1401 results about "Frequency offset" patented technology

The invention relates to the technical field of intelligent manufacturing and numerical control machining control, and discloses a machine tool dynamic characteristic sensing and intelligent machining control method and system based on a knowledge graph and a large model, and the method comprises the following steps: extracting frequency domain parameters through a vibration sensor, obtaining vibration displacement in combination with laser displacement, and comparing the vibration displacement with modal data to construct a graph; processing parameters and displacement are synchronously sampled, time sequence characteristics are extracted to generate tensors, dynamic characteristics are predicted and corrected, and frequency response adjustment rotating speed is matched to generate optimized track control parameters which are converted into G code instructions. According to the method, a dynamic characteristic map is constructed by fusing vibration signals and displacement, a sliding window synchronizes processing parameters and vibration data, LSTM extracts joint characteristics, GRU predicts rigidity and damping ratio, an attention mechanism dynamically corrects weight, characteristic coupling analysis and prediction precision is improved, nonlinear modeling captures dominant frequency offset and harmonic distribution, response speed is enhanced, and the method has the advantages of being high in precision and high in precision. Cutting vibration is inhibited, and the process stability is guaranteed.

A wireless transmit / receive unit (WTRU) may receive subband non-overlapping full duplex (SBFD) configuration information. The SBFD configuration information may be associated with subbands for uplink transmission and subbands for downlink reception. The WTRU may receive scheduling information associated with physical uplink shared channel (PUSCH) transmissions. The scheduling information may comprise a first frequency domain resource allocation (FDRA). The WTRU may transmit a first PUSCH transmission using a first frequency resource. The WTRU may determine that at least a second PUSCH transmission is to be sent using at least one OFDM symbol. The WTRU may determine that the first frequency resource overlaps. The WTRU may receive one or more of a second FDRA or a frequency offset for the second PUSCH transmission. The WTRU may determine a second frequency resource for transmitting the second PUSCH transmission. The WTRU may transmit the second PUSCH transmission using the second frequency resource.

The invention provides an OTFS radar communication integrated signal processing method and system based on time-frequency-space domain joint optimization. According to the method, pilot symbol positions and densities are configured in an OTFS time-frequency grid according to channel time-varying characteristics and bandwidths, and a Doppler index range is set to optimize channel information acquisition; deploying a controllable reflecting surface, constructing a phase modulation matrix based on a target position and communication channel parameters, dynamically adjusting a phase gradient direction, and separating energy of a target echo and a communication signal; within a set Doppler index range, calculating frequency offset estimation, correcting a time domain sampling point of a received signal, and generating a phase correction vector; and positioning a spatial aliasing main interference area, and inhibiting symbol interference and spatial aliasing caused by a high-speed target through frequency domain beam forming weighting and phase rotation compensation in combination with a phase correction vector and a sub-Doppler parameter in the area. According to the invention, time-frequency-space domain cooperative efficient processing of OTFS radar communication integrated signals is realized.

The invention relates to the technical field of wireless charging, and provides a foreign matter detection method and system for a wireless charging system and a storage medium. The method comprises the following steps: firstly, calibrating at multiple temperature points and establishing a temperature-parameter comparison table under the condition of no foreign matters; in a no-load standby state, the inversion module sends out detection drive and collects voltage, current and temperature; calculating a real-time quality factor and resonant frequency according to sampling, obtaining a compensation reference according to a temperature look-up table, and solving the variation of the quality factor and the resonant frequency; and performing fusion judgment by adopting dual-condition locking or weighted scoring, and triggering fault protection when a foreign matter is confirmed. Due to the fact that equivalent inductance and resistance changes are caused by metal foreign matters, quality factors are remarkably reduced along with resonant frequency deviation, temperature excursion and foreign matter effects are distinguished through temperature compensation, and dual-condition locking or weighted scoring fusion judgment is combined, the interference immunity and accuracy of detection are improved, false alarms and missing alarms are remarkably reduced, and the detection accuracy is improved. The method is suitable for high-power wireless charging scenes.

