123 results about "Phase drift" patented technology

The invention relates to a phase-sensitive optical time domain reflectometer based on multi-frequency reference switching. Continuous laser generated by a continuous laser is divided into a local path and a detection path through an optical coupler; the local path is input to the polarization coherent receiving module, the detection path is incident to a light intensity modulator driven by the signal generation circuit module, and the light intensity modulator is converted into a multi-frequency pulse laser sequence with intensity modulation; the multi-frequency pulse laser sequence enters the sensing optical fiber to be measured through the optical circulator; generated Rayleigh backscattered light and local continuous laser are subjected to beat frequency coherent receiving in a polarization coherent receiving module through a circulator; and the signal acquisition circuit adopts a demodulation algorithm to compensate phase drift and sensitivity difference of detection pulse demodulation signals with different frequencies so as to realize dynamic strain sensing. Compared with the prior art, the phase drift and the sensitivity difference between the frequencies are extracted to realize the compensation of the interleaved signals, and the method does not depend on the fixed reference frequency, so that the robustness and the adaptability of the system in a complex environment are remarkably enhanced.

The invention discloses a continuous variable quantum key distribution method, device and system, and belongs to the field of wireless communication. Firstly, a sending end generates continuous light pulses for discrete coding, a one-dimensional discrete modulation signal is generated, quantum signal light is generated through an attenuator, and the quantum signal light is coupled to a quantum channel for transmission. Then, a receiving end adopts a homodyne detector to measure the regular component of the quantum signal in a self-calibration manner; and after a local measurement base direction and a phase drift angle introduced by a dynamic compensation quantum channel are adjusted in real time, a covariance matrix is calculated and input into a post-processing module, the code rate of the system is further calculated, and a security key is generated by using a protocol between a receiving end and a transmitting end. According to the device, the intensity modulator is connected between the laser and the attenuator, so that one-dimensional discrete modulation is realized, and dependence on a phase reference signal is avoided. According to the system, a traditional phase locking module is removed, an asymmetric phase space coding mechanism is adopted, dependence on a phase reference signal is eliminated, and the safety and stability of the system are improved.

The invention discloses a beam synchronous phase on-line measurement method, device and equipment and a medium. The beam synchronous phase on-line measurement method comprises the steps of obtaining an original cavity pressure Vc * and an original forward voltage Vf * of a radio frequency cavity; processing the original cavity voltage Vc * and the original forward voltage Vf * to obtain normalized cavity voltage Vc and forward voltage Vf; calculating steady-state values UC and UF of the cavity pressure Vc and the forward voltage Vf, and solving detuning delta omega in a steady state; carrying out linear fitting on the cavity pressure change Vcb caused by the beam current to obtain a phase angle Vcb; according to the selected time window TW, calculating a deflection angle alpha th of a phase angle Vcb caused by detuning delta omega; deducting the deflection angle alpha th from the phase angle Vcb to obtain the phase angle Vb of the beam equivalent voltage; and extracting a beam phase # imgabs0 # based on the phase Vb of the beam equivalent voltage. The calculation result of the method is not influenced by phase drift caused by environmental factors any more, and is not influenced by cavity detuning any more.

The invention discloses a laser phase noise quantum random number generator which comprises a light source module, an unequal arm interference light path, a detection module, a sampling module, a control processing module and a driving module. The light source module generates light signals and outputs the light signals to the detection module through the unequal-arm interference light path, the detection module detects the intensity of the interference light signals, the sampling module carries out high-speed sampling on output results of the detection module, and sampling data of the sampling module is calculated and analyzed through the control processing module to obtain the size of phase drift. Then, an electric signal is generated through a driving module to load a compensation phase to the unequal arm interference light path to offset phase drift, so that the laser phase noise quantum random number generator reaches a stable state; and when the laser phase noise quantum random number generator reaches a stable state, the control processing module performs entropy evaluation and randomness extraction on the sampling data to generate a random sequence. Through the structural arrangement, the control precision and the feedback compensation speed are effectively improved.

