158 results about "Doppler frequency" patented technology

The application provides a user positioning method and device for low-orbit satellite communication and satellite network equipment, relates to the technical field of satellite communication, and the device comprises a receiving unit configured to receive a transmission delay and a Doppler frequency shift reported by a terminal device; a first processing unit configured to control the satellite network equipment to perform the following first operation: calculating a first included angle from the terminal device to a subsatellite point via a satellite according to the transmission delay and an orbital height of the satellite; calculating a second included angle from the subsatellite point to the terminal device in a satellite moving direction via the subsatellite point from a satellite overhead angle according to the first included angle, the Doppler frequency shift, a carrier frequency and a satellite moving speed; and determining position information of the terminal device according to the first included angle and the second included angle. The application can automatically estimate the position information of the terminal device without the terminal device reporting the position information, ensure the service continuity of a communication architecture depending on the terminal device information, and protect the user privacy and safety.

The application discloses a kind of mobile communication base station and communication method, communication method includes: communication base station sends pilot configuration instruction to user, carries out estimation to Doppler frequency offset, obtains phase-compensated received pilot signal, and is converted into vectorization received signal;Linear regression model is constructed, adaptive sparse channel estimation is carried out based on variational bayes inference, and output downlink frequency domain channel matrix, angle domain channel matrix;Angle domain channel matrix is quantized using Lloyd-Max non-uniform quantizer, and the global channel matrix of base station end is obtained;Output optimal analog precoding matrix and digital precoding matrix;Communication base station generates radio frequency signal based on precoding after transmission signal vector, and sends to user.Communication base station includes distributed antenna unit, baseband processing unit, radio frequency link and central control unit.The technical scheme of the application covers the whole process signal processing link of mobile communication base station, and the calculation complexity is low, and can be directly adapted to existing 3GPP standard and hardware platform.

This invention provides a fast Doppler localization method based on opportunistic signals. The method includes: establishing instantaneous Doppler frequency shift measurements for each satellite based on the receiver's initial position and velocity information, the wavelength of the opportunistic signal, and the position and velocity information of each satellite; establishing an instantaneous Doppler localization equation based on the relationship between the instantaneous Doppler frequency shift measurements for each satellite and the receiver's position information; determining regularization parameters using the variance expansion factor method; obtaining constraint parameters based on the regularization parameters and the stable functional; and solving the instantaneous Doppler localization equation under the condition of minimizing the constraint parameters to obtain the instantaneous Doppler localization result based on the opportunistic signal. The localization result includes the receiver's final position information, final velocity information, and frequency offset.

This application relates to the fields of SAR signal processing and marine remote sensing applications, and provides a method and apparatus for sea surface current field inversion based on electromagnetic vortex wave radar data. The method determines the Doppler spectrum using electromagnetic vortex wave radar image data, obtains the measured frequency position of the trough feature point in the Doppler spectrum, and determines the theoretical frequency position using the position and angle of the two main lobes and the angle of the trough feature point in the radar antenna pattern. Then, the difference between the measured frequency position and the theoretical frequency position is used to obtain the anomalous frequency offset. Next, the Doppler frequency offset caused by wind and wave motion is removed from this anomalous frequency offset to obtain the target Doppler frequency offset. Finally, the radial velocity of the sea surface is calculated using the Doppler frequency offset, thus realizing sea surface current field inversion. This effectively expands the applicability of the Doppler frequency shift-based ocean current inversion method and improves the application potential of electromagnetic vortex wave radar in sea surface current field detection.

The application provides a kind of InSAR deformation monitoring point high-precision geometric positioning method combined with three-dimensional model data, belongs to synthetic aperture radar technical field, comprising: converting three-dimensional model data into space rectangular coordinates, combined with satellite orbit parameter iteration to solve row and column coordinates in SAR image, calculate the slant range projection distance of satellite-observation vector, screen and eliminate invalid data in shadow area;With the screening result as a mask, obtain a subset of three-dimensional model data, calculate the row and column coordinates of the InSAR deformation monitoring point of the subset of three-dimensional model data, and search for candidate points based on plane geometric constraints, match the accurate elevation of the monitoring point by height system deviation;Based on the determined accurate elevation, construct the RD positioning model of distance constraint, Doppler frequency constraint and ellipsoid constraint, and solve the high-precision geometric position of InSAR deformation monitoring point. It can realize the high-precision geometric positioning of infrastructure InSAR deformation monitoring point, and improve the applicability in infrastructure fine deformation monitoring.

