42 results about "Nyquist frequency" patented technology

A method for filtering periodic noise and a filter using the method are provided. The method includes: obtaining an input signal; detecting a fundamental frequency corresponding to a maximum peak in a spectrum of the input signal, detecting a harmonic frequency according to the fundamental frequency, and detecting an aliasing frequency corresponding to the harmonic frequency in response to the harmonic frequency corresponding to the fundamental frequency being greater than a Nyquist frequency of the input signal; filtering the fundamental frequency and at least one of the harmonic frequency and the aliasing frequency of the spectrum to generate a first filtered spectrum, and restoring the input signal according to the first filtered spectrum to generate an output signal; and outputting the output signal. The method for filtering the periodic noise and the filter using the method may filter the periodic noise in the input signal affected by an aliasing effect.

Circuitry for determining an impedance of an electrochemical cell comprising at least one first electrode and a second electrode, the circuitry comprising: drive circuitry configured to apply a stimulus to the electrochemical cell, the stimulus having a stimulation frequency and a stimulation amplitude; and measurement circuitry configured to: sample an output of the electrochemical cell at a sampling frequency to generate an output signal; determine an output amplitude of output signal at one or more alias frequencies, the one or more alias frequency based on the stimulation frequency and the sampling frequency; and determine the impedance of the cell at the stimulation frequency based on the output amplitude at the one or more alias frequencies and the stimulation amplitude; and control circuitry configured to: control the sampling frequency and the stimulation frequency such that a Nyquist rate of the sampling frequency is greater than stimulation frequency.

The application provides a sidelobe suppression method without loss of resolution, which can completely remove sidelobes and does not lose signal resolution. The method is based on the characteristic that the main lobe width of IPR is twice the sidelobe width. If N sample data of IPR are set, the main lobe width is 4xpi / N, and the sidelobe width is 2xpi / N. By using the fact that the main lobe width is different from the sidelobe width, the positions of the main lobe and the sidelobe in IPR can be located. As long as the positions of the main lobe and the sidelobe are determined, the unwanted sidelobe can be eliminated. The method provided by the application does not need to limit the data sampling rate to be an integer multiple of Nyquist frequency, and is directly applied to the spectrum of a signal, and is simple to calculate.

Provided is a machine learning image processing method, wherein: a first frequency characteristic of a first teacher image is calculated; a sample frequency characteristic of a sample image, which serves as a sample of a low-quality image obtained by imaging with a low-image-quality endoscope, is calculated; a ratio of the sample frequency characteristic and the first frequency characteristic is calculated as a first frequency response characteristic; the first frequency response characteristic is compared with a predetermined second frequency response characteristic for student image generation; when a Nyquist frequency of the first frequency response characteristic is N2 and a Nyquist frequency of the second frequency response characteristic is N1, if N1 < N2, the image size of the first teacher image is reduced to generate a second teacher image; and if N1 ≥ N2, the first teacher image is reduced in image quality using a low-pass filter set on the basis of the second frequency response characteristic to generate a first student image.

The invention belongs to the field of magnetic resonance sounding signal noise filtering, and particularly relates to a magnetic resonance sounding signal de-noising method based on backtracking generalized OMP, and the method comprises the steps: employing a magnetic resonance sounding water detector to carry out the sampling of a sparse signal at a frequency lower than the Nyquist frequency, and obtaining a noisy MRS signal; converting the noisy MRS signal into a two-dimensional matrix signal; dictionary learning is carried out on the two-dimensional matrix signals through a KSVD algorithm, and an updated dictionary is obtained after iteration; calculating a recovery matrix and measurement data by using an independently distributed Gaussian random matrix; performing iterative operation on the measurement data by using a backtracking generalized orthogonal matching pursuit algorithm, selecting an atomic sequence of maximum projection of the measurement data and a recovery matrix module, and obtaining a sparse coefficient matrix of the measurement data under the recovery matrix; and calculating a recovery signal according to the dictionary and the sparse coefficient matrix of the measurement data under the recovery matrix.

The application provides a passive equalizer for inter-core particle interconnection and an inter-core particle interconnection system, which comprises upper sawtooth metal copper wires, lower sawtooth metal copper wires, a first via and a second via; the upper sawtooth metal copper wires are provided with the second via on one side and connected to the lower sawtooth metal copper wires through the first via on the other side; and the upper sawtooth metal copper wires and the lower sawtooth metal copper wires are both provided in a sawtooth shape and staggered. The double-layer sawtooth cross metal copper wires embedded in the metal grounding layer can effectively solve the serious inter-symbol interference (ISI) problem existing in the high-speed parallel data transmission system, and the voltage transmission curve of the channel in the transmission system is flattened in the range of direct current frequency and Nyquist frequency, so that the eye diagram quality of the receiver is obviously improved.

