A method and system for inverting sea wave parameters using coherent radar under shipboard navigation conditions

Abstract

This invention discloses a method and system for inverting coherent radar wave parameters under shipboard navigation conditions. The method extracts the left and right boundaries of each range cell from the range Doppler spectrum and calculates the spectral width. Based on the spatial average spectral width and compression factor, the target spectral width is clipped. Then, the widening side is determined based on the spatial variance of the left and right boundaries, and unilateral adaptive clipping is implemented. Subsequently, the radial velocity is estimated using the clipped Doppler spectrum. The influence of ship speed is removed by spatial mean reduction. Then, a directed wavenumber spectrum is obtained through one-dimensional Fourier transform and linear wave theory. The directed wavenumber spectra are fused to obtain an undirected wavenumber spectrum, which is then converted into an undirected wave spectrum, ultimately yielding wave parameters such as significant wave height and average wave period. This invention does not rely on long-term continuous observation and two-dimensional Fourier transform to construct the frequency wavenumber spectrum, making it suitable for robust inversion of shipboard wave parameters under time-sampling rate constraints.

Description

Technical Field

[0001] This invention belongs to the field of microwave radar marine remote sensing and signal processing technology, and particularly relates to a method for wave parameter inversion by means of range Doppler spectrum broadening identification, one-sided adaptive clipping, and spatial velocity correction. Specifically, it is a coherent radar wave parameter inversion method and system applicable to shipborne navigation conditions. Background Technology

[0002] Ocean wave parameters, especially significant wave height, mean wave period, and directional spectrum, are crucial fundamental information for ensuring maritime navigation safety, marine engineering operation and maintenance, marine environmental monitoring, and research on air-sea interactions. Coherent microwave radar can acquire Doppler information from sea surface echoes and invert wave parameters using the physical relationship between the motion of sea surface scatterers and ocean waves, thus possessing high application value in ocean wave remote sensing.

[0003] When wave breaking occurs, the sea surface generates breaking short waves, causing broadening of the radar echo Doppler spectrum. This broadening alters the Doppler center estimation results and further affects the accuracy of velocity inversion and wave parameter estimation. Existing processing methods mainly rely on techniques such as space-time velocity sequences, frequency-wavenumber spectrum construction, and dispersion relation filtering, which typically require high time sampling rates and long continuous observation times.

[0004] On shore-based platforms, the radar is stationary, and the same range element corresponds to a fixed sea surface area over time. The statistical characteristics of sea state can be approximated as stable within the observation window. Therefore, processing methods based on the time-Doppler spectrum (such as time-dimensional statistical analysis of fixed range elements) can work effectively. However, under shipboard navigation conditions, the ship is in continuous motion, its position shifts in real time, and the actual sea surface scattering area corresponding to the same range element changes constantly at different times. Sea surface swells and scattering characteristics also fluctuate dynamically. This means that the core assumption of "fixed sea surface area and stable sea state" upon which existing time-dimensional processing methods rely cannot be met from a physical perspective in shipboard scenarios. This is not a problem of algorithm robustness, nor is it a defect that can be solved by parameter optimization; rather, it is a structural mismatch between the model's premise and physical reality.

[0005] Meanwhile, shipborne radar systems often employ a multi-antenna time-division multiplexing operating mode, which limits the time sampling rate of a single antenna. Furthermore, the ship's speed is superimposed on the observed signal, making traditional methods relying on long time sequences and two-dimensional Fourier transforms to construct frequency-wavenumber domain hard filters somewhat limited in engineering applications. Therefore, mature time-Doppler spectrum processing methods used in shore-based scenarios cannot be directly applied to shipborne mobile radar platforms in principle. Summary of the Invention

