16 results about "Quadrature demodulation" patented technology

The application discloses a laser phase noise measurement method based on delay self-heterodyne and digital demodulation, and relates to the technical field of laser measurement, and comprises the following contents: after being adjusted by a variable optical attenuator, to-be-measured laser is divided into a frequency shift arm and a delay arm, the frequency shift arm is frequency-shifted by an acousto-optic modulator, the delay arm is delayed by a delay optical fiber, and original electric beat frequency signals are obtained by a balanced photoelectric detector after the two arms are coupled; homologous and synchronous quadrature demodulation is carried out on the original electric beat frequency signals, envelope credibility judgment and abnormal sample repair are combined, and a continuous differential phase sequence is obtained; actual optical time delay is determined according to the beat frequency spectrum characteristics and the continuous differential phase sequence, and a differential phase power spectral density is formed; then, transmission relationship conversion is carried out according to the actual optical time delay, bounded spectrum compensation is implemented on a zero point neighborhood and a low credibility frequency point, and an intrinsic phase noise power spectral density is obtained. The application can improve the stability, continuity and result credibility of phase noise measurement under the condition of short delay.

This invention provides a low-crosstalk signal demodulation device and method for fiber optic laser communication, belonging to the field of fiber optic communication technology. The device includes a fiber optic signal input port, an optical circulator, a polarization beam splitter / combiner module, a balanced photodetector unit, a low-noise amplification and quadrature demodulation module, an adaptive crosstalk cancellation unit, a MIMO equalization and decision unit, and a digital signal output port, connected in series according to the signal flow direction. It also includes a crosstalk monitoring and feedback unit bidirectionally connected to the low-noise amplification and quadrature demodulation module, the adaptive crosstalk cancellation unit, and the MIMO equalization and decision unit. This invention, employing the aforementioned low-crosstalk signal demodulation device and method for fiber optic laser communication, overcomes the limitations of traditional single-domain crosstalk suppression. Through the synergistic effect of optical path, circuit, and algorithm layers, it effectively suppresses crosstalk caused by multi-channel multiplexing, polarization mode dispersion, and backscattering, significantly improving demodulation accuracy, anti-interference capability, and system stability.

The application discloses a kind of dual-frequency modulation transfer spectroscopy laser frequency stabilization device and method, construct the dual-frequency modulation signal including first frequency component and second frequency component, according to dual-frequency modulation signal driving fiber electro-optic phase modulator to laser is carried out dual-frequency electro-optic phase modulation;Photoelectric detector carries out detection to the polarized beam splitter output light and obtains saturated absorption signal, to saturated absorption signal in turn carries out quadrature demodulation and low-pass filter processing and obtains first error signal and second error signal, first error signal and second error signal are superimposed to obtain dual-frequency error signal;Further, tunable laser is carried out closed-loop feedback control, realizes laser frequency stabilization.The application obtains two different frequency components error signal using dual-frequency modulation transfer spectroscopy detection technology, improves slope and intensity by adding operation, improves frequency discrimination sensitivity and anti-interference ability, is conducive to peak search determination and realizes the precision locking of laser frequency to rubidium absorption peak, with good practicability.

The present application relates to the technical field of precision phase measurement and digital signal processing, and particularly relates to a method and system for suppressing spectral aliasing and nonlinear distortion. The beat frequency signal is preprocessed and spectrum is constructed to obtain a normalized spectrum; peak value search is performed in a preset target frequency range to identify beat frequency, side frequency and pilot frequency signals to form an effective spectrum line set; nonlinear parasitic components are calculated to obtain folded parasitic spectrum lines, and the parasitic spectrum lines to be evaluated are obtained through constraint screening; branch processing is realized through suppression standard judgment, and selective narrowband notch suppression is performed on the parasitic spectrum lines meeting the conditions; digital heterodyne quadrature demodulation and low-pass filtering are performed on the signals before and after processing; and the suppression effect quantitative evaluation is completed according to the phase error and phase noise index, and the parameters are dynamically adjusted to realize the working condition adaptive optimization. The advantage lies in: accurately predicting and suppressing the composite interference, protecting the integrity of the effective signal, significantly improving the phase measurement accuracy and robustness, and widely applying to various scenes.

This application discloses a fully digital magnetic field measurement device and method, relating to the field of magnetic field measurement technology. The device generates a constant AC-DC superimposed current signal with adjustable frequency and amplitude, and outputs it to a Hall sensor placed in the magnetic field to be measured. It acquires the Hall voltage generated by the Hall sensor and performs analog-to-digital conversion to obtain a digital Hall signal. The digital Hall signal is quadrature demodulated to extract the in-phase and quadrature components. The magnetic field strength amplitude and phase are calculated based on the in-phase and quadrature components. The current is sampled in real time, and a closed-loop control signal is generated based on the deviation between a preset target current value and the actual sampled value to adjust the AC-DC superimposed current amplitude. Through a fully digital signal processing architecture and closed-loop control and output, high-precision, high-speed, and low-noise measurement of magnetic field strength and direction is achieved.

