A method and system for measuring and analyzing sea wave parameters based on millimeter wave radar

Abstract

The application discloses a sea wave parameter measurement and analysis method and system based on a millimeter wave radar, and comprises the following steps: a plurality of millimeter wave radars are used to form a measurement array, a dielectric lens is used to reduce the radar beam width, the plurality of radars measure the distance from the sea surface to the radar in a vertical vision and oblique vision cooperative manner, and the ocean surface fluctuation data of multiple points are obtained. By using the ocean surface fluctuation data, the sea wave effective wave height, the effective wave period, the average cross-zero wave period and the sea wave propagation direction and other parameters are calculated through a sea wave analysis method. In combination with the high precision and high sampling rate characteristics of the millimeter wave radar, the application can measure the sea wave parameters with high precision all day long and all weather long, the high cost of the traditional measurement means for the sea wave measurement, the slow data updating, the great difficulty in continuous observation and the influence of bad weather factors and other problems are solved, the high precision and high sampling rate characteristics of the millimeter wave radar are fully utilized, and the accuracy and real-time performance of the sea wave parameter measurement are improved.

Description

Technical Field

[0001] This invention belongs to the field of ocean wave observation, specifically relating to a method and system for measuring and analyzing ocean wave parameters based on millimeter-wave radar. Background Technology

[0002] Ocean wave parameters are a crucial aspect of marine research, and understanding them is essential for marine conservation, maritime shipping, marine weather forecasting, and offshore oil field development. Currently, commonly used wave measurement methods include buoys, satellite remote sensing, optical measurement, high-frequency ground-wave radar, and X-band radar. Buoy measurement utilizes attitude sensors to measure its own attitude state during wave propagation. However, in practical applications, deployment and maintenance are costly, and in harsh sea conditions, the buoy's anchor chain may break, leading to buoy loss.

[0003] While satellite remote sensing offers a wide measurement coverage, its limitations—long orbital revisit periods and instantaneous observation characteristics—make it impossible for a single satellite to achieve high-frequency continuous sampling of the wave field, hindering sustained observation of waves in a designated area. Optical photography for wave measurement is susceptible to weather and lighting conditions, making it ineffective in foggy or nighttime conditions and preventing all-day wave measurements. High-frequency ground-wave radar, while covering a large area, suffers from signal strength attenuation with distance, significantly reducing wave inversion accuracy at long distances and hindering reliable full-area wave field reconstruction. X-band wave-measuring radar offers advantages such as immunity to weather and high measurement accuracy, but in high sea states, spectral expansion makes accurate wave period measurement difficult. Summary of the Invention

[0004] This invention addresses the problems of high cost, slow data updates, difficulty in continuous observation, and susceptibility to adverse weather conditions associated with traditional wave measurement methods. It provides a wave parameter measurement and analysis method based on millimeter-wave radar. This method uses a millimeter-wave radar as a sensor to form a sampling array, measuring wave targets at designated points. By measuring the distance between the wave target and the radar, it obtains data on the undulation of ocean waves. Then, it uses wave analysis algorithms to obtain wave parameters and calculates a cross spectrum based on the wave undulation data from the millimeter-wave radar. An inverse Fourier transform is performed on the cross spectrum to obtain the wave direction spectrum, thus determining the wave propagation direction. This improves the radar's perception performance and measurement accuracy for single-point wave undulations.

[0005] According to one aspect of this specification, a method for measuring and analyzing ocean wave parameters based on millimeter-wave radar is provided, comprising:

[0006] Construct a millimeter-wave radar sampling array, determine the range resolution and maximum detection range of each millimeter-wave radar, and reduce the beamwidth of the millimeter-wave radar antenna by using a dielectric lens;

[0007] The range spectrum is calculated based on the radar difference frequency data acquired by millimeter-wave radar. The wave target is detected in the range spectrum, and the range data between all millimeter-wave radars and the wave target is obtained by combining the spectrum refinement method.

[0008] Based on the distance data between all millimeter-wave radars and ocean wave targets, ocean wave undulation data is extracted and spectrum analysis is performed to obtain the effective wave height, effective wave period and average zero-wave period of the ocean waves.

[0009] The cross spectrum is calculated based on the wave undulation data of the millimeter-wave radar sampling array. The wave direction spectrum is obtained from the cross spectrum, and then the wave propagation direction is obtained.

