Sea wave observation method and device based on FMCW millimeter wave MIMO radar

Abstract

The invention relates to the technical field of radar measurement, in particular to a wave observation method and device based on an FMCW millimeter wave MIMO radar, and the method comprises the steps: determining the required radar ranging resolution and ranging range, so as to set the waveform parameters of the frequency-modulated continuous wave millimeter wave MIMO radar; arranging the frequency modulation continuous wave millimeter wave multiple-input multiple-output radar with the waveform parameters set on the observation sea surface according to a preset arrangement requirement so as to measure radar echo data; preprocessing the radar echo data to obtain a radar echo data power spectrum; and processing the radar echo data power spectrum by using a beam forming technology to obtain a wave height time sequence of a sea surface observation point in a required direction, and calculating a sea wave one-dimensional spectrum according to the wave height time sequence of the sea surface observation point in the required direction. Therefore, the problems that a traditional sea wave observation method is complex in operation process, high in instrument manufacturing cost, difficult in instrument arrangement and maintenance, greatly limited by environmental conditions and the like are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of radar measurement, and particularly to a method and device for observing ocean waves based on an FMCW millimeter-wave MIMO radar. Background Art

[0002] At present, ocean wave observation methods can be divided into two types: contact type and non-contact type. The contact type of ocean wave observation method mainly measures by directly contacting the ocean waves. This method usually includes using devices such as buoys and wave gauges. These devices can be directly placed in seawater or fixed at specific positions, and the height, period, direction and other parameters of ocean waves are obtained by recording the sensor data on the devices. The advantage of the contact type method is that the accuracy and reliability of its data are relatively high. The non-contact type of ocean wave observation method mainly relies on remote sensing technology, and this method includes technical means such as satellite remote sensing and radar remote sensing. Satellite remote sensing can provide ocean wave information over a large range, with the characteristics of wide coverage and high update frequency; radar remote sensing can provide high-precision ocean wave information and is suitable for observation under specific regions or specific conditions. All current ocean wave observation methods have a common drawback, that is, the cost of the observation equipment is high, the equipment maintenance cost is high, and it is easily affected by the ocean environment.

[0003] Regarding the drawbacks of the current traditional ocean wave observation methods, there is an urgent need for a new type of non-contact ocean wave observation device. This device should not only be able to adapt to various weather and ocean conditions to achieve stable operation all day and all night, but also a data acquisition and processing method with wide applicability needs to be determined to ensure that accurate ocean wave parameters such as ocean wave spectrum and ocean wave direction spectrum can be obtained. In addition, this device also needs to have advantages such as high economic efficiency, simple installation and good maintainability for wide application. Summary of the Invention

[0004] The present invention provides a method and device for observing ocean waves based on an FMCW (Frequency Modulated Continuous Wave) millimeter-wave MIMO (Multiple-Input Multiple-Output) radar to solve the problems of complex operation process, high cost of instruments, difficulty in instrument installation and maintenance, and large limitation by environmental conditions of the traditional ocean wave observation methods.

[0005] An embodiment of the first aspect of the present invention provides a method for observing ocean waves based on an FMCW millimeter-wave MIMO radar, including the following steps: determining the required radar ranging resolution and ranging range, and setting the waveform parameters of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar according to the radar ranging resolution and the ranging range; placing the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the set waveform parameters on the observation sea surface according to the preset placement requirements to obtain radar echo data; preprocessing the radar echo data to obtain the power spectrum of the radar echo data; using beamforming technology to process the power spectrum of the radar echo data to obtain the wave height time series of the sea surface observation points in the required direction, and calculating the one-dimensional ocean wave spectrum according to the wave height time series of the sea surface observation points in the required direction.

[0006] Optionally, when the ranging range is 1 - 25 m and the wave height accuracy is 5 cm, set the frequency modulation slope of the frequency-modulated continuous-wave signal of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar to 60 MHz / μs, the duration of the frequency-modulated continuous-wave signal to 60 μs, the sampling frequency of the analog-to-digital converter to 10 MSPS, one frame result consists of 16 cycles, 12 transmitting antennas work sequentially in each cycle, and the frame period is 100 ms.

[0007] Optionally, the preset placement requirements are as follows:

[0008] Install the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the set waveform parameters in a wide sea area, and make the RF board of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the set waveform parameters parallel to the sea surface so that the electromagnetic wave irradiates the sea surface vertically;

[0009] The distance between different sea surface observation points is determined according to the placement height and observation angle of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the set waveform parameters, and the distance between any two observation points should be less than 1 / 2 of the observation wavelength.

[0010] Optionally, the preprocessing of the radar echo data to obtain the power spectrum of the radar echo data includes:

[0011] Multiplying the radar echo data by a calibration matrix to obtain calibrated radar echo data;

[0012] Performing a fast Fourier transform on the calibrated radar echo data to obtain the power spectrum of the radar echo data.

[0013] Optionally, the processing of the power spectrum of the radar echo data using beamforming technology to obtain the wave height time series of the sea surface observation points in the required direction and calculating the one-dimensional ocean wave spectrum according to the wave height time series of the sea surface observation points in the required direction includes:

[0014] Extract the maximum value point and its index value in the power spectrum of the radar echo data, and multiply the index value by the radar ranging resolution to obtain the vertical distance between the radar and the sea surface at each observation time;

[0015] Calculate the mean value of the vertical distances between the radar and the sea surface at each observation time to obtain the standard distance between the radar and the sea level;

[0016] Construct a three-dimensional rectangular coordinate system with the standard distance between the radar and the sea level directly below the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set as the origin;

[0017] Based on the three-dimensional rectangular coordinate system, subtract the standard distance between the radar and the sea level from the vertical distances between the radar and the sea surface at each observation time respectively to obtain the wave height time series of the radar vertical points;

[0018] Adopt beamforming technology to enhance the signal intensity in the power spectrum of the radar echo data, obtain the power spectrum after beamforming, and subtract the power spectrum after beamforming from the power spectrum of the radar echo data to obtain the differential power spectrum;

