321 results about "Frequency compensation" patented technology

The invention provides a single-tube boost PFC circuit control method and system for single-cycle control, and relates to the technical field of data processing, and the method comprises the steps: generating a self-adaptive PWM control signal according to a duty ratio adjustment amount and a frequency compensation factor, and dynamically limiting the pulse current amplitude of a power switch tube through a peak current prediction algorithm, a load current change rate is generated based on the real-time relevance between the pulse current amplitude and the load current; setting a first monitoring point in a dynamic duty ratio change path of the PWM control signal, and extracting a duty ratio change rate and a switching frequency fluctuation parameter in real time; setting a second monitoring point in a feedback path of a load current change rate, and extracting a load current slope characteristic and a transient change amplitude in real time; and based on the parameters of the first monitoring point and the second monitoring point, generating a correction factor through a dynamic response correlation model. According to the invention, a high power factor can be realized under wide input voltage and load fluctuation.

The invention discloses a rapid calibration method and system for automatic testing equipment of a vehicle machine, and relates to the technical field of automatic calibration, and the method comprises the steps: inputting a preset standard calibration signal to the testing equipment, and collecting the response data of each testing channel of the equipment as calibration reference data; comparing the calibration reference data with a built-in standard reference value of the equipment, and calculating deviation data of each test channel; based on the deviation data, calibration parameters of each channel are calculated, and the calibration parameters comprise a gain compensation coefficient, a frequency compensation coefficient and a phase compensation coefficient; the calibration parameters are loaded to the corresponding channels of the test equipment, a preset standard calibration signal is input for verification test, and when errors of the channels are smaller than a preset residual error threshold value, calibration is completed, and the calibration parameters are stored. By establishing the gain-frequency-phase joint compensation model and combining the parallelization verification and increment optimization algorithm, the high-precision rapid calibration of the automatic test equipment of the vehicle machine is realized.

The invention discloses a low-dose CT image denoising method and system based on a conditional diffusion model, and the method comprises the steps: constructing a denoising network model, only employing a standard-dose CT image in a training process, and simulating a generation process of the standard-dose CT image through the training of the denoising network model. And abundant image priori knowledge is constructed. Meanwhile, the de-noising network model uses a U-Net encoder-decoder structure, a multi-scale cross axis attention mechanism is added in a decoder and an encoder, important image details are reserved in the de-noising process, irrelevant noise components are removed at the same time, and smooth areas and continuous boundaries of the image can be recovered. In addition, the frequency compensation block in the jump connection can compensate the insufficiency of medium-high frequency signals in the training process, so that the original structure and texture information of the image are recovered.

The invention provides a grid-connected inverter impedance detection method based on an L-shaped filter, and belongs to the technical field of grid-connected inverter impedance detection. A multi-frequency-point disturbance signal is injected into a preset grid-connected inverter working point, time domain data of inverter side current and common coupling point voltage are collected, fast Fourier transform analysis is carried out on the collected data, amplitude and phase information corresponding to each injection frequency point is extracted, and a frequency domain feature vector matrix is established; and establishing a frequency compensation matrix model to compensate and correct high-frequency band measurement data based on a frequency characteristic attenuation vector, calculating to obtain optimal estimated values of power grid impedance and grid-connected inverter output impedance, performing error analysis and precision verification on an impedance detection result, and outputting a verified impedance parameter value. The technical problem of insufficient power grid impedance detection precision caused by high-frequency band attenuation of the L-shaped filter is solved.

The invention discloses a temperature drift compensation method for a miniature crystal oscillator chip, and particularly relates to the field of temperature drift compensation for electromagnetic interference signal measurement, which comprises the following steps of: arranging a double-shaft Hall sensor array around a temperature sampling channel of the miniature crystal oscillator chip, and carrying out spatial distribution acquisition on a low-frequency electromagnetic field in a chip operation environment; generating an electromagnetic disturbance signal for representing a parasitic electromagnetic interference behavior; and pilot frequency convolution processing is carried out on the electromagnetic disturbance signal and a thermal response signal obtained in a temperature sampling channel, coupling response characteristics related to an electromagnetic interference behavior are extracted, and a spectrum fitting template of an electromagnetic parasitic injection behavior is constructed. A low-frequency electromagnetic disturbance sensing channel is synchronously introduced outside a temperature sampling path, and an interference identification, stripping and compensation dynamic linkage mechanism is constructed to realize active detection and correction of latent electromagnetic interference components in a temperature response signal, so that the problems of frequency compensation error and long-term offset accumulation in the prior art are solved.