The present disclosure provides an ultrasonic radar speed measurement method, a speed measurement circuit and an electronic device, and relates to the field of ultrasonic speed measurement. The ultrasonic radar speed measurement method comprises: low-noise amplifying an ultrasonic echo signal reflected by a target object; performing analog-to-digital conversion processing on the amplified ultrasonic echo signal to obtain a digital echo signal; inputting the digital echo signal into a frequency shift extraction unit; filtering the digital echo signal by a band-pass filter in the frequency shift extraction unit; the frequency shift extraction unit comprises a plurality of parallel band-pass filters, and the center frequency of each band-pass filter corresponds to a Doppler frequency shift; determining the target Doppler frequency shift corresponding to the digital echo signal based on the output signal amplitude of the band-pass filter; and determining the speed of the target object based on the target Doppler frequency shift. Thus, the speed of the target object can be quickly and accurately determined.

This invention discloses a method for acquiring spread spectrum signals to eliminate the influence of high-speed data symbols, comprising the following steps: When down-converting the input signal obtained from the ADC sampling receiver, a fixed frequency offset is artificially introduced; a local pseudo-code sequence is correlated with the down-converted signal; the correlated signal is low-pass filtered; the I-path and Q-path of the filtered signal are multiplied, and the result is input to the FFT calculation module; the highest energy spectral line is found in the spectrum output by the FFT module, and the Doppler frequency offset of the input signal is calculated if the energy of this spectral line exceeds a threshold, then pseudo-code locking and carrier locking are performed; it is determined whether pseudo-code locking and carrier locking are completed: if locked, the acquisition process ends; if not locked, the phase of the local pseudo-code sequence is adjusted and the process returns to the down-conversion step. This invention can eliminate the influence of high-speed data symbol flipping on spread spectrum signal acquisition, is applicable to different data rates, and significantly enhances the communication capability of spread spectrum communication systems.

This invention discloses a radar clutter signal simulation method based on dynamic scene simulation, mainly addressing the problems of low computational efficiency and insufficient flexibility of traditional clutter simulation methods under conditions of large scenes, long time series, and multiple dynamic factors. The implementation scheme includes: constructing a digital simulation scene based on radar signal parameters and dynamic scene information to determine the clutter region to be simulated; discretizing the clutter region into a uniform basic grid in the range-azimuth plane, and then aggregating it into multiple independently processable clutter channels; calculating the amplitude, Doppler frequency, and phase parameters of the center point of each channel in parallel, constructing a two-dimensional convolution kernel reflecting spatial correlation, and using this convolution kernel to efficiently expand the center point parameters to the entire channel, generating a continuously distributed parameter field; and transmitting the parameter fields of each channel to a hardware logic unit to complete signal modulation and synthesis, outputting a high-fidelity radar clutter signal. This invention can achieve rapid, high-fidelity parameter generation from point to field, and significantly improves computational efficiency while strictly maintaining physical accuracy. It can be used for radar system simulation, electronic countermeasures testing, and radar performance evaluation.

This application relates to an OTFS high-precision Doppler frequency estimation method, apparatus, and device. The method includes: at the receiving end, recovering the same received signal based on the upper boundary parameter value, center point parameter value, and lower boundary parameter value of the Doppler frequency search unit; calculating the cross-correlation function between the recovered received signal and the transmitted signal; performing a coarse Doppler frequency estimate based on the cross-correlation function of the recovered received signal and the transmitted signal using the center point parameter value; inputting the obtained coarse Doppler frequency estimate into a PN code-based red-blue frequency shift discriminator for frequency shift discrimination; and performing a red-shift or blue-shift correction on the coarse Doppler frequency estimate based on the cross-correlation function of the recovered received signal and the transmitted signal using the upper and lower boundary parameter values ​​to obtain the final Doppler frequency estimation result. This method can reduce the computational complexity of Doppler frequency estimation without affecting its accuracy.