[0019] Extract the maximum value point and its index value in the differential power spectrum, and multiply the index value by the radar ranging resolution to obtain the slant range between the radar and the sea surface observation point in the required direction at each observation time;

[0020] Project the slant range between the radar and the sea surface observation point in the required direction at each observation time onto the z-axis in the three-dimensional rectangular coordinate system to obtain the vertical distance between the radar and the sea surface observation point in the required direction at each observation time;

[0021] Subtract the standard distance between the radar and the sea level from the vertical distances between the radar and the sea surface observation point in the required direction at each observation time respectively to obtain the wave height time series of the sea surface observation point in the required direction;

[0022] Draw the vertical point wave height time series diagram of the wave height time series of the radar vertical points and the wave height time series diagram in the required direction of the wave height time series of the sea surface observation point in the required direction respectively, and perform median filtering on the outliers in the vertical point wave height time series diagram and the wave height time series diagram in the required direction to obtain the filtered vertical point wave height time series diagram and the filtered wave height time series diagram in the required direction;

[0023] Calculate the sea wave parameters according to the filtered vertical point wave height time series diagram and the filtered wave height time series diagram in the required direction;

[0024] Based on the periodogram method, calculate the one-dimensional ocean wave spectrum of each observation point according to the filtered vertical wave height time series diagram and the filtered wave height time series diagram in the required direction.

[0025] Optionally, the expression of the one-dimensional ocean wave spectrum of each observation point is:

[0026]

[0027] where S is the one-dimensional spectrum, ω is the ocean wave frequency, n ∈ [1,..., N], N is the total number of observation point data, Δt is the time interval between two adjacent observation times, and x n is the wave height at the observation time.

[0028] An embodiment of the second aspect of the present invention provides an ocean wave observation device based on an FMCW millimeter-wave MIMO radar, including: a parameter setting module for determining the required radar ranging resolution and ranging range, and setting the waveform parameters of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar according to the radar ranging resolution and the ranging range; an observation module for placing the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set on the observation sea surface to obtain radar echo data; a preprocessing module for preprocessing the radar echo data to obtain the power spectrum of the radar echo data; a calculation module for processing the power spectrum of the radar echo data by using beamforming technology to obtain the wave height time series of the sea surface observation points in the required direction, and calculating the one-dimensional ocean wave spectrum according to the wave height time series of the sea surface observation points in the required direction.

[0029] An embodiment of the third aspect of the present invention provides an electronic device, including: a memory, a processor, and a computer program stored on the memory and executable on the processor, and the processor executes the program to implement the ocean wave observation method based on the FMCW millimeter-wave MIMO radar as described in the above embodiments.

[0030] An embodiment of the fourth aspect of the present invention provides a computer program product, and when the computer program / instructions are executed by a processor, the ocean wave observation method based on the FMCW millimeter-wave MIMO radar as described above is implemented.

[0031] An embodiment of the fifth aspect of the present invention provides a computer-readable storage medium, and the computer-readable storage medium stores a computer program, and when the program is executed by a processor, the ocean wave observation method based on the FMCW millimeter-wave MIMO radar as described above is implemented.

[0032] The method and device for observing ocean waves based on FMCW millimeter-wave MIMO radar proposed in the embodiments of the present invention solve the limitations of traditional ocean wave observation methods, have the characteristics of convenient equipment deployment and strong environmental adaptability, and can realize all-day and all-weather ocean wave observation; compared with the existing millimeter-wave radar ocean wave observation solutions, the present invention can complete high-precision measurement of ocean wave parameters with only a single radar by combining the MIMO radar system and beamforming technology; by optimizing the data processing flow and designing an ocean wave observation point array, the present invention can realize accurate measurement of ocean wave parameters in a more concise manner and successfully invert the one-dimensional ocean wave spectrum, making the FMCW millimeter-wave MIMO radar expected to become a new and efficient device in the field of ocean wave observation; compared with traditional ocean wave observation methods, the solution proposed by the present invention not only has high economic value and strong feasibility, but also has better equipment maintainability and higher measurement accuracy, and is applicable to a variety of marine environment monitoring scenarios.

[0033] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. Description of the Drawings

[0034] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the drawings, where:

[0035] Figure 1 is a flowchart of a method for observing ocean waves based on FMCW millimeter-wave MIMO radar provided by an embodiment of the present invention;

[0036] Figure 2 is a diagram of an ocean surface observation point array provided by a specific embodiment of the present invention;

[0037] Figure 3 is a schematic diagram of the input directional ocean wave spectrum during simulation provided by a specific embodiment of the present invention;

[0038] Figure 4 is a schematic diagram of the simulated ocean surface situation at a certain moment during simulation provided by a specific embodiment of the present invention;

[0039] Figure 5 is a comparison diagram of the output non-directional ocean wave spectrum and the input non-directional ocean wave spectrum during simulation provided by a specific embodiment of the present invention;

[0040] Figure 6 is a time series diagram of the wave surface height at the detection point directly below the radar during the wave-making pool experiment provided by another specific embodiment of the present invention;

[0041] Figure 7Schematic diagram of the undirected ocean wave spectrum output during the wave pool experiment provided by another specific embodiment of the present invention;

[0042] Figure 8 Block diagram of a wave observation device based on FMCW millimeter-wave MIMO radar provided by an embodiment of the present invention;

[0043] Figure 9 Schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. Detailed implementation manners

[0044] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0045] The wave observation method and device based on FMCW millimeter-wave MIMO radar according to the embodiments of the present invention will be described below with reference to the drawings. In view of the problems of the traditional wave observation method mentioned in the above background technology, such as complex operation process, high instrument cost, difficult instrument installation and maintenance, and large limitation by environmental conditions, the present invention provides a wave observation method based on FMCW millimeter-wave MIMO radar, determines a data acquisition and data processing process, and calculates accurate wave parameters and undirected ocean wave spectrum.