The invention is suitable for the technical field of electronic microphone audio signal processing, and provides an electronic microphone audio signal processing system and method, and the system comprises a server which is connected with a signal collection module, a digital signal processing module, a digital-to-analog conversion module, and an output module. The signal acquisition module comprises a sound sensor, an analog front end and an analog-to-digital converter; the sound sensor adopts an MEMS microphone array and converts sound wave pressure change into an analog electric signal; a pre-amplifier, a biasing circuit and an anti-aliasing filter are arranged in the analog front end; the pre-amplifier amplifies an electric signal output by the microphone; the anti-aliasing filter is used for filtering high-frequency components higher than the Nyquist frequency before analog-digital conversion, and aliasing distortion is prevented. According to the invention, digital audio signals can be accurately processed in real time, echoes are effectively eliminated, noise is suppressed, the volume is stabilized, the voice definition and the tone quality are improved, and the audio signal processing quality of the electronic microphone is greatly improved.

The invention relates to a high-speed and high-precision current steering type digital-to-analog converter with excellent dynamic characteristics, which is characterized in that a segment decoding module receives digital signals and performs segment decoding processing to obtain control signals of each segment and sends the control signals to a switch driving circuit; the switch driving circuit is used for processing obtained control signals of each section, respectively corresponding to an in-phase driving control signal section and a reverse-phase driving control signal section of which the cross points are lower than common-mode voltage, and transmitting the control signals to a control input end of the differential switch array; the differential switch array works to realize the output of a forward analog signal and a reverse analog signal corresponding to a digital signal, so that the influence of a small load change effect, especially the influence of the problems of limited output impedance caused by parasitic capacitance, signal-dependent switching transient and the like on the dynamic characteristics of the current steering digital-to-analog converter can be solved; the design scheme has good dynamic characteristics when the signal frequency is close to the Nyquist frequency band, and the application requirements of multiple fields such as a communication system are met.

The application discloses a new energy automobile power battery thermal balance integrated monitoring system. In the application, a data buffer module effectively isolates a signal source from subsequent circuits through the characteristics of high input impedance and low output impedance, ensures the stability and integrity of the signal in the transmission process, and a self-adaptive gain controller module further optimizes the quality of the signal by monitoring and automatically adjusting the amplifier gain in real time, so that the output signal is ensured to be in a suitable dynamic range, distortion caused by too small signal is prevented, and saturation caused by too large signal is avoided. A data noise suppression module uses a low-pass active filter and a noise gate technology to specifically reduce noise components in the signal, and further improves the quality and definition of the signal. An anti-aliasing filter module effectively removes signal components higher than the Nyquist frequency before signal sampling, prevents aliasing from occurring, and ensures the accuracy of the sampling data.

The invention relates to a rotary machine modulation feature extraction method based on an adaptive Hoyer-L moment envelope spectrum, and the method comprises the steps: firstly collecting vibration or radiation noise data of a rotary machine as a monitoring signal, calculating a spectrum coherence function of the monitoring signal, and obtaining a double-variable spectrogram; dividing a Nyquist frequency band along a frequency axis by adopting frequency resolution; performing spectral integration on each sub-band to generate an enhanced envelope spectrum, and quantifying the modulation intensity of each sub-band based on a comprehensive evaluation index of an L moment and a Hoyer operator; then adaptively optimizing the sub-band with high modulation intensity based on a golden section method; and selecting a sub-band with high modulation intensity to perform spectrum integration along a frequency axis to obtain a demodulation spectrum of the signal. According to the invention, the demodulation performance of the rotating machine in a complex environment can be significantly improved.

The invention relates to the technical field of machine vision, and discloses an enameled wire surface defect detection and classification method based on machine vision, which comprises the following steps: firstly, collecting a wire scanning image, extracting a single-pixel time sequence of a fixed transverse position, performing frequency domain transformation after window processing, and obtaining a single-pixel time sequence; determining the position of a main peak according to the power spectrum in a range from zero frequency to Nyquist frequency; calculating a spiral bispectrum locking degree by taking a main peak as a reference; determining a phase sampling resolution according to the locking degree, and performing phase resampling on a single pixel time sequence and an adjacent pixel time sequence to generate phase-aligned two-dimensional blocks; then parameterizing channel gain and channel bias of each layer of the convolutional neural network by using a spiral bispectrum locking degree, and inputting a two-dimensional block into the network to obtain a defect probability; a binary cross entropy loss function is optimized by taking a power function of the spiral bispectrum locking degree as a sample weight; the arithmetic mean value of the defect probabilities of the same axial section is obtained, and when the mean value reaches or exceeds a preset threshold value, it is judged that defects exist.