The invention relates to a channel estimation method based on frequency domain deviation compensation and dynamic DCT denoising, and belongs to the technical field of wireless communication. The method comprises the following steps: establishing a wireless channel model and an OFDM system model; estimating the frequency offset in the received signal by using the phase rotation characteristic of the pilot signal; calculating a preliminary channel frequency domain response # imgabs2 # at a pilot frequency position through a least square criterion based on the compensation signal # imgabs1 #; obtaining a receiving pilot frequency signal # imgabs4 # according to the sending pilot frequency Xp and the roughly estimated channel frequency response # imgabs3 #; estimating a current signal-to-noise ratio SNRest based on the pilot frequency signal # imgabs5 # and a noise power ratio; and establishing an adaptive DCT denoising strategy based on a signal-to-noise ratio threshold, and selecting different denoising strategies according to different signal-to-noise ratios to perform denoising processing on # imgabs6 # to obtain final channel estimation # imgabs7 #. The adaptive denoising strategy design of the invention effectively balances the relationship between noise suppression and channel structure fidelity, and improves the precision and stability of overall channel estimation.

The invention relates to the technical field of ecological system service function evaluation. The invention relates to a frequency offset correction algorithm in HPLC (High Performance Liquid Chromatography) + HRF (High Radio Frequency) dual-mode communication. The method comprises the following steps: S1, collecting phase sequence data from an HPLC communication link, collecting frequency offset estimation data and corresponding confidence data from an HRF communication link, and adaptively adjusting a preset detection threshold value of the phase sequence data according to the confidence data; s2, performing pulse abnormal sample point detection and elimination on the phase sequence data according to the adjusted preset detection threshold value; according to the method, the detection threshold is dynamically adjusted through the confidence data, so that the anomaly detection process can be matched with the current interference environment in real time, the integrity of the phase sequence data is maintained, and the problem of insufficient adaptability of a fixed detection threshold in an electromagnetic interference dynamic change scene is solved; and a more reliable phase data basis is provided for subsequent interpolation compensation and frequency offset estimation, so that the frequency offset correction precision of the dual-mode communication system is improved.

The embodiment of the invention provides a time-space synchronization method and device, electronic equipment and a medium, which are used for solving the problem of inaccuracy of a local clock in related technologies. In the embodiment of the invention, the electronic equipment combines the average deviation pseudo-range, the RTT jitter and the target frequency offset into the multi-dimensional observation vector, so that the error source of clock synchronization is fully covered. The time deviation and the frequency deviation of the clock are accurately and effectively determined through a Kalman filtering algorithm, recursive processing of observation vectors and dynamic estimation of the time deviation and the frequency deviation of the clock, and high-precision synchronization of the local clock in a complex environment is achieved in combination with the optimization capability of the Kalman filtering algorithm. And the time of the local clock is the time determined according to the time of the multiple clocks, so that the clocks are more accurate.

The invention discloses an active island detection method and system based on harmonic impedance characteristic identification, and the method comprises the steps: analyzing the harmonic impedance difference of grid-connected points in a grid-connected state and an island state, and building a state criterion based on resonant frequency deviation and impedance amplitude through the comparison of the frequency response characteristics of island impedance and grid-connected impedance; fitting the grid impedance into an RLC parallel model in a selected frequency band, and mapping the topological difference of the power grid into a parameter difference; embedding a low-voltage ride-through strategy in the control of the voltage source converter, and adjusting reactive current in a grading manner according to the voltage drop degree of a grid-connected point; fundamental waves and harmonic waves are separated through a cascade notch filter, two synchronous harmonic waves are injected into the system through constant current control, and it is ensured that injection signals of a multi-voltage source converter are in the same phase in a phase locking link; and solving an overdetermined equation set based on the double-frequency response data to identify RLC parameters, setting an island criterion, and synchronously completing island judgment in a low-voltage ride-through time window. Detection precision is improved, dynamic response is optimized, and power generation efficiency is improved.

