81 results about "Modulation spectrum" patented technology

Provided are device, method, and medium for generating an audio fingerprint and retrieving audio data. The device for generating an audio fingerprint includes: a coefficient extracting section partially decoding audio data in a compression area and extracting MDCT (Modified Discrete Cosine Transform) coefficients; a coefficient selecting section selecting an MDCT coefficient robust to noises from the extracted MDCT coefficients; a modulation spectrum generating section transforming the selected MDCT coefficient by the use of a Fourier transform method and generating a modulation spectrum; and a bit conversion section quantizing the generated modulation spectrum and generating an audio fingerprint. As a result, it is possible to accurately and rapidly retrieve the audio data recorded in a variety of environments. Since elements based on MP3 are used, it is possible to apply to MP3 applications in various manners. In addition, it is possible to apply to classification of audio data such as classification of music moods and classification of music genres and various other fields such as extraction of a specific event from moving images of sports.

A system and method is disclosed for reconstructing high frequency components of a digital audio signal using a harmonic enhancer in a baseband integrated circuit of a receiver handset. The original spectrum of the digital audio signal is upsampled in a times two (2) upsample unit to double the size of the bandwidth. A low pass filter then removes a high frequency alias of the original spectrum. The spectrum is then modulated with a first carrier frequency and sent to a first filter bank where a low pass filter and a high pass filter shape the modulated harmonic spectrum. After gain adjustment, the modulated harmonic spectrum is added to a delayed version of the original spectrum. Additional harmonic spectra are similarly created at other carrier frequencies and added to the audio output spectra to reconstruct high frequency components of the audio signal.

An audio information retrieval method, medium, and system that can rapidly retrieve audio information, even in noisy environments, by extracting a modulation spectrum that is robust against noise, converting features of the extracted modulation spectrum into hash bits, and using a hash table. The audio information retrieval method may include extracting a modulation spectrum from audio data of a compressed domain, converting the extracted modulation spectrum into fingerprint bits, arranging the fingerprint bits in a form of a hash table, converting a received query into an address by a hash function corresponding to the query, and retrieving the audio information by referring to the hash table.

A method and apparatus for speech processing in a distributed speech recognition system having a front-end and a back-end. The speech processing steps in the front-end are as follows: extracting speech features from a speech signal and normalizing the speech features in order to alter the power of the noise component in the modulation spectrum in relation to the power of the signal component, especially with frequencies above 10 Hz. A low-pass filter is then used to filter the normalized modulation spectrum in order to improve the signal-to-noise ratio (SNR) in the speech signal. The combination of feature vector normalization and low-pass filtering is effective in noise removal, especially in a low SNR environment.

The invention relates to a method and a device for detecting gas, in particular to a modulation spectrum gas detection method based on quasi-continuous diode laser, and a device thereof. The invention adopts a technical proposal that a quasi-continuous diode laser spectrum modulation method for gas detection comprises the following steps: a modulation signal generator outputs a modulation signal and a reference signal; the modulation signal is supplied to a laser driver for controlling the injection current of a quasi-continuous diode laser; the reference signal is supplied to a lock-in amplifier and used as the reference signal; laser emitted by the quasi-continuous diode laser passes through to-be-detected gas and then is received by a photodetector; the output of the photodetector is transmitted to a preamplifier, amplified and then sent into the lock-in amplifier; and output signals of the lock-in amplifier are sent into a computer via an AD converter, processed and analyzed, so as to obtain the species and concentration data of the detected gas. The method is mainly applied to occasions needing trace gas detection with high sensitivity and high resolution.