The invention discloses a data processing method and system of a chromatographic instrument, and relates to the technical field of data processing, and the method comprises the following steps: collecting whole-course original detection signals and external interference signs generated in a chromatographic analysis process, carrying out time alignment under a unified time scale, generating an interference rhythm index, and calculating the interference rhythm index; the reference is used as a unified reference for subsequent signal comparison; and based on the interference rhythm index, performing phase drift comparison on the acquired signal, calculating the phase difference between the detection signal and the interference signal, drawing a beat frequency wandering graph, extracting candidate signal segments of pseudo-period interference according to beat frequency change, and generating a pseudo-period candidate segment list. According to the invention, by establishing the interference rhythm index and comparing the interference rhythm index with the phase drift, the time decoupling of the detection signal and the interference signal is realized, and the sampling anti-interference capability is improved; and through dynamic control of a false peak characteristic fingerprint draft and a misjudgment reason table, signal rhythm correction and peak identification optimization are completed, so that the detection accuracy and the data stability are improved.

The invention relates to the field of data storage, in particular to a multi-layer optical storage data reading method and system for dynamic inter-layer crosstalk suppression. Comprising the following steps that chromatography interference signals of a target data layer in a multi-layer optical storage medium are collected through a low-coherence interferometer, spatial frequency characteristics of adjacent data layers are synchronously obtained, and the spatial frequency characteristics comprise power spectral density, frequency band width and phase distribution parameters. According to the invention, through frequency domain convolution quantization of coherent coupling coefficients and deep network weight generation, dynamic analysis of transient coherent crosstalk intensity is realized for the first time. The real-time aperture regulation (0.45-0.85 NA continuous change) of the variable aperture diaphragm is utilized to match the frequency band suppression priority, and the band limit constraint of a traditional fixed filter is broken through; and a multi-channel interference reference light path and a second-order differential compensation algorithm are combined, so that the interlayer spacing error is compressed to a submicron order, and the phase drift caused by the medium refractive index gradient is effectively inhibited.

The invention discloses a double-field quantum key distribution system. The double-field quantum key distribution system comprises a Charlie end, an Alice end and a Bob end, the invention also discloses a double-field quantum key distribution method which is realized based on the double-field quantum key distribution system. The invention discloses a double-field quantum key distribution system and method, and the method comprises the steps: carrying out the interference of uncoded signal light transmitted and returned by an Alice end and a Bob end at a Charlie end, and feeding back a phase drift distance according to an interference result to compensate the phase drift of the coded signal light during the transmission in an optical fiber, thereby achieving the stable phase, and achieving the high-precision transmission of the coded signal light. The method can adapt to an operation environment with dramatic phase change in long-distance transmission, and the stability and the high efficiency of a quantum network and a transmission link are improved.

The invention relates to the technical field of X-ray imaging, and discloses an X-ray grating comprehensive imaging information extraction method and system. The method comprises the steps of obtaining and preprocessing original data; acquiring multi-dimensional interference parameters formed by grating phase drift distance, photon statistical noise density and imaging object deformation rate; dynamically calculating a phase correction coefficient, a noise suppression weight and information extraction confidence; phase compensation and noise filtering are executed based on the confidence coefficient, and structure and density information is extracted; parameter changes are monitored in real time, and the extraction process is updated; the system correspondingly realizes the method. The problem of low dynamic scene information precision caused by multi-interference coupling is solved, and the imaging information extraction stability and quality are improved.