[0006] To address the problem of robustly suppressing wave broadening and accurately retrieving wave parameters in existing technologies under shipborne and time-sampling rate-limited scenarios, this invention provides a coherent radar wave parameter inversion method suitable for shipborne navigation conditions. This method acquires the range Doppler spectrum at a single moment, extracts the left and right boundaries of the signal bands of each range cell, calculates the spatial variance of the left and right boundary sequences to determine the broadening side, keeps the non-abnormal side unchanged, performs unilateral clipping of the broadening side according to a preset target spectral width, estimates the Doppler center frequency within the clipped boundary, converts the radial velocity, and removes the ship speed influence through spatial mean removal, thereby inverting the wave parameters. This achieves the goal of robustly suppressing breaking wave broadening and accurately retrieving wave parameters without requiring long-term continuous observation and two-dimensional Fourier transform.

[0007] According to one aspect of the present invention, a method for inverting coherent radar sea wave parameters under shipboard navigation conditions is provided, comprising: Obtain the range Doppler spectrum of the shipborne coherent radar at a single moment and in a single observation direction; Extract the left and right boundary frequencies of the signal band for each range unit from the range Doppler spectrum; Calculate the spatial variance of the left boundary frequency sequence in the distance dimension and the spatial variance of the right boundary frequency sequence in the distance dimension, and determine the broadening side based on the comparison of spatial variances; Keep the boundary of the non-expanded side unchanged, and perform unilateral cropping of the boundary of the expanded side according to the preset target spectral width; Within the clipped boundary, the Doppler center frequency is estimated and converted into radial velocity. The spatial velocity sequence at the same time and in the same observation direction is subjected to mean removal to eliminate the influence of ship speed, and then the wave parameters are inverted.

[0008] As a further technical solution, the preset target spectral width is obtained by performing spatial statistics on the spectral widths of all distance cells at the same time and under the same observation direction to obtain the average spectral width. Introduce a preset compression factor ,in Calculate the target spectral width for cropping. .

[0009] As a further technical solution, the comparison and determination of the broadening side based on spatial variance includes: when the spatial variance of the right boundary frequency sequence is greater than the spatial variance of the left boundary frequency sequence, the right side is determined to be the broadening side; when the spatial variance of the left boundary frequency sequence is greater than the spatial variance of the right boundary frequency sequence, the left side is determined to be the broadening side.

[0010] As a further technical solution, the unilateral cropping includes: if the right side is determined to be the widening side, then the left boundary is kept unchanged, and the right boundary is updated to the sum of the left boundary and the cropping target spectral width; if the left side is determined to be the widening side, then the right boundary is kept unchanged, and the left boundary is updated to the difference between the right boundary and the cropping target spectral width.

[0011] As a further technical solution, the process of inverting wave parameters does not use two-dimensional fast Fourier transform to construct the wave number frequency spectrum, but only uses one-dimensional fast Fourier transform to process the mean-removed spatial velocity sequence.

[0012] As a further technical solution, the wave parameters include significant wave height and mean wave period; the directed wave number spectrum obtained by inversion from multiple observation directions is fused into an undirected wave number spectrum, and then the undirected wave number spectrum is converted into an undirected wave spectrum; the significant wave height is calculated based on the zero-order moment of the undirected wave spectrum, and the mean wave period is calculated based on the ratio of the zero-order moment to the first moment of the undirected wave spectrum.

[0013] According to one aspect of the present invention, a coherent radar wave parameter inversion system suitable for shipboard navigation conditions is provided, comprising: The range-Doppler spectrum acquisition module is used to acquire the range-Doppler spectrum of the shipborne coherent radar at a single moment and in a single observation direction; The boundary extraction module is used to extract the left and right boundary frequencies of each range unit signal band from the range Doppler spectrum. The variance calculation and broadening determination module is used to calculate the spatial variance of the left boundary frequency sequence and the right boundary frequency sequence in the distance dimension, and determine the broadening side based on the comparison of spatial variance. The boundary clipping module is used to keep the boundary of the non-expanded side unchanged and to clip the boundary of the expanded side on one side according to the preset target spectral width. The velocity estimation and inversion module is used to estimate the Doppler center frequency within the clipped boundary and convert it into radial velocity. It inverts the wave parameters by removing the ship speed influence from the mean of the spatial velocity sequence.