The invention discloses a plane target classification method based on a time domain and a Doppler domain, and relates to classification methods for moving targets in the air. According to the implementation process of the plane target classification method, a radar conducts observation many times and receives echo signals of a plane target for clutter rejection; time domain waveform entropy and Doppler domain waveform entropy of the signals are calculated; an entropy matrix S' is constructed; the time domain waveform entropy mean value, the time domain waveform entropy 1 order moment and the Doppler domain waveform entropy mean value of each row of the entropy matrix S' are figured out; classifiers are trained by means of the time domain waveform entropy mean values, the time domain waveform entropy 1 order moments and the Doppler domain waveform entropy mean values; test samples are input to the classifiers for classification. The method mainly solves the problems that when the radar carries out observation once under the condition that beam dwell time is shorter than a time domain echo cycle of a rotating part, a micro-doppler modulation spectrum is broadened and the resolution ratio of the micro-doppler modulation spectrum is lowered. Classification accuracy is obviously improved, and the method is used for classification and identification of plane targets.

The invention discloses a music similarity detection method based on mixed characteristics and a Gaussian mixed model. According to the basic thought, the method comprises the steps of using a gamma-tone cepstrum coefficient for conducting similarity detection, and using weighting similarities of various characteristics as a final detection result; providing a modulation spectrum characteristic based on a frame shaft, using the characteristic for representing a music long-time characteristic, and using the combination of the long-time characteristic and a short-time characteristic as the input of modeling in the next step; using the Gaussian mixed model for conducting modeling on the music characteristics, firstly, utilizing a dynamic K mean value method for conducting initialization on the model, then, using an expectation-maximization algorithm for conducting model training, obtaining accurate model parameters, and finally using a log-likelihood ratio algorithm for obtaining the similarities between the pieces of music. According to the music similarity detection method, the obtaining of the music characteristics is more sufficient and thorough, the accuracy degree of music recommendation is improved, the characteristic vector dimensionality can be reduced, the information memory content of a music database is reduced, and the accuracy degree of the music recommendation is improved.

Processing of information signals separated according to modulation and carrier components in a more controlled way is made possible by a device for processing an information signal including a unit for converting the information signal to a time / spectral representation by block-wise transforming of the information signal and a unit for converting the information signal from the time / spectral representation to a spectral / modulation spectral representation, wherein the unit for converting is designed such that the spectral / modulation spectral representation depends on both a magnitude component and a phase component of the time / spectral representation of the information signal. A unit then performs a manipulation and / or modification of the information signal in the spectral / modulation spectral representation to obtain a modified spectral / modulation spectral representation. A further unit finally forms a processed information signal representing a processed version of the information signal based on the modified spectral / modulation spectral representation.

An apparatus and method generating an optical pulse of picosecond class (having a high duty ratio), which accurately and stably operates at an arbitrary repetition frequency, has a high OSNR, and is not restricted by an RF modulation frequency, are provided. New modulation spectrum components are generated by performing phase modulation for light output from a single wavelength laser light source with an optical phase modulator. The phases of the modulation spectrum components are aligned by a phase adjuster, so that a pulse wave in a time domain is generated.

The invention provides a device and a method automatically generating music structural interface information, and a system for searching musical files by humming music melody. The device comprises: a bit quantification modulation spectrum characteristic extraction unit used for extracting the modulation spectrum characteristic of a music signal and carrying out bit quantification to the modulation spectrum characteristic; a similarity matrix calculation unit used for calculating the similarity matrix by using the bit quantification modulation spectrum characteristic of the bit quantification modulation spectrum characteristic extraction unit; and a high-efficiency dynamic matching searching unit for automatically searching the starting time and attribute of song paragraph based on the similarity matrix calculated by the similarity matrix calculation unit and outputting the music structural interface information containing the starting time and attribute of the paragraph.