This invention discloses a high-speed cable optimization method and system based on impedance continuity compensation, relating to the field of high-speed cable optimization. The method includes: identifying the location, amplitude, and type of each impedance abrupt change point; calculating the reflection phase difference between any two abrupt change points; identifying the locations of coherent traps where reflected signals from multiple abrupt change points coherently superimpose within the Nyquist frequency range; constructing a coherence elimination objective function; determining compensation parameters for geometric pre-compensation, dielectric constant gradient compensation, and active dynamic compensation; adjusting the reflection coefficient amplitude of the abrupt change points according to the target residual impedance abrupt change amplitude; changing the reflection phase distribution according to the optimal control parameters of dielectric constant gradient compensation; and introducing an adjustable reflection coefficient to adjust the standing wave condition according to the target terminal matching impedance value. The advantages of this invention are: effectively eliminating the coherent superposition effect of multi-level reflections in high-speed cables, achieving impedance continuity and signal integrity of high-speed cables across the entire frequency band.

Methods, systems, and devices for a rearrangement scheme for a Faster-than-Nyquist (FTN) waveform are described. An example method includes a user equipment (UE) receiving a phase rearrangement indication from a network entity, the phase rearrangement indication indicating one or more parameters associated with a phase rearrangement process for a FTN discrete Fourier transformation spread orthogonal frequency division multiplexing (DFT-s-OFDM) transmission scheme. The method may also include transmitting a signal based at least in part on the phase rearrangement indication and according to the DFT-s-OFDM transmission scheme. Another example method includes a network entity transmitting a phase rearrangement indication indicating one or more parameters associated with a phase rearrangement process for a DFT-s-OFDM transmission scheme and receiving a signal based at least in part on the phase rearrangement indication and according to the DFT-s-OFDM transmission scheme.

Systems and methods for adaptive filtering in an Analog-to-Digital Converter (ADC) address the issue of spurious tones affecting the Signal-to-Noise Ratio (SNR). In an illustrative, non-limiting embodiment, a system may include a processor configured to execute program instructions for estimating and compensating spurious signals in the ADC output. The system may identify the frequency, phase, and amplitude of spurious signals using Gi-Gq computation. In some cases, the ADC output path and spurious estimation processing may be oversampled to compensate for high-frequency spurs (e.g., closely below the ADC's Nyquist frequency). Also, such a system may operate before or during the reception of the signal, ensuring no impact on the useful signal reception and reducing power consumption. In another illustrative, non-limiting embodiment, a method may include adaptive filtering or cancellation of unwanted tones by learning and applying coefficients to the in-phase (I) and quadrature (Q) components of a digital signal.

The invention relates to a weighted MTF (Modulation Transfer Function)-based tolerance analysis method for an optical-digital combined system, and aims to solve the technical problem that the reliability of a tolerance range obtained by tolerance analysis is relatively low because an evaluation result highly depends on a test scene due to the fact that an image quality evaluation index is not objective enough in the prior art. Monte Carlo experiments based on full-band weighted MTF in the Nyquist frequency are performed on the surface shape error, the installation and adjustment eccentricity error and the installation and adjustment inclination error of the free-form surface optical element respectively, critical values of all tolerances are found out, the critical values of all the tolerances are zoomed through zooming coefficients, the experiments are repeated, and the free-form surface optical element is obtained. And finally determining a critical value of each tolerance item.

According to the full-band equalization adjustment method and circuit adapting to different medium channel attenuation characteristics provided by the embodiment of the invention, the tangent slope of the ascending section of the equalization frequency response curve can be freely adjusted on the premise that the power consumption and the area are not obviously increased, so that the channel loss of different media and characteristics is met. According to the invention, the equalization capability adjustment of the signal at the Nyquist frequency can be realized, and the equalization compensation capability of the medium-high frequency band can be flexibly adjusted according to different application scenes and different transmission line transmission parameter characteristics on the premise that the equalization capability at the DC gain and the Nyquist frequency is not changed. The problem that a current continuous time linear equalizer (CTLE) is generally neglected is solved, and the eye pattern quality and the signal integrity are optimized.

