117 results about "Octave band" patented technology

The invention discloses a method for judging a main low-frequency vibration noise source of a pumped storage power station ground. Considering basic characteristics of noise of a pumped storage power station and on the basis of analyzing a possible noise source, the background values and the noise values of the sound level A before and after unit operation and the background value and the noise value of an octave band sound pressure level are measured in an underground power house, emphasis is given to the analysis of the spectral characteristics, the background values and the noise values before and after unit operation are measured inside and outside a typical peak resident house and the field ground in a splattering mode, after the spectral characteristics of the background values and the noise values are fully compared, the noise 1/3 octave vibration acceleration level is measured, the attenuation law of noise vibration spreading and the correlation degree of possible noise sources are analyzed, and the judgment about whether the possible noise sources are main noise sources is made finally. The method solves the problem that in a traditional method, the large noise source deeply buried in an underground cave is hard to actually observe.

Data signals transmitted over transmission media suffer from attenuation caused by the transmission media. Equalization circuitry may be provided to compensate for attenuation caused by the transmission media. Equalization circuitry may include multiple stages arranged in series to allow the frequency responses of the stages to aggregate together. Each stage may be programmable to insert a zero, which causes the frequency response of the stage to increase in magnitude by 20 dB/decade. The frequency location of the zero may also be programmable to allow each stage to contribute a certain amount of gain for a specific frequency. Each stage may also be programmable to determine the location of poles for reduction of high frequency noise and cross-talk cancellation.

A method and apparatus to compensate for imperfections in a sound field includes determining a frequency-response characteristic of a test signal, extracting a difference spectrum by filtering the frequency-response characteristic on different octave band scales, detecting frequency parameters of peak and dip components that deviate from a critical value in the difference spectrum, and calculating filter coefficients from the frequency parameters to filter an input audio signal.

Adaptive entropy encoding and decoding which utilizes Set Partitioning within Generalized Hierarchical Trees (SPRIGHT) and a method of designing trees utilizing directionality. After decorrelation and quantization a tree structure is selected from multiple candidates, based on geometric relationships within the image block, for coding the coefficients toward improving zero-clustering of coefficients. Trees for the SPRIGHT encoding are created in response to finding frequency position of each coefficient and scaling frequency position followed by use of octave-band partitioning of coefficient patterns into squares and L-shapes, and the L-shapes are iteratively partitioned into squares. The tree comprises leaf nodes containing coefficients associated with each non-leaf node. The number of zero clustered coefficients can be increased, thus decreasing the number of nodes coded into the encoded image output.

In some embodiments, a system may include a passive uniplanar single-balanced millimeter-wave mixer. In some embodiments, a three-port diode-tee IC forming a mixer core is coupled between an end of a slotline balun and a second coplanar balun. The operational bandwidth of a mixer structure is enhanced by optimizing the distance between the mixer diode-tee core and the back-short circuits. The frequency separation of LO and IF signals may be accomplished by means of stand-alone three-port filter-diplexer device. The system may allow wider than a frequency octave operational bandwidth for a frequency converter device all the way into millimeter wave frequencies at the same time as supporting the operational bandwidth for baseband IF signal over more than six frequency octaves. In some embodiments, the system may accomplish a 500 MHz to 34.5 GHz continuous IF bandwidth with RF signal sweeping from 33 GHz to 67 GHz and local oscillator at 67.5 GHz fixed frequency.

The invention discloses a high-temperature-condition sound field measurement and analysis device and an analysis method thereof. The device comprises a sound guide tube array, a flexible semi-infinite tube, a sound sensor, a data collector and a computer. Through the combination design of the sound guide tubes and the semi-infinite tube, the tail end reflection of the guide tube can be restrained, and the measurement accuracy can be enhanced. The device can conduct sound field data acquisition and processing, and can realize the time domain, frequency domain and reconstruction analysis of a sound field. In the data processing process, data at the tail end of the sound guide tube can be corrected by utilizing a method of correcting the sound pressure amplitude value of the one-third octave band-based sound guide tube, and the measurement accuracy can be enhanced; the optimization of a conventional beam-formed sound field reconstruction method can be realized through kurtosis weighing computation, and accurate sound pressure distribution and strength information can be obtained. The high-temperature-condition sound field measurement and analysis device and the analysis method thereof have the advantages of being capable of conducting the sound field measurement under severe environments in which the conventional microphone can not directly conduct measurement, accurately reconstructing the distribution and strength information of the sound field at a high-temperature environment, and providing a data support for the fatigue invalidation analysis of materials/members under thermal sound coupling environments.

The invention discloses a noise and vibration measurement system based on a virtual instrument technology, which is equipped with analogue signal input and analogue signal output. Signals can be input and output simultaneously or separately. An analogue signal can be input by two modes, i.e. IEPE sensor input and voltage signal input; and the output mode thereof is analogue voltage signal output. The input and the output are both connected with a data acquisition module through BNC wires, the data acquisition module is connected with a computer through a USB to input a sensor signal to the computer; and a computer software processing module integrates the following analysis and measurement modules: a spectrum analysis module, an octave band analysis module, a transfer function measurement module and a recorded signal viewing module.

Low-frequency duct noise is relatively difficult to deli with by passive methods such as porous duct lining. Reactive methods like expansion chamber are rather bulky, while compact resonators are too narrow-banded. This invention shows that a suitably stretched thin membrane backed by a slender cavity can achieve a satisfactory performance from low to medium frequencies over an octave band.