[0046] It can be understood that millimeter-wave radar is an advanced technology that uses electromagnetic waves in the millimeter-wave band for detection and measurement. Its main characteristics and advantages lie in high resolution, strong penetration ability, strong anti-interference ability and low power consumption. The high resolution of millimeter-wave radar can ensure that it can accurately measure parameters such as the height, period and wave direction of ocean waves. The strong anti-interference ability enables it to operate normally in a harsh working environment. At the same time, due to the small size of the antenna of millimeter-wave radar, the installation and maintenance difficulty of the equipment is greatly reduced. Therefore, the application of millimeter-wave radar in ocean observation has broad development prospects.

[0047] Specifically, Figure 1 Flow chart of a wave observation method based on FMCW millimeter-wave MIMO radar provided by an embodiment of the present invention.

[0048] As Figure 1 shown, the wave observation method based on FMCW millimeter-wave MIMO radar includes the following steps:

[0049] In step S101, determine the required radar ranging resolution and ranging range, and set the waveform parameters of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar according to the radar ranging resolution and ranging range.

[0050] In some embodiments, when the ranging range is 1 - 25 m and the wave height accuracy is 5 cm, the frequency modulation slope of the frequency modulation continuous wave signal of the frequency modulation continuous wave millimeter wave multiple input multiple output radar is set to 60 MHz / μs, the duration of the frequency modulation continuous wave signal is 60 μs, the sampling frequency of the analog-to-digital converter is 10 MSPS, one frame of results consists of 16 cycles, 12 transmitting antennas work in sequence in each cycle, and the frame period is 100 ms.

[0051] In the actual execution process, the frequency of the radar transmitting signal linearly increases with time. This signal has a certain initial frequency and working frequency band. When the signal frequency reaches the limit of the working frequency band, it will pause working and start linear frequency modulation again from the initial frequency in the next cycle. This signal is also called a linear frequency modulation pulse. The time-frequency relationship of this signal can be expressed by the following formula:

[0052]

[0053] This signal can be expressed as:

[0054]

[0055] In the formula, A represents the amplitude of the transmitting signal, f c is the carrier frequency, t is the sea surface time, B is the modulation bandwidth, is the initial phase of the transmitting signal. Assuming there is a stationary target at a distance R from the radar, then after the radar signal is transmitted, it passes through and is received by the radar receiving antenna. At this time, the echo signal can be expressed as:

[0056]

[0057] In the formula, K r is the object reflection coefficient, w(t) is the additive white Gaussian noise in the radar signal propagation channel, c is the speed of light, and T is the frequency modulation period. After the radar receives the echo signal, the phase of the signal transmitted by the transmitting antenna is shifted by half a period and then mixed with the received echo signal, and the intermediate frequency signal and the accompanying noise can be obtained after passing through a low-pass filter. The intermediate frequency signal can be expressed as:

[0058]

[0059] In actual situations is a small quantity, so the τ 2 term can be ignored, and the above formula can be simplified to:

[0060]

[0061] It can be seen from this that the frequency of the intermediate-frequency signal is related to the distance between the radar and the target. By performing a fast Fourier transform on the sampled discrete intermediate-frequency signal, the discrete spectrum of the intermediate-frequency signal can be obtained, and the distance between the radar and the object can be deduced by analyzing the spectrum.

[0062] When multiple targets appear within the radar beam range, echo signals with different time delays will be generated. After mixing and filtering the echo signals, intermediate-frequency signals with different frequencies will be obtained, and the distance information of different targets can be obtained by analyzing the frequency components of the signals. When using a millimeter-wave radar to observe the sea surface, the distance between the radar and different observation points will be affected by two factors: the signal angle and the sea surface wave height. Therefore, when the beamforming technology is used in the embodiments of the present invention to improve the signal-to-noise ratio at the angle where the observation point is located, the wave height situation at the observation point at this time can be analyzed based on the frequency information of the echo signal.

[0063] To meet the needs of sea surface observation, the waveform parameters of the FMCW millimeter-wave MIMO radar set in the embodiments of the present invention are as follows: the frequency modulation slope of the frequency-modulated continuous-wave signal Chirp is set to 60 MHz / us, the duration of Chirp is 60 us, the sampling frequency of the analog-to-digital converter is 10 MSPS, one frame of results consists of 16 loop cycles, 12 transmitting antennas work in sequence in each loop, the frame period is 100 ms, the number of sampling points for a single chirp is 512 points, the distance resolution of the radar is 5 cm at this time, and the maximum detection distance is 25 m.

[0064] In step S102, the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set is placed on the observed sea surface according to the preset placement requirements to obtain radar echo data.

[0065] In some embodiments, the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set is installed in a wide sea area, and the RF board of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set is parallel to the sea surface, so that electromagnetic waves irradiate the sea surface vertically;

[0066] The distance between different sea surface observation points is determined by the installation height and observation angle of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set, and the distance between any two observation points should be less than 1 / 2 of the observation wavelength.

[0067] In the actual implementation process, an open sea area should be selected during the process of observing ocean waves to avoid the influence of structures such as bridges or ships on the propagation of electromagnetic waves and ocean waves. At the same time, an appropriate installation height should be determined. The distance between different sea surface observation points is determined by the installation height and observation angle of the FMCW millimeter-wave MIMO radar after setting the waveform parameters. The distance between any two observation points is preferably less than 1 / 2 of the main wavelength of the observed ocean waves. The RF board of the FMCW millimeter-wave MIMO radar after setting the waveform parameters should be parallel to the sea level, that is, to make the electromagnetic waves vertically irradiate the sea surface. If there is an inclination in the installation of the FMCW millimeter-wave MIMO radar after setting the waveform parameters, it may affect the measurement accuracy. When the FMCW millimeter-wave MIMO radar after setting the waveform parameters starts to work, the back-end data processing system of the FMCW millimeter-wave MIMO radar after setting the waveform parameters will store the acquired digital discrete intermediate-frequency signals in the solid-state drive of the system according to the frame structure.