[0014] As a further technical solution, the preset target spectral width in the boundary clipping module is obtained by: performing spatial statistics on the spectral width of all distance cells at the same time and under the same observation direction to obtain the average spectral width. Introduce a preset compression factor ,in Calculate the target spectral width for cropping. .

[0015] According to one aspect of the present invention, an electronic device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method described herein.

[0016] According to one aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the method described thereon.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. It directly processes the range-Doppler spectrum without relying on long-term continuous observation and two-dimensional Fourier transform to construct the frequency wavenumber spectrum, making it suitable for time-sampling rate-limited scenarios in shipborne multi-antenna time-division multiplexing mode; 2. By determining the broadening side through the variance of the left and right boundary spaces and implementing unilateral adaptive pruning, the broadening caused by wave breaking can be suppressed more effectively, avoiding the loss of normal spectral energy due to bilateral symmetrical compression. 3. This method does not rely on the time dimension assumption of "fixed sea surface area and stable sea state", which fundamentally solves the problem that the principle of time dimension processing method is not applicable under shipboard navigation conditions, and is adapted to the physical characteristics of shipboard platforms. 4. The method has a short process and is simple to implement, requiring only one-dimensional fast Fourier transform, with low computational load, making it suitable for engineering real-time or near-real-time applications. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart illustrating a method for inverting coherent radar sea wave parameters under shipboard navigation conditions, provided as an embodiment of the present invention; Figure 2 This is a schematic diagram of a two-dimensional range Doppler spectrum at a certain observation direction and a certain time, provided in an embodiment of the present invention. The diagram shows the original left and right boundaries and the cropped boundaries. Figure 3 This is a schematic diagram comparing the spatial velocity sequences before and after trimming, provided in an embodiment of the present invention. Figure 4 This is a schematic diagram comparing the omnidirectional wave spectrum and the corresponding effective wave height and mean wave period obtained by inversion using the method of this invention, provided for embodiments of the present invention. Detailed Implementation

[0020] To address the limitations of traditional methods—such as the invalidation of the time-stationarity assumption under shipboard navigation conditions, the limitation of time sampling rates, and the reliance on long-term continuous observations and two-dimensional Fourier transforms to construct frequency-wavenumber spectra—this invention provides a wave parameter inversion method suitable for shipboard navigation conditions. This method abandons the dependence on time-dimensional stationarity and instead utilizes the range Doppler spectrum acquired by shipboard radar at a single moment and in a single observation direction. Breaking wave suppression is achieved through spatial broadening identification and unilateral adaptive pruning. Based on this, wave parameters are inverted in one dimension, eliminating the need for long-term continuous observations and two-dimensional Fourier transforms.

[0021] The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover a non-exclusive inclusion, such as a process, method, system, product, or apparatus that includes a series of steps or units, not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the technical features of the various embodiments or individual embodiments provided by the present invention can be arbitrarily combined to form new technical solutions. Such combinations are not bound by the order of steps and / or structural composition patterns, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0023] Example 1

[0024] This embodiment uses a shipborne coherent S-band radar as an example to illustrate in detail the specific implementation steps of the wave parameter inversion method provided by this invention. The overall flow of the method is as follows: Figure 1 As shown, it includes the following steps.

[0025] Step 1: Obtain the range Doppler spectrum of the shipborne coherent radar at a single moment and in a single observation direction.

[0026] The aforementioned shipborne coherent S-band radar employs a multi-antenna time-division multiplexing operation, with a single complete scan encompassing multiple observation directions. The beamwidth for each observation direction is 30 degrees, and the range resolution is 7.5 meters. This embodiment uses time... Observation direction Let's take an example. The distance-Doppler spectrum obtained in this observation direction is denoted as... ,in For distance units, This is the nth observation direction.

