functional electrical stimulation fuzzy control method, which relates to the technical field of disabled person rehabilitation medical appliances and comprises the following steps that: the surface electromyographic signals are collected by multiple channels; a high-pass filter is adopted for carrying out filtering processing to filter the low-frequency noise caused by the electrode sliding; the filtering processing is carried out through fast independent component analysis for filtering industrial industry interference; the time domain analysis is carried out on the surface electromyographic signals after the secondary filtration to obtain the root-mean-square; errors and error variation rates between the output root-mean-square matrix value and the expected root-mean-square matrix value are used as the input of a fuzzy controller, and the stimulation current intensity precision quantity is used as the output; the errors and the error variation rates are converted to the discourse domain value according to the proper proportion, and the membership function is determined; the control rule and the membership function are used for deducting the errors and the error variation rate to obtain the stimulation current fuzzy quantity; and the defuzzification processing is carried out to obtain the stimulation current intensity precision quantity. The accuracy and the stability of a functional electrical stimulation (FES) system are effectively improved.

The invention proposes an upstream and downstream wave field decomposition-based inverse-time migration method and system. The method comprises the steps of building an analysis wave field of an earthquake source and earthquake record; performing wave field positive and negative prolongation on the analysis wave field; performing Hilbert transform on the wave field in an imaging gridding at each propagation moment along a depth direction to obtain a transformed conversion wave field; solving an upstream wave field and a downstream wave field according to an original wave field and the conversion wave field; and selecting the wave field in a special direction to image according to a mutual correlation imaging condition. By the upstream and downstream wave field decomposition-based inverse-time migration method, the low-frequency noise in inverse-time migration can be effectively prevented, and the imaging profile accuracy is improved; and meanwhile, the method has relatively good wavelet amplitude-maintaining performance, and technological guarantee is also provided for subsequent fidelity processing.

The invention specifically discloses a GIS (gas insulated switchgear) single-time partial discharge signal extraction and trigger moment adjusting method. The method comprises the steps that (1) a single partial discharge fault of a GIS is obtained by utilizing an ultrahigh frequency electromagnetic wave sensor; (2) the high frequency noise in the fault signal in the step (1) is filtered out by utilizing the wavelet denoising method; (3) the fault signal subjected to filtering in the step (2) is normalized and is processed to obtain the absolute value; (4) the numerical differentiation of the signal obtained in the step (3) is worked out; (5) taking the differentiation signal as the basis, the threshold method is utilized to locate the position of the leading edge of the discharge wave crest of each discharge signal in the fault signal; (6) the positions of the discharge signals in the original fault signal, obtained in the step (5) and the corresponding sampling values are taken as the basis; (7) the position of the initial point of each discharge wave crest in the original fault signal is determined; and (8) the single discharge signal is adjusted to have the specific discharge initial position by adopting the method of supplementing system white noise according to each discharge signal intercepted in the step (7).

The invention discloses a narrowband switching millimeter wave voltage-controlled oscillator with a wide tuning range, and the narrowband switching millimeter wave voltage-controlled oscillator comprises a negative resistance unit which provides energy for maintaining oscillation for a resonant cavity, and a main oscillation circuit which employs an improved pi-type differential circuit structureand is used for achieving the oscillation and improving the quality factor of a resonant circuit; the filter capacitor and the tail current source MOS tube form a low-pass filter, so that the phase noise of the oscillator is reduced; the narrowband switching circuit comprises four basic LC VCOs. The output buffer circuit connects the four narrow-band VCOs in a common-drain manner, outputs the selected narrow-band VCO, and provides driving for subsequent circuits. According to the invention, based on the 65nm CMOS process design, good noise performance is realized.

The invention provides an active filter and a communication system. The active filter comprises a main circuit and a control circuit, wherein the control circuit is used for detecting first current output by a negative electrode at the input end of a conversion circuit so as to obtain a harmonic component in the first current and generating a control signal according to the harmonic component; the main circuit is used for generating second current opposite to the phase of the harmonic component under the control of the control signal so as to enable source current formed by the first current and the second current through a power supply. According to the active filter provided by the invention, effective suppression on low-frequency noise can be realized.

The invention provides a multi-scale image noise reduction method and device. The method comprises the following steps: carrying out three-layer wavelet decomposition on an input N*N image block; performing soft threshold shrinkage on each layer of wavelet high-frequency sub-band; performing bilateral filtering on the low-frequency sub-band after wavelet decomposition; and performing wavelet inverse transformation reconstruction according to the high-frequency sub-band subjected to soft threshold shrinkage and the low-frequency sub-band subjected to bilateral filtering to obtain a reconstructed N*N image block. According to the method, through multi-scale image noise reduction combining wavelet decomposition and bilateral filtering, high-frequency noise and low-frequency noise of differentscales in the Y-channel image can be suppressed at the same time.