[0068] In step S103, the radar echo data is preprocessed to obtain the power spectrum of the radar echo data.

[0069] In some embodiments, preprocessing the radar echo data to obtain the power spectrum of the radar echo data includes:

[0070] Multiplying the radar echo data by a calibration matrix to obtain calibrated radar echo data;

[0071] Performing a fast Fourier transform on the calibrated radar echo data to obtain the power spectrum of the radar echo data.

[0072] In the actual implementation process, due to a series of factors such as the deviation of the antenna distance in the actual evaluation board (which may not be half a wavelength), calibration helps to improve the accuracy of radar ranging to a certain extent. Therefore, in the embodiments of the present invention, the radar echo data is multiplied by a calibration matrix to calibrate the radar echo data; the calibrated data is subjected to a fast Fourier transform to obtain the power spectrum of the radar echo data, thereby completing the preprocessing of the radar echo data.

[0073] In step S104, beamforming technology is used to process the power spectrum of the radar echo data to obtain the wave height time series of the sea surface observation point in the required direction, and the one-dimensional ocean wave spectrum is calculated according to the wave height time series of the sea surface observation point in the required direction.

[0074] In some embodiments, using beamforming technology to process the power spectrum of the radar echo data to obtain the wave height time series of the sea surface observation point in the required direction, and calculating the one-dimensional ocean wave spectrum according to the wave height time series of the sea surface observation point in the required direction includes:

[0075] Extract the maximum value point and its index value in the power spectrum of radar echo data, and multiply the index value by the radar ranging resolution to obtain the vertical distance between the radar and the sea surface at each observation moment;

[0076] Calculate the mean value of the vertical distance between the radar and the sea surface at each observation moment to obtain the standard distance between the radar and the sea level;

[0077] Construct a three-dimensional rectangular coordinate system with the point directly below the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with waveform parameters set as the origin and the standard distance between the radar and the sea level;

[0078] Based on the three-dimensional rectangular coordinate system, subtract the standard distance between the radar and the sea level from the vertical distance between the radar and the sea surface at each observation moment to obtain the wave height time series of the radar vertical point;

[0079] Adopt beamforming technology to enhance the signal intensity in the power spectrum of radar echo data, obtain the power spectrum after beamforming, and subtract the power spectrum after beamforming from the power spectrum of radar echo data to obtain the difference power spectrum;

[0080] Extract the maximum value point and its index value in the difference power spectrum, and multiply the index value by the radar ranging resolution to obtain the slant range between the radar and the sea surface observation point in the required direction at each observation moment;

[0081] Project the slant range between the radar and the sea surface observation point in the required direction at each observation moment onto the z-axis in the three-dimensional rectangular coordinate system to obtain the vertical distance between the radar and the sea surface observation point in the required direction at each observation moment;

[0082] Subtract the standard distance between the radar and the sea level from the vertical distance between the radar and the sea surface observation point in the required direction at each observation moment to obtain the wave height time series of the sea surface observation point in the required direction;

[0083] Respectively plot the vertical point wave height time series graph of the wave height time series of the radar vertical point and the wave height time series graph in the required direction of the wave height time series of the sea surface observation point in the required direction, and perform median filtering on the outliers in the vertical point wave height time series graph and the wave height time series graph in the required direction to obtain the filtered vertical point wave height time series graph and the filtered wave height time series graph in the required direction;

[0084] Calculate the sea wave parameters according to the filtered vertical point wave height time series graph and the filtered wave height time series graph in the required direction;

[0085] Based on the periodogram method, calculate the one-dimensional sea wave spectrum of each observation point according to the filtered vertical point wave height time series graph and the filtered wave height time series graph in the required direction.

[0086] In the actual implementation process, when the radar irradiates the sea surface, each point on the sea surface within the radar beam will generate reflections or scatterings of the radar signal. Therefore, the intermediate-frequency signal processed by the radar includes the distance information between the radar and each point on the sea surface. At the same time, the distance between the radar and different observation points is affected by two factors: the propagation angle of the electromagnetic wave and the sea surface height. Therefore, when the embodiment of the present invention uses beamforming technology to improve the signal-to-noise ratio of the signal at the angle where the observation point is located, the slant range between the radar and the target observation point can be obtained. After obtaining the slant range, the sea surface height can be deduced, and the wave parameters and the omnidirectional wave spectrum in the observation area can be calculated based on the time series of the sea surface height at multiple observation points.

[0087] Therefore, in the embodiment of the present invention, the maximum value point of each frame of the radar echo power spectrum is extracted from the radar echo data power spectrum, and the index value of the maximum value point is multiplied by the radar ranging resolution. The obtained value is the vertical distance between the radar and the sea surface at each observation moment. The average value of the vertical distance between the radar and the sea surface at each observation moment is calculated to obtain the standard distance R between the radar and the sea level. mean 。

[0088] Taking the point at a distance of R directly below the radar mean as the origin, that is, regarded as the sea level point, the line where R mean is located is the z-axis, and the xOy plane is parallel to the sea level. A three-dimensional rectangular coordinate system is established. Subtracting the vertical distance between the radar and the sea surface at each observation moment from the standard distance R mean can obtain the time series of the wave height h of the radar vertical point 1i , i ∈ [1,..., N].

[0089] After obtaining the time series of the wave height of the radar vertical point, it can be plotted through a plotting software to obtain the time series diagram of the wave height of the vertical point, so as to observe the amplitude and period of the sea wave movement.

[0090] Using beamforming technology, the signal intensity of the echo signal in a certain direction in the radar echo data power spectrum is enhanced, and the difference spectrum is obtained by subtracting the power spectrum after beamforming from the total power spectrum of the radar echo data. The maximum value point of the obtained difference spectrum is taken, and the index value of the maximum value point is multiplied by the radar ranging resolution. The obtained value is the slant range between the radar and the sea surface observation point in the required direction at each observation moment. Projecting the slant range onto the z-axis in the three-dimensional rectangular coordinate system gives the vertical distance R' between the radar and the sea surface observation point in the required direction at each observation moment mi , i ∈ [1,..., N], and then subtracting R' mean from the standard distance R mi can obtain the time series of the wave height h of the sea surface observation point in the required direction mi , i ∈ [1,..., N].

