97 results about "Waveform correlation" patented technology

The invention provides an identification method for transformer inrush current which belongs to power system main equipment relay protection technology field. The method has characteristics in that the method identifies inrush current and fault current base on waveform correlation degree. By comparison with each sampling point algebraic sum in dynamic differential current short data window, non-saturation region of transformer under inrush current and fault current is searched, two form standard sine waves are constituted of max value and position of sampling data in non-saturation region, then differential current sampling waveform in non-saturation region and two form standard sine waves correlation degrees are calculated respectively, inrush current and fault current are differentiated according with correlation coefficient average. The method can open longitudinal differential protection rapidly when internal fault and no-load closing with fault occur in transformer operation; and can lock longitudinal differential protection reliably when on-load closing occurs inrush current.

A method and an apparatus for detecting a frequency correction burst embedded in a signal which includes ordered samples. The method comprises the following: (a) correlating K sequences of the ordered samples with a predetermined waveform to produce K correlation outputs, each of the K correlation outputs corresponding to one of the K sequences, having a magnitude and being associated with an order index, K being an integer, the predetermined waveform corresponding to the frequency correction burst; (b) storing the K correlation outputs in a buffer according to the order indices; and (c) estimating a parameter based on the K correlation outputs, the parameter indicating detection of the frequency correction burst. The estimated parameter includes a frequency error and an ending time of a frequency correction burst. A quality metric associated with each frequency error is also computed.

A surface-consistent refraction analysis method to automatically derive near surface corrections for seismic data processing. The method uses concepts from surface-consistent analysis applied to refracted arrivals. The method includes the use of CMP-offset-azimuth binning, evaluation of mean travel time and standard deviation for each bin, rejection of anomalous first break (FB) picks, derivation of CMP-based travel time-offset functions, conversion to velocity-depth functions, evaluation of long wavelength statics and calculation of surface-consistent residual statics through waveform cross-correlation. Residual time lags are evaluated in multiple CMP-offset-azimuth bins by similarity analysis with a pilot trace for all the other traces in the gather where the correlation window is centered at the refracted arrival. The similarity analysis may take the form of computerized cross-correlation, or other criteria such as semblance. The residuals are then used to build a system of linear equations that is simultaneously inverted for surface-consistent shot and receiver time shift corrections plus a possible subsurface residual term. All the steps are completely automated and require a fraction of the time needed for coventional near surface analysis.

The invention discloses a distribution network fault line selection method based on a zero sequence current variable quantity waveform correlation coefficient matrix. According to the distribution network fault line selection method disclosed by the invention, a row off-diagonal element of each feeder zero sequence current variable quantity waveform correlation coefficient matrix and feeders in minimum corresponding before and after switching of a parallel resistance are utilized to carry out line selection for a fault line principle; and zero sequence voltage of a distribution network bus is larger than 15% phase voltage, the parallel resistance is switched by keeping arc suppression coil parameters invariable, a zero sequence current sampling value of each feeder flowing before and after switching of the parallel resistance is measured, the zero sequence current variable quantity waveform correlation coefficient matrix is further calculated, and the row off-diagonal element of each feeder zero sequence current variable quantity waveform correlation coefficient matrix and the feeders in minimum corresponding are selected as fault lines. With the adoption of the method, a line selection result is not influenced by factors such as transition resistance, line parameters, line length, distribution network running mode and fault position, the line selection principle is simple, and the line selection result is high in reliability and strong in practicability.

Improved apparatus and methods for utilizing holographic waveforms for a variety of purposes including communication, ranging, and detection. In one exemplary embodiment, the holographic waveforms are transmitted over an RF bearer medium to provide, inter alia, highly covert communications, radar systems, and microwave data links. The bearer (i.e., carrier) is optionally frequency-hopped, and various pulse modulation techniques applied in order to further increase communications efficiency and covertness including selective shaping of pulses associated with the holographic waveforms. Methods of providing multiple access and high bandwidth data transmission are also disclosed. Improved apparatus utilizing these features; e.g., a wireless miniature covert transceiver/locator, are also disclosed.