The invention provides a power transformer fault prediction and diagnosis method based on audio characteristics. The method specifically comprises the steps that S1, detecting effective signals of power transformer audio data under the noise background based on chaotic oscillators; S2, calculating a logarithm energy spectrum on the nonlinear Mel scale to serve as a characteristic quantity of the audio signal of a power transformer; S3, calculating a principal component of the audio signal characteristic quantity of the power transformer by adopting a principal component analysis method; S4, optimizing the optimal hyper-parameter training power transformer fault prediction model of the vector machine algorithm by adopting a quantum particle swarm optimization algorithm; and S5, if the powertransformer is in a fault state, adopting a 1/3 octave algorithm to extract the fault characteristic frequency range amplitude, comparing the fault characteristic frequency range amplitude with an expert experience rule base, and predicting/obtaining the fault type of the power transformer. According to the method, the identification precision of power transformer operation state fault predictioncan be improved, and the calculation amount is reduced; fault judgment can be carried out based on other measurement data or infrared images.

The invention discloses a digitized acoustic detection system, which comprises a microphone, a front end circuit, an analog-to-digital (A/D) converter, a signal processor, a touch screen and a keyboard. After the microphone converts an acoustic signal into an electric signal, the signal is input into the front end circuit. After the front end circuit amplifies the signal, the electric signal is input into the A/D converter for analog-to-digital conversion. The converted signal is input into the signal processor for signal processing. The touch screen and the keyboard are connected with the signal processor. A calibration module, a sound level measuring module, a spectrum analysis module and a fast Fourier transform (FFT) analysis module are arranged in the signal processor, wherein the calibration module is used for channel calibration and microphone calibration; the sound level measuring module supports A, C and Z frequency weighting; the spectrum analysis module is used for conducting real-time measurement by using 1/1 and 1/3 octave frequency bands within an allowable wide frequency range; and the FFT analysis module is used for measuring the transient sound level, the maximum sound level and the minimum sound level of the selected frequency range. The digitized acoustic detection system has the advantages that the basic detection of various sound levels and sound intensity calculation can be realized, the real-time spectrum and statistical analysis can be conducted to sound vibration signals, the sound vibration signals can be automatically monitored, the data redundancy of low-frequency parts is reduced and the spectrum leakage is reduced through windowing.

The invention relates to a measuring and estimating method for civil architecture room noise in the field of environmental noise assessment, which comprises the following steps: A. choosing measuring point and measuring A medium of sound level (LA), getting real value of octave-band sound pressure level at the same time; B. computing the value of NR by using equation NR= LA-b and the measured A medium of sound level (LA); C. corresponding the value of step B and the NR curve tablet as normalized value of octave-band sound pressure level; D. comparing the real value of octave-band sound pressure level from A and normalized value from C.

A DSP subtracts the sound pressure Pgen of a notification sound from the sound pressure Pout of an octave band including the notification sound among the sound pressures P1 to P8 of octave bands having center frequencies f1 to f8 acquired by the octave analysis of ambient noises including the notification sound, and thereby acquires the octave band characteristics of only the ambient noises. Next, the DSP detects the sound pressure Pmin of an octave band of the ambient noises which has the lowest sound pressure and the sound pressure Pmax of an octave band of the ambient noises which has the highest sound pressure from these octave band characteristics. Then, the DSP generates an output waveform of the sound pressure Pgen that is almost equal to the sound pressure Pmax of the octave band having the highest sound pressure in the octave band having the lowest sound pressure.

An aspect of the present invention is a voltage controlled oscillator that provides multi octave band tenability. The oscillator preferably includes one or more multi planar resonators which allow it to be implemented in integrated circuit form. Oscillators implemented in accordance with the aspect of the present invention provide as wide a tuning range as the YIG based resonators but are much more compact and efficient. Therefore, they are amenable to implementation in integrated circuits and suited for adaptation in third and future generation wireless devices.

The invention provides a gain calculation method for a caustic convergence region under a deep sea complete sound channel based on a ray normal mode theory. The gain calculation method is characterized in that under the deep sea complete sound channel condition, a typical deep sea Munk sound velocity profile situation is analyzed by using a ray normal mode theory, and then an expression of the sound pressure is obtained; the sound intensity is calculated according to the expression of the sound pressure; the average sound intensity value of the energy is calculated in the bandwidth of the 1/3octave of the central frequency; the average propagation loss value of the energy is calculated; the spherical wave propagation loss value at the caustics of the convergence region is calculated; andthe energy average propagation loss value is compared with the spherical wave propagation loss value, so that the gain value at the caustic convergence region is solved, and the result proves that thegain calculation method provided by the invention has a very good effect.

The invention provides a method for determining the noise equivalent frequency of a motor vehicle, which is suitable for different travel speeds and different vehicle types, has simple calculation and high precision, and is used for accurately calculating the insertion loss of a sound barrier. The method for determining the noise equivalent frequency of the motor vehicle comprises the following steps of: step 1, acquiring the noise sample data of the vehicle, including 1/3 octave sound pressure level of a single vehicle, the vehicle type and the travel speed; step 2, using a method of Appendix B of Norm on Acoustical Design and Measurement of Noise Barriers to calculate the noise equivalent frequency; and step 3, analyzing a great number of sample data in a statistical manner according to different vehicle type intervals and different travel speed intervals, and determining the noise equivalent frequency which has the maximum probability of occurrence.