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328 results about "Time frequency spectrum" patented technology

Joint Time Frequency Spectrum. Joint-Time Frequency analysis divides a data set into time intervals and performs a Fast-Fourier Transform (FFT) on the data in each time interval separately. This enables you to inspect how the frequency content of a signal develops over time.

High resolution post processing method for a speech decoder

A post-processing method for a speech decoder which outputs a decoded speech signal in the time domain provides high frequency resolution based on a frequency spectrum having non-harmonic and noise deficiencies. This is obtained by transforming the decoded time domain signal to a frequency domain signal by using a high frequency resolution transform (FFT). Then an analysis of the energy distribution of the frequency domain signal is made throughout its frequency area (4 kHz) to find the disturbing frequency components and to prioritize such frequency components which are situated in the higher part of the frequency spectrum. Next, the suppression degree for the disturbing frequency components is found based on prioritizing. Finally the steps of controlling a post-filtering of the transform in dependence of the finding, and inverse transforming the post-filtered transform in order to obtain a post-filtered decoded speech signal in the time domain are performed.
Owner:TELEFON AB LM ERICSSON (PUBL)

Gear transmission condition monitoring method and apparatus

A gear transmission monitoring method includes: forming a good operating condition baseline matrix by, for each of a plurality of different gear mesh frequencies, obtaining a good operating condition signal indicative of gear transmission conditions over a segment of time and transforming the obtained good operating condition signal into a good operating condition time-frequency spectrum; and then obtaining a gear mesh frequency and a test signal over a segment of time, transforming the obtained test signal into a test time-frequency spectrum, and using the gear mesh frequency and the good operating condition baseline matrix to examine the test time-frequency spectrum to monitor gear transmission conditions.
Owner:GE GLOBAL SOURCING LLC

Electric energy metering automation simulation laboratory

The invention provides an electric energy metering automation simulation laboratory which is used for experimenting, researching and producing an electric energy metering meter or evaluating the running capability of a traditional electric energy meter. A mode of simulating a true power utilization environment is adopted, an actual power utilization site environment is reproduced by using the modes of an interference signal source, a lightning stroke surge signal source, three-phase independent impedance simulation, the true access of an electric appliance and the like, the interference noiseof a power utilization network is recorded by a real-time frequency spectrum and waveform recording system, the running conditions of an electric energy metering device and a remote meter reading system under various power utilization environments are also observed, recorded and calculated, the obtained mass data are analyzed, and the relevant performance parameters of the electric energy metering device and a remote electric energy data collection system are summarized so as to obtain concrete quantitative data and provide a data support for constructing a relevant standard.
Owner:YUNNAN POWER GRID +2

Vibration control method for wind generator set tower

The invention discloses a vibration control method for a wind generator set tower. The method comprises the steps of collecting motor rotation speed data in real time and utilizing a cabin vibration sensor to collect vibration signals; converting the collected vibration signals into vibration signal peak-to-peak values, and when the vibration signal peak-to-peak values exceed a set alarm value, triggering vibration alarm and performing real-time frequency spectrum characteristic analysis; obtaining real-time frequency spectrum characteristics and a wind wheel rotating speed value at the time; comparing a complete machine vibration frequency point corresponding to the wind wheel rotating speed value in complete machine vibration frequency characteristics obtained in advance and energy concentration degree under the frequency in a real-time frequency spectrum characteristic spectrum, and analyzing vibration reasons and correspondingly performing vibration reduction processing according to the different reasons. According to the vibration control method, the reasons for causing complete machine vibration are distinguished through a spectral analysis algorithm, so that cabin vibration of a wind generator is controlled to guarantee complete machine safety, times of shutdown caused by vibration is reduced, and the wind generator set utilization rate is improved.
Owner:STATE GRID CORP OF CHINA +2