The invention discloses a wind turbine generator blade damage judgment method and detection system based on voiceprint detection, and belongs to the technical field of wind turbine generator blade detection. The damage judgment method comprises the following steps: acquiring environmental parameters of a wind power plant, and establishing a sound velocity correction model based on the environmental parameters; acquiring a blade resonance sound signal, and correcting the blade resonance sound signal based on the sound velocity correction model to obtain a blade resonance sound signal with a high signal-to-noise ratio; performing FFT spectrum analysis on the blade resonance sound signal with the high signal-to-noise ratio, identifying the peak position of the first three-order natural resonance frequency of the blade, and performing analysis to obtain the current modal frequency, damping ratio and sub-band energy distribution entropy value of the blade; historical baselines of the modal frequency, the damping ratio and the sub-band energy distribution entropy of the blade in the healthy state are obtained, and the modal frequency offset, the damping ratio change rate and the acoustic impedance spectrum entropy of the blade are obtained; and wind turbine generator blade damage determination is carried out by using a high-precision time difference detection technology.

The invention discloses a reference-clock-free clock and data recovery circuit, a use method and an integrated circuit. The circuit comprises a first circuit and a second circuit, the first circuit comprises a voltage-controlled oscillator, the second circuit comprises a comparison module and a frequency capture module, and the comparison module is used for comparing a first clock signal with a high-speed serial data signal, generating a first signal and outputting the first signal to the frequency capture module. The frequency capture module outputs a first control signal, the first control signal is used for adjusting the first oscillation frequency so as to enable the frequency deviation between the first oscillation frequency and the second oscillation frequency to be smaller than a first deviation threshold value, and the second circuit generates a second clock signal and outputs the second clock signal to the first circuit; the first circuit adjusts the voltage-controlled oscillator using a second clock signal such that the frequency offset is less than a second offset threshold. According to the invention, the CDR and PLL functions are fused and an external reference clock is replaced by the CDR recovery clock, so that a clock and data recovery system without an external clock is realized.

The invention discloses a construction method and a modulation method of a three-port multi-frequency MMC topology based on bridge arm multiplexing, and relates to the technical field of power electronics. The construction method comprises the steps that sub-modules of a traditional double-bridge-arm MMC are integrated and optimized into a three-bridge-arm structure through a current conversion branch, independent energy interaction of three ports is achieved through an auxiliary bridge arm, multi-frequency operation modes of power frequency, frequency division, direct current and the like are supported at the same time, and therefore the utilization rate of the bridge arm sub-modules is increased, and the energy utilization rate of the MMC is increased. And the overall size and the manufacturing cost of the converter are reduced. Based on three-port multi-frequency coordination control and power balance requirements, a modulation method of the topological structure is provided, a multi-frequency coordination modulation strategy is adopted, frequency offset is performed through an auxiliary bridge arm to reduce cross interference of port frequency, and output waveform quality is improved through multi-objective optimized capacitor voltage balance control. And meanwhile, direct-current side faults are effectively eliminated by means of the auxiliary bridge arm.

The invention discloses a multi-path cooperative communication method, belongs to the technical field of wireless communication, and is used for solving the problems of inaccurate path selection, unreasonable power distribution and inaccurate signal combination caused by dynamic change of a channel state in multi-path communication. The method comprises the following steps: acquiring channel state information of at least three communication paths in real time through a transmitting end, wherein the channel state information comprises signal strength, frequency offset and noise power spectral density; dynamically dividing and distributing the data stream to each path based on the path quality factor, and adjusting the transmitting power by combining the signal strength and the noise difference value; a receiving end carries out time domain alignment by adopting a sliding window cross-correlation algorithm, and carries out phase compensation based on a minimum mean square error criterion; path reallocation is triggered when the continuous bit error rate exceeds a threshold. According to the method, the multi-path resource utilization rate can be optimized, and the communication stability and the data transmission efficiency are improved.

