978 results about "Frequency noise" patented technology

The invention discloses a hand movement tracking system and a hand movement tracking method. The invention comprises an attitude and heading reference system based on an accelerometer, a gyroscope and a magnetic sensor, and a hand movement tracking method based on the attitude and heading reference system. The hand movement tracking method comprises the following steps: firstly, obtaining a triaxial acceleration measured by the accelerometer, a triaxial angular velocity measured by the gyroscope and a triaxial magnetic-field component measured by the magnetic sensor, performing error compensation on the magnetic sensor by adopting a least square method to establish an error model after an upper computer receives sensor data, eliminating high-frequency noise of the triaxial acceleration by virtue of a window low-pass filter, and establishing an error model for the gyroscope so as to perform error compensation on random drift of the gyroscope; secondly, effectively integrating the gyroscope, the accelerometer and the magnetic sensor by virtue of an improved adaptive complementary filtering algorithm to obtain an attitude angle and a path angle; and finally, performing gravity compensation and discrete digital integration on acceleration signals to obtain a velocity and a track of a hand movement. The tracking system and the tracking method disclosed by the invention can be applied to a man-machine interactive system, is convenient to operate, and is strong in experience feeling.

This document describes a general system for noise reduction, as well as a specific system for Magnetic Resonance Imaging (MRI) and Nuclear Quadrupole Resonance (NQR). The general system, which is called Calculated Readout by Spectral Parallelism (CRISP), involves reconstruction and recombination of frequency-limited broadband data using separate narrowband data channels to create images or signal profiles. A multi-channel CRISP system can perform this separation using (1) frequency tuned hardware, (2) a frequency filter-bank (or equivalent), or (3) a combination of implementations (1) and (2). This system significantly reduces what we call cross-frequency noise, thereby increasing signal-to-noise-ratio (SNR). A multi-channel CRISP system applicable to MRI and NQR are described.

There is provided a narrow linewidth semiconductor laser device comprising a semiconductor laser and a low noise current source operatively connected to the laser for supplying current thereto, the current source being particularly adapted to prevent a significant degradation of the frequency noise spectrum of the laser. The laser device also has an optical frequency discriminator providing an error signal representative of the optical frequency of the laser. The laser device also has control means having a feedback network for providing a frequency feedback signal. The feedback network is particularly adapted to the frequency noise spectrum of the frequency discriminator, the frequency noise spectrum of the laser and the tuning response of the laser. The control means is also provided with sequencing means for allowing to automatically enable frequency locking of the laser on the frequency reference of the optical frequency discriminator. The laser device is provided with an enclosure for enclosing the frequency discriminator to isolate the frequency discriminator from external perturbations. Such an arrangement is particularly advantageous since it allows to provide an improved sub-kHz linewidth and a high coherence while being compact, lightweight and highly reliable. Moreover, the narrow linewidth semiconductor laser device of the present invention can advantageously be automatically operated.

The invention discloses a nuclear magnetic resonance underground water detection signal noise eliminating method. The method comprises the steps of: recoding response data entry three groups, each of these three sets of data Fourier transform nuclear magnetic resonance to determine the frequency of the data center in each neighborhood contains frequency harmonics, and frequency harmonic structure and the same frequency, and magnetic resonance corresponding data with sine function of the length of the cosine function, and composition and magnetic resonance response data observed signal using independent component analysis for each group observed signals to separate the mixed signal obtained solution for data reconstruction to eliminate frequency harmonic interference, the three groups of removing harmonic frequency data as observational signals, and then use algorithm processing, weaken the remaining random noise. The invention is to eliminate harmonic frequency noise at the same time, the signal will not destroy any details, without laying a reference coil, simple operation, suppress random noise does not require a lot of data, reducing the processing time.

High noise immunity sensing methods and apparatus are provided for a capacitive touch device, which sense the capacitive touch device for self capacitance or mutual capacitance or both with different scan frequencies in a frame, to thereby suppress certain frequency noise interference. By combining time domain and space domain noise-eliminating approaches, probabilities of noise interference are reduced, without compromising other parameters.