A plurality of variables representing the characteristics of a knock is obtained from an output signal of a sensor. The variables include a peak value of the knock frequency component in the output signal of the sensor and a waveform correlation coefficient representing the correlation between the waveform of the output signal and an ideal knock waveform, which is the waveform specific to a knock. The peak value and the waveform correlation coefficient are normalized, and a detection distribution is created using the obtained normalized data values. A correlation coefficient for knock determination representing the correlation between the detection distribution and an ideal knock distribution is calculated. The correlation coefficient for knock determination is compared with a predetermined knock determination threshold value, and the knock determination threshold value is corrected in accordance with the comparison result. As a result, the accuracy and the reliability of knock determination are improved.

The invention provides a microseism event positioning method. The method includes: utilizing a rule that any two waveforms are mutually correlated; calculating pickup first arrival time difference; utilizing weighted stacking of differences between the pickup first arrival difference among all wave detector pairs and calculated first arrival difference as a target function to perform optimized iterative positioning on a microseism event. By the method, the problem that low signal-to-noise-ratio coaxial axis is discontinuous can be effectively overcome; by utilizing weighted stacking of the differences between the pickup first arrival difference among all wave detector pairs and the calculated first arrival difference as the target function, N(N-1)/2 combinations of wave detectors can be provided for an observation system containing N wave detectors, so that massive information redundancy is provided, and positioning accuracy of the microseism event is improved.

The invention discloses a high precision water level elevation extraction algorithm comprising simulation of a universal waveform; mutual correlation retracing algorithm of the universal waveform and a Level 1b interference waveform; atmosphere and geophysical correction; elevation computation and exclusion of abnormal values; and water level filtering and noise analysis based on SSA. Due to limitation of a satellite altimeter and complex geographical environment, a Cryosat-2 Level 2 altimeter data product has a lot of data losses and precision losses in an inland or nearshore region, the invention improves an altimeter echo waveform retracing algorithm to extract a high precision wave level sequence product, and thus the defect that inland water body or nearshore height measurement data is small in quantity and not high in precision is remedied.

The invention discloses a multi-input multi-output radar waveform design and processing method, specifically comprising the following steps: setting waveform parameters according to the resolution power of radar and the zero side lobe band request, and forming a multi-phase sequence matrix; forming the multi-phase encoding sequences of various transmission waveforms by using various lines orderly connected with each other in series in the multi-phase sequence matrix; using the multi-phase encoding sequences connected in series to respectively perform encoding modulation for the base pulse to generate the transmission signals of various transmission array elements of the transmission array; transmitting the generated transmission signals by various transmission array elements; receiving the echo signals of the transmission signals reflected by the target object through the receiving array elements of the receiving array; performing base band conversion and A/D conversion for the echo signals; regarding the transmission signal as the reference signal, and performing pulse compression processing for the echo sequence of various receiving array elements from the frequency domain; and using the scheduled range gate to intercept the pulse pressure output echo sequence according to the stated time interval to limit the interference of the side lobe. The application of the waveform processing method can fully eliminate the interference of the correlative side lobes with different transmission waves in the multi-input multi-output radar pulse compression output signal sequence in the range of the stated distance so that the precise separation for the target scattering information in different observation channels can be realized so as to improve the precision of the following radar signal and data processing.

The invention discloses a reflective trough wave advance detection method for coal roadway excavation along floor or roof of thick coal seam According to the detection method, explosives in a coal seam hole at the position on the head-on tunnel surface of the excavated coal roadway with a distance of 1/4 coal thickness from the floor or roof of the coal seam is taken as a shot point for trough wave epicentre excitation, two columns of linearly-arranged detectors are arranged in the coal seam hole at the position on two side coal walls of the excavated coal roadway with a distance of 1/4 coal thickness from the floor or roof of the coal seam, and explosion of the explosives is artificially stimulated to generate Rayleigh trough waves propagating into head-on surrounding coal seams of the excavated coal roadway; the reflective Rayleigh trough waves are received by the two detector columns on both sides of the coal roadway, energy and waveform correlation coefficient calculation of the reflective Rayleigh trough waves is carried out, the location of the geological structure interface in the surrounding coal seams of the excavated coal roadway is determined through comparison, so the purpose of the geological structure in the head-on front of the coal roadway and the coal seams at the two sides during excavation along the roof or the floor of the thick coal seam is realized.