The invention relates to the technical field of micro-grid control, and provides an island micro-grid distributed control method, system and device and a storage medium. Comprising the following steps: performing voltage compensation gain and frequency compensation gain calculation based on droop control output of each distributed power generation unit, droop control output of all neighbor distributed power generation units, and a voltage dynamic tracking error and a frequency dynamic tracking error which are obtained by calculating a microgrid global recovery target to obtain secondary adjustment output; and after corresponding items in the droop control output and the secondary regulation output are summed to generate comprehensive reference output, voltage synthesis is carried out according to the comprehensive reference output to obtain voltage regulation output for output control of a corresponding inverter. Based on a distributed regulation and control mechanism for cooperatively calculating the compensation amount of each power generation unit by using neighbor information and a global recovery target, the dynamic response speed and the power distribution precision can be improved, voltage drop and frequency deviation caused by load disturbance are effectively eliminated, and rapid recovery is realized.

The invention discloses a parallel converter cooperative grid-connected control method and device based on a fuel cell power generation grid-connected system, and the method comprises the steps: generating a PWM drive signal of a converter through employing a droop control strategy and a sliding mode control strategy when the converter of each power generation unit operates; operating data of each power generation unit and the health state of the fuel cell are collected in real time, information interaction data of adjacent power generation units are combined, and voltage and frequency compensation values of each power generation unit are calculated and used for conducting primary correction on the PWM driving signal; the amplitude deviation between the frequency, the voltage and the phase angle at the common coupling point of the alternating current bus of the power grid and each power generation unit is obtained in real time, a trigger instruction used for controlling switching of a grid-connected mode and an island mode is generated based on the deviation, and a synchronization item is generated based on the deviation in the grid-connected mode and used for conducting secondary correction on the PWM driving signal. The method can improve the stability and operation efficiency of the system, and ensures that the system is stably switched between the grid-connected mode and the island mode.

The invention provides a crystal oscillator monitoring method and system based on a multi-sensor network. The method comprises the following steps: acquiring operation environment data of the quartz crystal oscillator, monitoring an output signal of the quartz crystal oscillator, and acquiring output frequency and time for measuring the crystal oscillator in each batch; calculating the daily frequency change rate of the quartz crystal oscillator, and establishing an aging linear regression equation of the quartz crystal oscillator through a least square method based on the operation environment data, the output frequency, the daily frequency change rate and the time; and predicting an output frequency prediction value of the quartz crystal oscillator based on the aging linear regression equation, and performing frequency compensation on the quartz crystal oscillator according to the difference between the output frequency prediction value and a target frequency prediction value. Through the method and the corresponding system, the frequency stability and the anti-interference capability of long-term operation of the quartz crystal oscillator system and the overall operation reliability of the terminal equipment can be greatly improved.

The invention discloses a frequency voltage decoupling control method and a frequency voltage decoupling control system under a fault of a hybrid wind power plant, and belongs to the technical field of wind power generation. First voltage compensation is added to the following net type draught fan and the net constructing type draught fan through the frequency adjusting parameters and the current active power variable quantity; when only the active voltage support is started, first frequency compensation is added to the following net type draught fan and the construction net type draught fan through the voltage adjusting parameters and the current reactive power variable quantity; and when the active frequency support and the active voltage support are started at the same time, adding second voltage compensation and second frequency compensation to the following grid type fan and the constructing grid type fan by using the frequency adjustment parameter, the voltage adjustment parameter, the current active power variable quantity and the current reactive power variable quantity. According to the scheme, active and reactive feed-forward decoupling is carried out on the following / constructing network type fan through decoupling compensation control, and the interaction influence in the frequency voltage supporting process is restrained.

The invention relates to the technical field of signal processing, in particular to a microseismic sensor front-end signal conditioning circuit based on lag correction frequency expansion. The microseismic sensor front-end signal conditioning circuit based on lag correction frequency broadening comprises a differential amplification circuit used for converting a differential signal input by a microseismic sensor into a single-ended vibration signal and carrying out pre-amplification processing on the vibration signal according to a preset gain to obtain an amplified vibration signal; and the filtering and lag correction circuit is used for widening the frequency range of the amplified vibration signal in a filtering and lag correction mode to obtain a conditioned vibration signal. According to the invention, frequency expansion can be carried out on the magnetoelectric sensor through a low-frequency compensation technology, and the response capability of the magnetoelectric sensor to a low-frequency signal is improved.

