23 results about "Narrowband noise" patented technology

The invention discloses an underground disease detection method and system based on a three-dimensional multi-channel ground penetrating radar image, and belongs to the technical field of underground disease detection. When the underground disease detection model is trained, not only is a disease target trained and recognized, but also a conventional target is included, the conventional target is prevented from being recognized as the disease target, so that the accuracy of disease recognition is improved, and by setting different bounding boxes for the two types of targets, it is guaranteed that the efficiency and accuracy requirements of model training are balanced. By setting a cache mechanism, the model is prevented from operating the same image for multiple times, and the operation overhead of the model is reduced; a channel difference threshold value and a mileage difference threshold value are set to identify a single disease, so that the single disease is prevented from being recorded for multiple times, and meanwhile, the disease identification accuracy can also be improved; and through a minimum continuous channel number threshold value, narrowband noise artifacts triggered by few channels are automatically eliminated.

This invention discloses a bioacoustic complexity index method with low sensitivity to noise, comprising: performing a short-time discrete Fourier transform on the field bioacoustic monitoring recording data during the analysis period to obtain its time-frequency power spectrum; estimating the narrowband noise average power of each frequency point using a set of noise time-frequency points without bioacoustic signals; performing power spectrum subtraction on each frequency point to obtain the noise-enhanced bioacoustic time-frequency power spectrum; subdividing the analysis bandwidth and analysis period into time-frequency domains according to a certain frequency step and time step, and calculating the time-frequency partition index value; and summing all the time-frequency partition index values ​​within the analysis bandwidth and analysis period to obtain the final bioacoustic index value, i.e., the noise-reduced bioacoustic complexity index based on the change in bioacoustic time-frequency power after noise enhancement. This invention significantly reduces the sensitivity of the index results to noise and significantly expands the spatiotemporal application range of similar acoustic index strategies.

The invention discloses an online modeling and control method for a narrowband active noise control system, which comprises the following steps of: (1) performing frequency estimation on a signal picked up by a reference microphone by using a triangular cascade adaptive notch filter algorithm, and calculating an online estimated value of a signal-to-noise ratio by using energy of an input signal and an output signal of a notch filter; (2) when the online estimated value of the signal-to-noise ratio is larger than a preset value, modeling and control are started, a reference signal and auxiliary noise are generated based on the estimated frequency, and a control signal is calculated; (3) estimating auxiliary secondary sound by using the auxiliary noise; (4) estimating the sum of the primary sound and the secondary sound of the error signal at the noise frequency by using the reference signal; (5) updating the estimation of the frequency response of the secondary path at the auxiliary noise frequency and the frequency response of the auxiliary filter at the narrow-band noise frequency; (6) obtaining the estimation of the frequency response of the secondary path at the narrowband noise frequency in an interpolation mode; (7) updating the filter coefficient of the controller; and (8) outputting a control signal to drive a secondary source loudspeaker to produce sound, propagating the sound through a secondary path, and coherently superposing the sound with the initial noise signal at the error microphone to realize a noise reduction function. According to the method, the secondary path can be accurately modeled online, compared with an existing algorithm, the auxiliary noise energy is low, the convergence speed is high, the noise reduction effect is good, meanwhile, the problem that the same parameter operation results are different in a traditional auxiliary white noise online modeling algorithm is solved, and the algorithm stability is better.

The invention discloses an industrial data transmission optimization management system based on service link quality, and relates to the technical field of data transmission. Weak delay oscillation and a periodic packet loss rule are reserved through multi-scale processing, so that the system can discover precursor anomalies which are difficult to capture by a traditional monitoring mechanism; minute-level even second-level early warning of link disturbance is realized, and data congestion caused by sudden quality reduction is avoided; a dynamic discrimination mechanism driven by a precursor score is utilized, so that a scheduling decision is converted from passive response to active adjustment, and the probability of cascade failure caused by mass mutation is greatly reduced; an interference spectrum adaptive strategy enables the system to adaptively match the optimal coding mode and the redundant structure when facing narrow-band noise, periodic interference or transient impact, so that the anti-interference capability and the bandwidth utilization efficiency are improved; priority adjustment is carried out in combination with a link risk trend and a state evolution rule, and the protection timeliness and resource allocation efficiency of the key link are remarkably improved.