The invention discloses an underwater acoustic target radiation noise modulation spectrum reconstruction method based on the group sparse structure. The method comprises the following steps that step1, a continuous spectral component R<c> (t) and a linear spectral component R<l> (t) of underwater acoustic target radiation noise are simulated to form underwater acoustic target radiation noise R (t); step 2, the R (t) is subjected to amplitude modulation to obtain a modulating signal x (t); step 3, the x (t) is subjected to normalization, and a band-pass filter is used for obtaining noise modulation signals y<l> (t) of L frequency bands; step 4, amplitude modulation data of the y<l> (t) on each sub-band are estimated, wherein the formula (please see the specification for the formula); step5, a formula (please see the specification for the formula) are subjected to discrete sampling and are represented by a sparse frequency coefficient, wherein the formula (please see the specificationfor the formula), and through designing of prior distribution of a formula (please see the specification for the formula), a high resolution modulation spectrum generation model based on the group sparse structure is constructed; step 6, posteriori distribution of a formula (please see the specification for the formula) is derived based on the expectation maximization method; and step 7, a parameter estimation formula is used for an iterative solution of a formula (please see the specification for the formula) to estimate a high resolution sparse modulation spectrum. Correlation of modulationspectrum positions of sub-bands of underwater acoustic target radiation noise is used for achieving high resolution reconstruction of the underwater acoustic target radiation noise modulation spectrum.

A device for recognizing bearing damage of a bearing (3), on which an object (4) which rotates at a rotational frequency is mounted, having at least one oscillation sensor (2) for converting an oscillation signal output by the bearing (3) into an electrical signal and having a calculation unit (8) for performing a first frequency transformation for multiple time windows of the oscillation signal to generate multiple time window spectra associated with the particular time windows and for performing a second frequency transformation for multiple frequency bands of the time window spectrograms to generate a multiband modulation spectrum, which, for modulation frequencies which are a function of the rotational frequency of the rotating object (4) because of bearing damage of the bearing (3), have signal amplitudes, the level thereof disclosing an extent of the bearing damage.

A voice signal dynamic feature extraction method based on MUSIC (multiple signal classification) and modulation spectrum filter mainly comprises voice signal preprocessing, MUSIC spectrum estimating, modulation spectrum filter, spectrum energy modulating and calculating, log energy calculating and discrete cosine transformation (DCT). The modulation spectrum filter can not only fully reflect dynamic features among voices but has low sensitivity of voice environment owing to the modulation spectrum filter has a time-frequency clustering, so that according to different reflections of interference signals and voice signals on the modulation information, the modulation spectrum filter uses spectrum estimating technology based on multiple signal classification, modulates the spectrum filter of obtained MUSIC spectrum and extracts cepstrum coefficients of the MUSIC spectrum as feature parameters. Compared with the prior art, the voice signal dynamic feature extraction method based on MUSIC and modulation spectrum filter has good robustness and not only significantly improves the recognition rate of a voice recognition system but has played a good foreshadowing role for follow-up studies of voice signals.

The invention establishes a calibration-free modulation spectrum measuring software system based on a tunable diode laser absorption spectrum by virtue of a wavelength modulation technique adapted to a severe environment. The system comprises a digital phase-locking signal demodulation module, a modulation spectrum simulation module and a measured parameter extraction module which comprise 14 sub-modules. The system has the specific functions that a photoelectric signal is demodulated by virtue of a digital phase-locking algorithm so as to obtain a harmonic signal; a simulation database of the harmonic signal can be obtained by carrying out accurate theoretical calculation; the speed, temperature and constituent concentration of a flow field can be extracted by combining the harmonic signal with the simulation database.

A microangiography method and system based on full-space modulation spectrum splitting and angle compounding is disclosed. Label-free three-dimensional optical coherence tomography angiography is realized by combining the three-dimensional space resolution capability of an optical coherence tomography and the motion recognition capability of a dynamic scattering technology. Probe light of different incident angles is encoded with a transverse scanning modulation spectrum in a spatial frequency domain, incident angle-resolved sub-angiograms which are independent of one another are obtained by splitting the modulation spectrum, and an angiogram with multiple space angles compounded is realized. Conjugate mirror images are removed from a depth (z) domain, a complex-valued OCT interference spectra are reconstructed, the full-space modulation spectrum is obtained in the spatial frequency domain, and the overlap of the modulation spectrum conjugate mirror images is avoided. And the absolute flow velocity of blood flow can be measured through a multi angle-resolved probing technology.

