5results about How to "Avoid phase error" patented technology

The invention discloses a power grid lightning arrester on-line monitoring system based on a PHM, and the system comprises a voltage on-line collection module which is used for collecting a voltage signal of a corresponding lightning arrester; the synchronous control module is used for acquiring synchronous sampling data of the leakage current signal and the bus voltage signal; the signal processing module is used for acquiring fundamental components of the leakage current signal and the bus voltage signal and harmonic components of preset times; the feature generation module is used for generating resistive current feature data of the lightning arrester; the data integration module is used for forming a multi-parameter operation state data set of the lightning arrester; the health state evaluation module is used for obtaining a health state evaluation result; the trend analysis module is used for acquiring lightning arrester health state change trend information; and the fault risk assessment module is used for generating a lightning arrester fault risk assessment result and realizing online assessment, trend early warning and fault risk prediction of the health state of the lightning arrester.

A method for synchronous excitation of multiple exciters relates to the field of dynamic testing and vibration control technology for large civil structures. The method includes the following steps: after constructing a unified time reference based on satellite navigation signals and a rubidium atomic clock, excitation amplitude and phase parameters are obtained based on the target modal requirements, and these parameters are sent to all exciter slave stations; the exciter slave stations generate a reference trajectory based on the excitation amplitude and phase parameters, enabling the exciter motor shaft angle to follow the reference trajectory in real time and output the target excitation; the phase error is obtained based on the measured excitation phase value and the reference trajectory, and then the motor angular velocity of the exciter is corrected based on the phase error. This invention solves the problems of startup phase error and long-term frequency drift in master-slave triggering schemes, ensuring synchronous start-up of all exciters. Combined with dynamic correction of the exciter motor angular velocity, it suppresses phase drift during long-term operation, significantly improving the excitation efficiency of higher-order modes and the clarity of the response signal.

The present invention discloses a satellite-aircraft bistatic synthetic aperture radar combined mode imaging method, belonging to the field of signal processing technology. The phase error introduced by azimuth spectrum aliasing in the range processing process is avoided by improving the range processing flow; the azimuth processing flow is improved, while avoiding aliasing in the time-frequency domain of azimuth processing, more degrees of freedom are introduced, and the high-order space variation in azimuth is balanced; an accurate calculation method for Doppler space variation parameters of combined mode satellite-aircraft bistatic SAR is proposed, which can obtain high-precision de-skew factors and NLCS equalization factors, and realize efficient and high-precision processing of combined mode satellite-aircraft bistatic SAR. The method of the present invention solves the problem of imaging processing difficulties caused by the complex range migration characteristics and Doppler characteristics of bistatic SAR echo signals, and solves the problem of decreased keystone interpolation accuracy caused by azimuth spectrum aliasing. Simulation results show that the method can effectively realize accurate imaging processing in the satellite-aircraft bistatic SAR combined imaging mode.

The application discloses a large squint SAR error estimation method and device, electronic equipment and a storage medium, and belongs to the technical field of radar signal processing, and the method comprises the steps of: performing distance spectrum segmentation on a frequency domain echo signal of a to-be-measured target to obtain a steering vector of a plurality of sub-spectrum echo signals; performing eigenvalue decomposition on a covariance matrix between channels to obtain a noise subspace of each sub-spectrum; based on a local error estimation model, solving a channel error of each sub-spectrum according to the noise subspace of the sub-spectrum and the steering vector of the sub-spectrum echo signal; and fusing the channel error of the sub-spectrum to obtain a globally optimal channel error estimation value. The application effectively constrains the spectrum widening degree in each sub-spectrum by performing spectrum segmentation on the distance spectrum, and can solve the estimation misalignment problem caused by spectrum widening in the spaceborne large squint scene.

The invention discloses a mirror surface shape measurement system and method based on ultrafast high-precision laser scanning, and aims to solve the problems that the surface shape detection precision is low, the surface shape detection size is small, the absolute positioning precision is insufficient, and the system and method are liable to be vibrated in the environment in the conventional surface shape detection technology. The system specifically comprises a pulse laser, a beam expanding and splitting module, an interference module, a four-step phase shift module, a detection module, a receiving module and an upper computer. The pulse laser emits pulse laser; the beam expanding and light splitting module divides the pulse laser into 0-level diffraction light and + / -1-level diffraction light which are parallel to each other; the interference module receives the 0-level diffraction light and the + / -1-level diffraction light to form multi-level diffraction interference light; the four-step phase shift module performs four-step phase shift light splitting on the multi-stage diffraction interference light; the detection module receives the phase-shifted light beam and performs photoelectric conversion to form a 0-level phase-shifted signal, a + 1-level phase-shifted signal and a-1-level phase-shifted signal; the receiving module receives a 0-level phase shift signal, a + 1-level phase shift signal and a-1-level phase shift signal; and the upper computer is used for restoring the surface shape information of the to-be-measured mirror.