The invention relates to an optical fiber sensing signal quality evaluation method and device under composite disturbance, and the method comprises the following steps: firstly, collecting a composite disturbance signal, and carrying out the multi-mode preprocessing; then the image is input into a joint demodulation model, and the model comprises a group convolution-residual network module and a feature pyramid network module which are connected in sequence and are respectively used for performing multi-scale feature extraction and feature cross-layer fusion; finally, the output of the joint demodulation model is input into a double-detection-head network, composite disturbance decoupling and signal quality evaluation are conducted, and the double-detection-head network comprises a classification detection head used for predicting disturbance types and a positioning detection head used for outputting disturbance position offset parameters. The disturbance position offset parameters comprise a signal-to-noise ratio, a phase drift tolerance and a multi-disturbance coupling coefficient. Compared with the prior art, the method can significantly improve the accuracy and reliability of signal quality evaluation under composite disturbance.

The invention discloses a quantum key distribution method and system based on phase adaptive compensation. The method comprises the following steps: firstly, generating first quantum light and a coded signal, and obtaining an error rate of last operation of the quantum key distribution system; according to the bit error rate of last operation of the quantum key distribution system, the current first phase compensation amount of the quantum key distribution system is calculated; performing phase modulation and phase compensation on the first quantum light according to the coded signal and the first phase compensation amount to obtain second quantum light; generating a decoding signal, and performing phase demodulation on the second quantum light according to the decoding signal to obtain demodulated third quantum light; detecting the third quantum light to obtain a detection signal; and finally, generating a security key according to the detection signal. By implementing the invention, the problem of phase drift generated in the system can be solved, and the stability of the quantum key distribution system is improved.

The invention provides an optical time domain reflection system and demodulation method based on reference optical fiber phase compensation, and the system comprises a signal generator, a distributed feedback laser, a semiconductor optical fiber amplifier, a first amplifier, a circulator, a second amplifier, a wave filter, a detector, a reference optical fiber, and an optical fiber to be measured. A continuous laser signal of the distributed feedback laser is converted into a pulse optical signal through the semiconductor optical fiber amplifier and is amplified through the first amplifier; the amplified pulse optical signal enters a second port of the circulator through a first port of the circulator and sequentially enters a reference optical fiber and an optical fiber to be detected, and an optical fiber Rayleigh scattering signal enters a third port of the circulator through the second port and sequentially passes through a second amplifier and a filter to be detected; and the detector obtains Rayleigh interference spectrums of the reference optical fiber and the optical fiber to be detected according to the filtered scattering signals. According to the invention, the technical problem of insufficient measurement precision caused by the influence of light source phase drift on the traditional phase-OTDR system can be solved.

The invention discloses a photoetching machine multi-light-source cooperative high-precision exposure control system, and relates to the technical field of photoetching machine control. Initial energy parameters of all light sources are obtained, a coupling feature set of energy change and light spot morphology change is constructed, and light intensity errors, phase errors and light spot distortion errors are used as input, so that a multi-light-source cooperative high-precision exposure control system is constructed; respectively generating an inter-light-source time sequence offset matrix and a light source energy compensation matrix, constructing a light source collaborative error model through matrix superposition and eigenvalue decomposition, inputting exposure disturbance obtained by real-time monitoring of a photoetching machine into the error model, and obtaining a primary compensation amount; a final target exposure compensation parameter is obtained by adopting a quadratic optimization algorithm under a constraint condition, and light source energy output, a light path phase and a pulse trigger time sequence are cooperatively adjusted according to the target exposure compensation parameter, so that energy deviation, phase drift and time sequence mismatch can be reduced at the same time, the exposure stability and the pattern forming precision are remarkably improved, and the image forming precision is improved. The method is suitable for high-resolution and multi-light-source photoetching equipment.