[0010] Furthermore, the sampling interval of the millimeter-wave radar sampling array satisfies the spatial sampling theorem and is greater than... ,in, The distance between the millimeter-wave radar and the sea surface. This refers to the half-beamwidth of a millimeter-wave radar antenna.

[0011] Furthermore, the dielectric lens is a single-curved dielectric lens.

[0012] Furthermore, the surface equation of the single-curved dielectric lens is:

[0013]

[0014] in, For the thickness of the dielectric lens, The radiation aperture of the dielectric lens, The operating frequency of the dielectric lens, is the refractive index of the dielectric lens material.

[0015] Furthermore, the range spectrum is calculated based on the radar difference frequency data acquired by the millimeter-wave radar, and wave targets are detected in the range spectrum, including:

[0016] The range spectrum is obtained by performing a discrete Fourier transform on the radar difference frequency data acquired by the millimeter-wave radar.

[0017] Based on the distance spectrum, wave targets are detected using a constant false alarm rate (CFAR) detection algorithm.

[0018] Furthermore, based on the distance data between the radar and the wave target, wave undulation data is extracted and spectral analysis is performed to obtain the significant wave height, significant wave period, and average zero-crossing wave period, including:

[0019] The distance data between the radar and the sea wave target is low-pass filtered and the mean is removed to obtain the sea wave fluctuation data;

[0020] The wave undulation data is divided into K segments and the power spectral density of each segment is calculated. The wave power spectral density is obtained by averaging the power spectral density of each segment.

[0021] Defined by wave power spectral density Step moment, using The effective wave height, effective wave period, and average zero-crossing wave period of the ocean waves are obtained by step moment calculation.

[0022] Furthermore, the expression for the wave direction spectrum is:

[0023]

[0024] in, Let be the vector difference between the position of the i-th sensor and the position of the j-th sensor. It is the set of all sensor position vector differences. The wave number vector of the ocean waves. Angular frequency, For cross spectrum, For directional spectrum.

[0025] Furthermore, the method also includes: obtaining the range resolution and maximum detection range of each millimeter-wave radar by designing a radar linear frequency modulation waveform for each millimeter-wave radar.

[0026] According to one aspect of this specification, a wave parameter measurement and analysis system based on millimeter-wave radar is provided, comprising:

[0027] On the hardware configuration side, it is used to build a millimeter-wave radar sampling array, determine the range resolution and maximum detection range of each millimeter-wave radar, and reduce the beamwidth of the millimeter-wave radar antenna through a dielectric lens;

[0028] The data processing unit detects ocean wave targets based on radar difference frequency data acquired by millimeter-wave radar. It combines the spectrum refinement method to obtain the distance data between all millimeter-wave radars and ocean wave targets, and extracts ocean wave undulation data to obtain the effective wave height, effective wave period, and average zero-crossing wave period of the ocean waves. At the same time, it calculates the cross spectrum based on the ocean wave undulation data of the millimeter-wave radar sampling array, obtains the ocean wave direction spectrum based on the cross spectrum, and then obtains the propagation direction of the ocean waves.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. This invention utilizes the high-precision ranging characteristics of millimeter-wave radar to construct a millimeter-wave radar sampling array and design a radar linear frequency modulation waveform, thereby realizing centimeter-level precision measurement of ocean wave undulation data and all-day, all-weather non-contact measurement of ocean wave parameters.

[0031] 2. This invention uses a dielectric lens to constrain the antenna beamwidth, which improves the radar's ability to perceive single-point wave undulations. Compared with other measurement methods, it has higher measurement accuracy and better real-time performance, making it suitable for scenarios that require high-precision real-time measurement of waves. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 A flowchart of a wave parameter measurement and analysis method based on millimeter-wave radar provided for an embodiment of the present invention;

[0034] Figure 2 This is a design diagram of a radar wave sampling array provided in an embodiment of the present invention.

[0035] Figure 3 The radar vertical and oblique measurement design diagrams provided for embodiments of the present invention.

[0036] Figures 4(a)-(b) show the horizontal and vertical orientations of the antenna beamwidth constrained by a dielectric lens according to an embodiment of the present invention.

[0037] Figure 5 This is a diagram showing the detection results of ocean wave targets in the range spectrum provided in an embodiment of the present invention.