Method and device for a harmonic rendering of a melody line

In order to implement the melody extraction or the automatic clearly more stable or to improve the transcription result, respectively, at the resulting segments or trajectories, respectively, of a melody line gained from a spectrogram of the audio signal a harmony mapping is performed such that a follower segment directly neighboring a reference segment in time direction is virtually shifted in the frequency direction by stages of octave, fifth and / or third in order to examine whether among the resulting lines of the octave, fifth and / or third there is one that fulfills a predetermined condition, like e.g. that the time / spectral representation along this line comprises a minimum which is larger by a certain factor than a minimum that it comprises along the reference segment line, and, if such a line exists, selects the same and actually performs the shifting of the follower segment. This way, errors in melody line determination may be corrected again. By a suitable selection of predetermined conditions for the lines of the octave, fifth and / or third, the direct neighborhood and further possible conditions, a faulty shifting may be prevented.
Owner:FRAUNHOFER GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG EV

Seismic wave absorption and attenuation compensation method

The invention relates to a seismic wave absorption and attenuation compensation method, and belongs to the geophysical exploration data processing technology. The method comprises the following steps: selecting one of VSP (vertical seismic profiling) initial data as reference data, carrying out generalized S-transform on the reference data, selecting sampling points as reference points, and recording the time and time-frequency spectrums of the sampling points; carrying out generalized S-transform on data of each sampling point, and dividing the time-frequency spectrum of corresponding frequency in the time-frequency spectrums of the reference points by the time-frequency spectrum of each sampling point so as to obtain an absorption and attenuation curve; determining a natural logarithm to figure out a phase compensation operator according to a formula of frequency difference of absorption and attenuation signals in a time frequency domain; and carrying out absorption and attenuation compensation and phase compensation in the time frequency domain to obtain a fine VSP wave field profile. The method has the advantages that noise can be eliminated during the process of fitting the absorption and attenuation curve; generalized S-inverse transform without energy loss is realized; signal-to-noise ratio and resolution of the data are improved after compensation; log resolution control is realized; the reference points are selected flexibly; and algorithm is simple and efficient.
Owner:BC P INC CHINA NAT PETROLEUM CORP +1

Flutter online monitoring method for machining equipment

The invention discloses a flutter online monitoring method for machining equipment. The method comprises the steps that a proper sampling window is selected; empirical mode decomposition is carried out on sampled vibration signals; decomposed eigen modalities are screened to obtain a characteristic eigen modality; Hilbert transformation is carried out on the characteristic eigen modality to obtain a time-frequency spectrum; statistical pattern analysis is carried out on the time-frequency spectrum to obtain characteristic parameters; the statistical characteristic parameters are compared with a set characteristic threshold value and the statistical characteristic parameter of a historical adjacent signal, and the vibration state of a system is judged. The flutter online monitoring method aims to solve the problems that a flutter detecting method is strong in sample dependency and poor in generalization ability, threshold value measurement is difficult, and judgment is not carried out in time, the method combining Hilbert-Huang transformation and statistical pattern recognition is provided, statistical modeling and clustering analysis are carried out on the time-frequency spectrum of the vibration signal based on the aggregation character of energy on frequency in the fluttering process, the characteristic parameters are utilized, the physical characteristic of cutting flutter is represented essentially, the cutting vibration state is effectively monitored in real time, and the judgment result is accurate and visual.
Owner:HUAZHONG UNIV OF SCI & TECH

Fault diagnosis method and apparatus for rolling bearing

The embodiments of the invention provide a fault diagnosis method and apparatus for a rolling bearing. The fault diagnosis method for the rolling bearing comprises the following steps: acquiring vibration signals of the rolling bearing, and solving a time-frequency spectrum of the vibration signals; according to the time-frequency spectrum, determining an optimal order component of the vibration signals; according to the optimal order component, performing angle re-sampling on the vibration signals to obtain angle domain signals; and performing envelope analyzing on the angle domain signals, and determining fault positions of the rolling bearing, wherein determination of the optimal order component comprises: setting an equivalent frequency conversion scope and searching for all order components from the time-frequency spectrum; and calculating order energy of the order components and determining the optimal order component from the equivalent frequency conversion scope. The fault diagnosis method and apparatus for the rolling bearing realize automatic and rapid determination of the optimal order component so as to provide a basis for fault diagnosis of the rolling bearing, improve the fault diagnosis accuracy and avoid interference of manual factors.
Owner:XINJIANG GOLDWIND SCI & TECH