An image generation apparatus for machine learning performs reduction processing on components in at least part of a frequency band higher than a Nyquist frequency of a training image, for a candidate correct answer image with a resolution higher than the training image, and generate a correct answer image. The correct answer image and the training image are used as a pair for machine learning to improve a resolving power of an input image.

A signal analysis apparatus includes: a reception unit outputting sampling sequences obtained by adding different delay times and sampling each signal at a sampling rate lower than a Nyquist rate; a time-frequency conversion unit converting each sampling sequence to a frequency domain signal; a signal processing unit collectively performing phase compensation processing and processing for canceling phase rotation between the sampling sequences; a frequency estimation unit estimating frequency of the target signal by determining a sub-Nyquist zone in which the target signal has been folded; a frequency selection unit selecting a frequency group with a higher estimated spectrum amplitude value based on a sum of values for each sub-Nyquist zone, the values being obtained by multiplication of the sampling sequences by the corresponding coefficients; and a separation unit performing separation processing for separation of an error in the target signal by using the frequency group selected.

In the image generation method for machine learning, a reduction process for reducing the components of at least some of the frequency bands higher than the Nyquist frequency (ftn) of a training image (IT) is performed with respect to a positive image candidate (ICC) having a higher resolution than the training image (IT), thereby generating the positive image (IC). A positive solution image (IC) and a training image (IT) are used in pairs in machine learning for improving the resolution of an input image.

The invention discloses a grid-connected inverter passivity optimization design method based on boundary frequency, and relates to the technical field of power electronics. Establishing an inverter output admittance model considering the phase lag effect of the PR controller, and defining a first type of boundary frequency and a second type of boundary frequency according to frequency points of admittance real part symbol change; analyzing the relative position relation of the two types of boundary frequencies, revealing the internal relation that the second type of boundary frequency is equal to the phase crossing frequency, and defining a non-passive area of system output admittance; proposing an accurate phase compensation strategy based on boundary frequency, determining a first-order compensator structure of the cascaded PR controller according to a system output admittance non-passive area, and adjusting parameters of the first-order compensator structure; common connection point voltage feed-forward control without an additional sensor is introduced, and a feed-forward coefficient is adjusted according to phase characteristics of output admittance of the inverter. Finally, the passivity of the output admittance of the grid-connected inverter system within the Nyquist frequency range is realized, and the robustness of the system at the boundary frequency is enhanced.

The present invention relates to a method for estimating a rotor position without a position sensor in an active magnetic bearing system, wherein a voltage including a voltage component of the Nyquist frequency is applied to a winding, a current flowing through the winding is measured, a state-space model including state transition equations and output equations for state variables is derived from an electrical circuit model based on the voltage applied to the winding and the current, a predicted value of the current is calculated based on the state-space model, an estimated value of the state variable is corrected based on the error between the measured value and the predicted value of the current, and the rotor position is estimated from the corrected estimated value of the state variable.

The application claims a time-interleaved ADC clock skew blind spot sensing joint calibration method and an implementation system. The method folds a target input frequency to a single-channel sampling bandwidth, generates a blind spot ratio or blind spot weight according to the distance of the folded frequency from 0, f ch / 4, f ch / 2, and other blind spot reference points; when the target frequency observation degenerates, a joint observation set containing at least an auxiliary frequency observation is constructed, and each frequency observation shares the same set of channel clock skew variables; and the channel clock skew is jointly estimated in combination with phase preliminary estimation, linearized correlation preliminary estimation, frequency weight, and regularization constraint. The scheme can stably suppress interleaved spur in special frequency points and Nyquist frequency band without increasing additional ADC channels, and is suitable for on-chip digital calibration implementation.

A sound processing method includes receiving, as an input, a first sound signal sampled at a first sampling frequency. The sound processing method also includes generating, as an output, a second sound signal that is based on aliasing noise for the first sound signal from a frequency range that is higher than a first Nyquist frequency of the first sound signal, using a trained model, in order to produce a third sound signal with a frequency component higher than the first Nyquist frequency. The sound processing method also includes mixing the first sound signal and the third sound signal to create a fourth sound signal.

Test and measurement instruments, such as oscilloscopes, have Nyquist frequencies lower than analog bandwidth. These instruments include: an input configured to receive a signal under test; a single analog-to-digital converter configured to receive the signal under test, sample the signal under test at a sampling rate, and generate digital samples of the signal under test at a single output; and one or more processors configured to determine the frequency of the signal under test without triggering and without hardware clock recovery, and to reconstruct a representation of the signal under test based on the determined signal frequency, the pattern length of the signal under test, and / or the sampling rate.