[0038] Figure 6 The image shows the results of wave spectrum measurement provided in an embodiment of the present invention.

[0039] Figure 7 This is a comparison chart of the effective wave height measurement results of ocean waves and the buoy measurement results provided in an embodiment of the present invention.

[0040] Figure 8 This is a comparison chart of the effective wave period measurement results and buoy measurement results provided in an embodiment of the present invention.

[0041] Figure 9 This is a comparison chart of the average wave crossing zero-wave period measurement results and buoy measurement results provided in an embodiment of the present invention.

[0042] Figure 10 The image shows the measurement results of the frequency directional spectrum of ocean waves provided in an embodiment of the present invention.

[0043] Figure 11 This is a comparison chart of the measurement results of the wave propagation direction and the numerical model provided in an embodiment of the present invention. Detailed Implementation

[0044] 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, and 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.

[0045] Specifically, such as Figure 1 As shown, this invention provides a method for measuring and analyzing ocean wave parameters based on millimeter-wave radar, comprising: constructing a millimeter-wave radar sampling array, wherein the sampling interval of the millimeter-wave radar sampling array satisfies two distance conditions; designing a radar linear frequency modulation waveform for each millimeter-wave radar, and determining the range resolution and maximum detection range of each millimeter-wave radar; reducing the beamwidth of the millimeter-wave radar antenna by using a dielectric lens to improve the spatial directivity of the radar and reduce the effective illumination range of the millimeter-wave radar; calculating the range spectrum based on the difference frequency signal acquired by the millimeter-wave radar, detecting ocean wave targets in the range spectrum, and combining the local frequency signal corresponding to the ocean wave target with the range spectrum. The spectrum refinement method is employed to reduce errors caused by the picket fence effect during frequency estimation, thereby improving the accuracy of distance estimation for wave targets and obtaining high-precision distance data between each millimeter-wave radar and the wave target. Based on the distance data between the millimeter-wave radar and the wave target, wave undulation data is extracted and spectral analysis is performed to obtain the effective wave height, effective wave period, and average zero-crossing wave period of the waves. A cross spectrum is calculated based on the wave undulation data from the millimeter-wave radar sampling array. An inverse Fourier transform is then performed based on the cross spectrum and radar array information to obtain the wave direction spectrum. This, combined with the constructed millimeter-wave radar sampling array, yields the wave propagation direction. The four parameters—effective wave height, effective wave period, average zero-crossing wave period, and wave propagation direction—are defined as wave parameters.

[0046] Specifically, millimeter-wave radar has the advantages of high ranging accuracy and good real-time performance, and is unaffected by weather factors. Millimeter-wave radar can be used to acquire real-time, high-precision data on ocean wave undulations, making it suitable for all-day and all-weather monitoring of ocean waves.

[0047] Specifically, in constructing the millimeter-wave radar sampling array, to avoid the problem of direction-finding ambiguity, the measurement array is designed as a triangular or linear array structure, such as... Figure 2 As shown, a combination of vertical and oblique line measurements is employed. Of the three measurement points, one uses radar for vertical measurement, while the other two use radar for oblique line measurements. Simultaneously, to improve the system's structural compactness, as... Figure 3As shown, this embodiment of the invention employs a measurement structure that combines vertical-looking and oblique-looking radars, effectively reducing the overall system size while meeting the requirements for wave spatial measurement. Furthermore, by loading a dielectric lens at the radar front end, the beam coverage is reduced and spatial directivity is enhanced, enabling the oblique-looking radar to more accurately correspond to designated measurement points on the sea surface. Based on the above structure, the measurement array not only ensures the system's wave measurement capabilities but also significantly reduces the system's deployment space, demonstrating superior structural integration advantages.

[0048] To satisfy the Nyquist sampling theorem for space, the sampling interval of millimeter-wave radar sensors on the sea surface... The following two distance conditions must be met: 1. The spatial sampling theorem must be satisfied: ,in 1. Minimum wave wavelength. 2. To prevent overlapping measurement areas and meet the following requirements. ,in This represents the distance between the radar and the sea surface. This refers to the radar antenna's half-beamwidth. In actual measurements, when the radar signal illuminates the sea surface, it forms a circular coverage area. When the antenna's half-beamwidth is... The distance between the radar and the sea surface (wave target) is At that time, the radius of the radar's illumination area on the sea surface is... To ensure that the measurement areas of the measurement array do not overlap, the following must be satisfied: .