Fluid conveying pipe leakage acoustic emission time-frequency positioning method

ActiveCN104747912AImprove completenessSolve the problem of large leak location errorsPipeline systemsFrequency spectrumTime delays
The invention relates to a fluid conveying pipe leakage acoustic emission time-frequency positioning method. The fluid conveying pipe leakage acoustic emission time-frequency positioning method comprises the following steps of picking up acoustic emission signals through an acoustic sensor and a vibration sensor which are arranged at two ends of a pipe leakage point respectively and performing cross-correlation analysis on the acoustic emission signals which are picked up; performing time-frequency analysis on cross-correlation functions of the two channels of acoustic emission signals through smooth pseudo Wigner-Ville time-frequency distribution; extracting the time and frequency information corresponding to time-frequency spectrum peak values of the cross-correlation functions of the acoustic emission signals during pipe leakage; serving the time information corresponding to the peak values as the time delay of two observation signals and determining the transmission speed of the leakage acoustic emission signals along a pipe through table look-up on a frequency dispersion curve according to the frequency information of the peak values; determining the pipe leakage position through the time delay and the timely determined acoustic speed. The fluid conveying pipe leakage acoustic emission time-frequency positioning method can be used for performing accurate positioning on the leakage point under the conditions that the leakage acoustic emission frequency dispersion of the fluid conveying pipe is serious and the acoustic speed is difficult to be determined and meanwhile the correlation functions of the single frequency leakage signals are extracted for the time delay estimation and accordingly the degree of correlation of the leakage signals is enhanced and the leakage positioning error is further reduced.
Owner:重庆富世恒睿物联网科技有限公司

Time-varying mixed-phase seismic wavelet extraction method based on time-frequency spectrum simulation

The invention discloses a time-varying mixed-phase seismic wavelet extraction method based on time-frequency spectrum simulation. The method is characterized in that on the basis that improved generalized S transformation is carried out on a non-stationary seismic record, a time-frequency filter is introduced for the first time to filter a time-frequency spectrum of the seismic record, then a wavelet amplitude spectrum at each moment is estimated according to the spectrum simulation method, a mixed-phase spectrum of the wavelets is reconstructed in the seismic record with the time-varying wavelet amplitude spectrums removed according to the bispectrum method of high-order cumulants under the assumed condition that the phases of the wavelets are time-invariant, and the amplitude spectrums and the phase spectrum are combined to achieve extraction of the time-varying mixed-phase wavelets. Compared with a conventional stage extraction method, the time-varying wavelet extraction method has the advantages that the assumption that stages of the wavelets are stable is not needed, the time-varying wavelets can be accurately estimated even though the attributes of the wavelets at adjacent stages vary greatly, the mixed phase of the extracted wavelets is more consistent with the reality and seismic data can be analyzed and processed more finely and more accurately. The method has great application value in improving the resolution of the seismic data.
Owner:CHINA UNIV OF PETROLEUM (EAST CHINA)

Non-stationery vibration signal instantaneous frequency estimation algorithm in start and stop period of rotating machinery

