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377 results about "Frequency Unit" patented technology

Method for determining downlink multi-access system transmission mode, transmitting end device and receiving end device

The invention relates to a method for determining a downlink multi-access system multi-service transmission mode, a transmitting end device and a receiving end device. A multi-frame structure is adopted in information transmission, and a time domain data frame in the multi-frame structure has flexible and variable length. The adopted time frequency slicing technology comprises the following stepsof: performing basic time frequency unit division on time and sub-carrier resource, wherein the basic time frequency unit consists of one or more sub-carriers positioned in the same time domain data frame and occupies fixed signal bandwidth; performing time frequency sub-channel distribution by using the basic time frequency unit; determining a transmission mode according to system available resources, channel conditions and multi-service requirements; obtaining the transmitting end device based on the determination of the transmission mode; and obtaining the receiving end device corresponding to a certain time frequency sub-channel according to the determination of the transmission mode and the transmitting end device. The method supports multiple service transmission requirements, and can flexibly dispatch system resources and flexibly configure system parameters according to the externally obtained system available resource information, channel conditions and specific service requirements.
Owner:TSINGHUA UNIV

Rolling bearing fault feature extraction method based on signal sparse representation theory

The invention discloses a rolling bearing fault feature extraction method based on the signal sparse representation theory, and the method comprises the following steps: constructing an over-complete dictionary representing local damages of a rolling bearing through employing a multi-stage inherent frequency unit impulse response function; recognizing the multi-stage inherent frequency and damping ratio of the rolling bearing and a sensor system from a vibration response signal through a related filtering method, and obtaining an optimized dictionary; solving a sparse coefficient through employing a matching tracking algorithm, and improving the solving speed and precision through reasonable segmentation; reconstructing an impact response signal of each segment, and obtaining the sparse representation of a fault feature signal; carrying out time domain index statistic characteristic analysis of time intervals of adjacent impact response components in a sparse signal, and diagnosing the type of a fault through combining a mean value and a mean square deviation value. The method has the advantages of an analytical method and an adaptive method, improves the precision of waveform features, and can iron out the defects that a conventional method based on Fourier transform is not suitable for rotating speed fluctuation.
Owner:SOUTH CHINA UNIV OF TECH

Self-adaptive denoising method and system based on sub-band noise analysis

The invention relates to the field of voice technologies, in particular to a self-adaptive denoising method based on sub-band noise analysis. The method includes the steps that firstly, framing and short time frequency domain transformation are conducted on input time domain audio signals with noise, and then frequency domain audio signals with noise are generated; secondly, a noise energy spectrum of the frequency domain audio signals with noise is estimated through a minimum value tracking method; thirdly, the posterior signal to noise ratio and the prior signal to noise ratio of the noise energy spectrum are calculated; fourthly, through a nonlinear gain extension method, denoising gains of all time frequency units are calculated through the posterior signal to noise ratio and the prior signal to noise ratio; fifthly, smoothing filtering is conducted on the denoising gains of all the time frequency units to reduce tone quality distortion; sixthly, the denoising gains act on all the time frequency units of the audio signals with noise in the first step, and then denoised frequency domain audio signals are acquired; seventhly, short time frequency domain inverse transformation is conducted, and then the final denoised time frequency audio signals are acquired and output. According to the method and system, stable noise in target signals can be greatly lowered.
Owner:厦门莱亚特医疗器械有限公司

Power flow-boundary element model based elevated rail traffic vibratory-noise simulating and predicting method

The invention relates to a power flow-boundary element model based elevated rail traffic vibratory-noise simulating and predicting method. The power flow-boundary element model based elevated rail traffic vibratory-noise simulating and predicting method comprehensively considers bridge noise and steel-rail noise of the medium-frequency range (200-1000Hz) in elevated rail traffic, and is higher in noise prediction accuracy than that of a method only considering bridge noise or steel-rail noise. The method includes firstly establishing a rail- bridge system power flow model, calculating input power of bridges and vibration speed of steel rails when harmonic force units different in frequency act on the steel rails; secondly, calculating wheel-rail contact force spectrum under a wheel-rail-bridge coupling system through a wheel-rail combination roughness spectrum so as to obtain vibration states of the bridges and the steel rails under the action of random wheel-rail force; thirdly, respectively establishing an acoustic-radiation two-dimension finite-element-boundary element weak-coupling model for the bridges and the steel rails, and calculating vibration power and radiation sound field under the action of the harmonic force units at different frequencies; finally, acquiring practical vibration power by the power flow method and vibration power by the finite-element-boundary element model, scaling field-point sound pressure under the action of unit force to obtain the bridge noise, the steel-rail noise and the total noise thereof.
Owner:TONGJI UNIV