[0049] Specifically, in the radar linear frequency modulation waveform design of the embodiments of the present invention, the radar range resolution of the linear frequency modulation system is... It can be represented as:

[0050]

[0051] in, For frequency modulation bandwidth, The speed of light. To achieve sufficiently high accuracy in radar distance measurement, the frequency modulation bandwidth can be increased. This is done when setting the maximum detection range. At that time, among them This represents the number of sampling points for the radar difference frequency signal. To avoid interference from secondary reflections between the radar and the sea surface, the maximum detection range should satisfy the following relationship:

[0052]

[0053] in, It is the distance between the millimeter-wave radar and the sea surface.

[0054] Specifically, when using a dielectric lens to control the beamwidth of a millimeter-wave radar antenna in this embodiment of the invention, it is necessary to ensure that the beamwidth is narrow enough to improve the single-point range measurement accuracy of the millimeter-wave radar. Commonly used millimeter-wave radar antennas generally have wide beamwidths. When directly used for wave measurement, they measure targets over a large area of ​​the sea surface. When multiple wave targets overlap, it becomes impossible to obtain a single-point wave undulation signal. Therefore, it is necessary to reduce the radar antenna beamwidth to decrease the area illuminated by the radar on the sea surface, thereby improving measurement accuracy. Using a dielectric lens can effectively reduce the radar antenna beamwidth. Based on Fermat's principle and the law of refraction, the surface equation of the single-curved dielectric lens is obtained as follows:

[0055]

[0056] in, For the thickness of the dielectric lens, The radiation aperture of the dielectric lens, The operating frequency of the dielectric lens, Let be the refractive index of the dielectric lens material. A single-curved dielectric lens designed using this equation can reduce the antenna beamwidth.

[0057] Specifically, in this embodiment of the invention, after performing a Discrete Fourier Transform (DFT) on the radar difference frequency data, a Constant False Alarm Rate (CFAR) algorithm is used to detect wave targets, and the number of sampling reference units is set to [number missing]. Then the signal detection threshold can be expressed as:

[0058]

[0059] Where i represents the nth data point selected from the M detection thresholds. This represents the probability of a false alarm. The signal power is within the reference cell. When the signal power is greater than... When the signal power is less than 10, it is identified as a target; when the signal power is less than 10, it is When the target is detected, it is determined to be a non-target. In the range spectrum, the wave target is first detected using the CFAR detection method, and then the spectrum near the wave target is refined using the spectrum refinement algorithm to break through the range resolution limitation, thereby achieving high-precision range estimation of the wave target.

[0060] Specifically, when using the ZoomFFT spectral refinement method to perform high-precision estimation of target distance in this embodiment of the invention, the following steps can be taken: Step 1, the signal... Perform spectrum shifting. Pair the signal with a complex exponential phase factor. Multiply, For relocation frequency, The sampling interval is used to shift the target frequency band to near zero. Step 2 involves applying an anti-aliasing low-pass filter to the frequency-shifted signal to preserve the target frequency band. In the case of quadrature sampling, the cutoff frequency of the low-pass filter can be set to the signal's spectral width. The spectral refinement factor is then... , The sampling frequency is set to [value]. Step 3: Resample the signal. Set the sampling frequency to [value]. After resampling, the signal length is reduced to Step 4: Window the resampled signal and perform an N-point Discrete Fourier Transform by zero-padding to obtain a refined local spectrum, thereby improving the accuracy of distance estimation.

[0061] Specifically, when using a millimeter-wave radar with a linear frequency modulation system, the transmitted signal after antenna radiation... It can be represented as:

[0062]

[0063] in, The angle between the signal and the antenna normal. This is the radiation pattern of the transmitting antenna. For radar transmitter gain, This is the radar's initial frequency modulation frequency. For linear frequency modulation slope, For the signal transmission time, This is the linear frequency modulation time. When the radar signal propagates to the sea surface, the signal is reflected by the sea surface and received by the radar through the receiving antenna. Represented as:

[0064]