The invention relates to a non-stationery vibration signal instantaneous frequency estimation algorithm in a start and stop period of rotating machinery; firstly, an experiment table working model of a rotor of the rotating machinery is built, a non-stationery vibration signal sensor for measuring vibration signal, and a photo-electric sensor for measuring the rotating speed of a reference axis are arranged along the horizontal and vertical direction of the reference axis; after the obtained signal is analyzed by an order analysis software of an upper computer through a dynamic signal analyzer, STFT time-frequency spectrum containing multi-level component is obtained; the working frequency of the rotating machinery is used as an estimated starting frequency point, according to the requirements of sampling frequency and calculation accuracy, the frequency obtained by the STFT time-frequency analysis is equally divided into M groups, the start and stop period is equally divided into N time points for building grid meshes of N time points and M groups of frequency points; the route of minimum-deviation frequency point from the start point to the stop point is computed through Viterbi algorithm, after fitting is carried out, the instantaneous frequency estimation function value of the reference axis of the non-stationery vibration signal of the rotating machinery in the start and stop period is obtained.
Owner:NANJING UNIV OF INFORMATION SCI & TECH

Time-frequency decomposition earthquake-fluid recognition method

The invention relates to the technical field of petroleum exploration, in particular to a time-frequency decomposition earthquake-fluid recognition method which includes establishing a time-frequency atom dictionary D according to Morlet wavelet function m(t)=exp[-betaXf2(t-tau)2]exp[i(2pif(t-tau)+phi)], and acquiring an initial matching atom of the Morlet wavelet function through calculation with a seismic trace and complex seismic trace method; performing matching decomposition on the seismic trace, performing iterative optimization with constraints of the time-frequency atom dictionary D in the neighborhood of the initial matching atom to acquire an optimal matching atom, stopping matching decomposition when preset conditions are achieved, and representing the initial seismic trace as a series of linear combinations of Morlet wavelet atoms; transforming the optimal matching Morlet atom into the time-frequency domain so as to acquire a time-frequency spectrum distribution of the initial seismic trace; extracting directly properties of earthquake fluid activity on a target stratum section on the time-frequency spectrum of earthquake materials; and predicting distribution range and space distribution of gas deposit according to the properties of the fluid activity. By the method, the distribution range and the space distribution of the gas deposit can be accurately predicted, so that a technical support is provided for favorable target optimization of natural gas exploration.
Owner:CHINA UNIV OF PETROLEUM (BEIJING) +1

Communication protocol signal identification method based on depth residual network

The invention belongs to the technical field of radio signal identification, in particular to a communication protocol signal identification method based on a depth residual network. The method comprises the following steps of: performing time-frequency analysis on a communication protocol signal in a sample library, and converting a time-frequency spectrum diagram of the signal into a gray-scaleimage; training The depth residual network model by gray-scale image. The trained depth residual network model is used to detect and identify the specific communication protocol signals trained in thetransmission process. As that depth residual network is applied to the field of communication signal identification, the invention overcomes the defect of high signal quality requirement and high prior information requirement of the traditional method, etc. At low SNR, multipath delay, When Doppler frequency offset and some features of signal are obscured by strong interference noise, Doppler frequency offset can still accurately identify the protocol type, and it does not depend on the prior information of received signal, so it can directly process the received IF signal, and has robust performance and high efficiency, which provides ideas for the subsequent research in this field, and has strong practical application value.
Owner:PLA STRATEGIC SUPPORT FORCE INFORMATION ENG UNIV PLA SSF IEU

Time-frequency spectrum curve extracting method based on edge detection

The invention discloses a time-frequency spectrum curve extracting method based on edge detection. The method includes the steps that firstly, a k-order origin moment of signal time-frequency distribution is calculated, then, a matrix containing time-frequency spectrum edge information is acquired according to an edge detection method, a time-frequency spectrum curve is acquired by judging the matrix and combining the edge information, parameter space is established according to an existing curve model so that parameters of the curve are estimated, and the time-frequency spectrum curve is extracted. Compared with a tradition detection method, the time-frequency spectrum curve extracting method has the advantages that the structural attributes of signal time-frequency distribution are fully used, the curve extraction accuracy is improved, and especially under the conditions that the signal to noise ratio is low and multiple time-frequency spectrum bands exist, the time-frequency spectrum curve can still be extracted through the method while the performance of a traditional extraction method is reduced and even the traditional extraction method fails. The performance of the method is better for time-frequency spectrum curve extraction.
Owner:UNIV OF ELECTRONIC SCI & TECH OF CHINA