The invention discloses a distributed sound wave sensing device based on PDH frequency locking and a demodulation method. The distributed sound wave sensing device comprises a narrow linewidth laser, a first optical fiber coupler, a heterodyne phase sensitive optical time domain reflectometer and a frequency stabilization feedback module. The frequency stabilization feedback module comprises a frequency stabilization modulation and demodulation module, a reference cavity and a server; the frequency stabilization modulation and demodulation module comprises an electro-optical modulator or an acousto-optical modulator, a photoelectric detector, a multiplier and a low-pass filter; the first path of light enters a reference cavity for resonance after being modulated by an electro-optical modulator or an acousto-optical modulator, a resonance signal enters a photoelectric detector through cavity reflection, and a signal output by the photoelectric detector is subjected to signal demodulation by a multiplier and a low-pass filter and then is used as feedback to be input into a server for proportional-integral processing; the laser is fed back and output to a modulation interface of the narrow-linewidth laser, and frequency compensation is performed on the laser, so that the laser is locked on the reference cavity; according to the invention, through frequency stabilization and homologous modulation and demodulation, line width and phase drift of the laser can be suppressed at the same time.

The invention discloses a high-precision vector regulation and control device and method for a signal generation link, and belongs to the technical field of information. A frequency mixing feedback loop is adopted to replace a traditional ALC detection loop, the amplitude of a signal can be stabilized, the phase of the signal can also be stabilized, and impedance matching of a channel can also be regulated and controlled; a path feedback signal is converted into a digital signal for high-speed transmission, and the ADC, the signal processing module and the DDS are interconnected through a high-speed bus, so that high-speed vector regulation and control can be quickly performed, and the loop control speed is higher; according to the invention, the direct digital frequency synthesizer is in a loop, which means that the amplitude and phase drift in the DDS can also be captured by the loop for correction; according to the method, vector information of the amplitude and phase drift of the channel can be obtained at the same time, so that closed-loop dual control, namely vector control, is carried out, and the purpose of regulating and controlling the amplitude and phase of the signal at the same time is achieved.

The invention relates to the technical field of fruit quality detection, and discloses a fruit quality detection method and system based on multispectral structured light, and the method comprises the steps: firstly collecting a structured light image sequence and a spectral intensity image of a to-be-detected fruit, and solving an initial truncation phase field; performing subsurface scattering phase reverse compensation on the initial truncation phase field by using a spectral intensity image, and reconstructing a unit normal vector field of the surface of the fruit to be measured through unwrapping; carrying out physical reverse compensation on the spectral intensity image by utilizing a unit normal vector field and an illumination direction vector, and decoupling to obtain real spectral reflectivity distribution; and finally, outputting a comprehensive grading result of the to-be-detected fruit by fusing the geometrical morphology characteristics and the spectrum biochemical characteristics. According to the method, the phase is corrected by calculating the gray absorption item and the gradient scattering item of the image, so that the problem of phase drift caused by light permeation due to the semitransparent fruit skin is effectively solved, the depth measurement error caused by light diffusion in a medium is eliminated, and the fruit detection precision is further improved.

The utility model discloses a system for measuring the half-wave voltage of a phase modulator. The system comprises a laser generation module, an optical coupler, a first phase modulator, a second phase modulator, a first Faraday mirror, a second Faraday mirror, a signal generator, a photoelectric detector and an oscilloscope. The utility model discloses a system for measuring the half-wave voltage of a phase modulator, which is characterized in that a high-frequency periodic square wave electric signal is loaded to a second phase modulator through a signal generator, and the phase drift amount caused by unstable factors such as a light source, an optical device and an external environment can be regarded as perturbation in a small time period; the half-wave voltage of the second phase modulator is obtained by accurately calculating the variable quantity of the number of the peak (valley) values of the sine (cosine) waveform, so that the judgment on the light intensity extreme point of an interference pattern is avoided, the measurement precision is improved, and the key core application in the fields of quantum communication and quantum calculation is realized.