[0065] in, For the overall system gain, This is the antenna pattern of the receiving antenna. For signal delay, In order to transmit signals, This is the radiation pattern of the transmitting antenna. It is Gaussian white noise. In radar signal processing, the received and transmitted signals are mixed, and after low-pass filtering, the difference frequency signal is obtained. Then, the sampling frequency is... The analog-to-digital converter performs sampling and quantization to obtain a discrete difference frequency digital signal. After discrete Fourier transform, the signal spectrum is obtained as follows:

[0066]

[0067] in, , , This is the overall system orientation diagram. , , , This indicates a quantitative relationship but has no physical meaning. When radar measures the sea surface, a significant peak will be observed in the signal spectrum. By employing a constant false alarm rate (CFAR) detection algorithm, wave targets can be detected, and then a zoomFFT spectrum refinement algorithm is used to further improve the accuracy of distance measurement.

[0068] Specifically, in this embodiment of the invention, the distance data measured by the millimeter-wave radar sensor is filtered by a low-pass filter to remove high-frequency noise, and then the mean value of the data is removed to obtain wave undulation data. A spectrum analysis method is then used to obtain the effective wave height, effective wave period, and average zero-crossing wave period of the waves. The wave undulation data... Perform power spectral density estimation:

[0069]

[0070] in, The energy normalization factor for the window function. To segment and window the wave fluctuation data, the wave fluctuation data is divided into... For each segment of data, calculate the power spectral density, and then... The power spectral density of the ocean waves is obtained by averaging the power spectral density of the data segments:

[0071]

[0072] Defined by the power spectral density of ocean waves The order moments are as follows:

[0073]

[0074] in, For frequency of Power of 1 and These are the minimum and maximum frequencies of the ocean waves, respectively, using... The moment of the wave can be used to calculate the effective wave height. Effective wave period and average cross-zero wave period :

[0075]

[0076]

[0077]

[0078] in, It is the zeroth moment. For a first-order moment, It is a second moment.

[0079] Specifically, in this embodiment of the invention, the wave undulation data extracted from the distance data measured by each millimeter-wave radar sensor is used to calculate the cross spectrum:

[0080]

[0081] in, Let be the vector difference between the position of the i-th sensor (including radar, and may also include other measuring devices) and the position of the j-th sensor. For the first Fourier transform results of sensor data For the first The conjugate Fourier transform results of the data from multiple sensors are used. By combining this with millimeter-wave radar information and performing an inverse Fourier transform on the cross-spectral results from multiple sensors, the wave direction spectrum can be obtained. :

[0082]

[0083] in, The wave number vector of the ocean waves. It is the set of all sensor position vector differences. Let ω be the angular frequency. By integrating (or summing) the wave direction spectrum along the frequency dimension, the directional distribution of wave energy can be obtained. Further identification of the direction corresponding to the peak value of this directional distribution can be used to estimate the direction of wave propagation.

[0084] Specifically, this embodiment of the invention provides an ocean wave measurement experiment, specifically conducted in a county from June 15th to June 22nd, 2024. The radar was installed at a height of approximately 8m, with a maximum detection range of 15m and an array spacing of 2.1m. Long-term measurements of wave undulation data were performed, and wave undulation data were obtained from the distance measurements taken by the radar. Wave parameters were then analyzed. Figure 4 shows the antenna radiation pattern results, where Figure 4(a) is the horizontal antenna radiation pattern and Figure 4(b) is the vertical antenna radiation pattern. After using a dielectric lens, the radar antenna beamwidth was reduced to within 2.4 degrees, effectively improving the radar's spatial directivity and reducing the illumination area on the sea surface, thereby improving the accuracy of wave measurement. Figure 5The radar range spectrum is obtained by measuring ocean waves with radar. Ocean wave targets are then detected using a cell-average constant false alarm rate (CFAR) detection algorithm, and their distances are extracted. The range spectrum refers to the spectrum of the radar signal after spectral analysis. To identify ocean wave targets from this spectrum, their frequency values ​​are converted into distance values. Therefore, the process involves first detecting ocean wave targets and then using a spectrum refinement method to improve the accuracy of target distance estimation. Figure 6 The wave power spectral density is obtained by performing a piecewise Fourier transform on the wave fluctuation data and then averaging the results. Figure 7 The significant wave height of the ocean waves was calculated using the wave power spectral density. The radar and buoy measurements were compared; during the experimental period, the results were largely consistent, with the radar measurement showing minimal fluctuation. Figure 8 The effective wave period of ocean waves was calculated using the wave power spectral density to obtain the measurement results. The radar and buoy measurement results were compared. During the experimental period, the radar and buoy measurement results were largely consistent, with the radar measurement results showing relatively small fluctuations. Figure 9 The average wave crossing period is calculated from the wave power spectral density. The radar and buoy measurements were compared; during the experimental period, the results were largely consistent, with the radar measurement showing minimal fluctuation. Figure 10 To obtain the directional distribution of ocean waves, the wave direction spectrum is summed along the frequency dimension to obtain the wave energy distribution in different directions, and the main propagation direction of the wave is obtained at its maximum position. Figure 11 The direction of wave propagation was calculated using the wave direction spectrum. The radar measurements were compared with the numerical model results; during the experimental period, the radar and numerical model results were largely consistent.