Broadband digital receiver and real-time frequency spectrum processing method thereof

InactiveCN103973324AEnables synthetic broadband processingImprove resource utilizationTransmissionTime frequency spectrumDigital conversion
The invention belongs to the field of digital signal processing, and particularly relates to a broadband digital receiver. The broadband digital receiver is used for solving the problem that an existing digital receiver is narrow in real-time frequency spectrum processing bandwidth and low in frequency spectrum resolution. The broadband digital receiver comprises an input end and an output end, and further comprises a first filter bank, an analog mixing module, a second filter bank, an analog-digital conversion module, a time-frequency transformation module and a frequency spectrum joint module, wherein the first filter bank is connected with the input end and the analog mixing module, the second filter bank is connected with the analog mixing module and the analog-digital conversion module, the time-frequency transformation module is connected with the analog-digital conversion module and the frequency spectrum joint module, and the output end is connected with the frequency spectrum joint module. The broadband digital receiver is suitable for the fields of electronic reconnaissance receiving, real-time frequency spectrum analysis, radars, communication and the like.
Owner:UNIV OF ELECTRONIC SCI & TECH OF CHINA

Ground object classification method based on robustness time frequency characteristics

The invention discloses a ground object classification method based on robustness time frequency characteristics, which is mainly used for solving the problem that the prior art takes long time to perform classification on the vehicle objects and the human body objects under a low signal to noise ratio condition. The realization process comprises steps of performing normalization on recorded high signal-to-noise ratio signals to obtain training signals, 2 extracting a three-dimension time frequency characteristic and training a classifier from a time frequency spectrum of the training signals, 3 performing normalization on recorded low signal-to-noise ratio signal energy to obtain test signals, 4 extracting 3-dimension time frequency characteristics from the time frequency spectrum of the test signals, 5 transmitting the 3D time frequency characteristics of the test signal into the trained classifier to obtain an classification result. Under the condition that the signal-to-noise ratio is low and has no need of performing beforehand de-noise processing, the ground object classification method based on robustness time frequency characteristics can quickly and effectively realize the classification of the vehicle objects and the human body objects and can be used for radar object identification.
Owner:XIDIAN UNIV

Instant frequency estimation method based on edge detection

InactiveCN106370403ARealize instantaneous frequency estimationComplexity advantageMachine part testingSubsonic/sonic/ultrasonic wave measurementPattern recognitionFast Fourier transform
The invention discloses an instant frequency estimation method based on edge detection. Through the use of the time-frequency spectrum of the short-time Fourier transform, one can effectively feel the frequency variation of the signal components and the boundary technology of effectively extracting the picture pixel changes in SOBEL operator edge detection. When the two are combined, the frequency of some order component of the signal can be effectively extracted. According to the invention, the edge detection technology in picture processing technology is employed. Under proper parameters, it is possible to rapidly and accurately determine the frequency edges. In comparison to other methods, the method is advantageous both in terms of the complexity and the calculation amount.
Owner:NANJING UNIV OF INFORMATION SCI & TECH

Early fault identification method of rolling bearing under variable rotating speed working condition