This invention relates to the field of electronic microphone audio signal processing technology, and provides an electronic microphone audio signal processing system and method, including a server connected to a signal acquisition module, a digital signal processing module, a digital-to-analog converter module, and an output module. The signal acquisition module includes a sound sensor, an analog front-end, and an analog-to-digital converter. The sound sensor uses a MEMS microphone array to convert changes in sound wave pressure into analog electrical signals. The analog front-end internally includes a preamplifier, a bias circuit, and an anti-aliasing filter. The preamplifier amplifies the electrical signal output by the microphone. The anti-aliasing filter filters out high-frequency components above the Nyquist frequency before analog-to-digital conversion, preventing aliasing distortion. This invention can process digital audio signals in real time and accurately, effectively eliminating echo, suppressing noise, stabilizing volume, and improving speech clarity and sound quality, greatly improving the audio signal processing quality of electronic microphones.

Test and measurement instruments, such as oscilloscopes, have Nyquist frequencies lower than analog bandwidth. These instruments include: an input configured to receive a signal under test; a single analog-to-digital converter configured to receive the signal under test, sample the signal under test at a sampling rate, and generate digital samples of the signal under test at a single output; and one or more processors configured to determine the frequency of the signal under test without triggering and without hardware clock recovery, and to reconstruct a representation of the signal under test based on the determined signal frequency, the pattern length of the signal under test, and / or the sampling rate.

The present application relates to a kind of LCL type active power filter composite active damping optimization control method, including inverter side current active damping optimization control and grid voltage active damping optimization control.The beneficial effects of the present application are: the present application obtains the wide active damping boundary close to Nyquist frequency using the inverter side current active damping optimization control based on cascaded resonant controller, and has accurate adjustment ability to fundamental current component, to ensure the stable operation of system when grid impedance fluctuates in a large range.In addition, the present application also uses the grid voltage active damping optimization control based on weighted proportional order reduction generalized integrator, solves the potential instability risk caused by the phase margin reduction of active power filter harmonic control unit due to large grid impedance.In summary, the present application effectively improves the weak grid adaptability of LCL type active power filter.

This machine learning image processing method comprises: generating, from a first teacher image, a first student image having a lower image quality than the first teacher image; calculating a first frequency characteristic of the first student image; calculating a sample frequency characteristic from a sample image obtained by capturing an image with a low-quality endoscope, said sample image being set as a low-quality image sample; comparing the first frequency characteristic with the sample frequency characteristic; and if the Nyquist frequency of the first frequency characteristic is lower than the Nyquist frequency of the sample frequency characteristic, reducing the image size of the first teacher image to generate a second teacher image, and lowering the image quality of the second teacher image to generate a second student image.

The application belongs to the field of magnetic resonance sounding signal noise filtering, and particularly relates to a magnetic resonance sounding signal denoising method based on backtracking generalized OMP. A magnetic resonance sounding water detector is used to sample a sparse signal at a frequency lower than a Nyquist frequency to obtain a noisy MRS signal. The noisy MRS signal is converted into a two-dimensional matrix signal. A KSVD algorithm is used to learn a dictionary from the two-dimensional matrix signal, and an updated dictionary is obtained after iteration. An independently distributed Gaussian random matrix is used to calculate a recovery matrix and measurement data. A backtracking generalized orthogonal matching pursuit algorithm is used to iteratively operate on the measurement data, and an atom sequence with the maximum projection of the measurement data and the recovery matrix is selected to obtain a sparse coefficient matrix of the measurement data under the recovery matrix. A recovery signal is calculated according to the dictionary and the sparse coefficient matrix of the measurement data under the recovery matrix.

The application provides a kind of analysis method and device for VSC high frequency band impedance characteristic, comprising, the disturbance voltage and disturbance current of target VSC are collected, and sampling voltage and sampling current are determined respectively;Determine the corresponding PWM modulation signal of the frequency component of the PWM sideband;Determine the frequency coupling coefficient between each frequency;Determine the VSC port voltage corresponding to the frequency component according to the frequency coupling coefficient;When VSC port sampling filter, determine the VSC port current of the time;Judge whether the difference between the amplitude and phase value of the VSC port current of the time and the amplitude and phase value of the VSC port current of the previous time meets the preset error allowable value;If not, then determine the VSC port current of the next time again;If satisfied, then calculate the VSC input impedance according to the VSC port current of the time and the corresponding disturbance voltage.The application considers the influence of sampling and PWM sideband effect frequency coupling effect on VSC impedance characteristic, and improves the analysis accuracy of VSC high frequency band impedance characteristic above Nyquist frequency.