5 results about "Step frequency" patented technology

The application discloses a kind of robust frequency-modulated stepped frequency ISAR imaging radar velocity estimation methods, belong to radar technical field, first construct multiple frames frequency-modulated stepped frequency data model;Again, the velocity estimation and compensation of rough accuracy are realized using the same frequency point offset estimation of multi-frequency point synthesis;Then, the high-resolution imaging of the coarse resolution distance unit where the special point is located is obtained by the IFFT of intra-frame sub-pulse dimension, and the high-precision velocity estimation and compensation are realized using the high-resolution image of multiple special point synthesis;Finally, ISAR imaging is realized through the FFT between frames.The application realizes the estimation and compensation of velocity gradually using two-step method, first realizes the estimation and compensation of large motion amount by rough estimation, then realizes the residual motion estimation and compensation of high precision by synthesis high resolution;Offset estimation is realized using envelope cross correlation, motion parameter estimation is realized using offset fitting, and the amount of calculation is small;The robustness of algorithm is improved using the characteristics that multiple frequency points are not easily disturbed simultaneously, and the robustness of high-resolution velocity estimation is improved using the motion identity of multiple special points.

A racehorse movement modal recognition method and system based on centimeter-level real-time trajectory, the method first acquires the three-dimensional coordinate sequence when the horse moves, and extracts the kinematic characteristic parameters; then judges the horse movement state, and classifies the horse gait modal; then acquires the absolute stride length of the horse horizontal displacement trajectory, constructs the stride / step frequency ratio factor, and determines the corresponding normal fluctuation interval; finally, the current stride / step frequency ratio factor of the horse is acquired and compared with the corresponding normal fluctuation interval to determine the horse gait health state; the invention uses centimeter-level real-time absolute position change for modal analysis, effectively avoids false positives caused by inertial sensor nonlinear impact and attitude jitter, and through the construction of stride / step frequency ratio factor and the corresponding normal fluctuation interval by sub-modal, early warning of fatigue state and precise detection of gait abnormality are realized, and the accuracy of gait modal recognition is effectively improved.

The application discloses a kind of power electronic transformer off-state partial discharge measurement method and device, it is related to power electronic equipment detection technical field, by high-frequency impedance device is accessed into measurement system to complete calibration coefficient calculation, again access power electronic transformer and according to preset frequency step interval set step frequency point, point by point adjustment to ideal compensation state and record parameter, then start high-frequency no partial discharge excitation source sweep, maintain compensation and voltage stability and collect electric signal, capture partial discharge pulse signal, finally according to the series of steps of acquisition data calculation and the impedance module value of calibration coefficient correction, calculate complex impedance parameter and extract partial discharge characteristic quantity, reach in power electronic transformer off-state, realize the integrated measurement of partial discharge characteristic quantity and complex impedance parameter precision, synchronization.

The application discloses a variable mode decomposition method for step frequency continuous wave signal noise reduction, and belongs to the field of signal modulation. The method solves the problem that the intensity of noise components in the existing spectrum synthesis is much higher than that of effective signals, and the effective suppression cannot be obtained. The method comprises the following steps: collecting a step frequency continuous wave echo signal, and decomposing the step frequency continuous wave echo signal into a plurality of independent single frequency signals; performing variable mode decomposition on each single frequency signal to obtain a plurality of intrinsic mode functions; screening modes with the same center frequency as the frequency of the effective signal as effective signal modes, and screening the remaining modes as noise modes; calculating the maximum information coefficient MIC between the effective signal modes and the noise modes; iteratively optimizing the parameters of the variable mode decomposition based on a Bayesian optimization method until the MIC value of the effective signal modes and the noise modes is lower than a set threshold; retaining the effective signal modes, and reconstructing a step frequency continuous wave signal after noise reduction. The application is applied to the fields of high-resolution target imaging and ranging.