This invention discloses a method, electronic device, and storage medium for ultra-large-scale MIMO synchronization, relating to the fields of wireless communication and channel measurement technology. The method includes: first, estimating the delay and direction parameters of at least one strong path as an anchor path based on reference subarray channel data; then, for each pair of adjacent subarrays, extracting the phase of the same path on the boundary elements based on the anchor path parameters, calculating the observed phase difference, and thus obtaining the observed value of the common phase drift between subarrays; next, fusing multiple observations to obtain a robust estimate of the common phase difference between adjacent subarrays; finally, accumulating the estimated values ​​of each segment with the first subarray as a reference to obtain the common phase drift of each subarray, performing phase compensation, and then stitching the data of each subarray according to coordinates into an equivalent ultra-large-scale array to achieve ultra-large-scale MIMO synchronization. Therefore, this invention can estimate and compensate for the common phase drift of subarrays without additional hardware time synchronization.

This application relates to a satellite-to-ground frequency synchronization system and method. The system includes: a communication satellite transponder for receiving uplink signals transmitted by a ground synchronization system, generating a beacon signal and a first downlink signal, combining the first downlink signal and the beacon signal to obtain a combined signal, and then transmitting the combined signal back to the ground synchronization system; and a ground synchronization system for receiving the combined signal, separating the combined signal to obtain the first downlink signal and the beacon signal, eliminating phase drift of the first downlink signal based on the beacon signal to obtain a second downlink signal, and determining uplink phase compensation, downlink phase compensation, and beacon phase compensation based on the second downlink signal and the uplink signal. These uplink phase compensation, downlink phase compensation, and beacon phase compensation are then used for signal phase compensation during subsequent signal transmission and reception. This method can eliminate phase drift of onboard crystal oscillators and improve satellite-to-ground frequency synchronization accuracy.

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 invention relates to the technical field of Beidou navigation satellite signal intelligent processing, in particular to a Beidou navigation satellite positioning data gross error elimination algorithm close to a wide water area. The method comprises the following steps: acquiring a satellite receiving signal; performing signal preprocessing on the satellite receiving signal to generate a standard satellite receiving signal; performing indirect path interference analysis on the standard satellite receiving signal to obtain a direct path receiving signal and an indirect path receiving signal; and performing signal phase disturbance analysis on the direct path receiving signal and the indirect path receiving signal by using the deduction comprehensive signal model, and generating a phase drift distance of the indirect path receiving signal. According to the invention, a signal processing and repairing algorithm is utilized to intelligently identify the reflection signal generated by the large-area water area, and the gross error generated by the reflection signal is automatically eliminated, so that the correctness and the stability of the measurement result are ensured.

The invention provides an optical fiber phase stabilization device and method, and the device comprises a crystal oscillator, a power divider, an optical module, a phase comparison time delay control module, an optical fiber beam splitter, an optical switch, and a first circulator, the crystal oscillator is used for transmitting a signal source, and inputting the signal source into the power divider; the power divider is used for dividing the electric signal into two paths, one path is input into the optical module, and the other path is input into the phase comparison time delay control module; the output end of the optical module is connected with the optical fiber beam splitter, and the input end of the optical module is connected with the optical switch; the optical fiber beam splitter is used for dividing an optical signal output from the optical module into two paths, one path is input into the first circulator, and the other path is input into the optical switch; the phase comparison time delay control module receives two paths of different optical signals through an optical switch. According to the invention, the problem that the optical fiber length measurement control precision is affected due to the fact that the electro-optical modulation device and the photoelectric detection device both have certain slow phase drift in the current high-precision optical fiber length change measurement process can be solved.

The invention relates to the technical field of film coating optics, in particular to a compensation method for transverse displacement and phase drift of a multilayer film surface, and the method specifically comprises the steps: S1, determining a corresponding spatial frequency according to an incident field of incident light at an incident position x, and calculating a reflection coefficient corresponding to the spatial frequency through a scattering matrix; s2, according to the phase corresponding to the reflection coefficient, transverse displacement and phase drift generated on the surface of the multi-layer film when the incident light is reflected in the multi-layer film are obtained; and S3, substituting the incident field, the reflection coefficient, the lateral displacement and the phase drift into the proposed compensation model to obtain a reflection field. According to the method, homeomorphic Fourier transform and a plane wave angular spectrum theory are used for deducing a compensation model of transverse displacement and phase drift of reflection rays of geometric rays on the top surface of the multilayer film, the calculation precision is effectively improved, and the calculation complexity is obviously lower than that of a traditional plane wave angular spectrum method adopting strict Fourier transform; and no obvious difference exists in calculation results.