The application discloses a kind of freight train image detection method and system based on Doppler vibration coupling perception, it is related to railway freight car fault monitoring technical field.Joint state vector is constructed by collecting train bogie image, vibration data and Doppler frequency shift and signal-to-noise ratio of millimeter wave communication;Vibration feature map is generated by Fourier transform to vibration data, and spatial attention map is generated to enhance image features;Doppler frequency shift, signal-to-noise ratio and vibration intensity in state vector are used to dynamically calculate suppression threshold, anchor frame size and confidence threshold;Candidate box is generated using dynamic anchor frame size, and after screening by confidence threshold and deduplication by suppression threshold, component information is output.The communication physical layer parameters, mechanical vibration and image semantic depth are coupled, the adaptive adjustment of detection parameters is realized, the problem of high small target miss detection rate and poor detection stability in high-speed running scene is solved, and the fault recognition ability under complex working conditions is improved.

The application discloses a carrier Doppler frequency shift and code Doppler frequency shift simulation method and device. First, original optical carriers output by a light source module are received, and non-spur frequency shift of the original optical carriers is realized. A carrier Doppler frequency shift amount and a code Doppler frequency shift amount output by a synchronous control module are received. A periodic sawtooth wave signal frequency and a slope are updated based on the carrier Doppler frequency shift amount, and a frequency-shifted optical carrier signal is obtained. A sampling clock frequency is adjusted based on the code Doppler frequency shift amount, and a code Doppler simulation baseband code element signal is obtained. Finally, the code Doppler simulation baseband code element signal is loaded on the frequency-shifted optical carrier signal, an adjusted optical signal loaded with the optical carrier and the code Doppler frequency shift at the same time is obtained, and is output to a laser communication terminal to be measured. The problem of poor sufficiency of Doppler frequency shift simulation is solved.

This invention discloses a signal Doppler tolerance and sidelobe optimization method based on a weighted ambiguity function template. The method includes determining a discrete ambiguity function based on a two-dimensional ambiguity function of a continuous signal and a radar transmitted signal; obtaining matched filtering results for signals with different Doppler frequency shifts and determining the main lobe and sidelobe positions based on the Doppler frequency shift results; for the Doppler frequency shift case, establishing a cost function for Doppler tolerance optimization and a weighted cost function for joint optimization of Doppler tolerance and sidelobe based on the main lobe and sidelobe positions, respectively; setting the weight coefficients of the weighted cost function according to signal characteristic requirements to obtain the target cost function; and using simulation parameters for iterative updating to obtain the optimization result. This invention can improve signal Doppler tolerance while reducing signal sidelobes, significantly improving the practicality of random noise signals; and it allows for setting weight coefficients according to signal characteristic requirements to adjust the optimization ratio of signal Doppler tolerance and sidelobe, providing strong flexibility.

The application provides a communication method and a communication device, the method is applied to a terminal device, and the method comprises the following steps: receiving first system information, the first system information indicating a first inference model; measuring a first reference signal to obtain a first signal measurement result; in the case that a GNSS positioning state of the terminal device is a positioning invalid state, determining a first compensation value based on the first inference model and the first signal measurement result, the first compensation value comprising a propagation time delay compensation value and a Doppler shift compensation value; and sending a random access request message based on the first compensation value. By using the method, the compensation value of the propagation time delay and the compensation value of the Doppler frequency offset can be accurately determined, and the terminal device access success rate is improved.

The application provides a space-time model direct positioning method and system based on medium and low orbit satellite fusion, comprising: position rough measurement; constructing a direct positioning scene and a satellite receiving data model; constructing a space-time model of satellite receiving data; deriving a maximum likelihood estimator target function based on a least square estimation criterion; introducing an optimal weight vector, solving the weight vector according to a minimum variance distortionless response criterion, and deriving a target function based on the minimum variance distortionless criterion; drawing a space spectrum diagram according to the target function value, performing spectrum peak search, and determining the position of a ground radiation source. The application reduces the search range and the calculation amount by using the rough estimation result of single satellite direction finding positioning to obtain the direct positioning area to be searched; the space-time direct positioning model based on the angle of arrival and the Doppler frequency shift is established by using Doppler information, high-precision positioning can be realized under low signal-to-noise ratio, and high resolution can still be realized when the ground radiation sources are very close.