ActiveCN109682601AAvoid dependenceSolve the problem of being unable to process time-domain vibration signals under variable speed conditionsMachine part testingCharacter and pattern recognitionFrequency spectrumSignal-to-noise ratio (imaging)
The invention relates to an early fault identification method of a rolling bearing under a variable rotating speed working condition. The method comprises the following steps that firstly, time-frequency analysis is carried out on a vibration signal of the rolling bearing to obtain a time-frequency spectrum; secondly, a peak value search method is adopted to extract an instantaneous frequency conversion in the time-frequency spectrum and data fitting is carried out; then high-pass filtering is carried out on an original vibration signal, and equal angle sampling is carried out on the originalvibration signal according to the instantaneous frequency conversion after data fitting to obtain an angle domain signal; finally, noise reduction processing is carried out on the original vibration signal and envelope spectrum analysis is carried out on the noise-reduced signal to identify faults of the rolling bearing. The method does not rely on a rotation speed sensor or human experience, andself-adaptively searches optimal parameters of the MCKD, moreover, the method is convenient and reliable, and is particularly suitable for vibration signal analysis of the rolling bearing with low signal-to-noise ratio under variable rotation speed working conditions.
Owner:CYBERINSIGHT TECH CO LTD

High-precision time-frequency analysis method

The invention provides a high-precision time-frequency analysis method, and belongs to the field of digital signal processing. The method comprises the following steps of: (1)inputting original digital signals x(t), then carrying out empirical mode decomposition (EMD)to the original digital signals x(t), decomposing the original digital signals x(t) into sets of intrinsic mode function (IMF)components, namely ci(t) is the IMF component; (2) carrying out matching pursuit (MP)decomposition to each IMF component ci(t) respectively to obtain a time-frequency spectrum of each IMF component; and (3) carrying out mutual superposition to the time-frequency spectrum of each IMF component obtained in the step (2) to obtain the time-frequency spectrum of a high time-frequency resolution of the original digital signals x(t). The high-precision time-frequency analysis method disclosed by the invention avoids inaccuracy of time-frequency atoms when MP decomposition matching is implemented for composite signals directly, and MP decomposition is implemented for each IMF component, thereby being capable of obtaining the time-frequency spectrum with higher accuracy and time-frequency resolution and richer information.
Owner:CHINA PETROLEUM & CHEM CORP +1

Distribution network fault classification method based on convolution depth confidence network

InactiveCN109325526AAutomatic extraction of fault featuresAccurate Fault Classification RateCharacter and pattern recognitionNeural architecturesFrequency spectrumLow voltage
The invention relates to a distribution network fault classification method based on a convolution depth confidence network. The method comprises the steps of firstly collecting the three-phase voltage, zero-sequence voltage and three-phase current of a low-voltage bus of a main transformer and a low-voltage side of the main transformer, and respectively interceptting the signal waveform data of one cycle wave before and after each fault condition as training samples; secondly, carrying out the time-frequency decomposition on the training sample data of step S1 by using the discrete wavelet packet transform, and obtaining the time-frequency matrix, then constructing the pixel matrix of the time-frequency spectrum map, and constructing the time-frequency spectrum map as the input of the subsequent CDBN model; then constructing the CDBN model to train two convolution-constrained Boltzmann machines in unsupervised learning mode, and adding the softmax classifier after the second CRBM to train the network model to effectively extract and automatically classify the fault features, and finally, using the trained model to realize the fault classification of distribution network. The method of the invention can realize accurate fault location.
Owner:FUZHOU UNIV

Sound source localization based on binaural signals

Techniques are disclosed for sound source localization based on joint learning and evaluation of ITD and ILD representations that are measured in a complementary, correlation-based way using binaural time-frequency spectrums. According to one embodiment, from these measurements and learned representatives, which may, for example, be created by combinations of measurements from signals belonging to the same class, i.e., the same azimuthal location, probability distributions over frequency and class are computed. These probability distributions can be combined over cue and frequency using information-theoretic approaches to get a robust classification of the location and additionally a confidence measure for the quality of the classification result.
Owner:HONDA RES INST EUROPE

Rotary machinery fault feature extracting method based on local mean decomposition (LMD) and local time-frequency entropy