[0027] In step S1, the range Doppler spectrum signal band is determined by the following method: the range Doppler spectrum power and the noise floor power are compared. Does the difference exceed the preset threshold? Comparison yields satisfaction The continuous frequency range is defined as the signal band range.

[0028] Step 2: Extract the left and right boundary frequencies of the signal band for each range unit from the range Doppler spectrum.

[0029] Extract the left boundary of the distance cell signal band and right boundary And calculate the corresponding spectral width.

[0030]

[0031] Figure 2 The original left and right boundaries (white lines) of the two-dimensional range-Doppler spectrum at a certain observation direction and time are shown. It can be seen that the boundaries of some range cells are significantly broadened, which is due to wave breaking.

[0032] Determine the target spectral width after cropping. Perform spatial statistics on the spectral width of all range cells at the same time and under the same observation direction to obtain the average spectral width.

[0033]

[0034] M represents the number of distance units.

[0035] Introducing compression factor ,in The target spectral width for cropping is obtained.

[0036]

[0037] Compression factor Used to control the intensity of broadening inhibition. The larger the value, the more of the original spectral energy is retained; The smaller the value, the stronger the suppression of broadening. In this embodiment, Take 0.8.

[0038] Step 3: Calculate the spatial variance of the left and right boundary frequency sequences in the distance dimension, and determine the broadening side based on the comparison of spatial variance.

[0039] This step calculates the spatial variance of the left and right boundaries in the distance dimension, and determines the side where broadening mainly occurs based on the relationship between the spatial variances of the left and right boundaries. When the right side has a larger spatial variance, the left boundary is kept unchanged and the right boundary is compressed according to the target spectral width. When the left side has a larger spatial variance, the right boundary is kept unchanged and the left boundary is compressed according to the target spectral width, thus obtaining the clipped boundary. and .

[0040] First, calculate the spatial mean of the left and right boundaries along the distance dimension:

[0041]

[0042]

[0043] Further calculations of the corresponding spatial variances are as follows:

[0044]

[0045]

[0046] The judgment rule is as follows:

[0047] when At that time, the right side was determined to be the widening side;

[0048] when At that time, the left side was determined to be the widened side;

[0049] Otherwise, if there is no significant widening, no cropping will be performed.

[0050] Step 4: Keeping the boundary of the non-expanded side unchanged, perform unilateral cropping of the boundary of the expanded side according to the preset target spectral width.

[0051] Based on the target spectral width determined in step 2 and the judgment result in step 3, perform unilateral cropping:

[0052] If the right side is the broadened side, then keep the left boundary unchanged and update the right boundary to the sum of the left boundary and the target spectral width for cropping. The cropped boundary satisfies:

[0053]

[0054] If the left side is the broadened side, keep the right boundary unchanged, and update the left boundary to the difference between the right boundary and the target spectral width for cropping. The cropped boundary satisfies:

[0055]

[0056] If there is no widening: the boundary remains unchanged.

[0057] Through the above processing, unilateral adaptive cropping on the expanded side is achieved.

[0058] Figure 2 The purple lines in the image show the new boundaries after cropping. The widening on the left side has been effectively compressed, while the right side remains unchanged, preserving the complete information of normal wave echoes.

[0059] Step 5: Estimate the Doppler center frequency within the clipped boundary and convert it into radial velocity. Perform mean-removal processing on the spatial velocity sequence to eliminate the influence of ship speed.

[0060] Recalculate the Doppler center frequency within the clipped boundary:

[0061]

[0062] The radial velocity is calculated as follows:

[0063]

[0064] in, The wavelength of radar electromagnetic waves.

[0065] Since the ship's speed is mainly represented by the overall translational component in the same direction at the same moment, the spatial velocity sequence at each moment and in each observation direction is mean-removed to obtain a new velocity sequence:

[0066]

[0067] After processing This represents a speed sequence after the influence of ship speed has been removed.