The invention discloses a parallel constant-voltage digital audio power amplifier and a broadcasting system. Comprising a line input module, a line output module, a first analog-to-digital conversion circuit, a second analog-to-digital conversion circuit, a third analog-to-digital conversion circuit, a digital signal processor, a single-chip microcomputer, a digital-to-analog conversion circuit, an error comparator, a modulator, an integrating circuit, a pulse width modulation input half-bridge output stage, and a first carrier frequency selection and gain adjustment module. A second carrier frequency selection and gain adjustment module, a first LC filter, a high-frequency compensation network, a communication bus and a power switch. The technical problems that an existing multi-channel parallel digital constant-voltage power amplifier is only limited to power amplifier channels in the same power amplifier, the parallel connection mode only uses the first channel as a main power amplifier and only uses the other channels as slave power amplifiers, and certain limitation exists are solved.

The present application relates to the technical field of speech processing, and particularly relates to a mixed speech processing method, an electronic device and a computer readable medium. The method comprises the following steps: collecting mixed speech and environmental influence parameters; performing bionics frequency domain analysis on the mixed speech to obtain low-frequency attenuation compensation feature data; performing multipath effect propagation analysis on the low-frequency attenuation compensation feature data through the environmental influence parameters to generate channel distortion data; performing time domain-frequency domain joint deconvolution processing on the mixed speech by using the channel distortion data to generate direct sound components and reflected sound components; performing adversarial training based on the direct sound components and the reflected sound components to generate anti-multipath speech enhancement data; and constructing a dynamic frequency compensation filter based on preset environmental acoustic characteristics. The present application improves the output quality of mixed speech through multi-stage signal processing, frequency compensation and real-time optimization technology.

The invention discloses a multi-loop anti-interference ride-through control system and method for a high-voltage three-level inverter, and is suitable for a three-phase T-type three-level grid-connected inverter. The system comprises a direct current side power supply circuit, an inversion main circuit, a filtering grid-connected circuit, a signal sampling and conditioning circuit, a multi-loop cooperative controller and a PWM driving and protecting circuit. According to the control method, a robust synchronous reference is provided through an outer ring virtual synchronous generator strategy; a middle ring adopts a virtual impedance model containing a high-frequency compensation item to selectively suppress switching noise; the inner ring adopts a quasi-proportional resonance controller to realize fundamental current zero-static-error tracking; the modulation layer dynamically optimizes a discontinuous pulse width modulation strategy based on a real-time EMI index; and the rings are switched to a low-voltage ride-through mode in cooperation when a fault occurs. On the premise of not increasing hardware, the anti-interference capability, the current quality and the ride-through stability of the inverter under the working conditions of strong electromagnetic interference and power grid drop are effectively improved.

The invention relates to the technical field of audio signal processing, and provides a self-adaptive frequency compensation system for small-sized multichannel sound equipment and a control method thereof, and the self-adaptive frequency compensation system for the small-sized multichannel sound equipment comprises an audio signal acquisition module, a frequency analysis module and a dynamic filtering compensation module which are electrically connected with one another in a communication manner; the audio signal acquisition module is used for acquiring an audio signal at a preset sampling rate through the ADC module; the frequency analysis module is used for executing FFT (Fast Fourier Transform) on the acquired audio signals to calculate energy distribution of corresponding frequency bands and identify missing or attenuated frequency ranges; and the dynamic filtering compensation module is used for selecting an FIR (Finite Impulse Response) or IIR (Infinite Impulse Response) filter according to a frequency analysis result, dynamically adjusting a filter coefficient and a gain value, performing real-time filtering processing on the audio signal and outputting a compensated audio signal. The missing frequency is identified and compensated by performing analysis, filtering, equalization and other processing on the audio signal.

The invention provides a method for improving transient stability of a submarine direct-current power supply system based on frequency compensation. The method comprises the following steps: acquiring a real-time electrical parameter detection item of a first system; based on the first system real-time electrical parameter detection item, judging whether the system load power is within a power range required by a transient stable operation condition; if not, the switching frequency compensation amount of the input-series output-parallel resonant converter sub-module is calculated; based on the switching frequency compensation amount, determining a switching signal of a sub-module switching tube of the input-series output-parallel resonant converter; acquiring a real-time electrical parameter detection item of a second system; based on a second system real-time electrical parameter detection item, judging whether the system load power is within a power range required by a transient stable operation condition; if yes, conventional frequency conversion control is adopted. The technical blank in the field is effectively filled, and the stability of the submarine direct-current power supply system in the transient process is remarkably improved.