The invention discloses a modulation spectrum characteristic fidelity enhancement method for ship propeller cavitation noise based on the adaptive window length. The method comprises the steps of first, carrying out broadband square demodulation on ship propeller cavitation noise signals; second, pre-estimating a demodulation spectrum, detecting the line spectrum position of the demodulation spectrum, and giving the frequency domain signal-to-noise ratio of each line spectrum; third, determining the harmonic frequency of each line spectrum frequency relative to a pre-estimated value of the propeller shaft frequency; fourth, carrying out weighted fusion on the line spectrum frequencies, and estimating the propeller shaft frequency; and fifth, adaptively adjusting the analysis window lengthof the demodulation spectrum according to the estimated propeller shaft frequency, and carrying out secondary estimation on the demodulation spectrum. The modulation spectrum characteristic fidelity enhancement method adaptively adjusts the analysis window length of the demodulation spectrum according to the estimated propeller shaft frequency by using the inherent integer multiple relationship between each demodulation spectrum line spectrum frequency and the propeller shaft frequency, carries out secondary estimation on the demodulation spectrum, and obtains the demodulation spectrum with fidelity enhancement of modulation spectrum characteristics.

Provided are device, method, and medium for generating an audio fingerprint and retrieving audio data. The device for generating an audio fingerprint includes: a coefficient extracting section partially decoding audio data in a compression area and extracting MDCT (Modified Discrete Cosine Transform) coefficients; a coefficient selecting section selecting an MDCT coefficient robust to noises from the extracted MDCT coefficients; a modulation spectrum generating section transforming the selected MDCT coefficient by the use of a Fourier transform method and generating a modulation spectrum; and a bit conversion section quantizing the generated modulation spectrum and generating an audio fingerprint. As a result, it is possible to accurately and rapidly retrieve the audio data recorded in a variety of environments. Since elements based on MP3 are used, it is possible to apply to MP3 applications in various manners. In addition, it is possible to apply to classification of audio data such as classification of music moods and classification of music genres and various other fields such as extraction of a specific event from moving images of sports.

An audio information retrieval method, medium, and system that can rapidly retrieve audio information, even in noisy environments, by extracting a modulation spectrum that is robust against noise, converting features of the extracted modulation spectrum into hash bits, and using a hash table. The audio information retrieval method may include extracting a modulation spectrum from audio data of a compressed domain, converting the extracted modulation spectrum into fingerprint bits, arranging the fingerprint bits in a form of a hash table, converting a received query into an address by a hash function corresponding to the query, and retrieving the audio information by referring to the hash table.

The invention relates to a propeller shaft frequency searching method based on improved noise envelope signal recognition. The method includes: enveloping an original hydrophone signal, and performingHilbert-Yellow transform on each wavelet packet signal to obtain a wavelet envelope signal; performing wavelet reconstruction to obtain an improved noise envelope signal; calculating a time correlation spectrum, take a line spectrum protruding at the peak of the low frequency band as the suspected shaft frequency; setting a step size smaller than the frequency resolution according to the demand;forming a suspected shaft frequency set with the suspected shaft frequency as the center; performing cyclic correlation calculation on a time correlation spectral signal on each suspected shaft frequency to obtain the frequency statistical amount of a cyclic modulation spectrum; and finally searching the shaft frequency of a target according to the frequency statistical amount. The method of the invention corrects axial frequency offset errors generated by the conventional cyclic modulation spectrum methods in the spectrum calculation process, improves the accuracy of the shaft frequency detection, greatly reduces the calculation amount of the loop iteration, and is convenient to implement in engineering application.