InactiveCN102866027AComplete Time-Frequency DistributionJudging the running state of the machineSubsonic/sonic/ultrasonic wave measurementStructural/machines measurementFrequency spectrumVibration acceleration
The invention discloses a rotary machinery fault feature extracting method based on local mean decomposition (LMD) and local time-frequency entropy. According to the technical scheme, the rotary machinery fault feature extracting method comprises the following steps of: (1) measuring rotary mechanical equipment by using an acceleration transducer, and acquiring vibration acceleration signals; (2) performing LMD on the vibration acceleration signals to obtain a plurality of pulse frequency (PF) components, and determining the instant amplitude and the instant frequency of each component; (3) making a time-frequency spectrum, dividing a time-frequency plane and calculating the local time-frequency entropy; and (4) extracting fault features by utilizing a local time-frequency entropy value as feature quantity and combining experiments. An analyzing process of a rotary machinery fault diagnosis system based on LMD is realized, difference of vibration signals of the equipment on time-frequency distribution and energy distribution in different states is researched, a local time-frequency entropy theory can be used for diagnosing fault of machinery, the local time-frequency entropy of the vibration signals in the different states is calculated after LMD conversion of the vibration signals, and the local time-frequency entropy value is used as the feature quantity to judge whether the equipment fails or not.
Owner:YANSHAN UNIV

Fault diagnosis method of variable-speed rotation machine based on time-frequency spectrum segmentation

The invention provides a fault diagnosis method of a variable-speed rotation machine based on time-frequency spectrum segmentation. The method includes following steps: step 1, obtaining normalized time-frequency spectrums of signals through multi-resolution generalized S transform, and generating multi-resolution binarized time frequency spectrums; step 2, combining the binarized time-frequency spectrums with all resolutions, and obtaining an optimal binarized time-frequency spectrum; step 3, segmenting the optimal binarized time-frequency spectrum into a plurality of connected domains, and performing information annotation on each connected domain; step 4, extracting an optimal expression atom of each connected domain, forming an optimal atom set, and calculating the expression of a fault signal in the optimal atom set; and step 5, calculating the appearance time and amplitude of an impact theory, and realizing fault diagnosis of variable-sped mechanical equipment through informationcomparison. According to the method, most strong background noises can be filtered, and fault diagnosis of impact type faults including cracking, pitting corrosion or spalling etc. of the variable-speed rotation machine can be realized.
Owner:WUHAN UNIV OF SCI & TECH +1

Bowel sound detection method, device and system under noisy environment

The invention discloses bowel sound detection method, device and system under noisy environment. The bowel sound detection method comprises steps of collecting a bowl sound mixed signal of a current user through a sensor, wherein the bowl sound mixed signal comprises a bowl sound signal and an environment interference signal; converting the bowl sound mixed signal to a digital signal; extracting a time-frequency spectrum characteristic of the digital signal; inputting the time-frequency spectrum characteristic of the digital signal into a trained convolution nerve network to process; and detecting a time point when the bowl sound happens so as to distinguish the bowl sound signal and the environment interference signal. The bowel sound detection method, device and system under the noisy environment utilize a difference of the time-frequency spectrum characteristics of the bowl sound signal and the environment interference signal, train a convolution nerve network to distinguish the bowl sound and the interference sound, can finish the detection on the bowl sound under the noisy environment, and can help to improve the accuracy of the bowl sound detection.
Owner:BEIJING YIMAI MEDICAL TECH CO LTD +1

A specific radiation source identification method and device based on a deep residual network

The invention belongs to the technical field of radiation source identification, and particularly relates to a specific radiation source identification method and device based on a deep residual network, and the method comprises the steps: carrying out the time-frequency analysis of a received signal, and converting an obtained Hilbert time-frequency spectrum into a grayscale image; And extractingradio frequency fingerprint characteristics reflected in the image by using a depth residual network with the gray level image as input, and obtaining an identification result of the radiation source. Aiming at the characteristics of non-stability and non-linearity of communication signals, the gray level image of the Hilbert time-frequency spectrum is used as the representation form of the signals, the radio frequency fingerprint characteristics of the radiation source are extracted by using the deep residual network, and the classification recognition is completed; Deep learning is appliedto the field of communication signal processing, the powerful self-learning capability is fully exerted, the artificial understanding limitation is overcome, and the processing efficiency is improved;A simulation experiment verifies that the recognition effect under the complex communication system and the complex channel condition has very high robustness, and the method has important guiding significance for the development of a radiation source signal recognition technology.
Owner:PLA STRATEGIC SUPPORT FORCE INFORMATION ENG UNIV PLA SSF IEU