[0085] Based on this reality, and building upon the above embodiments, the present invention provides a millimeter-wave radar-based wave parameter measurement and analysis system, which is used to execute a millimeter-wave radar-based wave parameter measurement and analysis method from the above method embodiments.

[0086] The system includes: a hardware configuration end, used to construct a millimeter-wave radar sampling array, determine the range resolution and maximum detection range of each millimeter-wave radar, and reduce the beamwidth of the millimeter-wave radar antenna through a dielectric lens; and a data processing end, used to detect ocean wave targets based on radar difference frequency data acquired by the millimeter-wave radar, obtain the distance data between all millimeter-wave radars and ocean wave targets by combining a spectrum refinement method, extract ocean wave undulation data to obtain the effective wave height, effective wave period, and average zero-crossing wave period of the ocean waves, and calculate the cross spectrum based on the ocean wave undulation data of the millimeter-wave radar sampling array, obtain the ocean wave direction spectrum based on the cross spectrum, and then obtain the propagation direction of the ocean waves.

[0087] The wave parameter measurement and analysis system based on millimeter-wave radar provided in this invention addresses the problems of high cost, slow data updates, difficulty in continuous observation, and susceptibility to adverse weather conditions associated with traditional wave measurement methods. It employs several modules, using millimeter-wave radar as the sensor to form a measurement array, and utilizes both vertical and oblique-view measurements to measure ocean waves at designated points. Wave undulation data is obtained by measuring the distance between the ocean surface and the radar, and wave parameters are then derived through wave analysis algorithms. Compared to other measurement methods, this system offers higher measurement accuracy and better real-time performance, making it suitable for scenarios requiring high-precision real-time wave measurement.

[0088] In summary, the present invention provides a method for measuring and analyzing ocean wave parameters based on millimeter-wave radar, comprising the following steps: constructing a millimeter-wave radar sampling array: by constructing a suitable radar sampling array to satisfy the space sampling theorem and The design of the millimeter-wave radar linear frequency modulation waveform was carried out: The range resolution and maximum detection range were determined at different installation heights. The millimeter-wave radar beamwidth was controlled by using a dielectric lens to limit the beamwidth, reducing the radar's illumination area on the sea surface and improving the accuracy of single-point wave undulation measurement. Difference frequency data from the millimeter-wave radar was acquired, and after performing a discrete Fourier transform, a constant false alarm rate (CFAR) detection algorithm was used to detect wave targets. A spectrum refinement algorithm was used to improve the accuracy of distance estimation between the radar and wave targets. Wave undulation data was extracted from the distance between the millimeter-wave radar and wave targets and low-pass filtered. Then, spectral analysis was performed on the wave undulation data over a period of time to calculate the wave power spectrum, obtaining the significant wave height, significant wave period, and average zero-crossing wave period. The cross spectrum of wave undulation data from multiple millimeter-wave radar sensors was calculated, and then a Fourier transform was used to obtain the wave direction spectrum, thereby calculating the wave propagation direction.

[0089] Finally, it should be noted that the above specific embodiments are merely illustrative examples of the present invention. Obviously, the present invention is not limited to the above specific embodiments and many variations are possible. Any simple modifications, equivalent changes, and alterations made to the above specific embodiments based on the technical essence of the present invention should be considered within the protection scope of the present invention.