The device includes digital modulation in base band, digital up-conversion quadraphase modulator, and D / A converter in high speed. The digital modulation part includes generation module of switching control signal, diverter switch of modulation output, two pieces of diverter switch of modulation input, GMSK and 8PSK modulation modules in base band. The generation module of switching control signal generates one route of output switching control signal and two routes of input switching control signal. The two routes are anti phase. There is only one time slot cycle between output switching control signal and one of input switching control signal. Two pieces of diverter switch of modulation input are connected to data to be modulated and fixed bit 1 respectively. Digital up-conversion quadraphase modulator includes CIC filter and low pass FIR filter. Advantages are: switching modulation modes smoothly, better wireless indexes including modulation spectrum and switch spectrum.

The invention discloses a complex analytic optimal wavelet demodulation method which is characterized by comprising the following steps of: obtaining a vibration signal spectrogram, and capturing an effective frequency band centralized region; setting a shape factor sigma of a Morlet wavelet and an initial value of the initial frequency omega 0, thereby obtaining the wavelet factor Cs(b, a); obtaining continuous wavelet amplitude value spectrum information measure SH; improving the wavelet kurtosis; calculating the smooth index; calculating the optimal wavelet envelope spectrum; and detailing a modulation spectrum, and locating the fault of a detected target. According to the invention, not only are analysis wavelet parameters optimized and selected, but also the conventional wavelet kurtosis calculation method is improved, and the accuracy of screening the wavelet coefficients is improved; meanwhile, in order to solve the problem that the wavelet coefficient features decomposed by fault signals at the early stage are not obvious, the smooth index is additionally set, which plays better positioning and screening effects on the wavelet coefficients for the fault frequency band. The method not only can disclose weak fault features in complex signals in the multi-component signals accurately and effectively, and has high practical value.

Provided are device, method, and medium for generating an audio fingerprint and retrieving audio data. The device for generating an audio fingerprint includes: a coefficient extracting section partially decoding audio data in a compression area and extracting MDCT (Modified Discrete Cosine Transform) coefficients; a coefficient selecting section selecting an MDCT coefficient robust to noises from the extracted MDCT coefficients; a modulation spectrum generating section transforming the selected MDCT coefficient by the use of a Fourier transform method and generating a modulation spectrum; and a bit conversion section quantizing the generated modulation spectrum and generating an audio fingerprint. As a result, it is possible to accurately and rapidly retrieve the audio data recorded in a variety of environments. Since elements based on MP3 are used, it is possible to apply to MP3 applications in various manners. In addition, it is possible to apply to classification of audio data such as classification of music moods and classification of music genres and various other fields such as extraction of a specific event from moving images of sports.

The invention discloses a spectral analysis type high-precision on-line detector for gas and liquid detection. The spectral analysis type high-precision on-line detector comprises a detection sensor probe, a detector host, and a laser device, a circuit board and a power supply battery which are mounted in a detector host shell, and a display screen, an alarm device and a communication interface which are arranged outside the shell. By the adoption of a light intensity modulation technology, and due to concentration calculation on a modulation spectrum subjected to wavelet analysis, the spectral analysis type high-precision on-line detector for gas and liquid detection has the characteristics of high detection sensitivity, high detection stability, short detection time, high detection precision and the like. According to the on-line detector, an optical fiber is connected with the detection sensor probe, so that the distance can be 4KM; the detector can be used in a fixed or portable state; when the detector is applied to gas detection, (a single or multiple serial connected) handheld, open and fixed gas probes can be adopted.

The present invention relates to a method and equipment for analyzing noise source, especially noise of vehicle. The method for analyzing the noise of the noise source comprises the following steps: determining a plurality of modulation spectra Pm (n, m) by Fourier transform using a signal characteristic of a signal of a function with measuring time as structural sound and / or airborne sound, calculating paramter characteristics of noise to be analyzed from the modulation spectra, and real time executing the calculation of the paramter characteristics from operation of the noise source. Improved calibration of the pulse type noise phenomenon can be realized by using the present invention.