The application provides a kind of air-ground channel modeling method suitable for millimeter wave phased array, comprising: step 1, establishing the Two-Ray channel geometric model of direct path and multiple reflection paths;Step 2, according to the geometric model, calculate the Rician factor;Step 3, according to the geometric model, determine the time delay of the reflection path;Step 4, according to the carrier frequency and the speed of motion, determine the Doppler frequency offset of the direct path;Step 5, according to the geometric model and Jacks distribution, determine the Doppler power spectrum of the reflection path;Step 6, based on the generalized stationary uncorrelated scattering model, establish the channel model. Through the application, a high-accuracy phased array air-ground channel model can be established, by considering the departure angle of the phased array transmitting antenna and the arrival angle of the receiving antenna in the air-ground channel model, the accuracy of the Rician factor calculation and the accuracy of the Doppler spread power spectrum in the fading channel can be improved.

The application discloses a kind of pseudo-random code control's multi-parameter composite modulation short-range detector high-precision ranging velocity measurement method, comprising: echo signal and local oscillator mixing, obtain the intermediate frequency signal containing Doppler signal and difference frequency signal by low-pass filter, filter out high-frequency component;The input signal is converted into complex signal first after FFT, determine the refinement interval, then utilize spectrum refinement algorithm to accurately measure difference frequency signal frequency, calculate target distance by difference frequency frequency;Difference frequency signal is under-sampled to extract Doppler frequency, and the frequency of Doppler signal is measured by FFT, and the target speed is calculated by Doppler frequency.The application is from the establishment of composite system difference frequency signal model, using CZT conversion and time domain under-sampling technique to process difference frequency signal, finally extract difference frequency and Doppler signal frequency.

This invention proposes a high-precision method for measuring airflow thrust by extracting the Doppler frequency shift difference from the scanning absorption spectrum. A tunable laser performs forward and reverse scanning of the absorption spectrum. The laser wavenumber scanning waveform is symmetrical about the lowest wavenumber point. The laser beam is split into two beams, which cross the longitudinal section of the airflow center. The target gas absorption spectrum curve is obtained by measuring the laser intensity curve. The sum of the central wavenumbers of the absorption spectrum in both forward and reverse scans along the airflow path is calculated, as is the sum of the central wavenumbers in both forward and reverse scans against the airflow path. The Doppler frequency shift difference is extracted from the difference between the two sums of central wavenumbers, thus measuring the airflow velocity. The static temperature of the airflow is obtained using colorimetric thermometry, and the static pressure of the airflow is obtained using a nonlinear fitting method. The thrust is calculated by combining the airflow velocity, static temperature, and static pressure. This invention achieves airflow velocity measurement resistant to temporal noise interference and has significant application prospects in the field of integrated space-ground thrust measurement for engines.

The application provides a small sample number underwater target recognition method based on deep learning, comprising the following steps: S1, modeling underwater target radiation noise, giving an underwater target radiation noise DEMON spectrum processing method, and pre-processing the DEMON spectrum; S2, processing the radiation noise, simulating different working states and motion states of the target, and extracting sample combinations to generate sample pairs for training, verification and testing of a neural network model; S3, designing a one-dimensional convolutional neural network-based twin network model, training parameters of the convolutional neural network, evaluating network performance by using a verification set containing different Doppler frequency offsets, different signal-to-noise ratios and different spectral line numbers, obtaining a convolutional neural network model, and using the model to calculate the "similarity" of two underwater target radiation noise samples, and further judging whether the two samples are the same target or not. The application has the beneficial effect that the small sample number underwater target recognition problem can be solved.

Embodiments of the present application provide a communication method, device, electronic equipment, storage medium and program product. The method comprises: a network device sends a synchronization signal block (SSB) and a pilot signal to a terminal device, the SSB is used to indicate the position of the pilot signal. The terminal device receives the pilot signal according to the SSB; and determines a Doppler frequency offset and a crystal frequency offset according to the SSB and the pilot signal. Through the above method, the terminal device can determine the Doppler frequency offset and the crystal frequency offset according to the pilot signal, thereby achieving the purpose of determining the Doppler frequency offset and the crystal frequency offset.

The application discloses a multi-path time delay estimation method based on orthogonal linear frequency modulation wave division multiplexing signals, and the process is as follows: an OCDM signal is transmitted by a transmitting end, a time domain receiving signal is obtained after the OCDM signal passes through a multi-path channel, a fractional domain Fourier transform (FrFT) is performed on the time domain receiving signal to obtain a fractional domain receiving signal, a covariance matrix of the fractional domain receiving signal is calculated after the fractional domain receiving signal is de-coherent, a subspace of the covariance matrix is decomposed and a spatial spectrum is calculated by using a MUSIC algorithm, and a time delay corresponding to a spectrum peak of the spatial spectrum is a time delay estimation value. The multi-path time delay estimation method disclosed by the application can accurately estimate a time delay of a dense multi-path channel with a Doppler effect, effectively reduces a relative root mean square error of time delay estimation, is still relatively accurate in estimating a time delay when the multi-path is dense, and has a certain resistance to a Doppler frequency offset.