Method and system for capturing weak GNSS (Global Navigation Satellite System) signal under condition of large-scale frequency deviation

The invention discloses a method and a system for capturing a weak GNSS (Global Navigation Satellite System) signal under the condition of large-scale frequency deviation. The method comprises the following steps of: according to a pre-detection integration time, a carrier frequency and a sampling rate, determining a maximum carrier frequency searching step; dividing the whole frequency range to be searched into a plurality of carrier frequency units according to the maximum frequency searching step to realize rough search of the carrier frequency; mapping a received satellite signal onto each carrier frequency unit and regulating a local pseudo code rate according to the carrier frequency units so as to reduce the influence of code Doppler; calculating correlation in a flexible zero-padding mode through FFT (Fast Fourier Transform)/IFFT (Inverse Fast Fourier Transform) so as to realize code phase parallel search; and carrying out FFT operation on different correlation values corresponding to the same code phase so as to fulfill the aim of carrying out fine search on the carrier frequencies in the carrier frequency units. By the method and the system, a capturing speed and a capturing sensitivity of a receiver can be improved, so that the receiver completes the work of capturing a weak navigation signal pseudo code under the condition of the large-scale frequency deviation.
Owner:TSINGHUA UNIV

Multi-speaker voice separation method based on convolutional neural network and depth clustering

The invention discloses a multi-speaker voice separation method based on a convolutional neural network and depth clustering. The method comprises the following steps: 1, a training stage: respectively performing framing, windowing and short-time Fourier transform on single-channel multi-speaker mixed voice and corresponding single-speaker voice; and training mixed voice amplitude frequency spectrum and single-speaker voice amplitude frequency spectrum as an input of a neural network model; 2, a testing stage: taking the mixed voice amplitude frequency spectrum as an input of a threshold expansion convolutional depth clustering model to obtain a high-dimensional embedded vector of each time-frequency unit in the mixed frequency spectrum; using a K-means clustering algorithm to classify thevectors according to a preset number of speakers, obtaining a time-frequency masking matrix of each sound source by means of the time-frequency unit corresponding to each vector, and multiplying thematrixes with the mixed voice amplitude frequency spectrum respectively to obtain a speaker frequency spectrum; and combining a mixed voice phase frequency spectrum according to the speaker frequencyspectrum, and obtaining a plurality of separate voice time domain waveform signals by adopting short-time Fourier inverse transform.
Owner:XINJIANG UNIVERSITY

Ku frequency band double-frequency dual-polarization micro-strip plane reflective array antenna

The invention discloses a Ku frequency band double-frequency dual-polarization micro-strip plane reflective array antenna. A plane medium substrate is provided with two kinds of frequency passive micro-strip resonance units, each kind of frequency units is arranged in equal rows and equal lines, the distance between every two rows is equal to that between every two lines, the distance is less than or equal to one half of the wavelength of the highest work frequency free space, and each second frequency unit is located at the center of every four first frequency units in a square array. The center of all the first frequency units is provided with a set of gaps, the center of all the second frequency units is provided with a set of gaps perpendicular to the gaps of the first frequency units, and polarization in the two perpendicular directions is formed. Each kind of frequency units is of loop line patch structures with at least two layers, and the size of a loop is determined according to the phase position needing compensation. According to the Ku frequency band double-frequency dual-polarization micro-strip plane reflective array antenna, the phase difference between a feed source and the space of each unit on the array surface is compensated by regulating the size of each micro-strip unit on the medium substrate, reflected waves achieve same-phase superposition in the special direction, pencil beams are formed, and the purpose of high gain is achieved.
Owner:BEIJING AEROSPACE FUDAO HIGH TECH

Sparse-decomposition-based hybrid fault feature extraction method of gear wheel and bearing

The invention discloses a sparse-decomposition-based hybrid fault feature extraction method of a gear wheel and a bearing, wherein the method can be used for diagnosing a hybrid fault formed by a distributed gear wheel fault and a local gear wheel and bearing fault in a gear case. When a steady modulation dictionary is constructed, atomic parameter optimization is carried out by using a discrete frequency spectrum correction technology, thereby improving precision of steady modulation component separation. When an impact modulation dictionary is constructed, an over-complete dictionary using a multi-stage inherent-frequency unit impulse response function as an atom is established and the inherent frequency and the damping ratio are identified in a self-adapting mode from a fault vibration signal, so that an impact response waveform caused by local faults of the gear wheel and the bearing can be represented well. After optimization of the steady modulation dictionary and the impact modulation dictionary, the dictionary redundancy is substantially reduce; and with a segmented matching tracking method, the point number of inner product calculation during the sparse coefficient solving process is reduced. On the basis of the two kinds of measures, the speed of signal sparse decomposition is improved.
Owner:SOUTH CHINA UNIV OF TECH

