30 results about "Cyclic autocorrelation function" patented technology

The invention belongs to the technical field of communication signal modulation analysis under non-Gaussian noise environments, and discloses a modulation parameter estimation method for OFDM signalsunder Alpha stable distribution noises. The method comprises the following steps: performing nonlinear transformation on received OFDM signals, and calculating generalized cyclic autocorrelation functions of the signals; extracting specific cyclic frequency sections of the generalized cyclic autocorrelation functions, and implementing available symbol length estimation on the OFDM signals by searching spectral peaks of the specific cyclic frequency sections; and extracting specific time delay sections based on available symbol length estimation, and implementing symbol length estimation on theOFDM signals by searching spectral peaks of the specific time delay sections. Under Alpha stable distribution background noises, when the mixed signal-to-noise ratio is greater than -1dB, the root-mean-square error of available symbol length estimation of the OFDM signals is close to 0, and when the mixed signal-to-noise ratio is greater than 3dB, the root-mean-square error of symbol length estimation of the OFDM signals is close to 0.

The invention discloses an online fault diagnosis method and system for a centrifugal pump. According to the method, a vibration sensor is utilized for measuring a radial vibration signal in the operating process of a pump; the radial vibration signal is transmitted to a signal processing module; analysis treatment is conducted based on the cyclostationary theory so that a cyclic autocorrelation function can be obtained and subjected to slice analysis; feature parameters for distinguishing whether the pump breaks down or not and recognizing the breakdown type after it is determined that the pump breaks down are obtained; and a relevant breakdown diagnosis result is obtained by performing comparison and analysis on the feature parameters and corresponding parameters generated when the pump runs normally under the design working condition. According to the online fault diagnosis method and system for the centrifugal pump, diagnosis on mechanical seal damage and cavitation failures can be achieved by measuring the radial vibration signal of the pump, the running feature information of the pump can be reflected in the vibration signal in real time, the information integration degree is high, the number of signal transfer paths is small, the anti-jamming capability is high, and measurement reliability is high; and by analyzing stable components in the cyclic autocorrelation function of the signal, the situation that running is unstable due to the bias condition and consequently signal analysis is disturbed can be avoided, and specific reasons which cause unstable flowing of the centrifugal pump are identified.