The present invention discloses a noise suppression method, system, wearable device and computer-readable storage medium, which relate to the field of electronic device control. A vibration sensor and a vibration generating device are pre-arranged on the heat dissipation module of the wearable device, replacing the microphone and speaker arranged in the airway in the prior art, to obtain the original vibration signal collected by the vibration sensor. Considering that narrowband noise presents periodic characteristics, a control signal representing the phase delay is determined based on the original vibration signal and an adaptive filtering strategy. Based on the control signal, the vibration generating device can be controlled to generate a suppressed vibration signal for counteracting the narrowband noise in the original vibration signal in an anti-phase manner. Therefore, without affecting the airway and ensuring the heat dissipation function of the heat dissipation module, the phase delay method is used to reliably and effectively achieve the anti-phase cancellation of the narrowband noise caused by the heat dissipation module when it is working, especially as its rotation speed increases, thereby greatly improving the user experience.

The invention provides a four-wave mixing suppression method and system for an IMDD optical fiber communication system, and the method comprises the steps: introducing two orthogonal bias terms which are gradually changed along with time into a judgment-guided equalizer, and tracking in-phase and orthogonal channel components of noise after orthogonal down-conversion, therefore, the narrow-band noise of the specified frequency band can be efficiently eliminated from the received signal; by monitoring the phase rotation direction and speed of a complex signal formed by the two offset terms, the frequency difference of the actual noise center frequency relative to the reference frequency can be directly calculated, so that the low-complexity adaptive tracking of the noise center frequency drift is realized. According to the invention, any center frequency narrow-band noise in a signal band can be efficiently suppressed and the center frequency change can be adapted without interrupting the service without a complicated spectrum analysis module, so that the signal quality is remarkably improved.

This invention discloses a method for a bird acoustic diversity index with low sensitivity to noise. The method first obtains the time-frequency power spectrum of field bird call monitoring data during the analysis period using short-time Fourier transform. Then, based on narrowband noise level estimation, it calculates candidate floating detection thresholds for each frequency point that meet local signal-to-noise ratio requirements. The full-scale relative level threshold is used as the lower limit to obtain the frequency-varying detection threshold after binarization of the time-spectrum. Finally, the Shannon index is calculated by counting the number of time-frequency points in each sub-band where the power is higher than the detection threshold, resulting in the acoustic diversity index based on frequency-varying threshold detection. This invention effectively addresses the fundamental limitation of ADI (Ambient Audio Diversity Index) being highly sensitive to noise, while remaining fully compatible with the ecological interpretations and findings of existing ADI studies. It provides a new tool for achieving stable and reliable rapid assessment of bird species diversity, and is of great significance for ecological and environmental acoustic monitoring.

This application relates to the field of noise reduction technology, disclosing a noise reduction method, apparatus, and vehicle. The method includes: determining a theoretical noise reduction signal corresponding to a narrowband noise signal; determining a first virtual second-order filter based on the noise frequency and target mapping relationship of the narrowband noise signal; determining a target noise reduction signal for the narrowband noise signal using the first virtual second-order filter; and performing noise reduction using the target noise reduction signal. The target mapping relationship characterizes the correspondence between the order coefficients of the first virtual second-order filter and the order coefficients of the reference filter when their simulation performance regarding the signal change of the theoretical noise reduction signal on the secondary path is consistent. The secondary path is the path from the transmitter of the theoretical noise reduction signal to the target noise reduction location, and the order of the reference filter is greater than 2. The technical solution provided by this application reduces the computational load and complexity in the noise reduction process and improves noise reduction efficiency.

The invention relates to the technical field of vehicle noise simulation, in particular to an accelerated driving in-vehicle noise simulation method and device, and the method comprises the steps: obtaining an engine rotating speed signal, so as to calculate the noise frequency of each order at a corresponding rotating speed, generating a noise time domain signal of each order according to the noise frequency of each order and a pre-constructed narrowband noise time domain signal database; obtaining an A-weighted sound pressure level order slice to obtain a sound pressure level curve of each order, and calculating an amplitude correction coefficient curve of an actual sound pressure value; and performing time domain signal amplitude correction by using the amplitude correction coefficient curve to generate a final engine order noise simulation signal so as to generate a playing audio for noise simulation in the accelerated driving vehicle. Therefore, the problems of long sound quality development period and high trial and error cost caused by the fact that the modified overall acoustics cannot be accurately predicted in the early stage of design due to the fact that an existing sound quality development mode excessively depends on personal experience and subjective hearing feeling of engineers in the prior art are solved.