The invention provides a frequency distribution system and method based on a fractional frequency division phase-locked loop, and the method comprises the steps: embedding a clock signal in a data link through a serial transceiver, precisely extracting an upstream reference clock from a data stream at a receiving end through a clock data recovery unit, and then obtaining a phase difference through a high-precision phase discriminator based on the fractional frequency division phase-locked loop, and the reconfigurable digital loop filter performs proportional-integral operation and noise filtering to generate a control signal to drive the phase-locked loop to output a local clock synchronous with the reference clock. The system realizes accurate regeneration and transmission of frequency information and phase information among multiple stages of nodes, effectively inhibits accumulated phase drift, reduces transmission jitter, avoids high-cost deployment of special optical fibers, remarkably improves the frequency distribution accuracy and stability, and has a wide application prospect. And a low-cost and high-flexibility synchronization solution is provided for large-scale networking.

The application discloses a photolithography machine multi-light-source cooperative high-precision exposure control system and relates to the technical field of photolithography machine control. The initial energy parameters of each light source are acquired, a coupling characteristic set of energy variation and light spot appearance variation is constructed, light intensity error, phase error and light spot distortion error are taken as inputs, a time sequence offset matrix between the light sources and a light source energy compensation matrix are respectively generated, a light source cooperative error model is constructed through matrix superposition and eigenvalue decomposition, exposure disturbance obtained by real-time monitoring of the photolithography machine is input into the error model, the final target exposure compensation parameters are obtained by using a quadratic optimization algorithm under a constraint condition after the preliminary compensation amount is obtained, the light source energy output, the light path phase and the pulse trigger time sequence are cooperatively adjusted according to the target exposure compensation parameters, the energy deviation, the phase drift and the time sequence mismatch can be simultaneously reduced, the exposure stability and the pattern shaping precision are significantly improved, and the application is suitable for high-resolution and multi-light-source photolithography equipment.

The invention discloses a cavity low-level tuning control device and method based on phase compensation. The device comprises a transmitter, a resonant cavity, a low-level control system and a transmission line. The low-level control system tuning loop is characterized in that the low-level control system tuning loop comprises a tuning module and a phase compensation module, the phase compensation module comprises a phase compensation comparison table and a mathematical curve fitted with the phase compensation comparison table, and the phase drift compensation amount calculated through the phase compensation comparison table and the mathematical curve fitted with the phase compensation comparison table is added to the phase of a low-level signal. And a forward signal fed back by a directional coupler on a transmission line is replaced. The invention provides a new algorithm for a high-frequency system with the bearing power of an N-type coupler and the bearing power interval of a high-frequency line. According to the method, a high-frequency line is used for power feeding, a directional coupler and a feed tube are omitted, the space of the device is greatly reduced, the cost of the device is greatly reduced, and meanwhile, the device and the method provide a new thought for all accelerator tuning methods.

A method for eliminating phase drift in distributed acoustic sensing, comprising: acquiring each signal component in a distributed acoustic sensing system and performing phase demodulation to obtain the phase value of each signal component at the current moment (S1); initializing a Kalman filter and, for each signal component, by means of a Kalman filter time update equation, updating the priori estimate covariance at the current moment on the basis of the posteriori estimate covariance at the previous moment (S2); for each signal component, substituting the priori estimate covariance at the current moment into a Kalman gain equation to calculate a Kalman gain coefficient (S3); on the basis of the phase value and the Kalman gain coefficient of each signal component at the current moment, calculating a phase drift estimated value of each signal component at the current moment and updating the posteriori estimate covariance of each signal component at the current moment (S4); and using the phase value and the phase drift estimated value of each signal component at the current moment to calculate drift-free phase values at the current moment and outputting same, thus eliminating the phase drift of each signal component at the current moment (S5). The method is applicable to various distributed acoustic sensing systems, and can eliminate the phase drift of each signal component to keep the phase consistency of each signal component in real time.