The application discloses a kind of monitoring method and system of electric power grounding system, applied to resistance detection technical field, method includes: obtaining the position distribution information of each ground body in target electric power grounding system;Based on position distribution information, the mutual impedance information of each ground body is obtained;Determine the target excitation frequency point of ground body;The target excitation signal is applied to corresponding ground body, and corresponding response signal is obtained;Orthogonal demodulation is carried out to the target impedance component extracted from response signal, and resistance response component and reactance response component are obtained;According to resistance response component, the equivalent resistance value of ground body is obtained, and the impedance data of ground body is determined based on reactance response component to process equivalent resistance value;Based on the impedance data of ground body, the resistance monitoring data of target electric power grounding system is obtained.The monitoring method and system of electric power grounding system provided by the application effectively improve the accuracy of resistance monitoring of the electric power grounding system of multiple ground body.

The present application relates to the technical field of vibration monitoring, and discloses a kind of for historical building microvibration monitoring optical fiber sensing data analysis method and system, the method includes: the original interference signal is quadrature demodulated, and vibration in-phase component and quadrature component are obtained, and vibration complex signal is constructed with this as real part and imaginary part.The signal is unwound to obtain continuous vibration phase sequence, and vibration change sequence is obtained after high-pass filtering.The characteristic quantity of each band component in the synthesis sequence is formed to form the original characteristic vector.Based on the sensitivity of historical building monitoring site to vibration, the characteristic vector is fused to obtain the comprehensive vibration index.According to the concentration trend and dispersion degree of the index, determine the dynamic reference value and fluctuation range, judge the vibration deviation degree against the fluctuation range, and obtain the information evaluation conclusion;The present application can improve the accuracy of optical fiber sensing data analysis for historical building microvibration monitoring.

The application provides a differential quadrature demodulation method for dynamic direct current offset, and belongs to the technical field of signal processing.The method comprises the following steps: collecting a quadrature baseband signal containing target motion information, and sequentially performing differential operation and differential cross multiplication operation to obtain a preliminary demodulation phase; using the preliminary demodulation phase and the differential quadrature baseband signal to obtain a reconstructed quadrature baseband signal; calculating the variance of the differential demodulation phase according to the length of a preset window, obtaining a judgment threshold, detecting an abnormal region set of the differential demodulation phase, excluding all abnormal regions of the reconstructed quadrature baseband signal, and performing differential cross multiplication operation to obtain a fine calibration demodulation phase; and fitting and repairing all abnormal regions in the fine calibration demodulation phase to obtain a target motion trajectory subjected to differential quadrature demodulation.The application can effectively improve the robustness, real-time performance and accuracy of demodulation of motion information.

A demodulator (100) comprising: a demodulation element (10) which outputs a demodulated signal which is demodulated from a modulated signal; an integration element (60a) which integrates the demodulated signal; a zone detection element (60b) which detects a replacement target zone in the demodulated signal based on an integrated signal output by the integration element (60a); and a replacement element (60c) which replaces a signal of the replacement target zone in the demodulated signal with a replacement target signal; wherein the demodulation element (10) comprises: an orthogonal demodulator (20) which demodulates from the modulated signal, which is FM modulated, an I signal and a Q signal which are orthogonal to each other; an A / D conversion element (30) which converts the I signal and the Q signal, which are in an analog form and are received by the orthogonal demodulator (20), into digital signals;a filter element (40) which cuts out a high-frequency band higher than a predetermined cut-off frequency from the I signal and the Q signal, which have been converted into digital signals by the A / D conversion element (30); and an FM demodulator (50) which outputs the demodulated signal obtained by correcting a differential value of the arctangent of the I signal and the Q signal to lie within a predetermined numerical range, wherein the differential value is obtained by differentiating the arctangent of the I signal and the Q signal received by the filter element (40).

This invention belongs to the field of power equipment condition monitoring and fluid non-destructive testing technology, specifically relating to a method and system for ultrasonic detection and dynamic visualization of moving air bubbles in the insulating oil of oil-filled electrical equipment such as ultra-high voltage transformers, using multi-angle dynamic focusing for bubble velocity measurement and positioning. It is applied to bubble detection in the complex oil duct environment of ultra-high voltage transformers. The method performs orthogonal demodulation and filtering on the received signal to extract the low-frequency Doppler component. Then, digital beamforming technology is used to achieve multi-angle dynamic focusing of the bubble echo, and the data is converted from a fast time dimension to a slow time dimension. The Doppler frequency shift is extracted by analyzing the time-frequency characteristics of the signal using short-time Fourier transform. The bubble velocity vector is estimated based on least squares fitting, thereby simultaneously achieving velocity detection and spatial positioning. This invention, with limited data, calculates the vector velocity of the bubble movement based on spatial information from multiple dynamically focused angles and achieves positioning.