The invention discloses an intelligent peak regulation method with optimized combination of energy storage and conventional peak regulation means, and the method comprises the following steps: building a holographic situation awareness layer: capturing the voltage, current phase angle and frequency deviation of a power grid, and monitoring the pressure fluctuation in a diesel engine cylinder; data transmission and preprocessing: encrypting data of the miniature phasor measurement unit and the quantum sensor by using a quantum key distribution technology; the self-adaptive decision engine is used for performing Nash equilibrium calculation by utilizing a federal reinforcement learning architecture, through a local Agent based on a power generation / energy storage unit state autonomous optimization control strategy and in combination with a digital twin platform, solving multi-target conflicts of economy, reliability and carbon emission, and generating a global optimal scheduling instruction; the execution control layer is used for tracking resonance points and dispersing harmonic energy spectrums; dynamic topology reconstruction: a harmonic source is positioned by using a digital twin platform, and the topology of the energy storage system is automatically switched according to the harmonic frequency and position; continuously optimizing the digital twin platform; and full-process closed-loop feedback and self-learning are carried out.

The embodiment of the invention provides a downlink signal sending method and a downlink signal processing method, which are characterized in that a downlink signal is obtained on the satellite side based on a supplementary synchronization sequence, and then time-frequency synchronization is carried out on the terminal equipment side by using the downlink signal from the satellite. In the application, the terminal device can realize time-frequency offset tracking compensation without acquiring satellite ephemeris information and using GNSS (Global Navigation Satellite System) equipment, so that the influence of ephemeris errors and GNSS errors on time-frequency synchronization performance after the terminal device is shut down for a long time is eliminated, and the problem that the time-frequency synchronization performance of the terminal device is influenced in the related technology is solved. The problem of low precision of time-frequency offset tracking compensation in the satellite-ground communication process is solved, and the time-frequency synchronization success rate of satellite-ground communication under the conditions of inaccurate ephemeris and high speed is improved.

The invention relates to the technical field of data compression, in particular to a ZSTD compression algorithm optimization method based on joint coding and ternary decomposition, and the method comprises the following steps: S1, building a joint frequency table based on the joint distribution of the literal length and the matching length of a previous section, setting a frequency deviation criterion, and dynamically adjusting a low-frequency combination proportion; s2, decomposing the offset value structure into a leading segment, a trailing segment and a middle segment, performing bit width-entropy ratio analysis on the middle segment, and selecting a symbol index or bit stream coding; and S3, entropy discriminant coding is performed on the joint symbol and the offset symbol respectively, and a structure position is mapped synchronously to generate a structured compressed output stream. According to the method, collaborative optimization of frequency self-adaption, redundancy minimization and structured mapping is realized through joint symbol dynamic modeling and offset ternary structure entropy discriminant coding, so that the ZSTD compression efficiency and the coding stability are remarkably improved.

The invention provides a multi-antenna MIMO architecture synchronization method and device, a program product and a storage medium, and relates to the technical field of wireless communication. Receiving sampling signals through a plurality of receiving channels; performing down-sampling on each sampling signal to obtain a down-sampling signal; determining a plurality of cache regions to store each downsampling signal, and performing cross-correlation operation on each downsampling signal and a local synchronous time domain signal; when any receiving channel detects an effective peak value, determining the position of the effective peak value as a preliminary synchronization position; determining a corresponding search window range, and performing weighted stacking on the target cross-correlation results to obtain an overall correlation peak value; searching a maximum value in all the total correlation peak values, and determining a position corresponding to the maximum value as a final synchronization position; and calculating a frequency offset estimation value of each receiving channel according to each pilot signal, and carrying out weighted average on each frequency offset estimation value to obtain a final frequency offset estimation value. By adopting the method, the wireless frame synchronization precision can be improved.

The invention belongs to the technical field of signal processing, and particularly relates to a coherent light high-speed transmission signal processing method based on deep joint compensation, which comprises the following steps of: performing fine frequency offset and inter-carrier interference joint preprocessing on a coherent light receiving sampling sequence; obtaining a pre-processing output sequence and at least one estimation parameter derived from fine frequency offset and inter-carrier interference combined pre-processing; inputting the preprocessing output sequence into a diffusion type score guide joint compensation network module to obtain a deep joint compensation sequence; performing online judgment and decoding on the deep joint compensation sequence, and adaptively updating internal parameters of the diffusion type score guide joint compensation network module when a preset adaptive updating condition is met; according to the invention, the symbol residual error can be obviously reduced, the forward error correction gain can be improved, and the stability and robustness of the system under high-order modulation, high symbol rate and long-distance link scenes can be enhanced.