Claims

1. A method for measuring and analyzing ocean wave parameters based on millimeter-wave radar, characterized in that, include: Construct a millimeter-wave radar sampling array, determine the range resolution and maximum detection range of each millimeter-wave radar, and reduce the beamwidth of the millimeter-wave radar antenna by using a dielectric lens; The range spectrum is calculated based on the radar difference frequency data acquired by millimeter-wave radar. The wave target is detected in the range spectrum, and the range data between all millimeter-wave radars and the wave target is obtained by combining the spectrum refinement method. Based on the distance data between all millimeter-wave radars and ocean wave targets, ocean wave undulation data is extracted and spectrum analysis is performed to obtain the effective wave height, effective wave period and average zero-wave period of the ocean waves. The cross spectrum is calculated based on the wave undulation data of the millimeter-wave radar sampling array. The wave direction spectrum is obtained from the cross spectrum, and then the wave propagation direction is obtained.

2. The method for measuring and analyzing ocean wave parameters based on millimeter-wave radar according to claim 1, characterized in that, The sampling interval of the millimeter-wave radar sampling array satisfies the spatial sampling theorem and is greater than... ,in, The distance between the millimeter-wave radar and the sea surface. This refers to the half-beamwidth of a millimeter-wave radar antenna.

3. The method for measuring and analyzing ocean wave parameters based on millimeter-wave radar according to claim 1, characterized in that, The dielectric lens is a single-curved dielectric lens.

4. The method for measuring and analyzing ocean wave parameters based on millimeter-wave radar according to claim 3, characterized in that, The surface equation of the single-curved dielectric lens is: , in, For the thickness of the dielectric lens, The radiation aperture of the dielectric lens. The operating frequency of the dielectric lens, is the refractive index of the dielectric lens material.

5. The method for measuring and analyzing ocean wave parameters based on millimeter-wave radar according to claim 1, characterized in that, Range spectrum is calculated based on radar difference frequency data acquired by millimeter-wave radar. Ocean wave targets are detected within this range spectrum, including: The range spectrum is obtained by performing a discrete Fourier transform on the radar difference frequency data acquired by the millimeter-wave radar. Based on the distance spectrum, wave targets are detected using a constant false alarm rate (CFAR) detection algorithm.

6. The method for measuring and analyzing ocean wave parameters based on millimeter-wave radar according to claim 1, characterized in that, Based on the distance data between the radar and the ocean wave target, ocean wave undulation data is extracted and spectral analysis is performed to obtain the significant wave height, significant wave period, and average zero-crossing wave period, including: The distance data between the radar and the sea wave target is low-pass filtered and the mean is removed to obtain the sea wave fluctuation data; The wave undulation data is divided into K segments and the power spectral density of each segment is calculated. The wave power spectral density is obtained by averaging the power spectral density of each segment. Defined by ocean wave power spectral density Step moment, using The effective wave height, effective wave period, and average zero-crossing wave period of the ocean waves are obtained by step moment calculation.

7. The method for measuring and analyzing ocean wave parameters based on millimeter-wave radar according to claim 1, characterized in that, The expression for the wave direction spectrum is: , in, Let be the vector difference between the position of the i-th sensor and the position of the j-th sensor. It is the set of all sensor position vector differences. The wave number vector of the ocean waves. Angular frequency, For cross spectrum, This represents the direction spectrum of ocean waves.

8. The method for measuring and analyzing ocean wave parameters based on millimeter-wave radar according to claim 1, characterized in that, The method further includes: obtaining the range resolution and maximum detection range of each millimeter-wave radar by designing a radar linear frequency modulation waveform for each millimeter-wave radar.

9. A wave parameter measurement and analysis system based on millimeter-wave radar, characterized in that, include: On the hardware configuration side, it is used to build a millimeter-wave radar sampling array, determine the range resolution and maximum detection range of each millimeter-wave radar, and reduce the beamwidth of the millimeter-wave radar antenna through a dielectric lens; The data processing unit detects ocean wave targets based on radar difference frequency data acquired by millimeter-wave radar. It combines the spectrum refinement method to obtain the distance data between all millimeter-wave radars and ocean wave targets, and extracts ocean wave undulation data to obtain the effective wave height, effective wave period, and average zero-crossing wave period of the ocean waves. At the same time, it calculates the cross spectrum based on the ocean wave undulation data of the millimeter-wave radar sampling array, obtains the ocean wave direction spectrum based on the cross spectrum, and then obtains the propagation direction of the ocean waves.

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