The invention belongs to the technical field of energy storage converter control, and discloses a network construction type energy storage converter pre-synchronization control method based on virtual impedance and inertia compensation, and the method comprises the following steps: 1, obtaining parameters; 2, virtual instantaneous reactive power Qv is calculated; 3, calculating an energy storage grid-connected pre-synchronization frequency compensation amount omega v; 4, calculating the voltage amplitudes of the two sides of the bus-side circuit breaker BRK1; step 5, calculating the pre-synchronization voltage compensation amount of the network construction type energy storage grid connection; 6, frequency and voltage compensation feed-in control is carried out; step 7, determining a network construction type energy storage grid-connected condition; step 8, designing a first-order inertial link to slow down jump; and step 9, quitting pre-synchronization. After the pre-synchronization control method provided by the invention is adopted, when a line has a fault, rapid and stable grid connection of network construction type energy storage can be realized, and the reliability of grid connection after the fault is recovered and the transient stability of the system are remarkably improved.

The invention relates to the technical field of power grid switching, and provides a grid-connected and off-grid seamless smooth switching method and device, electronic equipment and a storage medium thereof. The method comprises the following steps: acquiring a power grid phase angle and dq-axis voltage in real time through SRF-PLL phase locking, performing Clarke-Park conversion on VSG output current, and calculating active power and reactive power; based on the power deviation, the virtual inertia and the damping coefficient, dynamic optimization is carried out to obtain self-adaptive inertia and damping; performing secondary voltage compensation by combining the dq-axis voltage amplitude difference and the real-time reactive power to generate excitation voltage; frequency compensation is realized by using a phase difference and a dynamic phase tracking model; a switching instruction is generated through multi-threshold judgment, linear transition is conducted on reference current and reactive power through a transition function during switching, a non-jump current instruction is output, and grid-connected and off-grid seamless switching is achieved by closing PWM. According to the invention, grid-connected and off-grid seamless switching and high-precision voltage frequency control are realized through multi-threshold judgment, soft-closed PWM and the like.

A cascade amplification circuit module based on complementary parameter amplifiers belongs to the technical field of integrated circuit amplifiers and comprises a first-stage complementary parameter amplifier (CPA) and a second-stage amplifier (floating inverting type or transconductance resistance type). The first-stage CPA adopts an NMOS and PMOS complementary structure, passive amplification is achieved through grid multiplexing, a grid capacitor is used for storing signals in the sampling stage, a depletion layer capacitor is switched to improve gain in the amplification stage, common-mode voltage is stabilized through complementary design, and an extra feedback circuit is not needed. And the second-stage amplifier provides driving capability and is combined with passive gain to suppress noise. The cascade structure does not need frequency compensation, the design is simplified, the problem of balancing gain, noise and power consumption of a traditional amplifier is solved, and the cascade amplifier has the advantages of being high in energy efficiency and low in complexity.

The present invention relates to a leakage current suppression system for an alternating-current power system. The leakage current suppression system comprises: a variable-frequency compensation control module, which regulates the frequency and signal amplitude in a circuit on the basis of an equipotential feature of a consumer loop of a power system, in order to match load characteristics and achieve dynamic signal amplitude fixation; a real-time monitoring module, which is used for monitoring the frequency, current and voltage of the power system; a central processing unit, which processes data from the monitoring module, and executes data analysis to identify frequency and current variations in the case of current leakage or electric shock; and a leakage current suppression module, which is connected to the real-time monitoring module and is configured with a mechanism which is automatically activated when frequency and current abnormalities are detected, and is used for dynamically adjusting a circuit response to suppress a leakage current. The modules are connected in parallel to the consumer loop, perform rapid adaptive tuning compensation for the parallel frequency resonance in a load loop, and dynamically regulate the current phase and amplitude, so that a zero potential difference at a target load end and current suppression for a target load are achieved, and a suppression and shielding effect on circuit leakage is achieved.