[0068] Figure 3 By comparing the spatial velocity sequences before and after trimming, it was found that the overall offset caused by the ship speed was eliminated and the abnormal velocity spikes were effectively suppressed after processing by this method.

[0069] Step 6: Invert wave parameters

[0070] This step does not use two-dimensional fast Fourier transform to construct the wavenumber frequency spectrum, but only uses one-dimensional fast Fourier transform to process the mean-removed spatial velocity sequence.

[0071] Perform a Fast Fourier Transform (FFT) along the distance dimension on the spatial velocity sequence after removing the ship's speed. To improve stability, data from multiple time periods can be averaged. Conversely, to increase the velocity, the number of time periods can be reduced (at least one time period is acceptable), resulting in the velocity spectrum:

[0072]

[0073] Where k is the wave number and B is the number of times the average is applied.

[0074] According to linear wave theory, the conversion relationship between the velocity spectrum and the wavenumber spectrum is given by the transfer function TF:

[0075]

[0076] in, This represents the number of spatial sampling points. For wavenumber resolution, denoted as angular resolution, and g as gravitational acceleration.

[0077] The directed wavenumber spectrum is then:

[0078]

[0079] in, Because of the water depth, This is the glancing angle corresponding to the nth observation direction.

[0080] Combine the directed wavenumber spectra of each antenna into an undirected wavenumber spectrum.

[0081]

[0082] Then it is converted into an undirected wave spectrum in the frequency domain.

[0083]

[0084] Significant wave height and mean wave period The outputs are calculated using the following formulas respectively.

[0085]

[0086]

[0087] in, .

[0088] like Figure 4 As shown, the low-frequency energy related to wave breakage in the wave spectrum is significantly suppressed, and the main peak position and spectral shape are clearer. Meanwhile, the effective wave height and average wave period displayed by the measuring device are 1.77 meters and 6.36 seconds, respectively. In contrast, the effective wave height and average wave period obtained without the method of this invention are 2.940 meters and 8.093 meters, respectively, while the effective wave height and average wave period obtained with the method of this invention are 1.696 meters and 6.992 seconds.

[0089] Example 2

[0090] This embodiment provides a coherent radar wave parameter inversion system suitable for shipboard navigation conditions. The system includes the following modules:

[0091] Range-Doppler spectrum acquisition module: This module acquires the range-Doppler spectrum of the shipborne coherent radar at a single moment and in a single observation direction. It connects to the data interface of the shipborne radar and receives the range-Doppler spectrum data formed after range compression and Doppler processing of the raw radar echo.

[0092] Boundary extraction module: This module extracts the left and right boundary frequencies of the signal band for each range cell from the range-Doppler spectrum. Internally, it implements a signal-to-noise ratio threshold comparison and continuity point determination algorithm, outputting the left and right boundary frequencies for each range cell.

[0093] The variance calculation and broadening determination module is used to calculate the spatial variance of the left and right boundary frequency sequences in the distance dimension, and determine the broadening side based on the comparison of spatial variances. This module first calculates the spatial mean and spatial variance of the left and right boundaries, and then determines whether the right side, left side, or no broadening is achieved based on whether the difference in variance exceeds a preset threshold.

[0094] Boundary clipping module: This module keeps the boundary of the non-broadened side unchanged and clips the boundary of the broadened side according to a preset target spectral width. First, it performs spatial statistics on the spectral width of all range cells at the same time and in the same observation direction to obtain the average spectral width. Then, it introduces a preset compression factor and calculates that the target spectral width is equal to the product of the average spectral width and the compression factor. Finally, based on the determination result of the broadened side, it updates the boundary of the anomalous side, while leaving the non-annomous side unchanged.