The embodiment of the invention discloses a non-contact heart rate measurement method and a device based on Euler image magnification, used for solving the technical problems existing in the existingnon-contact heart rate measurement method that the heart rate is great in same-frequency noise interference and is greatly influenced by an environment temperature, isolation signal authenticity lacksjudgment and the like. The non-contact heart rate measurement method and device based on Euler image magnification in the embodiment of the invention comprises the following steps: S1, magnifying tiny change of radial artery jump in a video through an Euler image magnification technology; S2, performing luminance variance statistics on a video frame pixel point luminance channel after magnifyingthe tiny change of radial artery jump in a time domain, performing skin segmentation on the video frame subjected to magnification of the tiny change of radial artery jump, and extracting a radial artery jump area; and S3, performing time-frequency analysis on the radial artery jump area so as to calculate the heart rate.

The invention discloses a line to decrease noise for Broad Band and manufacture method. The sound line has the noise elimination hole which is distributed randomly and the size is changed continuously. So it can decrease the noise of broad frequency noise. Because of whole forming, it can not generate the noise dispersion phenomena caused by the sound line joint to influence the noise decreasing effect. In process of Broad Band noise decreasing line, it can get the noise frequency and corresponding noise intension by value simulation of test and get the size range, changing interface and density of noise elimination hole; also it distributes the hole on the sound line basal board to have the good noise decreasing effect.

The invention relates to a measuring device of the noise characteristics of laser, consisting of a conversion system of noise fluctuation of the laser and a detecting and processing system. The measuring device mainly comprises a circulator, a 3*3 coupler, a first photoswitch, a second photoswitch, optical fiber, a first Faraday rotation reflector, a second Faraday rotation reflector, a frequencyshifter, a first photoelectric detector, a second photoelectric detector, a third photoelectric detector, a fourth photoelectric detector, a data acquisition card and a computer. The measuring devicedisclosed by the invention has the capability of simultaneously measuring the noise characteristics comprising the intense noise power spectral density, the phase noise power spectral density, the frequency noise power spectral density, the line width and the Allen variance with frequency instability, of the laser, has the characteristics of high integration level and simpler and more concise structure, has no any limitation to the laser to be measured without an extra active control measure, thereby increasing the measuring reliability of the noise characteristics of the laser.

The invention discloses a method of obtaining underwater acoustic channel reciprocity by using compressed sensing and relates to underwater acoustic communication. The method is used for obtaining accurate channel parameters from OFDM (Orthogonal Frequency Division Multiplexing) received signals and ensuring the reciprocity of underwater acoustic channels. According to a compressed sensing theory, an OMP algorithm is used for reconstructing time domain impulse noise interference and wide single frequency noise interference, and eliminating the noise interference by observed quantity. For the time domain impulse noise interference, the time domain impulse noise interference is estimated by virtual subcarrier at a receiving end, is reconstructed by the OMP algorithm and is eliminated; the wide single frequency noise extracted at the receiving end has sparsity at a frequency domain, domain conversion is not needed, a measurement matrix is utilized, and the wide single frequency noise interference is reconstructed according to the OMP algorithm and is eliminated. The upper row and the lower row of underwater acoustic channels after the time domain impulse noise interference and the wide single frequency noise interference are eliminated are identical in channel states, namely, the underwater acoustic channels are provided with the reciprocity.