The invention relates to the technical field of signal reconstruction, in particular to a complex electromagnetic environment-oriented millimeter wave signal blind source separation and reconstruction system, which comprises a frequency spectrum trend division module, a path fading construction module, an initial cluster label generation module, a multi-solution path screening module and a fusion reconstruction execution module. According to the method, power spectral density sequence processing is carried out on millimeter wave frequency domain data, a multi-dimensional feature group is formed according to a path loss factor, an angle of arrival and the like, and an initial feature cluster is screened through an Euclidean distance, so that the accuracy of signal source classification is effectively improved; after the frequency domain response and the phase contour are continuously subjected to point comparison, path screening is completed by integrating a mean square error residual value, the path misjudgment probability is reduced, time domain resampling and phase frequency offset standardization are executed in fusion reconstruction, the consistency and fidelity of signal reconstruction are enhanced, and the reconstruction precision is improved. The whole process improves the separation accuracy and reconstruction precision of mixed signals in a complex electromagnetic environment.

The invention discloses a high-frequency transformer transmission extreme value frequency rapid calibration and tolerance analysis method, which comprises the following steps of collecting operation parameters of a high-frequency transformer in real time, performing standardized preprocessing, and integrating the preprocessed parameters to construct operation condition vectors in a unified format; defining a frequency response range of the high-frequency transformer, constructing a frequency search space based on the frequency response range, and establishing a target function for fitness evaluation based on the frequency search space; searching extreme value frequency points in the frequency search space by adopting a quantum evolutionary algorithm; based on the working condition vector and the extreme value frequency point, a working condition frequency deviation prediction model is constructed, and the working condition frequency deviation prediction model outputs an extreme value frequency shift offset; and calculating the dynamic tolerance bandwidth according to the predicted offset and the fluctuation range of the working condition vector. According to the invention, rapid and accurate calibration of the extreme value frequency of the high-frequency transformer and dynamic determination of the tolerance range can be realized.

The invention provides a multi-sub-array FD-RIS distance-angle beam regulation and control far field communication method and system, an FD-RIS is uniformly divided into a plurality of sub-arrays, and each sub-array adopts different modulation frequencies to realize diversity of frequency deviation. Besides, in order to control unexpected harmonic signals, a novel time modulation method is utilized to periodically adjust phase shifts of all reflection units of the FD-RIS, and unwanted harmonic signals can be effectively restrained. Different time delays are added in the time modulation process of each component so as to amplify the spatial degree of freedom of the FD-RIS to an expected harmonic signal, and the space control capability of the FD-RIS to the expected harmonic signal is prevented from being limited by a time modulation mode.

The invention relates to a low-orbit satellite short burst signal high-precision capturing method and device, equipment and a medium. The method comprises the following steps: sequentially carrying out digital down-conversion and L-time signal pseudo code rate down-sampling on a low earth orbit satellite short burst signal sequence sampled by an ADC (Analog to Digital Converter) to obtain a down-sampled signal sequence; performing pre-accumulation processing on the down-sampling signals of every adjacent L points in the down-sampling signal sequence, and performing coarse capture on the pre-accumulated signal sequence by adopting a PMF-FFT algorithm to obtain a coarse pseudo code phase and a coarse frequency offset value; and performing serial code phase search on the down-sampling signal sequence based on the coarse pseudo code phase and the coarse frequency offset value, optimizing to obtain a fine pseudo code phase, and optimizing the estimation precision of the coarse frequency offset value according to the fine pseudo code phase and a frequency offset estimation algorithm based on a phase relation to obtain a fine frequency offset value. By adopting the method, the acquisition precision and speed of the short burst signal of the low-orbit satellite can be improved.