The invention relates to a sound insulation band gap material with a two-dimensional serial structure, belonging to the field of acoustics and relating to the fields of condensed matter physics, mechanics, machinery, materials science, and the like. The structure is formed by respectively arraying and serially connecting parallel pipes (solid pipes, hollow metallic pipes or non-metallic pipes) in air according to tetragonal lattices, triangular lattices and honeycomb lattices. The sound insulation band gap material with a two-dimensional serial structure is characterized in that the tetragonal lattices in a gamma-X direction at least include three layers, and the triangular lattices and the honeycomb lattices in a gamma-M direction at least include four layers; the arraying sequences of the three lattices have no relations, and the gamma-X direction of the tetragonal lattices and the gamma-M direction of the triangular lattices and the honeycomb lattices are parallel to the same straight line; and sound waves are transmitted along the gamma-X direction and the gamma-M direction in the serial structure. The sound insulation band gap material with a two-dimensional serial structure can better suppress environmental noise within a frequency range of 1-3kHz which is the most sensitive to the human ears, thereby being used for sound barrier and having wide engineering application potential in reducing the noise of highways, railways, urban traffics and rooms.

The invention belongs to the technical field of noise control, and provides a double-working mode acoustic liner for broadband noise suppression and a control method in order to overcome the problems that the existing acoustic liner cannot realize effective noise suppression in a relatively wide band range; when the acoustic absorptivity of the acoustic liner is not restricted by acoustic source frequency, the system is relatively large in volume and relatively slow in dynamic response; and the application of the acoustic liner will be restricted in an aircraft especially in an unmanned aerial vehicle. Piezoelectric materials form an array, thus forming a disturbed impedance adjustable acoustic liner system. A direct current within 30 V is imported between upper electrodes and lower electrodes, thus enabling the acoustic liner to work in a static mode. An alternate current of 30V is imported, thus enabling the acoustic liner to work in a dynamic mode. In two modes of the static mode and the dynamic mode, the relatively high acoustic absorptivity is kept in the broadband. A device realizes synchronous adjustment of acoustic impedance and two working modes. The system complexity is reduced to the greatest extent; system integration and miniaturization is convenient; and the band range of the acoustic liner is extended.

The invention belongs to a nuclear magnetic resonance gyroscope detection method, and specifically discloses a nuclear magnetic resonance gyroscope photomagnetic modulation detection system and a nuclear magnetic resonance gyroscope photomagnetic modulation detection method. The nuclear magnetic resonance gyroscope photomagnetic modulation detection system comprises a polarizer, a magnetic resonance gas chamber, a Faraday coil, an analyzer and a photoelectric detector, wherein the centers of the polarizer, the magnetic resonance gas chamber, the Faraday coil, the analyzer and the photoelectricdetector are sequentially positioned on the optical path of detection laser, the axis direction of the Faraday coil coincides with the optical path direction of the detection laser, the output end ofthe photoelectric detector is connected to a signal processing system, and the signal processing system drives the Faraday coil. According to the present invention, the signal output frequency of a signal generator is regulated to be equal to the design frequency of the Faraday coil, the magnetic resonance gas chamber is heated, the modulated laser signal is confirmed when the frequency of the output signal is the same as the frequency of the received drive signal of the Faraday coil, a lock-in amplifier is regulated so as to lock at the frequency of more than the Faraday coil modulation frequency, and then wave filtering treatment is performed; and with the method, the carrier ability of the detection laser and the integrity of the signal after the post-demodulation can be improved, andthe low-frequency noise of the gyroscope detection signal can be inhibited.

The invention discloses a Kalman and wavelet fused MEMS gyroscope adaptive anti-outlier denoising method. The method comprises the following steps: establishing a time sequence model of gyroscope signals; de-noising the gyroscope signal by adopting Kalman filtering; performing threshold processing on the low-frequency component and the high-frequency component of the gyroscope signal after Kalmanfiltering by using wavelet analysis; wavelet reconstruction is carried out on the high-frequency signals and the low-frequency signals of the gyroscope signals after threshold processing. The invention provides an adaptive anti-outlier denoising scheme integrating Kalman filtering and wavelet for MEMS gyroscope signals, the precision of the sensor can be more effectively improved, and errors are reduced.

The invention discloses a method for lowering the low-frequency noise of rear torsion beam automobile model braking, and belongs to the technical field of automobile braking. The method comprises thefollowing steps that: carrying out a noise detection experiment on a finished automobile when a rear-disk type brake works under different working conditions, and determining a working condition whichgenerates low-frequency noise; according to the working condition, simulating and reproducing low-frequency noise, meanwhile, carrying out a vibration frequency test, and determining a low-frequencynoise transferring path; carrying out modality analysis on parts, comparing with an experiment result, and identifying parts subjected to modality coupling with the low-frequency noise; and changing the modality of the modality coupling parts, and cutting off the noise transferring path. The method has the beneficial effects that a low-frequency noise generation mechanism is combined to determinethe noise transferring path, and the modality of the parts subjected to modality coupling with the low-frequency noise is changed to cut off the noise transferring path to inhibit the low-frequency noise. The method is simple and effective, is low in cost, is high in universality and has good economic benefit, and low-frequency noise under different working conditions can be further lowered and eliminated.