The invention relates to the technical field of analog integrated circuits, and discloses an LDO (Low Dropout Regulator) frequency compensation circuit based on a voltage-controlled current source, which comprises an input differential amplification module, a power regulation module, a frequency compensation module and a feedback voltage division module, and is characterized in that the output end of the input differential amplification module is electrically connected with the input end of the frequency compensation module; the frequency compensation module comprises a voltage-controlled current source and a compensation capacitor C1, the compensation capacitor C1 is matched with the voltage-controlled current source to adjust the loop frequency response, through a multi-stage current mirror and a Miller compensation network, pole distribution is optimized in a targeted mode, the Miller effect of the compensation capacitor C1 is matched, the dominant pole frequency can be actively lowered, a dominant pole is made to be away from a high-frequency area, and the loop phase margin is guaranteed; the self-excited oscillation is fundamentally suppressed, and the output voltage is stable and free of fluctuation.

The invention discloses a frequency offset estimation method and device, electronic equipment and a storage medium, and relates to the technical field of communication. The method comprises the following steps: receiving a baseband spread spectrum signal from a low earth orbit satellite to obtain a received signal; performing segmented sweep frequency compensation on the received signal to obtain a compensated measured signal; despreading and descrambling the compensated measured signal by using prior information determined from the received signal, and completing coarse frequency offset estimation on the measured signal despread and descrambled for the first time; and de-spreading and descrambling the signal data after the coarse frequency offset estimation again, and finishing fine frequency offset estimation on the signal data after the second time of de-spreading and descrambling. According to the invention, prior information is introduced to directly lock and track a specified target beam signal, so that the directionality and efficiency of measurement are remarkably improved; by designing a low-complexity signal processing flow, the algorithm burden can be remarkably reduced, it is ensured that adjacent satellite beam frequency offset estimation is rapidly completed in service proceeding, and the real-time requirement of seamless switching is met.

The invention discloses a method and device for reducing influence of rain attenuation on a communication link of a satellite gateway station, and belongs to the field of satellite communication. According to the method, through historical multi-round interaction data of a gateway station and a satellite, including transmitting / receiving power, frequency and position information of two communication parties, time-space coupled signal characteristics including rain attenuation influences are extracted in real time, then a dual-target optimization deep learning model is adopted, a power compensation value and a frequency compensation value are synchronously predicted, and the real-time performance of the satellite is improved. And finally, according to the power compensation value and the frequency compensation value, determining the transmitting power and the transmitting frequency of the signal transmitted to the satellite by the gateway station in the Nth round so as to ensure that the gateway station transmits the signal to the satellite at the optimal transmitting power and the optimal transmitting frequency in the Nth round of communication, thereby dynamically compensating the rain attenuation of the link. The technical problems that in the prior art, a satellite gateway station rain attenuation resisting scheme excessively depends on meteorological data, only the signal power is adjusted, hysteresis exists in the response speed, and limitation exists in the compensation efficiency are solved.

The invention relates to an electric leakage suppression system for an alternating-current power system, and the system comprises a variable-frequency compensation control module which adjusts the frequency and signal amplitude in a circuit according to the equipotential characteristics of a power utilization loop of the power system, so as to match the load characteristics and achieve the dynamic fixation of the signal amplitude; the real-time monitoring module is used for monitoring the frequency, current and voltage of the power system; the central processing unit is used for processing data from the monitoring module, executing data analysis and identifying frequency and current changes under the condition of electric leakage or electric shock; and the electric leakage suppression module is connected with the real-time monitoring module, is provided with a mechanism which is automatically activated when frequency and current are detected to be abnormal, and is used for dynamically adjusting circuit response to suppress leakage current. And the modules are connected in parallel to the power utilization loop, perform rapid self-adaptive modified modulation compensation on the parallel frequency resonance of the load loop, and dynamically adjust the current phase and amplitude so as to realize the zero potential difference of the target load end and the current suppression on the target load, and form the suppression and shielding effects on the leakage of the circuit.

A temperature coefficient of frequency (TCF) compensation layer may be disposed on a second surface of a piezoelectric layer opposite to a first surface to reduce the TCF of a microacoustic filter. The frequency response of a microacoustic filter with the TCF compensation layer on only the second surface of the piezoelectric layer includes spurious modes. In an exemplary microacoustic filter, another TCF compensation layer is disposed on the first surface of the piezoelectric layer between the electrode structure and the piezoelectric layer. Providing TCF compensation layers bilaterally on the first and second surfaces of the piezoelectric layer reduces spurious modes in the frequency response of the microacoustic filter. In some examples, the electrode structure is disposed on a substrate and may be isolated from the TCF compensation layer on the first surface of the piezoelectric layer by an air gap to reduce acoustic losses.