The present invention discloses a method for generating an interference signal for a UAV communication link based on binary coding, comprising: generating a narrowband noise sequence in an FPGA, and generating a narrowband noise signal based on the narrowband noise sequence; wherein the narrowband noise sequence includes two noise sequences, a real part and an imaginary part; generating either noise sequence by: generating two pseudo-random sequences; performing nonlinear mapping processing of Sin and Log on the two pseudo-random sequences, respectively, and multiplying the results of the nonlinear mapping of Sin and Log to obtain a nonlinear mapping sequence; performing binary coding on the nonlinear mapping sequence according to the symbol level of the nonlinear mapping sequence to obtain a binary coding sequence; and performing frequency division processing on the binary coding sequence to obtain a noise sequence with narrowed bandwidth. The present invention solves the problem of insufficient output power in existing swept-frequency narrowband noise interference schemes caused by truncation of the digital filter output.

This invention provides a low-noise casing for an axial flow fan and its design method, comprising an outer casing and an inner casing arranged coaxially. The outer casing has a double-layer resonant structure, including an outer cylinder plate and an inner cylinder plate. The outer and inner cylinder plates are divided into multiple resonant cavities by a supporting frame, and the supporting frame has de-weighting holes. Each resonant cavity corresponding to the inner casing has multiple perforations on its inner cylinder plate, while the resonant cavity corresponding to the impeller installed at the front end of the inner casing has no perforations on its inner cylinder plate. Multiple rear guide vanes are installed between the outer and inner casings, and the rear guide vanes are single-arc blades. The fan casing of this invention uses a double-layer casing structure, without filling with sound-absorbing material, and only utilizes the resonant cavities to eliminate narrowband noise of specific frequencies, thereby achieving a significant reduction in casing radiated noise; at the same time, it provides excellent support for noise reduction in the downstream ductwork.

This invention provides an active suppression method and system for background noise of partial discharge (PD) UHF signals. The method includes: determining the placement positions of a UHF sensor and a noise sensor on the outer wall of a GIS (Gas-Insulated Structure) device; acquiring the mixed noise PD signal using the UHF sensor; acquiring the noise signal using the noise sensor after determining the minimum acquisition period; inputting the acquired noise signal into a spectrum analyzer for spectrum analysis; extracting the obvious narrowband noise frequency band in the frequency domain, determining its frequency band and phase jitter; and actively suppressing narrowband noise in the frequency band where narrowband noise exists using a narrowband noise interference suppression formula. This invention solves the technical problem of poor applicability to narrowband interference from PD UHF signals of GIS equipment in field environments, which restricts the accuracy and reliability of interference suppression.

The invention discloses a photo-thermal spectrum device and method based on orthogonal pseudo-random code modulation, and the device comprises a control and signal processing unit, a pseudo-random code generator, a laser driver, a tunable laser, a collimator, an air chamber, a focusing lens, a quartz tuning fork, a pre-amplifier, a data collector, and a related demodulator. A pseudo-random code sequence with good self-correlation and cross-correlation characteristics is used for carrying out binary orthogonal modulation on laser intensity, and weak photo-thermal signals are extracted from strong noise through a correlation demodulation technology. The method has the advantages that the method is insensitive to narrow-band noise due to the broadband modulation characteristic, any noise irrelevant to pseudo-random codes can be effectively suppressed by relevant calculation, and the method has extremely high anti-interference capability; related processing is equivalent to long-time energy accumulation, and the noise bandwidth can be compressed; the broadband characteristic of the pseudo-random code enables the pseudo-random code to cover the drift range of the resonant frequency of the quartz tuning fork, and the system is higher in adaptability to environmental changes and higher in stability.