[0095] The velocity estimation and inversion module estimates the Doppler center frequency within the clipped boundary and converts it to radial velocity. It then inverts wave parameters by removing the influence of ship speed through mean removal of the spatial velocity sequence. This module uses the spectral moment method to calculate the center frequency, converts the radial velocity based on the Doppler effect, performs spatial mean removal, and then inverts the directed wavenumber spectrum using a one-dimensional fast Fourier transform and transfer function. These are then fused to obtain the undirected wave spectrum, ultimately outputting the significant wave height and mean wave period.

[0096] The above modules can be deployed on a radar signal processing computer or integrated into the embedded processor of the radar system.

[0097] Example 3

[0098] This embodiment provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor.

[0099] The memory is used to store computer programs and necessary intermediate data (such as range-Doppler spectra, left and right boundary sequences, radial velocity sequences, etc.). The processor can be a digital signal processor (DSP), a field-programmable gate array (FPGA), a graphics processing unit (GPU), or a general-purpose central processing unit (CPU).

[0100] When the processor executes the computer program, it implements the wave parameter inversion method described in any of the above method embodiments. Specifically, the processor is configured to perform the following operations: acquire the range Doppler spectrum of the shipborne coherent radar at a single moment and in a single observation direction; extract the left and right boundary frequencies of the signal band of each range unit from the range Doppler spectrum; calculate the spatial variance of the left and right boundary frequency sequences in the range dimension, and determine the broadening side based on the comparison of the spatial variance; keep the boundary of the non-broadening side unchanged, and perform unilateral clipping of the boundary of the broadening side according to a preset target spectral width; estimate the Doppler center frequency within the clipped boundary and convert it into radial velocity, perform mean-removing processing on the spatial velocity sequence to remove the influence of ship speed, and then invert the wave parameters.

[0101] Optionally, the effective wave height and average wave period obtained from the inversion can be output or displayed.

[0102] The electronic device can be a standalone industrial computer, an embedded board, or integrated into the cabinet of a shipborne radar.

[0103] Example 4

[0104] This embodiment provides a computer-readable storage medium on which a computer program is stored. The computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, or any other medium capable of storing program code.

[0105] When the computer program is executed by the processor, it implements the wave parameter inversion method described in any of the above method embodiments. The specific implementation steps are the same as the operations performed by the processor in the device embodiments, and will not be repeated here.

[0106] This computer-readable storage medium can be used for scenarios such as software upgrades, offline data processing, or algorithm verification of shipborne radar systems.

[0107] In summary, the wave parameter inversion method provided by this invention extracts the left and right boundaries of each distance cell from the range Doppler spectrum and calculates the spectral width. Based on the spatial average spectral width and compression factor, a target spectral width is obtained for trimming. Then, the broadening side is determined based on the spatial variance of the left and right boundaries, and unilateral adaptive trimming is implemented. Subsequently, the radial velocity is estimated using the trimmed Doppler spectrum, and the influence of ship speed is removed by spatial mean reduction. Then, a directed wavenumber spectrum is obtained through one-dimensional Fourier transform and linear wave theory. The directed wavenumber spectra are fused to obtain an undirected wavenumber spectrum, which is then converted into an undirected wave spectrum, ultimately yielding wave parameters such as significant wave height and average wave period. This invention does not rely on long-term continuous observation and two-dimensional Fourier transform to construct the frequency wavenumber spectrum, making it suitable for robust inversion of shipborne wave parameters under time-sampling rate constraints.