The application belongs to the field of space-based microwave radar, and discloses a space-based detection radar channel consistency calibration method based on an active calibrator. The active calibrator is arranged on the ground to actively emit a point frequency continuous wave signal, and the space-based detection radar beam direction is adjusted to make the beam dwell and continuously scan the active calibrator, so that a high signal-to-noise ratio, stable and controllable external radiation echo signal is obtained. The received point frequency continuous wave signal is multiplied by a carrier frequency signal and then subjected to quadrature demodulation to obtain demodulation signals of each channel; distance direction FFT is performed on the demodulation signals to obtain peak amplitude and peak phase; the phase difference and amplitude difference of each channel relative to a reference channel are calculated to generate a channel consistency calibration parameter file for radar calling. The precision and stability of the space-based detection radar channel consistency calibration are improved, the method is suitable for a multi-frequency band and multi-channel system, and has operability and popularization value in engineering application.

This invention discloses a dynamic harmonic synchronization phasor estimation method based on adaptive iterative orthogonal demodulation. The method acquires discrete sampled signals of grid voltage or current and sets a target frequency. Instantaneous phasor parameters are calculated based on the target frequency and the discrete sampled signals. The corresponding harmonic components are reconstructed based on these instantaneous phasor parameters, and the residual signal is updated. From the second iteration onwards, the target frequency is updated based on the spectral characteristics of the residual signal or a preset rule. The average change trend of the instantaneous frequency from the previous iteration is used to adjust the target frequency. Instantaneous phasor parameters are calculated based on the adjusted target frequency and the residual signal, and the corresponding harmonic components are reconstructed and the residual signal is updated accordingly. If the energy of the residual signal is below a threshold or other iteration stopping conditions are met, the instantaneous phasor parameters and reconstructed harmonic components of all iterations are output. This invention significantly improves the accuracy and robustness of harmonic measurement in scenarios with dynamic frequency changes and dense spectrum.

This disclosure provides an interface circuit for a capacitive MEMS sensor and a quadrature error suppression method. The quadrature error suppression method includes: acquiring a first-direction displacement from the capacitive MEMS sensor; providing a driving voltage to a driving electrode based on the first-direction displacement to cause the capacitive MEMS sensor to resonate along the first direction; acquiring a second-direction displacement from the capacitive MEMS sensor; amplifying and converting the second-direction displacement signal to obtain a detection signal containing a quadrature error component and an input angular velocity; performing in-phase quadrature demodulation on the detection signal; and obtaining an output signal characterizing the input angular velocity based on the demodulated quadrature component, in-phase component, and error elimination coefficient. The error elimination coefficient is obtained based on the changes in the in-phase component and quadrature component before and after an electrostatic force is applied to the torsion electrode. This application can obtain a more accurate error elimination coefficient, thereby improving the detection accuracy of the capacitive MEMS sensor.

The application discloses a parameter measurement system, method and electronic equipment, and relates to the technical field of electronic element parameter measurement, wherein the parameter measurement system comprises a sampling module, a frequency synthesis module, a quadrature demodulation module, a first filtering module, a second filtering module, an adaptive adjustment module and a parameter calculation module; the quadrature demodulation module is connected with the sampling module and the frequency synthesis module; the first filtering module is connected with the quadrature demodulation module; the second filtering module is connected with the first filtering module; the adaptive adjustment module is connected with the first filtering module, and the adaptive adjustment module is used for adjusting a decimation factor of a decimation processing based on a test frequency; the parameter calculation module is connected with the second filtering module, and the parameter calculation module is used for calculating impedance of a measured piece. The adaptive adjustment module is arranged to adjust the decimation factor of the first filter, and thus, high-frequency and low-frequency measurement ranges can be compatible.

The embodiment of the application provides a kind of high sensitivity acoustic wave sensing system and method, belong to optical fiber sensing technical field.The system includes: narrow line width laser output continuous coherent light, is divided into two ways by beam splitter;Reference arm is set in the acoustooptic modulator operating in continuous wave mode, and the light signal is shifted with fixed frequency, and the local oscillator light is output;Sensing arm is set in the suspended micro-nano fiber sensing probe, and the external acoustic wave signal is modulated as the phase change of light;Two-way light is combined by second optical coupler, and is converted into beat frequency electric signal by photoelectric detector;IQ demodulation module carries out quadrature demodulation to beat frequency electric signal, and extracts the phase change caused by acoustic wave signal.The application adopts suspended micro-nano fiber structure, eliminates mechanical resonance and damping;Combined with AOM continuous light heterodyne detection and IQ demodulation, acoustic wave signal is shifted to high frequency carrier, and environmental drift is directly filtered out by digital high-pass filter, without PZT feedback, realize never lose lock wideband high sensitivity detection.

This invention discloses a high-efficiency orthogonal demodulation method and apparatus based on envelope signals. The method, applied at a receiving end, includes: recovering the amplitude and phase based on the envelope information of the orthogonal modulation signal; subtracting the recovered phase from the phase of the low-frequency local oscillator signal used for digital down-conversion to obtain the phase of the baseband signal, thereby achieving equivalent digital down-conversion; and reconstructing the I and Q components of the baseband signal based on the recovered amplitude and the baseband signal phase. This invention significantly simplifies the calculation process and improves processing speed and efficiency.