The present invention provides an active noise control device. A coordination control unit (24) causes a booming noise control signal processing unit (20) to start feedforward signal processing. When a secondary path filter (C^) converges, the converged secondary path filter (C^) is set as a narrowband noise control signal processing unit (22), causing the narrowband noise control signal processing unit (22) to start feedback signal processing. Thus, even if the transmission characteristics change, the sound pressure of the noise can be reduced.

The present invention provides a method for actively suppressing narrowband interference from partial discharge ultrasonic signals. The method comprises: determining the placement of ultrasonic sensors and noise sensors on the outer wall of a GIS; collecting partial discharge signals using the ultrasonic sensors in a laboratory environment; collecting partial discharge ultrasonic signals mixed with noise using the ultrasonic sensors in a field environment; collecting noise signals using the noise sensors; inputting the collected noise signals into a spectrum analyzer for spectrum analysis; extracting significant narrowband noise frequency bands in the frequency domain to determine their frequency bands and phase jitter; and actively suppressing narrowband noise in frequency bands where narrowband noise exists using a narrowband noise interference suppression formula. The present invention proposes a method for actively suppressing narrowband interference from ultrasonic partial discharge signals of GIS equipment in a field environment, ensuring the accuracy and reliability of interference suppression.

The invention provides an active noise control method and device based on frequency dynamic tracking and a storage medium, and belongs to the technical field of active noise control. Comprising the following steps: configuring an active noise control system comprising an FxLMS algorithm unit: sending a reference signal into an adaptive filter for processing, and adding a frequency correction weight coefficient into the reference signal by a frequency correction unit; the output of the adaptive filter is summed by the first comparison unit and then sent to the secondary channel unit to generate a secondary output signal; the reference signal is also sent to the secondary channel estimation unit to obtain a filtering reference signal and is sent to the FxLMS algorithm unit; the second comparison unit sends an error signal between the target narrow-band noise and the secondary output signal into the FxLMS algorithm unit; and the FxLMS algorithm unit performs adaptive iteration updating on the weight coefficients of the first adaptive filter and the second adaptive filter and the frequency correction weight coefficient of the frequency correction unit until the active noise control system converges.

The present application provides an active and passive combined centroid jamming method, which includes calculating the long-range and short-range demarcation values of the ship. The long-range and short-range demarcation values of the ship are determined, and a multi-stage control strategy is adopted to flexibly select different jamming styles according to the distance of the incoming missile from the ship. In the long-range stage, narrowband noise jamming of the phased array active jamming equipment is adopted. In the short-range stage, an active and passive combined centroid jamming method is adopted. The present application uses a multi-stage control strategy, comprehensively considering the characteristics of the single-pulse angle measurement and tracking of the terminal guidance radar, and flexibly selects different jamming styles according to the distance of the incoming missile from the ship, thereby achieving targeted jamming of the seeker in different working stages and effectively improving the success rate of the whole process jamming.

The invention discloses an active noise reduction method and device for narrow-band noise, a storage medium and a terminal. The method comprises the following steps: acquiring the rotating speed of an engine, an initial sound field, an error signal, and a control order, the number of secondary loudspeaker units and the number of error microphone control points required in a multi-channel system; continuously executing the following steps until a preset number of iterations is reached: calculating an angular frequency corresponding to each control order according to the rotating speed of the engine, and constructing a first cosine reference signal and a first sine reference signal based on the angular frequency; performing amplitude correction on the first cosine reference signal and the first sine reference signal according to the weighting matrix factor to obtain a second cosine reference signal, a second sine reference signal and a filtering reference signal; according to the filtering reference signal and the error signal, updating a control weight to optimize loudspeaker output; and overlapping the optimized loudspeaker output with the initial sound field. The noise reduction effect is greatly improved.

The invention discloses a high-frequency narrow-band swept-frequency signal generation method based on an FPGA. The method comprises the following steps that S1, multiple paths of high-frequency swept-frequency signals are synthesized and output through multiple paths of parallel DDS modules; s2, generating a noise signal through a noise generation module, and then transmitting the generated noise signal to a multi-stage up-sampling module; s3, performing multi-stage up-sampling on the noise signal through a multi-stage up-sampling module to generate a single-path narrow-band noise signal; and S4, multiplying the multiple paths of high-frequency swept-frequency signals obtained in the S1 and the single-path narrow-band noise signals obtained in the S3 through a multi-path multiplier to form multiple paths of parallel high-frequency narrow-band swept-frequency signals, then serially reading the multiple paths of parallel high-frequency narrow-band swept-frequency signals by a high-sampling-rate DAC module, and finally outputting the high-frequency narrow-band swept-frequency signals by the high-sampling-rate DAC module. According to the invention, the problems of clock frequency limitation and overlarge resource consumption of the existing FPGA-based high-frequency narrow-band swept-frequency signal generation are solved.