[0091] It should be noted that beamforming technology sums up the data collected by each element of the array after linear time-invariant filtering, so as to obtain the beam output. Assume that the received signal x(n) of the array is an M*N-dimensional matrix, where M is the number of array elements and N is the number of sampling points. The beamforming weight vector is an M*1-dimensional vector with respect to . For different azimuth angles and elevation angles, that is, , there are different weight vectors. The beamforming output y(n) can be obtained by the following formula:

[0092]

[0093] Beamforming technology includes various types. The one used in the present invention is conventional beamforming, and the value of conventional beamforming is:

[0094]

[0095] Among them, is the steering vector, and M is the number of array elements. Conventional beamforming is also called delay-and-sum beamforming. When a far-field signal is incident on the array, time delays are generated among the elements due to different spatial arrangements. Conventional beamforming performs the opposite time-delay compensation and then sums them up, so that the signals in the desired direction are in-phase superimposed, while the noise and interference are not in-phase superimposed, thereby improving the output signal-to-noise ratio. For each , the beamforming output result in its direction can be obtained. After obtaining the beamforming output result, its power spectrum is calculated and subtracted from the power spectrum of the radar echo data to obtain the difference power spectrum. The significance of calculating the difference power spectrum is to further remove the interference information in other directions. Since beamforming improves the signal-to-noise ratio in a specific direction, it will be more obvious in the difference spectrum.

[0096] After obtaining the wave height time series of the sea surface observation point in the required direction, the wave height time series diagram in the required direction can be drawn by a drawing software, and the outliers in the vertical point wave height time series diagram and the wave height time series diagram in the required direction are median-filtered to obtain the filtered vertical point wave height time series diagram and the filtered wave height time series diagram in the required direction.

[0097] Furthermore, according to the filtered vertical point wave height time series diagram and the filtered wave height time series diagram in the required direction, sea wave parameters are calculated, where the sea wave parameters include significant wave height, dominant wave period, etc.

[0098] Among them, the significant wave height is the actual wave height value statistically calculated according to certain rules. Since the sea surface waves are actually an irregular combination of various waves with different wave heights, periods, and advancing directions, the wave height value of a single wave is not representative. The calculation formula of the significant wave height is:

[0099]

[0100] Among them, SWH is the significant wave height, h 1i is the wave height data at the point directly below the radar, N is the total number of data at the observation point, and i ∈ [1,..., N].

[0101] The dominant wave period represents the period of the main components of the measured sea waves. Its calculation method is to obtain the peak point in the one-dimensional spectrum of the sea waves, and the frequency corresponding to the peak point is the dominant wave frequency f main , then the dominant wave period T main can be expressed as:

[0102]

[0103] Finally, based on the periodogram method, the one-dimensional spectrum of the sea waves at each observation point is calculated according to the filtered vertical point wave height time series diagram and the filtered wave height time series diagram in the required direction, and the average value of the spectra at multiple points is taken as the one-dimensional spectrum of the sea waves in the observation area.

[0104] It should be noted that the periodogram method is specifically manifested as follows: in the discrete-time sea surface observation, assuming that the time interval between two adjacent observation times is Δt, then the one-dimensional spectrum of the sea waves can be expressed as:

[0105]

[0106] Among them, S is the one-dimensional spectrum, ω is the sea wave frequency, x n is the wave height at the observation time, n ∈ [1,..., N], N is the total number of data at the observation point, and since the calculation result is a discrete spectral value, so r is an integer, then the above formula can be sorted out as:

[0107]

[0108] Among them, then the above formula can be expressed as:

[0109]

[0110] Thus, the one-dimensional spectrum of the observed sea waves can be calculated from the wave height data through the fast Fourier transform.

[0111] In the embodiment of the present invention, the frame duration of the FMCW millimeter-wave MIMO radar is 100 milliseconds. Thus, it can be considered that the observation frequency of the FMCW millimeter-wave MIMO radar for the sea surface is 10 Hz, while the frequencies of ocean waves mostly concentrate between 0.1 - 0.3 Hz. It can be seen that the observation frequency of the FMCW millimeter-wave MIMO radar is slightly higher, and more calculation points are required to meet the accuracy requirements of the FFT. Therefore, in the embodiment of the present invention, the wave height data will be grouped before calculating the fast Fourier transform. The specific implementation steps are as follows:

[0112] Data can be divided into groups at intervals of 3 points. In this way, for a single observation point, the data can be divided into 4 groups, namely

[0113]

[0114] After such implementation, the observation frequency of the FMCW millimeter-wave MIMO radar is reduced to 2.5 Hz. At this time, a relatively small number of observation points can be used to achieve a high ocean wave frequency resolution. After performing the fast Fourier transform on each group of data, the average of the results of the four groups can be used as the discrete spectrum of this observation point.

[0115] The feasibility of the ocean wave observation method based on the FMCW millimeter-wave MIMO radar proposed in the embodiment of the present invention will be analyzed through two specific simulation embodiments below.

[0116] A total of nine points of observation data are obtained by using the beamforming technology mentioned above. The array layout of the observation points is as Figure 2 shown, including a point directly below the radar, and the other eight points are arranged in a square, with a distance of 1 meter between each adjacent two points.