A method for inhibiting the noise of a downwind type wind generator set based on a variable-helical-angle groove relates to a cylindrical tower truss wind generator set. The position and length of thegroove are determined on a cylindrical tower truss; on the cylindrical tower truss, the helical angle degree of the groove is determined; and the depth and width of the groove and the geometric shapeof the groove are designed. The method not only can inhibit the development of the Karman vortex street of cylindrical wake flow, but also can perform a drag reducing function. The low frequency noise of a paddle tip part is better inhibited by the variable-helical-angle groove on account of the large noise characteristic of the paddle tip part. The method for inhibiting the noise of the downwindtype wind generator set based on the variable helical angle groove has the advantages that the structure is simple, realization is convenient, an extra complicated control system is not needed, the noise reducing effect is remarkable, and the scheme for inhibiting the noise of the downwind type wind generator set is potential.

A dishwasher (10) including a housing (11) forming an exterior, a tableware cleaning tub (12) formed at an inside of the housing (11), and a power cord (30) configured to supply a power, the housing (11) including a housing body (40), a power cord (30) insertion hole (43) which is provided at one side of the housing body (40) for a portion of the power cord (30) to be inserted into an inside of the housing (11), and an open/close unit (41) rotatably coupled to the housing body (40) to open/close the power cord insertion hole (43), the open/close unit (41) equipped with a first accommodation groove (44) to accommodate the portion of the power cord (30) inserted into the inside of the housing (11), the power cord (30) including a fixing unit configured to fix the power cord (30) to the housing body (40) when the open/close unit (41) closes the power cord insertion hole (43), the fixing unit comprising a coupling member (32) which is coupled to the first accommodation groove (44) of the open/close unit (41), and a fixing member (31) which is fixed to the housing body (40).

An embodiment of the invention provides a received signal strength detection circuit and method. The circuit comprises a ripple-suppressed OOK signal amplitude detection module and a time domain analog-to-digital conversion module, wherein the OOK signal amplitude detection module for ripple suppression receives an OOK receiving signal, converts the OOK receiving signal into a direct-current analog amplitude signal, and suppresses alternating-current ripples in the conversion process; the time domain analog-to-digital conversion module converts the DC analog amplitude signal into an amplitudefrequency modulation signal, measures the frequency of the amplitude frequency modulation signal, and outputs a digital amplitude signal representing a measurement result. According to the circuit disclosed in the embodiment of the invention, the OOK signal amplitude detection module for ripple suppression can be used to perform high-efficiency and high-precision sampling on the OOK signal amplitude; sampling ripple interference can be effectively reduced, conversion from sampling voltage to frequency signals is achieved through the time domain analog-digital conversion module, low-frequency noise can be greatly restrained, and therefore ultra-low-power-consumption received signal strength detection is achieved.

A vehicle radar. In the vehicle radar, a high-pass filter is disposed on a signal line connecting a transmitting chip and a receiving chip, the signal line allowing a local oscillation signal to be transferred therethrough. The high-pass filter prevents noise from being introduced through the signal line, along which the local oscillation signal is transferred. This prevents the accuracy of detection from being lowered by low-frequency noise generated from the interior of the vehicle radar. The high-pass filter connected to the signal line is embodied as a variety of configurations, thereby providing a structure able to effectively suppress low-frequency noise while maintaining the existing structure of the vehicle radar.

The invention discloses a noise reduction device of a blade of a wind generating set. The noise reduction device is of a sawtooth-shaped strip-shaped structure, the sawtooth-shaped strip-shaped structure is arranged at the trailing edge of 70%-100% of a wingspan of the blade of the wind generating set, the sawtooth-shaped strip-shaped structure comprises saw teeth and a mounting surface, the height of the sawteeth is 10%-20% of the local chord length of the blade, and the saw teeth are in a half-sine wave fluctuation. The noise reduction device for the blade of the wind generating set can reduce the noise sound power level of the blade, meanwhile, noise modulation is inhibited, the noise annoyance degree is reduced, the advantages of being simple in structure and low in cost are achieved,and the feasibility is high.

The invention discloses a capacitance sensor interface circuit based on frequency switching. The circuit is composed of a frequency modulation circuit body based on capacitance change and a frequency voltage switching circuit body; the input end of the frequency modulation circuit body based on capacitance change forms the input end of the whole interface circuit and is connected with a measured capacitor; the output end of the frequency modulation circuit body based on capacitance change is connected with the input end of the frequency voltage switching circuit body; the output end of the frequency voltage switching circuit body forms the output end of the whole interface circuit; the frequency modulation circuit body based on capacitance change converts the measured capacitor value into a frequency value, and then frequency voltage switching circuit body converts the frequency value into a voltage value. The circuit can effectively inhibit the influence of noise on low-frequency positions, frequency signals can be converted into corresponding voltage signals only in a signal input period, the time-delay of outputting is reduced, and the reaction speed of the capacitance sensor interface circuit is greatly improved.