The invention discloses a low earth orbit satellite CSK signal joint capturing method based on Beidou system assistance, and relates to the technical field of satellite navigation signal processing, and the method comprises the steps: processing a Beidou satellite signal, and extracting prior information from the Beidou satellite signal; based on the prior information and pre-stored orbit parameters of a low-orbit satellite, Doppler frequency and time uncertainty of the CSK modulation signal are acquired; constructing a two-dimensional dynamic search window for searching a CSK modulation signal by taking Doppler frequency and time uncertainty as a center; and in the two-dimensional dynamic search window, performing joint capture processing on the received CSK modulation signal to determine the final code phase and the final Doppler frequency of the CSK modulation signal. The method can effectively adapt to high Doppler frequency shift and rapid change thereof caused by low-orbit satellites, and the capture success rate in a high dynamic environment and the overall reliability of a navigation system are improved.

The application provides a time domain detection and Doppler frequency offset estimation method and device of a data link signal, relates to the technical field of signal processing, and comprises the following steps: in the process of performing a sliding window detection on an entire real signal data, for each window, performing coarse scanning on a target frequency interval to determine a first frequency point with maximum integral power, performing fine scanning on the frequency corresponding to the first frequency point to determine a second frequency point with maximum integral power, taking the frequency corresponding to the second frequency point as a target peak frequency of the window, and taking the integral power at the second frequency point as a target integral power of the window; determining a current adjacent frequency reference power based on the integral power at the adjacent frequency points of the second frequency point; determining whether the window hits based on the target integral power and the current adjacent frequency reference power; determining a best hit window from a plurality of hit windows and performing frequency offset fine estimation to obtain a final frequency offset. The application can realize low-complexity fast frequency offset estimation and reduce the calculation amount and online time delay.

The application discloses a kind of based on ultrasonic scanning's tomography flowmeter method, comprising the following steps: in river channel, uniformly arranging inclined closed conduit, motor drive ultrasonic probe is stepped along conduit;Set scan starting position, step interval, scanning speed and sampling frequency;At each depth, gather echo intensity, echo delay and Doppler frequency shift to form raw data;Acoustic analysis identifies water surface and silt interface and calculates layered flow velocity to generate layered data set;Interpolation fitting constructs cross section tomography model, determines layered effective flow area and average flow velocity;Layered integration obtains cross section total flow and generates real-time flow data;Monitoring signal quality triggers self-cleaning.The application realizes the same journey to obtain interface and speed and outputs total flow by layered integration, structure simplification, data consistency, applicable to on-line flow measurement.

The application relates to a low-orbit satellite-based Internet of Things terminal random access method, which comprises the following steps: S1. acquiring a downlink synchronization signal and a system information block periodically broadcast by a target low-orbit satellite; S2. calculating a theoretical Doppler frequency offset value between a terminal and a satellite according to satellite ephemeris information and a terminal self-position; S3. selecting a target compensation value closest to the theoretical Doppler frequency offset value from the Doppler pre-compensation parameter group; S4. generating an access time slot selection seed by using a pre-defined hash function according to a current beam coverage area identifier; S5. non-uniformly selecting a target access time slot within a random access time window based on the access time slot selection seed; and S6. pre-compensating a preset random access preamble sequence in an uplink frequency by using the target compensation value in the target access time slot, and sending the compensated preamble sequence to the target low-orbit satellite to initiate random access.

Systems and methods for Wi-Fi sensing are provided. A networking device is configured to transmit a sensing trigger message including information about a plurality of fast sounding sensing signals to be transmitted. The networking device receives the plurality of fast sounding sensing signals transmitted by a sensing transmitter in response to the sensing trigger message within a transmission opportunity. The networking device performs a plurality of sensing measurements on the plurality of fast sounding sensing signals wherein the plurality of sensing measurements include measurements of Doppler frequency information associated with motion in a sensing space.