[0117] Based on Figure 2 the array layout of the observation points therein, the input directional ocean wave spectrum is obtained by using the JONSWAP ocean wave spectrum and the Longuet - Higgins direction distribution function. Then, the simulation sea surface is obtained by the single superposition method for the input directional ocean wave spectrum. The input directional ocean wave spectrum and the simulation sea surface situation at a certain moment are as Figure 3 and 4 shown. After obtaining the simulation sea surface, the specific positions of the observation points are determined according to the array layout of the observation points, and the time series of the wave height at these observation points are recorded. After obtaining the wave height data of these observation points, the data is analyzed according to the process. First, the significant wave height is calculated for the wave height time series obtained from the eight observation points respectively, and then the average value of the significant wave heights obtained from the eight points is taken as the result output. Secondly, the non - directional ocean wave spectrum is calculated for the wave height time series obtained from the eight observation points respectively by the periodogram method, and then the average value of the non - directional ocean wave spectra obtained from the eight points is taken as the non - directional ocean wave spectrum result output. The output non - directional ocean wave spectrum is as Figure 5As shown, by comparing it with the input undirected ocean wave spectrum, the overall error is within 1%, which shows that the inversion effect of the undirected ocean wave spectrum is better.

[0118] Secondly, the proposed wave spectrum inversion scheme is verified through the wave pool experiment. First, a high platform is built 15 meters above the pool and a radar is installed. The radar is started and the wave pool starts working. First, the wave height within the observation point is detected. The wave height time series diagram of the detection center point is shown in the figure below. Figure 6 As shown in the figure, it can be seen that there are obvious wave fluctuations. Then the one-dimensional wave spectrum is calculated based on the observation results of multiple points. The calculation results are shown in the attached figure. Figure 7 As shown in the figure, the spectrum has a peak at 0.20 Hz, which means the main wave period of the ocean wave is 5 s, which is consistent with the wave-making situation. By analyzing the experimental results of the wave pool, it can be seen that the use of FMCW millimeter-wave MIMO radar for ocean wave observation and wave spectrum inversion has a certain degree of reliability.

[0119] In summary, the ocean wave observation method based on FMCW millimeter wave MIMO radar proposed in the embodiment of the present invention has the following beneficial effects:

[0120] (1) It solves the limitations of traditional wave observation methods, has the characteristics of convenient equipment deployment and strong environmental adaptability, and can realize all-day and all-weather wave observation;

[0121] (2) Compared with the existing millimeter wave radar wave observation scheme, the present invention can complete high-precision measurement of wave parameters using only a single radar by combining the MIMO radar system and beamforming technology;

[0122] (3) By optimizing the data processing flow and designing the wave observation point array, the present invention can achieve accurate measurement of wave parameters in a simpler way and successfully invert the one-dimensional wave spectrum, making FMCW millimeter wave MIMO radar a new type of efficient equipment in the field of wave observation;

[0123] (4) Compared with traditional wave observation methods, the scheme proposed in the present invention not only has higher economic value and stronger feasibility, but also has better equipment maintainability and higher measurement accuracy, and is suitable for a variety of marine environment monitoring scenarios.

[0124] Next, a wave observation device based on FMCW millimeter wave MIMO radar proposed according to an embodiment of the present invention is described with reference to the accompanying drawings.

[0125] Figure 8 It is a block diagram of an ocean wave observation device based on FMCW millimeter wave MIMO radar according to an embodiment of the present invention.

[0126] like Figure 8As shown, the sea wave observation device 80 based on the FMCW millimeter-wave MIMO radar includes: a parameter setting module 801, an observation module 802, a preprocessing module 803, and a calculation module 804.

[0127] Among them, the parameter setting module 801 is used to determine the required radar ranging resolution and ranging range, and set the waveform parameters of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar according to the radar ranging resolution and ranging range. The observation module 802 is used to place the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set on the observation sea surface to measure the radar echo data. The preprocessing module 803 is used to preprocess the radar echo data to obtain the power spectrum of the radar echo data. The calculation module 804 is used to process the power spectrum of the radar echo data by using beamforming technology to obtain the wave height time series of the sea surface observation points in the required direction, and calculate the one-dimensional sea wave spectrum according to the wave height time series of the sea surface observation points in the required direction.

[0128] In some embodiments, when the ranging range is 1 - 25m and the wave height accuracy is 5cm, the frequency modulation slope of the frequency-modulated continuous-wave signal of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar is set to 60MHz / us, the duration of the frequency-modulated continuous-wave signal is 60us, the sampling frequency of the analog-to-digital converter is 10MSPS, one frame result consists of 16 cycles, 12 transmitting antennas work sequentially in each cycle, and the frame period is 100ms.

[0129] In some embodiments, the preset placement requirements are:

[0130] Install the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set in a wide sea area, and make the RF board of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set parallel to the sea surface so that the electromagnetic wave irradiates the sea surface vertically;

[0131] The distance between different sea surface observation points is determined according to the installation height and observation angle of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set, and the distance between any two observation points should be less than 1 / 2 of the observation wavelength.

[0132] In some embodiments, the preprocessing module 803 includes:

[0133] A calibration unit, which is used to multiply the radar echo data by a calibration matrix to obtain the calibrated radar echo data;

[0134] A transformation unit, which is used to perform a fast Fourier transform on the calibrated radar echo data to obtain the power spectrum of the radar echo data.

[0135] In some embodiments, the calculation module 804 includes:

[0136] The first extraction unit is used to extract the maximum value point and its index value in the power spectrum of the radar echo data, and multiply its index value by the radar ranging resolution to obtain the vertical distance between the radar and the sea surface at each observation moment;

[0137] The mean value unit is used to calculate the mean value of the vertical distance between the radar and the sea surface at each observation moment to obtain the standard distance between the radar and the sea level;

[0138] The construction unit is used to construct a three-dimensional rectangular coordinate system with the standard distance between the radar directly below the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set as the origin;

[0139] The first difference unit is used to, based on the three-dimensional rectangular coordinate system, subtract the standard distance between the radar and the sea level from the vertical distance between the radar and the sea surface at each observation moment to obtain the wave height time series of the vertical point of the radar;

[0140] The second difference unit is used to use beamforming technology to enhance the signal intensity in the power spectrum of the radar echo data, obtain the power spectrum after beamforming, and subtract the power spectrum after beamforming from the power spectrum of the radar echo data to obtain the difference power spectrum;

[0141] The second extraction unit is used to extract the maximum value point and its index value in the difference power spectrum, and multiply its index value by the radar ranging resolution to obtain the slant range between the radar and the sea surface observation point in the required direction at each observation moment;