The application discloses a kind of simulation methods of automobile uniform speed driving in-vehicle noise, including first white noise signal is randomly generated, after being carried out band pass filtering and amplitude calibration respectively, wide frequency noise simulation signal is obtained;Second white noise signal is randomly generated, after being carried out narrowband filtering and narrowband amplitude calibration, narrowband noise simulation signal is obtained;Third white noise signal is randomly generated, band pass filtering signal is generated after filtering, and according to the in-vehicle noise signal sample collected by real vehicle, overall window function is generated, after overall windowing to band pass filtering signal, impact amplitude calibration is generated, and impact noise simulation signal is generated;Wide frequency noise simulation signal, narrowband noise simulation signal, impact noise simulation signal are added to obtain the simulation signal of uniform speed driving in-vehicle noise for playback listening evaluation;The application realizes the simulation of automobile uniform speed driving in-vehicle noise, and the playback effect restores the in-vehicle auditory sensation when real vehicle is uniformly driven, can be quickly adjusted parameter changes sample, carries out playback evaluation to different sample, selects the sample meeting sound quality development requirement, realizes the quick and accurate formulation of uniform speed driving in-vehicle noise development target.

This application provides a noise testing method, system, and electronic device, relating to the field of power communication. The method includes: acquiring noise testing requirements and noise data to be tested, comprising broadband noise data and narrowband noise data; determining broadband and narrowband noise coupling characteristics matching the noise testing requirements based on the configuration of various mode structures in a multi-mode noise database and their mappings, the broadband and narrowband noise coupling characteristics including noise coupling operation modes, noise coupling data structures, and noise coupling condition parameters; coupling the noise data to be tested based on the broadband and narrowband noise coupling characteristics to generate broadband and narrowband coupled noise data; determining the network noise topology corresponding to the broadband and narrowband coupled noise data, enabling testing and analysis of the broadband and narrowband coupled noise data based on the network noise topology. This application solves the problem of low accuracy in existing broadband and narrowband coupled noise testing technologies.

The present application relates to a kind of partial discharge signal denoising method combined with singular value decomposition and wavelet transform, belong to signal processing field.The method includes: selecting suitable Hankel matrix is used to construct adaptive singular value decomposition model, responsible for the singular value decomposition of original noisy partial discharge signal;Calculate singular entropy increment, find the position of the maximum bending degree of singular entropy curve according to its asymptotic property;Use the position of maximum curvature as threshold, singular value greater than threshold is used to reconstruct original signal;Select suitable wavelet base function is used to construct one-dimensional two-stage double-tree complex wavelet transform, responsible for the decomposition and reconstruction of signal;Using q-shift scheme joint construction filter bank in DT-CWT interior.The present application can not only inhibit the narrow-band noise and white noise on PD signal well, but also can retain waveform mutation details, while having very low root mean square error and very high waveform similarity in index.

The invention relates to the field of partial discharge ultrasonic sensor verification, in particular to a transformer partial discharge ultrasonic sensor field verification signal denoising method, which comprises the following steps of: acquiring an original noisy verification signal from a to-be-tested ultrasonic sensor; the method comprises the following steps: decomposing an original signal by using MVMD to obtain IMF components, and screening useful IMF components based on a kurtosis criterion so as to remove narrowband noise; performing wavelet decomposition on the useful IMF component to obtain a wavelet detail coefficient, and processing the wavelet detail coefficient based on an improved threshold function and a general threshold to remove white noise; and performing wavelet reconstruction on the processed coefficients of each layer through wavelet inverse transformation to obtain a de-noised signal. According to the method, the white noise and the narrow-band noise contained in the verification signal output by the transformer partial discharge ultrasonic sensor are effectively reduced, and the accuracy of the verification result of the ultrasonic sensor to be tested is improved.