The invention discloses an angle composite speckle denoising method and system for full-channel modulation encoding. Generally, low-coherence detection is adopted during optical coherence tomography (OCT) imaging, and images obtained through the technology are likely to be influenced by speckle noise. A conjugated structural mirror image is deleted in a depth domain, a complex-value OCT interference spectrum is reconstructed, and a wide transverse scanning modulation spectrum without the conjugated structural mirror image is obtained in a full-channel space frequency domain; by means of the modulation spectrum, modulation encoding of detection light in different incident angles is achieved, and mutually independent incident angle resolution structural subgraphs are obtained by segmenting the modulation spectrum; the obtained structural subgraphs are subjected to composite average to obtain a final OCT structural image. The OCT structural image is obtained through the angle composite technology, speckle noise is reduced, the signal-to-noise ratio is increased, and structure details are clearer. Besides, the full-channel transverse scanning modulation spectrum is used for angle encoding and compositing so that speckle noise can be reduced and image quality can be improved to the maximum extent.

Utility data modulation is superimposed on a payload data modulator optical signal by exploiting spread spectrum techniques by virtue of one embodiment of the present invention. Utility data transmission rates of e.g., 200 Kbps, can be achieved without impairment to payload data transmission. The utility data modulated signal spectrum overlaps or is entirely within the payload data modulation spectrum, therefore, overcoming problems with optical amplifier gain control and pink noise.

The invention provides a method for electric brain stimulator. In the beginning, obtaining a brain functional amplitude modulation spectrum, wherein the brain functional amplitude modulation spectrum is a relationship between carrier frequency and amplitude-frequency on different brain sites. Then selecting a first alternating current frequency, wherein the first alternating current frequency is determined by the amplitude-frequency in which the brain functional amplitude modulation spectrum display a maximum power relation value, or a maximum correlation value with any behavior index of behavior and cognitive functions. And selecting a second alternating current frequency, wherein the second alternating current frequency is determined by the carrier frequency in which the brain functional amplitude modulation spectrum display a maximum power relation value, or a maximum correlation value with any behavior index of behavior and cognitive functions. In the end, outputting an alternating current signal, the alternating current signal is generated based on a first cosine function of the first alternating current frequency, a second cosine function of the second alternating current frequency, or a combination of the first cosine function and the second cosine function.

The invention provides a ship radiation noise characteristic recombination method based on statistical distribution. According to ship radiation noise characteristics, 1 / 2-dimensional spectrum analysis, LOFAR spectrum analysis and DEMON spectrum analysis are respectively performed on finite-length original noise signals, and probability distribution characteristics of a line spectrum and a modulation spectrum in a ship radiation noise spectrogram are acquired by using a statistical analysis method. In order to reduce feature information redundancy, the dimension of a feature sample is reducedthrough a principal component analysis method to construct a comprehensive feature sample, and finally the comprehensive feature sample is input into a recognition classifier to be trained and recognized to achieve classification of ship radiation noise. The recognition effect of the ship radiation noise characteristic recombination method is obviously higher than that of a single spectral analysis feature extraction method, and especially the more samples are, the higher the recognition accuracy is; the ship radiation noise characteristic recombination method can effectively solve a problem that the ship features are not obvious in an unknown and complex environment, and reduces the wrong recognition probability of a target; and the recognition efficiency of the comprehensive features isimproved, and the algorithm model is simple.

The invention discloses a pressure-modulation-spectrum-technology-based noninvasive glucose detection system comprising a light source, a power supply, a pressure modulator, a plurality of detectors, and a computer. The light source is controlled by the power supply to generate light with a needed waveband and the generated light reaches a human tissue; the pressure regulator presses the human tissue periodically; the light is reflected from the human tissue and then is transmitted to the detectors, wherein a certain distance is formed between the light incident position and the detector detection position; the detectors send collected data to the computer to carry out processing, thereby extracting spectrum information and concentration information of glucose. According to the invention, with the system, the absorption signal of the glucose can be substantially enhanced, so that the glucose detection becomes reliable; and repeated measurement can be carried out.