12 results about "Z-transform" patented technology

The application discloses a high-efficiency target distance migration compensation method based on Chirp-Z transformation and belongs to the field of radar target detection signal processing.The application realizes the method as follows: FFT is conducted on a reference signal and an echo signal along a fast time dimension, the fast time time domain is transformed into a frequency domain, and the echo signal is pulse compressed by conjugate multiplication, so that target echo energy is more concentrated in the fast time dimension; a Doppler ambiguity compensation function is transformed from an integer form into a fractional form, so that a compensation Doppler frequency interval is changed from a fixed value into a value that can be changed as required; a CZT formula with the fractional Doppler ambiguity number compensation function is used to transform the pulse-compressed signal, target distance migration is compensated, and the efficiency of target distance migration compensation is improved; IFFT is conducted on the fast time dimension of the signal, so that the fast time frequency domain is changed back into a time domain; and two-dimensional data containing target distance information and Doppler information are detected, so that distance and speed information of the target is obtained.

The application discloses a kind of pulse shaping method and system of nuclear signal, belong to signal processing technical field, for the problems of existing pulse signal width in prior art Widening, thereby increasing the accumulation event, and there is no better anti-noise effect to Gaussian white noise, the present application includes: the output signal of detector is acquired, and output signal is structured into digital function signal;The Z transform is carried out after the discrete of the digital function signal, and output Z transform signal is obtained;Definition input signal is exponential signal, and the Z transform is carried out to the exponential signal, and input Z transform signal is obtained;According to the input Z transform signal and the output Z transform signal, the transfer function of input signal pulse shaping is obtained;The inverse Z transform is carried out to the transfer function, and the pulse shaping signal of input signal is obtained, and its time domain expression.The purpose is: the pulse shaping signal obtained has better signal-to-noise ratio, and it is convenient to obtain amplitude.

This application discloses a SAR imaging method for sea surface ship targets based on inverted conjugate-frequency modulated Z-transform and maximum likelihood estimation, belonging to the field of radar target imaging technology. The method includes: establishing a geometric motion model of the ship target based on its motion; calculating a range-time domain echo signal model based on the geometric motion model; adaptively extracting the echo signal from the echo signal model based on the inverted conjugate-frequency modulated Z-transform; establishing a linear observation equation for phase error using the echo signal to optimally estimate the two-dimensional spatially varied phase error parameters; constructing a compensation function using the optimally estimated two-dimensional spatially varied phase error parameters and performing adaptive iteration based on bandwidth contraction to transform the iterated target signal from the time domain to the image domain, obtaining the final imaging result. This application can effectively eliminate complex two-dimensional spatially varied defocus, improving image resolution and focusing quality.

The invention discloses a partial ambiguity fixing method and system assisted by external displacement, and belongs to the technical field of GNSS carrier relative positioning. Constructing a satellite residual sequence based on the external displacement, a pre-acquired satellite position and a continuous epoch phase observation value; obtaining an ambiguity sequence and an integer variance matrix based on the satellite residual sequence, and executing an ambiguity fixing process: if a hot start Z transformation matrix exists, obtaining a first L matrix; if the first L array satisfies a preset element condition, performing ambiguity search based on the ambiguity sequence, the integer variance matrix and the first L array to obtain a current fixed ratio value; and if the current fixed ratio value is greater than a preset first threshold value, determining that fixation succeeds and outputting fixed ambiguity so as to realize fixation of partial ambiguity. According to the method, high-precision external displacement is used for assisting fixation of partial ambiguity, accurate selection of the ambiguity subset is achieved, the influence on the geometric distribution structure of the satellite is small, and the reliability of the ambiguity fixing effect is guaranteed.

The present invention discloses a circular arc SAR imaging method and system, comprising the following steps: S1. establishing a radar signal model and a motion geometry model to derive the range history of a target point at different times; S2. converting the range history to the Doppler frequency domain, analyzing the correspondence between range migration and Doppler frequency, designing a phase compensation coefficient, and correcting the range migration in the Doppler frequency domain in the time domain to obtain corrected range data; S3. analyzing the spectral characteristics of the azimuth response function and estimating the effective support domain based on an energy approximation threshold; S4. using a Chirp-Z transform to perform azimuth accumulation of the spectral data within the support domain to obtain an azimuth accumulation result; and S5. combining the corrected range data with the azimuth accumulation result to output a SAR imaging result. The present invention has the advantages of reducing computational complexity and memory requirements.

The invention discloses a short baseline synthetic aperture passive positioning method and system based on Chirp-Z spectrum estimation, and mainly solves the problem of large positioning error and frequency estimation error caused by residual frequency deviation in the prior art. According to the implementation scheme, the method comprises the steps that a geometric scene comprising a reconnaissance plane, two short baseline antennas and an unknown radiation source is built; obtaining signals of the radiation source received by the two short baseline antennas on the reconnaissance plane according to the geometric scene; performing down-conversion and correlation method processing on the received signal to obtain a single-frequency signal sequence; a Chirp-Z spectrum estimation algorithm is adopted for the single-frequency signal sequence to obtain a frequency estimation value, and the coordinates of the radiation source are calculated according to the frequency estimation value. According to the invention, frequency measurement is carried out by using a Chirp-Z spectrum estimation method, and Z transformation is converted into an FFT processable form through convolution operation, so that the operation complexity and spectrum estimation errors are reduced, phase ambiguity and signal coherence dependence are avoided, the reliability of the model is improved, and the method is suitable for large-scale popularization and application. The method can be used for an unknown signal source which has a short baseline and does not have a periodic discontinuous short signal sequence.