[0108] This invention addresses the limitations of shipborne coherent radar's time sampling rate, the difficulty in constructing frequency-wavenumber spectra, and its susceptibility to wave breakage and ship speed influences. It proposes a wave parameter inversion method based on range-Doppler spectrum spatial statistical discrimination and one-sided adaptive pruning. This method features short processing links, strong engineering applicability, and can output wave spectra, significant wave height, and average wave period without relying on long-term continuous observations, demonstrating promising application prospects.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A method for inverting sea wave parameters using coherent radar under shipboard navigation conditions, characterized in that, include: Obtain the range Doppler spectrum of the shipborne coherent radar at a single moment and in a single observation direction; Extract the left and right boundary frequencies of the signal band for each range unit from the range Doppler spectrum; Calculate the spatial variance of the left boundary frequency sequence in the distance dimension and the spatial variance of the right boundary frequency sequence in the distance dimension, and determine the broadening side based on the comparison of spatial variances; Keep the boundary of the non-expanded side unchanged, and perform unilateral cropping of the boundary of the expanded side according to the preset target spectral width; Within the clipped boundary, the Doppler center frequency is estimated and converted into radial velocity. The spatial velocity sequence at the same time and in the same observation direction is subjected to mean removal to eliminate the influence of ship speed, and then the wave parameters are inverted.

2. The method according to claim 1, characterized in that, The preset target spectral width is obtained by performing spatial statistics on the spectral widths of all distance cells at the same time and under the same observation direction to obtain the average spectral width. Introduce a preset compression factor ,in Calculate the target spectral width for cropping. .

3. The method according to claim 1, characterized in that, The comparison and determination of the broadening side based on spatial variance includes: when the spatial variance of the right boundary frequency sequence is greater than the spatial variance of the left boundary frequency sequence, the right side is determined to be the broadening side; when the spatial variance of the left boundary frequency sequence is greater than the spatial variance of the right boundary frequency sequence, the left side is determined to be the broadening side.

4. The method according to claim 1, characterized in that, The unilateral cropping includes: if the right side is determined to be the widening side, then the left boundary is kept unchanged, and the right boundary is updated to the sum of the left boundary and the cropping target spectral width; if the left side is determined to be the widening side, then the right boundary is kept unchanged, and the left boundary is updated to the difference between the right boundary and the cropping target spectral width.

5. The method according to claim 1, characterized in that, The process of retrieving wave parameters does not use two-dimensional fast Fourier transform to construct the wave number frequency spectrum, but only uses one-dimensional fast Fourier transform to process the mean-removed spatial velocity sequence.

6. The method according to claim 1, characterized in that, The wave parameters include significant wave height and mean wave period; the directed wave number spectrum obtained by inversion from multiple observation directions is fused into an undirected wave number spectrum, and then the undirected wave number spectrum is converted into an undirected wave spectrum; the significant wave height is calculated based on the zero-order moment of the undirected wave spectrum, and the mean wave period is calculated based on the ratio of the zero-order moment to the first moment of the undirected wave spectrum.

7. A coherent radar wave parameter inversion system suitable for shipboard navigation conditions, characterized in that, include: The range-Doppler spectrum acquisition module is used to acquire the range-Doppler spectrum of the shipborne coherent radar at a single moment and in a single observation direction; The boundary extraction module is used to extract the left and right boundary frequencies of each range unit signal band from the range Doppler spectrum. The variance calculation and broadening determination module is used to calculate the spatial variance of the left boundary frequency sequence and the right boundary frequency sequence in the distance dimension, and determine the broadening side based on the comparison of spatial variance. The boundary clipping module is used to keep the boundary of the non-expanded side unchanged and to clip the boundary of the expanded side on one side according to the preset target spectral width. The velocity estimation and inversion module is used to estimate the Doppler center frequency within the clipped boundary and convert it into radial velocity. It inverts the wave parameters by removing the ship speed influence from the mean of the spatial velocity sequence.

8. The system according to claim 7, characterized in that, The preset target spectral width in the boundary clipping module is obtained by performing spatial statistics on the spectral width of all distance cells at the same time and under the same observation direction to obtain the average spectral width. Introduce a preset compression factor ,in Calculate the target spectral width for cropping. .

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the method according to any one of claims 1 to 6.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by a processor, it implements the method described in any one of claims 1 to 6.

Images