[0142] The projection unit is used to project the slant range between the radar and the sea surface observation point in the required direction at each observation moment onto the z-axis in the three-dimensional rectangular coordinate system to obtain the vertical distance between the radar and the sea surface observation point in the required direction at each observation moment;

[0143] The third difference unit is used to subtract the standard distance between the radar and the sea level from the vertical distance between the radar and the sea surface observation point in the required direction at each observation moment to obtain the wave height time series of the sea surface observation point in the required direction;

[0144] The plotting unit is used to plot the vertical point wave height time series graph of the wave height time series of the vertical point of the radar and the wave height time series graph in the required direction of the wave height time series of the sea surface observation point in the required direction respectively, and perform median filtering on the outliers in the vertical point wave height time series graph and the wave height time series graph in the required direction to obtain the filtered vertical point wave height time series graph and the filtered wave height time series graph in the required direction;

[0145] The calculation parameter unit is used to calculate the sea wave parameters according to the filtered vertical point wave height time series graph and the filtered wave height time series graph in the required direction;

[0146] The spectrum calculation unit is used to calculate the one-dimensional spectrum of the waves at each observation point based on the filtered vertical point wave height time series diagram and the filtered wave height time series diagram in the required direction based on the periodogram method.

[0147] In some embodiments, the expression of the one-dimensional spectrum of the waves at each observation point is:

[0148]

[0149] Where S is the one-dimensional spectrum, ω is the wave frequency, n∈[1,...,N], N is the total number of observation point data, Δt is the time interval between two adjacent observation times, x n is the wave height at the time of observation.

[0150] It should be noted that the aforementioned explanation of the embodiment of the ocean wave observation method based on FMCW millimeter wave MIMO radar is also applicable to the ocean wave observation device based on FMCW millimeter wave MIMO radar in this embodiment, and will not be repeated here.

[0151] The ocean wave observation device based on FMCW millimeter wave MIMO radar proposed in an embodiment of the present invention has the following features:

[0152] Beneficial effects:

[0153] (1) It solves the limitations of traditional wave observation methods, has the characteristics of convenient equipment deployment and strong environmental adaptability, and can realize all-day and all-weather wave observation;

[0154] (2) Compared with the existing millimeter wave radar wave observation scheme, the present invention can complete high-precision measurement of wave parameters using only a single radar by combining the MIMO radar system and beamforming technology;

[0155] (3) By optimizing the data processing flow and designing the wave observation point array, the present invention can achieve accurate measurement of wave parameters in a simpler way and successfully invert the one-dimensional wave spectrum, making FMCW millimeter wave MIMO radar a new type of efficient equipment in the field of wave observation;

[0156] (4) Compared with traditional wave observation methods, the scheme proposed in the present invention not only has higher economic value and stronger feasibility, but also has better equipment maintainability and higher measurement accuracy, and is suitable for a variety of marine environment monitoring scenarios.

[0157] Figure 9 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. The electronic device may include:

[0158] A memory 901, a processor 902, and a computer program stored on the memory 901 and executable on the processor 902.

[0159] When the processor 902 executes the program, it implements the method for observing ocean waves based on an FMCW millimeter-wave MIMO radar provided in the above embodiments.

[0160] Furthermore, the electronic device further includes:

[0161] A communication interface 903 for communication between the memory 901 and the processor 902.

[0162] The memory 901 is used to store a computer program that can run on the processor 902.

[0163] The memory 901 may include a high-speed RAM memory, and may also include a non-volatile memory, such as at least one disk memory.

[0164] If the memory 901, the processor 902, and the communication interface 903 are implemented independently, the communication interface 903, the memory 901, and the processor 902 can be interconnected through a bus to complete communication with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For the sake of representation, Figure 9 only a thick line is used to represent it in the figure, but it does not mean that there is only one bus or one type of bus.

[0165] Optionally, in a specific implementation, if the memory 901, the processor 902, and the communication interface 903 are integrated on a chip, the memory 901, the processor 902, and the communication interface 903 can complete communication with each other through an internal interface.

[0166] The processor 902 may be a Central Processing Unit (CPU), or an Application Specific Integrated Circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present invention.

[0167] An embodiment of the present invention also provides a computer program product. When the computer program / instructions are executed by a processor, the above-mentioned method for observing ocean waves based on an FMCW millimeter-wave MIMO radar is implemented.

[0168] An embodiment of the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, the above-mentioned method for observing ocean waves based on an FMCW millimeter-wave MIMO radar is implemented.

[0169] In the description of this specification, the descriptions referring to terms such as "an embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0170] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "N" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0171] Any process or method description in the flowchart or described in other ways herein can be understood to represent a module, segment, or part of code including one or N executable instructions for implementing a customized logic function or process. The scope of the preferred embodiments of the present invention includes additional implementations, where the functions can be executed in a substantially simultaneous manner or in a reverse order according to the involved functions, rather than in the order shown or discussed. This should be understood by those skilled in the art to which the embodiments of the present invention belong.

[0172] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a definite sequence list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device), or in conjunction with these instruction execution systems, apparatus, or devices. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in conjunction with an instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of computer-readable media include the following: an electrical connection part (electronic device) having one or N wirings, a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically by optically scanning the paper or other media, followed by editing, interpretation, or otherwise processing as appropriate, and then stored in a computer memory.

[0173] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. If implemented in hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application specific integrated circuits having suitable combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

[0174] Those of ordinary skill in the art of this technology can understand that all or part of the steps carried by the methods of the above embodiments can be completed by instructing relevant hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments.