The invention provides an airflow pulsation suppression method and system for a liquid-driven compressor, and the method comprises the steps: obtaining a pressure pulsation frequency spectrum and flow data of an outlet pipeline of the liquid-driven compressor; generating a dominant frequency offset rule based on the pressure pulsation spectrum and the flow data; based on the main frequency offset rule and the main peak frequency of the pressure pulsation frequency spectrum, a target position adjusting signal is generated in combination with a fuzzy PID controller; the actual position of a movable baffle arranged in a resonant cavity of the hydraulic drive compressor is monitored in real time, and feedback compensation is conducted on the target position adjusting signal based on the actual position; and the position of the movable baffle is adjusted based on the compensated target position adjusting signal, so that the through-flow area of the resonant cavity is changed, and airflow pulsation of the outlet pipeline is restrained. According to the invention, the airflow pulsation suppression effect of the hydraulic drive compressor under variable working conditions is improved.

The invention provides a distributed coherent communication system synchronization method, and the distributed coherent communication system enables dispersed nodes in a space to cooperate with each other through the construction of a virtual antenna array, so as to form a directional wave beam, thereby achieving the control and enhancement of a signal direction. A distributed Kalman filtering framework is introduced, a frequency and phase joint state space model is constructed, local observation data of nodes and neighbor state information are optimally fused, and dynamic estimation and compensation of frequency offset and phase errors are achieved. An updating strategy is designed in combination with an event triggering mechanism, local Kalman filtering prediction is executed in conventional iteration to suppress random noise and control the communication burden and calculation complexity of a system, meanwhile, the standard deviation of a residual phase error is effectively reduced by one order of magnitude, and the synchronization performance is improved.

The invention discloses a carrier tracking method suitable for a multi-bit spread spectrum signal, and relates to the technical field of multi-bit spread spectrum, the carrier tracking method comprises the steps of coarse frequency offset correction, multi-bit spread spectrum, average phase estimation and delay phase correction.The carrier tracking method comprises the steps that firstly, a sliding DFT algorithm is adopted to estimate frequency offset, and a coarse frequency offset available correction signal is obtained; secondly, adaptively selecting the number of available windows according to historical data corresponding to the current signal-to-noise ratio; the method comprises the following steps: firstly obtaining a window intermediate point spread spectrum period, then extracting a carrier phase estimation value of the window intermediate point spread spectrum period, finally delaying a correlation value by the spread spectrum period to realize time sequence alignment and eliminate phase deviation, and finally obtaining information bits corresponding to each spread spectrum period by extracting and correcting a real part of the correlation value, matching a local sequence number and mapping. According to the method, the phase estimation precision under the low signal-to-noise ratio can be improved, parameter self-adaption to high and low dynamic scenes of a satellite is realized, the coherent judgment performance is improved, and the hardware complexity is reduced.

Disclosed are an auxiliary pilot adaptive optimization method, apparatus and device, and a medium, which relate to the technical field of wireless communications, and solve the problems of static configuration, resource waste and single function of the existing auxiliary pilot. An auxiliary pilot frequency sequence is designed into a synchronous prefix and an estimation core section, and the synchronous prefix adopts a pseudo-random sequence with high autocorrelation and is used for timing synchronization (positioning through a sequence autocorrelation peak value) and frequency synchronization (calculating frequency offset through a phase difference) in a demodulation process; the estimation core section adopts an orthogonal sequence with a low peak-to-average ratio and is used for accurate channel estimation; the double-segment sequence is connected through a preset code pattern, and it is ensured that a demodulation end can perform synchronous analysis. By sensing the channel state in real time, parameters of the auxiliary pilot frequency are dynamically adjusted, and a synchronization function is fused, so that the demodulation performance and the resource utilization rate are improved.