This invention discloses a dual-field quantum key distribution system, including a Charlie end, an Alice end, and a Bob end; it also discloses a dual-field quantum key distribution method based on the aforementioned dual-field quantum key distribution system. This invention discloses a dual-field quantum key distribution system and method that interferes with the unencoded signal light transmitted back from the Alice and Bob ends at the Charlie end, and feeds back the phase drift based on the interference result to compensate for the phase drift of the encoded signal light during transmission in the optical fiber, achieving phase stability. This allows it to adapt to the operating environment of drastic phase changes in long-distance transmission, improving the stability and efficiency of quantum networks and transmission links.

The present application relates to the field of data storage, in particular to a kind of dynamic interlayer crosstalk suppression multilayer optical storage data reading method and system.The present application includes the following steps: through low-coherence interferometer, the layer analysis interference signal of target data layer in multilayer optical storage medium is collected, and the spatial frequency characteristic of adjacent data layer is synchronously obtained, the spatial frequency characteristic includes power spectral density, frequency bandwidth and phase distribution parameter.The present application is first realized to the dynamic analysis of transient coherent crosstalk intensity through the frequency domain convolution quantization of coherent coupling coefficient and the generation of depth network weight.The real-time aperture control (0.45-0.85 NA continuously changes) of variable aperture diaphragm is used to match the priority of frequency band suppression, break through the band-limited constraint of traditional fixed filter;combined with multichannel interference reference light path and second-order differential compensation algorithm, the interlayer spacing error is compressed to submicron level, and the phase drift caused by medium refractive index gradient is effectively suppressed.

This application provides a fault identification method based on UHF phase characteristic changes, belonging to the field of fault identification technology. The method includes: acquiring the original electromagnetic signal of the target power equipment, performing preprocessing and phase demodulation to generate initial phase time series data; extracting the phase consistency coefficient, phase mutation index, and phase drift gradient within a preset time window to construct an initial three-dimensional phase feature vector; dynamically correcting the initial three-dimensional phase feature vector based on preset performance parameters of the phase-locked loop and historical data processing errors to generate an optimized three-dimensional phase feature vector; inputting the vector into a pre-trained fault classification model to calculate the matching probability between the output and each typical fault mode; performing multi-dimensional decision analysis based on the matching probability and the correlation weight matrix to identify and output the fault type identification result. This method solves the technical problems of insufficient identification accuracy and low precision in existing fault identification methods based on UHF phase characteristics.

The invention provides a method for removing residual amplitude noise in a Pound-Drever-Hall (PDH) laser frequency stabilization system based on a crystal birefringence theory and an orthogonal demodulation scheme. Comprising the following steps: analyzing a reason for generating residual amplitude noise in a system based on a crystal birefringence theory, and optimizing a PDH model; the method further optimizes the system according to the noise generation reason elaborated by the model, and comprises the following steps: firstly, adding a polarization controller in the system to restrain a laser input signal aiming at the problem that the laser incident polarization angle is not fixed; secondly, aiming at the problem that the phase of a demodulation signal is not clear due to signal phase drift, an orthogonal demodulation system is established, and updating of the demodulation phase is completed by analyzing the signal phase in real time; and finally, establishing a system based on the work, and optimizing the PDH frequency tracking system. According to the method, the problems of frequency stabilization point blanking, error curve distortion and the like caused by residual amplitude noise in a traditional PDH scheme can be solved, and the problems of low final optimization tracking precision and poor long-term stability are solved.