4 results about "Discrete-time Fourier transform" patented technology

The application relates to the technical field of power system analysis, and particularly provides a power quality monitoring method and device, which comprises the following steps: sampling power quality parameters by using a three-cycle sampling method; adopting a discrete-time Fourier transform method to analyze the amplitude of each frequency point of a sampling signal; and performing aggregate analysis on the power quality parameters based on the amplitude of each frequency point of the sampling signal to obtain an aggregate spectrum diagram corresponding to the power quality parameters. The technical scheme provided by the application can collect and analyze power quality parameters in a power grid in real time, and accurately judge the power quality state.

The application discloses an FID signal frequency estimation method and system based on improved interpolation DFT, and relates to the technical field of signal processing.The application adds a maximum sidelobe attenuation window to an input signal, derives an initial frequency estimation value under the condition of considering negative spectrum components, and significantly reduces the interference of negative spectrum leakage on frequency estimation on the basis of the initial frequency estimation value; on the basis, the application is no longer limited to discrete integer frequency points, but uses a discrete time Fourier transform (DTFT) to perform spectrum interpolation, thereby effectively alleviating the inherent fence effect of a fast Fourier transform (FFT), and making the frequency estimation no longer limited to the discrete interval of spectrum lines. A high-precision frequency estimation model further constructed can maintain consistent estimation performance in a full frequency band, and overcomes the defects of the existing IpDFT method that the precision fluctuates due to frequency changes. Therefore, higher estimation precision, smaller negative spectrum residual influence, and stronger robustness in a full frequency band can be realized in a complex electromagnetic environment.

The invention relates to the field of microphone array wind speed and wind direction measurement, in particular to a microphone array-based wind speed and wind direction measurement method. According to the technical scheme, the method comprises the following steps: synchronously acquiring acoustic signals by adopting microphone arrays which are distributed in central symmetry in east, south, west and north directions, and discretizing to obtain a time domain signal sequence; discrete time Fourier transform is carried out on the time domain signal segments, and an amplitude spectrum is calculated; determining a frequency point index according to the passband frequency band, extracting an energy integral in the passband frequency band, normalizing the energy integral to unit time, obtaining an energy mean value in each direction, calculating synthetic energy through a south-north energy difference and an east-west energy difference, obtaining an average wind speed in combination with an energy-wind speed calibration curve, and calculating a wind direction angle according to the average wind speed. The method is suitable for low-altitude meteorological wind speed and wind direction detection of the unmanned aerial vehicle.

The application provides a calibration method and device of a special-shaped linear array radar, a radar and a storage medium. The method comprises: performing discrete-time Fourier transform on echo intermediate frequency signals obtained by each antenna channel of the special-shaped linear array radar detecting a metal column, to determine actual phases of the echo intermediate frequency signals; based on the actual phases of the echo intermediate frequency signals received by each antenna channel, searching for actual position coordinates of the metal column in a position search range of the metal column by using an optimization problem; based on the actual position coordinates of the metal column, calculating theoretical phases of the metal column detected by each antenna channel; based on the actual phases and the theoretical phases of the echo intermediate frequency signals, determining channel calibration factors of each antenna channel; and using the channel calibration factors to calibrate target echo intermediate frequency signals received by the corresponding antenna channel. The application can avoid the problem of unfocused images caused by different gains and phases of different antenna channels in the special-shaped linear array radar, and improve the radar detection effect.