[0175] In addition, each functional unit in various embodiments of the present invention may be integrated into a processing module, or each unit may exist physically alone, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. When the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0176] The above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disc, etc. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for observing ocean waves based on an FMCW millimeter-wave MIMO radar, characterized in that It includes the following steps: Determine the required radar ranging resolution and ranging range, and set the waveform parameters of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar according to the radar ranging resolution and the ranging range; Place the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set according to the preset placement requirements on the observed sea surface to obtain radar echo data; Preprocess the radar echo data to obtain the power spectrum of the radar echo data; Use beamforming technology to process the power spectrum of the radar echo data to obtain the wave height time series of the sea surface observation points in the required direction, and calculate the one-dimensional spectrum of ocean waves according to the wave height time series of the sea surface observation points in the required direction.

2. The method for observing ocean waves based on an FMCW millimeter-wave MIMO radar according to claim 1, wherein When the ranging range is 1 - 25m and the wave height accuracy is 5cm, set the frequency modulation slope of the frequency-modulated continuous-wave signal of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar to 60MHz / us, the duration of the frequency-modulated continuous-wave signal to 60us, the sampling frequency of the analog-to-digital converter to 10MSPS, one frame result consists of 16 cycles, 12 transmitting antennas work sequentially in each cycle, and the frame period is 100ms.

3. The method for observing ocean waves based on FMCW millimeter-wave MIMO radar according to claim 1, characterized in that The preset placement requirements are as follows: Install the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set in a wide sea area, and make the RF board of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set parallel to the sea surface so that the electromagnetic wave irradiates the sea surface vertically; The distance between different sea surface observation points is determined according to the installation height and observation angle of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set, and the distance between any two observation points should be less than 1 / 2 of the observation wavelength.

4. The method for observing ocean waves based on an FMCW millimeter-wave MIMO radar according to claim 1, characterized in that, The preprocessing of the radar echo data to obtain the power spectrum of the radar echo data includes: Multiply the radar echo data by the calibration matrix to obtain the calibrated radar echo data; Perform a fast Fourier transform on the calibrated radar echo data to obtain the power spectrum of the radar echo data.

5. The method for observing ocean waves based on an FMCW millimeter-wave MIMO radar according to claim 1, wherein The use of beamforming technology to process the power spectrum of the radar echo data to obtain the wave height time series of the sea surface observation points in the required direction, and calculate the one-dimensional spectrum of ocean waves according to the wave height time series of the sea surface observation points in the required direction includes: Extract the maximum value points and their index values in the power spectrum of the radar echo data, and multiply the index values by the radar ranging resolution to obtain the vertical distance between the radar and the sea surface at each observation moment; Perform a mean calculation on the vertical distances between the radar and the sea surface at each observation moment to obtain the standard distance between the radar and the sea level; Construct a three-dimensional rectangular coordinate system with the standard distance between the radar directly below the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set and the sea level as the origin; Based on the three-dimensional rectangular coordinate system, subtract the standard distance between the radar and the sea level from the vertical distances between the radar and the sea surface at each observation moment respectively to obtain the wave height time series of the radar vertical points; The beamforming technology is adopted to enhance the signal intensity in the power spectrum of the radar echo data, obtaining the power spectrum after beamforming, and subtracting the power spectrum after beamforming from the power spectrum of the radar echo data to obtain the differential power spectrum; The maximum value point and its index value in the differential power spectrum are extracted, and the index value is multiplied by the radar ranging resolution to obtain the slant range between the radar and the sea surface observation point in the required direction at each observation time; The slant range between the radar and the sea surface observation point in the required direction at each observation time is projected onto the z-axis in the three-dimensional rectangular coordinate system to obtain the vertical distance between the radar and the sea surface observation point in the required direction at each observation time; The standard distance between the radar and the sea surface is subtracted from the vertical distance between the radar and the sea surface observation point in the required direction at each observation time to obtain the wave height time series of the sea surface observation point in the required direction; The vertical point wave height time series diagram of the wave height time series of the radar vertical point and the wave height time series diagram in the required direction of the wave height time series of the sea surface observation point in the required direction are respectively plotted, and the outliers in the vertical point wave height time series diagram and the wave height time series diagram in the required direction are median filtered to obtain the filtered vertical point wave height time series diagram and the filtered wave height time series diagram in the required direction; The sea wave parameters are calculated according to the filtered vertical point wave height time series diagram and the filtered wave height time series diagram in the required direction; Based on the periodogram method, the one-dimensional sea wave spectrum of each observation point is calculated according to the filtered vertical point wave height time series diagram and the filtered wave height time series diagram in the required direction; 6. The method for observing ocean waves based on an FMCW millimeter-wave MIMO radar according to claim 5, characterized in that The expression of the one-dimensional sea wave spectrum of each observation point is: Where S is the one-dimensional spectrum, ω is the ocean wave frequency, n ∈ [1,..., N], N is the total number of data at the observation points, Δt is the time interval between two adjacent observation times, and x n is the wave height at the observation time.

7. A sea wave observation device based on an FMCW millimeter-wave MIMO radar, characterized in that, Including: A parameter setting module, used to determine the required radar ranging resolution and ranging range, and set the waveform parameters of the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar according to the radar ranging resolution and the ranging range; An observation module, used to place the frequency-modulated continuous-wave millimeter-wave multiple-input multiple-output radar with the waveform parameters set on the observation sea surface to measure the radar echo data; A preprocessing module, used to preprocess the radar echo data to obtain the power spectrum of the radar echo data; A calculation module, used to process the power spectrum of the radar echo data by using the beamforming technology to obtain the wave height time series of the sea surface observation point in the required direction, and calculate the one-dimensional sea wave spectrum according to the wave height time series of the sea surface observation point in the required direction; 8. An electronic device, characterized in that, Including: A memory, a processor, and a computer program stored on the memory and executable on the processor, and the processor executes the program to implement the sea wave observation method based on the FMCW millimeter-wave MIMO radar according to any one of claims 1-6; 9. A computer program product, characterized in that, When the computer program / instructions are executed by the processor, the sea wave observation method based on the FMCW millimeter-wave MIMO radar according to any one of claims 1-6 is implemented; 10. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to be used to implement the sea wave observation method based on the FMCW millimeter-wave MIMO radar according to any one of claims 1-6.

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