The invention is suitable for the field of radar communication, and provides a frequency-based adaptive signal transmission method of a radar system under a frequency interference, a signal transmission system, a radar distance evaluation method and a radar distance evaluation system. According to the method of the invention, at the transmitting end of the radar system, frequency distribution of the interference is obtained through existing spectrum sensing technology; furthermore a frequency point without interference is selected as the carrier frequency of a transmitting signal; at the receiving end, a frequency point signal with a relatively low interference is selected through waveform correlation; and then distance evaluation is performed by means of frequency virtual expansion technology, thereby improving distance evaluation resolution and interference resistance of the system.

The invention relates to an FM/Chirp waveform division multiplex communication method and an application system thereof, belonging to the field of communication. The FM/Chirp waveform segmentation multi-channel communication method is: according to the FM/Chirp composite frequency modulation method, each baseband signal to be transmitted is subjected to carrier modulation, and the frequency domain position overlap, time domain position overlap and waveform mutual correlation degree of the corresponding number of channels are obtained. The modulated carrier is lower than the specified value; demodulate and recover the restored samples of each baseband signal to be transmitted from the synthetic communication signal formed by each modulated carrier through power amplification, attenuation, delay and linear superposition processing, and use each The inter-correlation degree of the modulated carrier waveform of one channel is lower than the specified value to suppress the interference brought by other modulated carriers; the present invention also provides the FCWDM system, FCWDMA system, uplink TDMA/FCWDMA system and downlink TDMA system realized by this method /FCWDMA system. The FM/Chirp waveform division multi-channel communication method and its application system provided by the present invention can realize multi-channel simultaneous transmission at the same frequency, and can use resonance power amplification to realize high-power transmission.

A polar transmitter includes a power amplifier (PA), an amplitude modulation (AM) path including an AM path adjustable delay, an AM path delay measurement circuit, a phase modulation (PM) path including a PM path adjustable delay, and a PM path delay measurement circuit. The AM path delay measurement circuit is configured to measure an AM path delay using waveform correlation, e.g., using peak magnitude events (PMEs) in signals transmitted along the AM path to a power supply port of the PA. The PM path delay measurement circuit is configured to measure a PM path delay using waveform correlation, e.g., using PMEs in signals transmitted along the PM path to a phase-modulated input of the PA. The measured AM and PM path delays are used to adjust the AM and PM path adjustable delays, to reduce the delay mismatch between signals appearing at the power supply and phase-modulated input ports of the polar transmitter's PA.

An ECU obtains two data values (a peak value and a waveform correlation coefficient) that show the characteristics of a knock from the output of a knock sensor. The ECO approximately obtains the mean of each data value by smoothing each data value, and approximately obtains a variance by smoothing the squared deviation between the data values before and after the smoothing process. The ECU then computes the square root of the variance to approximately obtain a standard deviation. The ECU normalizes each data value using the mean and the standard deviation, obtains a distribution of the normalized two data values, and calculates a correlation coefficient that shows the correlation between the obtained distribution and an ideal knock distribution. Based on the correlation coefficient, the ECU corrects a knock determination threshold value. Therefore, the mean and the standard deviation of the data values are computed with a small RAM capacity.

The invention discloses a laser ultrasonic transmission type time-delay detection method for internal defects of a material. The method comprises the following steps: firstly, enabling pulse laser excited by a laser device to act on the surface of a sample so as to excite ultrasonic body waves; secondly, focusing detection laser on a centering position of excited laser so as to detect ultrasonic body wave signals; thirdly, scanning a two-dimensional moving sample, and carrying out mutual correlation calculation on ultrasonic wave signals obtained at all scanning points by taking ultrasonic bodies with relatively high signal to noise ratios at non-defect position of the sample as reference waves; and finally, calculating the waveform correlation coefficients of the ultrasonic wave signals and time delay values of waveforms with the highest correlation coefficients, so as to finish the detection of the internal defects. The method has high sensitivity and stability to the detection of the internal defects, particularly sub-millimeter microdefects, the accurate positioning and quantification of the internal defects can be realized, and the method is suitable for nondestructive testingof various materials.