The invention discloses a method and system based on a differential phase contrast imaging reduction quantitative phase image, and relates to the field of the computer imaging. The stable method from a target image to a reduction quantitative phase image is established. The method is capable of firstly establishing a differential phase contrast imaging two-dimensional optical phase transfer function H(u), and establishing the relation between the H(u), a frequency domain function of a differential phase contrast image (the figure is as shown in the specification) and the quantitative phase information, finally executing the deconvolution operation to recover the quantitative phase information through the phase transfer function of the differential phase contrast imaging. The method is capable of further researching a method of quantitatively recovering the phase information under the asymmetrical illumination pattern formed by multi-axis division so as to enhance the reconstitution capacity of the phase information in the different directions, and using the mathematical optimization to reduce the frequency noise increase caused by the direct deconvolution. The method is capable of overcoming the defects that the traditional quantitative image acquisition operation is complicated and the imaging condition is rigorous, and the obtained image resolution is higher.

The invention belongs to the field of medical signal processing, particularly provides an eeg high-frequency oscillation signal detecting system based on a convolution neural network, and aims to solve the problem that in a conventional eeg high-frequency oscillation signal detection technique, the false drop rate is high caused by high-frequency noise and peaked wave shape. The eeg high-frequency oscillation signal detecting system comprises a user terminal, a data preprocessing module, a high-frequency oscillation signal predetecting module, the convolution neural network module and a static module, wherein the user terminal is used for acquiring an eeg signal; the data preprocessing module is used for performing data preprocessing; the high-frequency oscillation signal predetecting module is used for performing detection on the eeg signal to obtain suspected high-frequency oscillation fragments; and the convolution neural network module is used for classifying all the suspected high-frequency oscillation fragments. According to the eeg high-frequency oscillation signal detecting system disclosed by the invention, when HFOs are detected, the sensitivity can be effectively improved, the false drop rate is reduced, and the precision rate of epileptogenic focus positioning is increased; and besides, the eeg high-frequency oscillation signal detecting system can use scalp eeg and can also use cortex eeg, so that the egg high-frequency oscillation signal detecting system can enable a doctor to achieve more flexibility.

The invention discloses a method for characterizing a steel fatigue crack propagation behavior for casing drilling. The method comprises the steps of: firstly, sampling casing drilling steel, preparing a sample and cleaning; secondly, carrying out low-frequency noise testing on the sample before fatigue; thirdly, carrying out fatigue testing on the sample; fourthly, carrying out low-frequency noise testing on the sample after fatigue; and fifthly, analyzing, extracting and processing low-frequency noise data before and after the fatigue testing according to low-frequency l/f noise information before and after the fatigue, and characterizing a fatigue crack propagation behavior of the sample. Through two times of low-frequency l/f noise testing before and after the fatigue propagation, the influence of background noise of the sample is eliminated, more complex formula derivation and mathematical calculation in common characterizing methods are avoided, no strict requirements are required for the shape of the sample, the fatigue testing quantity is favorably reduced, the testing cost is lowered, and the fatigue crack propagation behaviors of various samples can be conveniently subjected to sampling and fatigue service life estimation; and the method has the characteristics of convenience in use, low cost and convenience in popularization.

The invention provides an integrated micromechanical thermopile infrared detection system and a manufacture method thereof. The system comprises a thermopile detector and a signal processing circuit, wherein the signal processing circuit comprises a preposed amplifier, a band-pass filter, a main amplifier and an oscillator. The method is characterized in that integrated design and manufacture of a uniwafer of the thermopile detector and the signal processing circuit are realized; and compatibility of a MEMS sensor and a CMOS circuit can be realized by manufacturing the thermopile detector and the signal processing circuit simultaneously and using a standard CMOS process. The structure of the thermopile detector in the system comprises a (silicon) matrix, a framework, a thermoelectric couple, a support arm, an infrared absorption layer, etching openings; and the intermediate suspended infrared absorption layer can be provided with the etching openings with different shapes, and dry etching working gas enters a substrate etched silicon releasing structure through the etching openings. The structure of the signal processing circuit in the system uses wave chopping technology to reduce the effect of low-frequency noise on a signal.

A hybrid valve assembly for an exhaust system includes an exhaust tube having a bore defining an exhaust flow path. A vane is mounted within the bore and is moveable between an open position and a closed position. A resilient member biases the vane toward the closed position. A valve actuator has an ON position where movement of the vane is actively controlled by the valve actuator and an OFF position where movement of the vane is passively controlled by exhaust gas flow.