Time-frequency analysis method based on improved matching pursuit algorithm

The invention relates to a time-frequency analysis method based on an improved matching pursuit algorithm. The time-frequency analysis method comprises the steps of constructing a complex analysis signal of a seismic signal, and determining instantaneous phases and optimal master frequencies at the arrival time and the delayed time; calculating the master frequency and the phase of a time delay position, and determining an atom form according to the master frequency and the phase which are used as Ricker wavelet parameters; calculating an instantaneous amplitude of a wavelet under a wavelet energy normalization condition; matching an atomic amplitude according to a given percentage, and subtracting a matching wavelet which is in maximum correlation with the seismic signal from a seismic channel after four key parameters such as the atom arrival time, the atom master frequency, the atom phase and the atom amplitude are determined to obtain a residual signal, and carrying out recursion iteration on the residual signal within a certain threshold range to finish decomposition of original signal; stacking the time frequencies of all the matching wavelets to obtain a time frequency spectrum of the seismic signal. According to the time-frequency analysis method, the accuracy of atom master frequency matching is guaranteed under the condition that the calculation frequency of matching pursuit time frequency analysis is improved, so that the problem of discontinuity of an inphase axis on the section of a seismic frequency division body is solved.
Owner:CHINA PETROLEUM & CHEM CORP +1

Ultrashort wave special signal reconnaissance method based on spectral map and depth convolution network

The invention belongs to the technical field of radio signal identification, in particular to an ultrashort wave specific signal detection method based on a spectrum map and a depth convolution network. The method comprises the following steps: short-time Fourier transform is carried out on the specific signal in a sample library to obtain a signal time-frequency spectrum, wherein the specific signal is a signal including a frame synchronization code in a signal transmission data frame structure; The depth convolution neural network model is trained by using time-frequency map, and the position target is predicted by using feature pyramid and feature map of different scales in the training process. The trained depth convolution neural network model is used to detect and recognize the special signals in ultrashort wave communication. The invention solves the problems of low signal-to-noise ratio and low detection and identification efficiency under the condition of strong channel interference in the prior method, realizes ultrashort wave specific signal detection, time-frequency positioning and classification identification, improves signal identification rate, has robust performance and high operation efficiency, provides ideas for subsequent related research in the field, and has strong practical application value.
Owner:PLA STRATEGIC SUPPORT FORCE INFORMATION ENG UNIV PLA SSF IEU

Resource adapting method, device and system

The invention discloses a resource adapting method, a device and a system. The method comprises the following steps: acquiring characteristic parameters of a short-time frequency spectrum resource; when the current load of a communication cell exceeds the preset threshold, acquiring service characteristics of a terminal bearing a service in the communication cell, and selecting a terminal to be switched to; and according to the characteristic parameters of the short-time frequency spectrum resource, adapting the terminal to be switched to a short-time frequency spectrum resource matching the service characteristics of the terminal to be switched to. The invention considers the short-term availability of the short-time frequency spectrum resource when switching the frequency, and can adaptthe service to the frequency spectrum resource matching the frequency spectrum characteristics, thereby increasing the success ratio of switching and ensuring the QoS characteristic of the service. The invention can overcome the defects of failure to ensure that the service characteristics of the service borne by the terminal match the frequency characteristics of the switched frequency band whenswitching the terminal, failure to ensure the QoS characteristic of the switched service, and the like in the prior art.
Owner:CHINA MOBILE COMM GRP CO LTD
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