The invention discloses an anti-multipath and anti-frequency offset satellite communication method based on chirp spread spectrum modulation joint architecture, and relates to the technical field of satellite or data chain communication, the method comprises the following steps: mapping input K bit information into a modulation symbol K, K belongs to {0, 1,..., N-1}; s02, a corresponding chirp baseband signal s [n] is generated according to the modulation symbol K, and the expression of the chirp baseband signal s [n] is as follows: n = 0, 1,..., N-1; and S03, carrying out digital-to-analog conversion on the chirp baseband signal. According to the invention, through integrated design of spread spectrum and modulation depth, and by use of the complete orthogonal autocorrelation characteristic of chirp signals and an FFT demodulation mechanism, the problems that a traditional architecture has significant bottlenecks in the aspects of resource efficiency, dynamic adaptability, anti-interference capability and the like and is difficult to meet high-performance communication requirements in a high-speed moving and complex multipath scene are effectively solved; the anti-multipath and anti-Doppler performance is significantly improved, and the calculation and resource overhead of the receiving end is greatly reduced.

The invention relates to the technical field of signal demodulation, and discloses an OFDM (Orthogonal Frequency Division Multiplexing) signal demodulation method of a signal analyzer. According to the invention, through joint optimization of a synchronous detection and frequency offset compensation mechanism, the symbol positioning precision in a low signal-to-noise ratio environment is improved, and subcarrier interference caused by a cyclic prefix pseudo peak value and frequency offset phase ambiguity is effectively suppressed; a time-frequency two-dimensional adaptive interpolation strategy is adopted to enhance the robustness of channel estimation to non-uniform pilot frequency distribution and a fast time-varying channel, and data subcarrier response distortion is reduced; in combination with minimum mean square error equalization and dynamic noise reduction processing, inter-symbol interference and a noise accumulation effect are greatly weakened, and the bit error rate performance of a high-noise scene is improved; the error control technology is updated through a closed-loop channel, a demodulation error propagation path is blocked, and cooperative improvement of system demodulation stability and precision in a complex multi-path environment is achieved.

A communication frame for an OTFS transmission system includes first-type and second-type blocks. The first-type block includes pilot signals, guard signals, and data signals, the second-type block exclusively includes data signals. The pilot symbols, guard signals, and data symbols of the first-type block, and the data symbols of the second-type block, are arranged along the points of a grid in the delay-Doppler domain. In the communication frame, a first-type block is followed by a second-type block, and a second-type block is followed by a first-type block. In the first-type block at least one pilot symbol is surrounded on at least three sides by one or more guard symbols. Points of the grid of the first-type blocks in the delay-Doppler domain that are not occupied by pilot symbols or guard symbols are used for data symbols. The communication frame permits determining oscillator frequency offset and channel coefficients in a receiver.

The invention provides a low earth orbit satellite communication initial time frequency offset estimation method, and belongs to the technical field of satellite communication. When satellite communication initial time-frequency offset estimation is carried out, initial time-frequency offset coarse estimation is firstly completed based on a first auxiliary synchronization signal, time-frequency offset coarse compensation is carried out on a received signal by using an estimation result, then initial time-frequency offset fine estimation is further completed based on a second synchronization signal, and the compensated signal is sent to a demodulation module for demodulation. The two-step time-frequency offset estimation method provided by the invention combines the advantages of the symmetric Chirp reference signal and the pseudo code sequence for time-frequency offset estimation, can realize rapid and accurate time-frequency offset estimation in a large-frequency offset scene, and improves the performance of a low-orbit satellite communication system.

The invention discloses a village island micro-grid virtual synchronous machine parameter optimization and cooperative control method oriented to frequency support, and relates to the technical field of electrical automation, and the method comprises the steps: obtaining village power distribution network parameters and load side parameters, and basic technical parameters of each virtual synchronous machine unit; constructing a standard dynamic model of the virtual synchronous machine based on the obtained parameters; introducing uncertainty integrated design on the basis of the standard dynamic model of the virtual synchronous machine, and performing equivalent aggregation on all the virtual synchronous machines to obtain a virtual synchronous machine uncertainty model; based on the uncertainty model of the virtual synchronous machine, establishing a cooperative control model by taking system frequency fluctuation minimization as a target; and solving the cooperative control model by using a commercial solver, and solving the power of each device. According to the invention, by constructing an optimization and cooperative control mechanism oriented to frequency support, the problem of over-limit of frequency deviation and frequency change rate is effectively suppressed, and the dynamic response capability of the island micro-grid under the condition of sudden load change is improved.