Method and device of measuring carrier interference noise ratio

InactiveCN101141429AEliminate Power ErrorsOvercoming the problem of inaccurate measurement of carrier-to-interference-to-noise ratioMulti-frequency code systemsFrequency UnitCarrier signal
The present invention discloses a method for measuring a carrier interference noise ratio. The method comprises that a plurality of sub-carriers are respectively selected from the frequency spot on the two symbols in one or a plurality of time frequency units, and the number of the sub-carriers selected from each time frequency unit is the same; one or two symbols is (are) respectively selected from the two symbols of the time frequency unit, the interference noise power of the frequency domain channel response estimated value of the sub-carrier on the symbols selected is accounted, and the interference noise power of the sum of the frequency domain channel response estimated value of the sub-carriers on the symbol; according to the characteristic that the frequency domain channel response of the sub-carrier on the symbol in the time frequency unit keeps invariable on the frequency domain, the power error caused by the frequency domain channel response changing along time in the former interference noise power is eliminated; according to the interference noise power of the sub-carrier frequency domain channel response estimated value after being eliminated, the carrier interference noise ratio is calculated. The present invention can accurately measure the carrier interference noise ratio when the terminal experiences a time-varying channel or a time-invariant channel.
Owner:HUAWEI TECH CO LTD

Wide-area low-power-consumption Internet-of-things communication system and transmission method thereof

The invention discloses a wide-area low-power-consumption Internet-of-things communication system, and belongs to the technical field of Internet-of-things. The wide-area low-power-consumption Internet-of-things communication system comprises a plurality of Internet-of-things terminals. Data are received and preprocessed through the Internet-of-things terminal module. The signals are transmitted to the satellite radio frequency unit to realize frequency conversion; the synchronous orbit communication satellite receives the signal through the emission behavior of the two-dimensional phased array antenna, receives the information and forwards the information to the satellite Interent-of-things gateway station, the satellite Internet-of-things gateway station receives the information and transmits the information to the cloud computing center, and the cloud computing center processes the information and uploads the information to the client Internet-of-things application platform; the beneficial effects of the invention are that the system enables various types of IOT terminals to form a wide-area IOT network through employing the synchronous orbit satellite and the gateway station, and achieves the wide-area IOT communication; the low-power-consumption design is adopted, the terminal satellite radio frequency unit is automatically awakened and closed by monitoring data, and the working time of the terminal is prolonged.
Owner:天宸星通(深圳)科技有限公司

LINC transmitter

The invention provides an LINC transmitter, belongs to the technical field of wireless communication, and relates to a transmitting apparatus in wireless communication technology, in particular to a linear amplification with nonlinear components (LINC)-based transmitter. The LINC transmitter comprises a signal separating unit, a variable-frequency unit, a signal amplifying unit, a signal synthesizing unit, a radio-frequency antenna and a feedback control unit, wherein the feedback control unit couples partial output signals; the partial output signals are subjected to attenuation and down-conversion and then compared with an input signal to obtain an error signal; the error signal is utilized to perform real-time regulation and control on the output power of any power amplifier in the signal amplifying unit so as to realize gain balance between a first switch type power amplifier and a second switch type power amplifier in the signal amplifying unit. The output power of the switch type power amplifiers in the LINC transmitter is fed back and controlled and the gain imbalance between two paths of signals are eliminated so as to improve the linearity of the LINC transmitter and enable the LINC transmitter to realize high-efficiency and high-linearity amplification on a wireless communication signal.
Owner:UNIV OF ELECTRONIC SCI & TECH OF CHINA

Voice enhancement method based on double-ear sound source positioning and deep learning in double-ear hearing aid

A vice enhancement method based on double-ear sound source positioning and deep learning in a double-ear digital hearing aid belongs to the field of voice signal processing. Firstly a two-stage deep neural network is used for accurately positioning a target voice, and noise in a direction which is different from the direction of target voice is eliminated according to spatial filtering. By means of a deep learning model in which a time delay control bidirectional long-short term memory deep neural network and a classifier are combined, an extracted multi-resolution hearing cepstrum coefficientis used as a characteristic input. Through nonlinear processing capability of deep learning, each time frequency unit of the noise-containing voice is classified to a voice time frequency unit or noise time frequency unit. Finally a voice waveform combining algorithm is used for eliminating the noise in the direction which is same with that of the target voice. The algorithm eliminates the noisein the direction which is different from the direction of the target voice and eliminates the noise in the direction that is same with the target voice, and finally obtains the enhanced voice which satisfies speech intelligibility and comfort of a deaf person. All deep learning models utilize offline training, thereby satisfying a requirement for real-time performance.
Owner:BEIJING UNIV OF TECH
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