The invention provides a constant-speed air conditioner beat vibration determining method and device. The method comprises the following steps: acquiring an overall noise value generated by a constant-speed air conditioner and a noise spectrum curve corresponding to the overall noise value; analyzing the noise spectrum curve to determine a first noise peak and a second noise peak which respectively correspond to two frequency points between which frequency difference is smaller than a preset frequency interval; calculating peak difference between the first noise peak and the second noise peak and determining a maximum noise peak in the first noise peak and the second noise peak; and judging whether the beat frequency noise of the constant-speed air conditioner meets a noise standard or not according to the overall noise value, the peak difference and the maximum noise peak of the constant-speed air conditioner. Alarm notification can be sent out in time when the beat frequency noise of the constant-speed air conditioner does not meet the noise standard, so that research staff can rectify and reform in time, and the problem that the user experience is poor due to poor tone quality and poor use comfort of the constant-speed air conditioner is solved.

The invention discloses a system and a method for testing laser frequency noise power spectrum density based on a Mach-Zehnder interferometer. A laser central frequency is locked at an orthogonal point of an interference curve of the Mach Zehnder interferometer through a feedback loop, so the system works in a good linearity range, converts laser frequency noise into light intensity, and fulfillsan aim of performing direct test through an electronic frequency spectrograph; and a frequency observation point avoids 1/f noise of the test system through the frequency shift by an acousto-optic frequency shifter. The invention provides the stable testing method which is used for testing laser frequency noise power spectrum density, is applied to an electronic frequency spectrograph, provides ameans for analyzing the influence of laser frequency noise on an optical system, and has significant scientific meaning and application value.

A method of controlling noise in a pulse width modulation circuit includes varying a sample frequency and a range of information levels, wherein each sample within a data sample stream at the sample frequency represents a level within the range of information levels, to shift in frequency noise generated at the sample frequency during encoding of the data sample stream into pulse width modulated patterns.

The invention provides a time sequence signal efficient denoising and high-precision reconstruction modeling method and system. The method comprises: carrying out data preprocessing on original pulsewave signals; selecting a preset signal duration, and dividing the pulse wave signals after data preprocessing into a prediction set, a training set and a test set; selecting a convolutional neural network as a basic model of the deep convolutional noise reduction auto-encoder, and obtaining a deep convolutional noise reduction auto-encoder model according to a signal denoising requirement; inputting the training set into a deep convolution noise reduction auto-encoder model for training, and optimizing and selecting parameters of the deep convolution noise reduction auto-encoder model by using the regularization parameters and the test set to obtain an optimal deep learning model; and inputting the noisy pulse wave signal prediction set into the optimal deep learning model to obtain deepstructure features, performing signal reconstruction and denoising processing, and evaluating model performance. According to the method, denoising and reconstruction of the pulse wave signals are effectively carried out, and a new thought is provided for filtering same-frequency noise interference in the pulse wave signals.

The invention discloses a method and system for identifying a marine oil spill object by a marine radar. The method of the invention comprises the following steps: A, converting output image signals from radar projection into Descartes projection; B, correcting images and compensating motion; C, processing the radar images corrected in the step B by a Gamma filtering method, reserving marginal information and simultaneously filtering high-frequency noise of the radar images; D, detecting a strong signal area in the images, according to the distribution of signal strength in the images, determining the saturated state strength as the strength threshold of the signal area, and directly deleting the signal data exceeding the strength threshold; and E, carrying out image segmentation by a gray level co-occurrence matrix method to abstract the marine oil spill object. The system comprises a radar main controller, a marine radar controller, a junction box, an acquisition device, a processing device and a display device. The invention utilizes the noise wave information such as ocean wave and the like to obtain a small object, identifies the oil spill object by a texture algorithm, and can better abstract the marine oil spill object.