The invention discloses a distribution network fault locating method based on transient waveform correlation. After a fault occurs, S-transform is carried out on transient waveform information, a time-frequency matrix is constructed, similarity calculation is carried out on the same and time-frequency matrices in all branch sample libraries, and a fault branch is determined according to similarityof an actual fault transient waveform and the branch sample libraries; and a proportional relationship of overall wave amplitude deviation and fault point distance is used to calculate a fault pointlocation. Simulation analysis shows that in different fault conditions, the method can always reliably locate fault point locations, and has higher locating accuracy.

Provided is an excitation surge current identification method based on a support vector classifier. The method selects seven characteristics of a secondary second harmonic, a third harmonic, a current dead angle, a wave width, a waveform distortion amount, a waveform correlation coefficient and an excitation side measured impedance as inputs of a support vector machine, then various running states of a transformer are trained, and a decision function identifying an excitation surge current and a fault current is constructed. When the transformer is out of order, data collected by a protection device collection system is calculated to obtain seven characteristics, the seven characteristics are put into the decision function and determination of an excitation surge current and a fault current is carried out. The identification method integrates advantages of principles of harmonic wave braking, a dead angle, waveform similarity and the like and avoids respective limitation, and the surge current identification credibility is raised. An algorithm can be converted into a convex optimization problem finally, and the local minimum problem which cannot be solved by a neural network is avoided. The method is free from a transformer wiring mode and is free from model parameters, the applicability is strong and the flexibility is good.

The invention relates to a satellite passive orbit measurement method and system, and relates to satellite technology. The satellite passive orbit measurement method of the present invention is to passively receive the radio signal broadcast by the satellite through the ground station, so as to realize the position measurement and orbit measurement of space objects such as satellites. The specific method is to set up 2 to 4 antennas in each measurement station, and use carrier signal waveform correlation to obtain the range difference D between the two antennas when receiving satellite signals. The rendezvous measurement model obtains the position and orbit of the satellite in space. While completing the above-mentioned rough orbit determination, 10-100 satellite position accuracy monitoring reference stations shall be established within the coverage area of ​​satellite signals. The vector correction number of the satellite position is obtained, so as to achieve the second high-precision orbit determination of the satellite.

Detecting timing of a synchronization sequence included in a data stream transmitted in a noisy channel. The synchronization sequence is a known data sequence purposely injected into the data stream for synchronization. A data stream waveform, is obtained from a noisy communication channel. The data stream waveform includes an instance of a synchronization sequence waveform. One or more samples of the synchronization sequence waveform are obtained. One or more samples of a model synchronization sequence waveform are obtained. The model synchronization sequence waveform models an expected waveform for the synchronization sequence being transmitted on the communication channel by applying the synchronization sequence to a model of the communication channel. The instance of the synchronization sequence waveform is correlated with the model synchronization sequence waveform by correlating one or more samples of the synchronization sequence waveform with the one or more samples of the model synchronization sequence waveform.

The invention relates to a micro-seismic migration imaging positioning method based on multiplication of waveform cross correlation coefficients, and belongs to the technical field of oil-gas reservoir fracture micro-seismic monitoring. The method includes the following steps of: preprocessing actual micro-seismic data; performing subsurface imaging point division, and calculating the travel timeof all imaging points to each receiving point on the ground; for a certain imaging point, eliminating the arrival time difference of the imaging point to different receiving points, calculating the cross-correlation coefficient of a micro-seismic record after the time difference correction; calculating the cross-correlation energy value E of the imaging point; repeating the third and fourth stepsto obtain the energy values E of all underground imaging points; and setting an energy threshold E0, obtaining the imaging point position of an energy maximum value greater than the energy threshold as the occurrence position of a micro-seismic source. The method realizes the dual-effect suppression of the noise by using the form of multiplication of the waveform cross-correlation coefficients soas to greatly improve an anti-noise capability, avoids the interference of the first arrival polarity on the positioning imaging results, has high calculation efficiency and satisfies the real-time monitoring of the micro-seism.