The invention discloses an unmanned aerial vehicle noise elimination method and device for cross-medium direct acoustic communication, and the method comprises the steps: carrying out the sampling of a known detection signal and a receiving signal, obtaining a frequency domain expression, calculating a cross-medium sound pressure transmission function, and extracting amplitude response, phase response and group delay; based on a normalization ratio and local maximum detection method, identifying a center frequency set of unmanned aerial vehicle propeller noise; the notch depth, bandwidth, frequency compensation and phase compensation are determined by combining channel characteristic parameters, and a cascade notch filter is constructed; and inputting the channel characteristic parameters into the deep learning model, outputting a filter parameter correction amount, realizing dynamic updating of the filter, obtaining the filter capable of suppressing noise, and further obtaining a denoised communication signal. According to the invention, precise detection of propeller noise frequency and multi-dimensional adaptive adjustment of filter parameters can be realized.

The invention discloses an island micro-grid control method and system based on adaptive virtual impedance droop control. The island micro-grid control method comprises the steps that active power and reactive power output by an inverter are measured in real time; inputting the active power and the reactive power into an improved droop controller, and generating a frequency reference value and a voltage amplitude reference value; calculating a difference value between the reactive power and a reference value, and dynamically adjusting the size of virtual impedance through an integral controller; adding the voltage amplitude reference value and the voltage compensation amount to obtain a voltage amplitude instruction, and adding the frequency reference value and the frequency compensation amount to obtain a frequency instruction; performing voltage synthesis by using the voltage amplitude instruction and the frequency instruction to generate a voltage reference value under a dq coordinate system, taking the voltage reference value as reference input of a double closed-loop control system, driving an inverter bridge after SPWM modulation, and regulating and controlling the output voltage; the system stability and reliability can be improved, reactive power loss and circulation can be reduced, the electric energy quality can be improved, and the load change coping capacity of the micro-grid can be enhanced.

The invention relates to an IRNSS navigation signal simulation generation method and system based on parameter compensation, and the method comprises the steps: receiving original signal data outputted by an IRNSS navigation receiver, and receiving a target machine position coordinate and a velocity vector; analyzing the navigation message to extract ephemeris parameters, and calculating the real-time position and velocity vector of the satellite; calculating a Doppler frequency compensation value and a pseudo code time delay compensation value; according to the pseudo code time delay compensation value and a preset target simulation coordinate, modifying a signal emission time field in the navigation message, generating a simulation navigation message frame, carrying out forward error correction coding processing, generating a coding symbol sequence, and carrying out modulo-two addition operation on the coding symbol sequence and a pre-generated PRN pseudo code sequence to obtain a baseband spread spectrum signal; generating an intermediate frequency carrier signal according to the Doppler frequency compensation value and the carrier phase; and modulating the baseband spread spectrum signal to the intermediate frequency carrier signal, and outputting an intermediate frequency analog signal. According to the invention, the concealment of signal simulation and the success rate of capturing the analog signal by the target receiver can be improved.

The invention discloses a time synchronization method, a time synchronization system and a storage medium, and the method comprises the steps: receiving and fusing multi-source time signals at the same time, and obtaining a local time reference signal; calculating the frequency compensation amount of a local clock source in real time based on an LSTM model trained by using a local time reference signal; detecting whether the time signal is available, and determining to switch an atomic clock taming mode or a timekeeping mode based on a detection result; inserting a timestamp with femtosecond precision for the initial data message through the PIC to obtain a target data message; and sending the time synchronization information and the target data message to a 6G network node through a precision time protocol of the FPGA chip. According to the invention, on the basis that the satellite signal is taken as a time reference, two conditions that the satellite signal is available and unavailable are considered, and a local clock source and photon time service are adjusted in combination with a multi-source satellite signal fusion result, so that the time synchronization precision is improved, and the 6G network requirement is met.

A phase-locked loop (PLL) circuit is provided for generating an output signal having an output frequency. The PLL circuit includes a voltage-to-current conversion circuit, a frequency compensation circuit, and a current controlled oscillator (ICO). The voltage-to-current conversion circuit is configured to generate a first control current according to a control voltage, where the control voltage is generated according to a reference signal and a feedback signal obtained from an output signal. The frequency compensation circuit is configured to generate a second control current according to the control voltage. A current controlled oscillator (ICO) generates an output signal according to an oscillating current, where the oscillating current is a sum of the first control current and the second control current. In response to the frequency compensation circuit detecting that the control voltage exceeds the predetermined range, the second control current is controlled to be negatively correlated with the output frequency.

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.