An optical sampling method and apparatus use a probe pulse source of a predetermined optical wavelength range, e.g., 1560 nm, to sample incoming optical pulses in approximately the same wavelength range. The probe pulse source is frequency-doubled e.g., using a frequency doubler such as a nonlinear PPLN crystal, to obtain an intermediate second harmonic which may be filtered with a 780 nm bandpass filter to eliminate at least source frequency noise background. The filtered intermediate second harmonic is then mixed with the user input signal using an optional polarizing beam splitter and a dichroic beam splitter. The mixed signal is sent to a sum frequency generating (SFG) nonlinear crystal, e.g., a PPLN crystal, where the resulting frequency is near the third harmonic. The output from the SFG PPLN crystal may be filtered using a bandpass 515 nm filter to remove unwanted wavelengths and processed to measure/sense the near third harmonic content using a photomultiplier tube (PMT). Beyond the PMT, the output may be sent to a microprocessor for analysis and display on a cathode ray oscilloscope as necessary. 80-85% power conversion efficiency in the frequency doubler, a 60 or 65% photon conversion efficiency in the sampler and handling of 600+ GHz bandwidths, as well as background noise reduction are possible by using the invention.

The invention discloses a drive circuit and method of a drive light source and a controller. The drive circuit comprises a frequency controller and a switching module, wherein the frequency controller receives a first dimming signal; if a light source is controlled according to the first dimming signal, the light source emits the preset brightness; when the frequency of the first dimming signal is within at least one preset range, the frequency controller generates a second dimming signal according to the first dimming signal, wherein when the frequency of the second dimming signal is beyond the at least one preset range, the switching module switches on and off alternately according to the second dimming signal so as to acquire the preset brightness; when the frequency of the first dimming signal is beyond the at least one preset range, the switching module switches on and off alternately according to the first dimming signal so as to acquire the preset brightness. The frequency of the dimming signal in the drive circuit is less than the preset maximum threshold value all along, therefore, the frequency noise cannot influence the dimming control of the light source and the precision of the drive circuit is improved.

The invention discloses an optical time domain reflectometer based on double acoustic-optical modulators and a common-mode rejection method of the optical time domain reflectometer. The method includes the following steps that a laser device outputs an optical signal; the optical signal is divided into two routes of optical signal bodies, and the optical signal bodies are modulated; direct frequency beating is conducted on the two routes of optical signal bodies so that frequency noise of the laser device can be eliminated and a reference signal can be generated; the first route of optical signal bodies enter a sensing optical fiber after being amplified, and a measurement signal is obtained after frequency beating is conducted on the back scattered light of the sensing optical fiber and the second route of optical signal bodies; the measurement signal and the reference signal are collected, phase demodulating is conducted, and phase comparison is conducted on the reference signal and the measurement signal to obtain a signal to be measured. The two acoustic-optical modulators are adopted, and by means of the method of conducting common-mode rejection by introducing the reference signal, influences of frequency noise of the laser device in the phase sensitive optical time domain reflectometer and frequency noise of the acoustic-optical modulators on the measurement result are reduced.

The invention discloses a high-frequency muffler used on an automobile intercooler intake pipe. The high-frequency muffler comprises a high-frequency muffling structure and a main pipeline connected on the intercooler intake pipe; a closed shell is positioned and connected on the periphery of the main pipeline, at least two partitions are arranged in the closed shell radially to enable at least two resonant cavities and an expansion cavity to be formed in the closed shell, each resonant cavity is communicated with the main pipeline through a group of small round through holes formed in the circumference of the main pipeline, the expansion cavity is directly communicated with the main pipeline, and the resonant cavities and the expansion cavities jointly form the high-frequency muffling structure. In a limited engine room space, the high-frequency muffler is wider in muffling frequency band, excellent in muffling performance and capable of more effectively lowering high-frequency noise such as squeal and surge generated in the working process of a turbocharger.