The application provides a stringed instrument fundamental frequency detection method, device, equipment and medium, the target frame signal obtained by preprocessing is updated to the preset cache; if the target frame signal in the updated cache is detected as a valid signal by using a preset detection strategy, the signal is windowed, and fast Fourier transform and absolute value operation are performed on the windowed signal; if it is determined that the first frequency with the maximum amplitude in the first spectrum information is less than the preset frequency, the first fundamental frequency is obtained by using cepstrum analysis; and the number of harmonics and the harmonic frequency of each harmonic are determined according to the first fundamental frequency and the preset harmonic frequency interval; the first fundamental frequency and the harmonic frequency of each harmonic are calculated by using a preset linear frequency modulation Z transform algorithm to obtain the maximum harmonic frequency of each harmonic; and the optimal fundamental frequency is determined according to the preset iteration algorithm, the preset loss function and the maximum harmonic frequency of each harmonic, thereby reducing the detection error of the low frequency band and improving the accuracy of the fundamental frequency detection.

The present invention discloses a time domain gate filter signal processing method and device, which are used to solve the technical problem that the design method of traditional time domain gate technology is too dependent on the skill level and experience requirements of the operator and has a low degree of automation, resulting in poor signal processing efficiency. The method includes obtaining a direct parameter frequency domain signal and a reflector parameter frequency domain signal; generating a subtraction time domain signal based on the direct parameter frequency domain signal and the reflector parameter frequency domain signal; using a preset unit average constant false alarm rate algorithm to perform target detection on the subtraction time domain signal and determine the start and end time of the time domain gate; constructing a time domain gate function based on the start and end time of the time domain gate, and performing a linear frequency modulation Z transform on the time domain gate function to generate a frequency domain time domain gate function; using the frequency domain time domain gate function and the time domain gate start and end time to perform signal processing on the frequency domain signal of the sample to be tested, and outputting a time domain gate filter signal.

The present invention discloses a microgrid inertia constant estimation method based on the African vulture algorithm. After Laplace transform, discretization and Z transform of the generator rotor motion equation, a transfer function expression containing the inertia constant H and damping coefficient D to be determined is obtained. The power and frequency change signals at the outlet of each unit during system operation are obtained through the PMU measurement device. Based on the measured data, the system inertia constant containing virtual inertia is finally obtained through algorithm optimization. This is used to solve the problem that existing inertia constant evaluation methods cannot be used for systems containing virtual inertia. First, a unified inertia constant analytical model of the equivalent virtual inertia of the new energy VSG and the rotational inertia of the synchronous generator is established. The problem of solving the inertia constant is converted into an algorithm optimization problem. The power-frequency time series data obtained by the PMU is used to solve the inertia constant in the unified analytical model using the African vulture algorithm. The present invention realizes the rapid identification of the system inertia constant.

The application belongs to the technical field of power electronics, and provides a filter-containing rectification load parameter identification method and system based on Z transformation, which comprises the following steps: obtaining an equivalent topology of a filter; determining a transfer function between an alternating current side current and an alternating current side voltage of the filter according to the obtained equivalent topology of the filter; obtaining a matrix expression between the alternating current side voltage and the alternating current side current based on a bilinear transformation and Z transformation processing of the determined transfer function; obtaining an unknown element parameter expression in the equivalent topology according to the obtained matrix expression; and solving unknown parameters in the obtained unknown element parameter expression in the equivalent topology based on a gradient identification algorithm, so as to complete the filter topology parameter identification based on Z transformation.

The invention discloses a high-precision time delay estimation method for a ranging communication composite signal based on ultra-narrow band modulation, and the method employs an improved linear chirp Z transform (MCZT) algorithm to replace a conventional FFT algorithm, and can overcome the fence effect of the conventional FFT and improve the frequency spectrum resolution through calculating the refined frequency spectrum of a signal. According to the method, the cross spectrum is calculated after the refined frequency spectrums of the two paths of signals are obtained, the FICP carries out frequency domain zero padding on the cross spectrum of the signals, an obtained waveform is an amplification form of a correlation peak obtained through an FFT method, and the signal time delay estimation precision is further improved by improving the resolution near the peak value of a correlation function.

The invention discloses a flicker parameter estimation method and module based on windowing optimization linear frequency modulation Z transformation, and relates to the field of electric energy quality monitoring. The method comprises the steps that a voltage flicker signal in a power distribution network is acquired; performing envelope extraction on the voltage flicker signal by adopting an improved square detection algorithm to obtain a flicker envelope signal; a Kaiser-Nuttall mixed window function is applied to the flicker envelope signal, linear frequency modulation Z transformation analysis is carried out, and a discrete frequency spectrum is generated; and based on the discrete spectrum, correcting the frequency and amplitude of the flicker parameter by adopting a triplet spectrum interpolation algorithm to obtain a high-precision flicker parameter estimation result. According to the method, accurate extraction of a flicker envelope is realized by improving square detection and analytic modal decomposition, spectrum leakage is inhibited by combining a Kaiser-Nuttall mixed window with linear frequency modulation Z transformation, and finally, high-precision estimation of a module on a flicker amplitude value and a frequency parameter in an electric energy quality monitoring device is realized by combining a triplet spectrum interpolation algorithm.