Radar sea wave monitoring method and device

Abstract

The invention discloses a radar sea wave monitoring method and device, the device comprises a radar and a radar image analyzing and processing module, sea wave images are collected through the radar, sea wave image data are analyzed and processed through the radar image analyzing and processing module, and wave elements are calculated through two-dimensional wave spectrums of sea wave radar echoes and correlation of the two-dimensional wave spectrums. According to the radar sea wave monitoring method and device, image data are collected through the radar, data processing and calculation are achieved through the computer, systematization, numeralization, imaging, business, networking, intelligentization, unattended operation, real-time display and full-automatic radar sea wave monitoring of sea wave information are achieved, and precision is improved.

Description

Technical Field

[0001] The invention relates to the technical field of marine environment monitoring. Background Art

[0002] Due to the influence of extreme weather, large wave disasters at sea (storm surges, typhoons) are becoming more frequent and severe, and my country has put forward higher requirements for the monitoring of marine environmental waves in coastal waters. Real-time monitoring of waves is one of the important contents of today's marine environmental monitoring, forecasting, early warning and emergency disaster management.

[0003] Ocean waves are one of the forms of seawater movement. They are the result of the combined effects of external forces, gravity and the surface tension of seawater. The study of ocean waves is of great significance to marine engineering construction, marine development, transportation and shipping, marine fishing and aquaculture. Ocean waves in a narrow sense are a general term for wind waves, swells and nearshore waves. Ocean waves in a broad sense also include tsunamis, storm surges and internal ocean waves formed by external and internal forces such as celestial gravity, submarine earthquakes, volcanic eruptions, collapse and landslides, changes in atmospheric pressure and uneven distribution of seawater density, which can cause huge fluctuations in seawater.

[0004] At present, the main means of monitoring ocean waves in the world are still monitoring by ocean vessels, ocean buoy stations, shore and island ocean stations. There are 6 types of commonly used wave observation instruments: (1) line-of-sight wave meter, also called optical wave meter; (2) knife resistance and capacitance wave meter; (3) pressure wave meter; (4) acoustic wave meter; (5) gravity wave meter; (6) remote sensing wave meter. However, there is still a long way to go to provide accurate wave information quickly over a large area. Summary of the invention

[0005] In order to improve the accuracy of ocean wave information monitoring, the present invention provides a radar ocean wave monitoring method and device.

[0006] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: a radar wave monitoring method, comprising the following steps:

[0007] S1: Ocean wave image acquisition, collecting ocean wave images through radar;

[0008] S2: Analysis and processing of wave image data, converting the two-dimensional wave echo image data from the spatial domain to the frequency domain for analysis; S3: Calculation of wave elements, calculating the wave elements through the two-dimensional spectrum of the wave radar echo and its correlation.

[0009] In step S2, assuming that g(x, y) represents two-dimensional wave echo data, its two-dimensional Fourier transform can be expressed as:

[0010]

[0011] u, v represent wave numbers, u=0,1,2……N-1; v=0,1,2……M-1, j is the sequence unit;

[0012] Its two-dimensional energy spectrum is described as:

[0013]

[0014] represents the conjugate complex number of G(u,v);

[0015] The continuous scanning results of the wave data are obtained, and the cross-power spectrum is obtained by the following formula:

[0016]

[0017] G 1 (u,v),G 2 (u, v) are two continuously observed wave echo signals;

[0018] The autocorrelation function and cross-correlation function are obtained by inverse Fourier transform of the energy spectrum and cross-power spectrum, respectively:

[0019] Autocorrelation function:

[0020]

[0021] Cross-correlation function:

[0022]

[0023] In step S2, the wave data is first subjected to original filtering using median filtering, and the median of the pixel values ​​within the filtering window is selected as the output, and the mathematical formula is as follows:

[0024] g(x,y)=median{f(s,t):(s,t)∈Sxy}

[0025] Among them, g(x,y) is the pixel value of the filtered image at point (x,y),

[0026] f(x,t) is the pixel value of the original image at point (x,t),

[0027] Sxy is the filter window centered at (x,y).

[0028] In step S3, the wave elements are calculated by the two-dimensional spectrum of the wave radar echo and its correlation:

[0029] 1) Wavelength:

[0030]

[0031] Dl is the radar range resolution, N is the image data size;

[0032] 2) Wave direction:

[0033]

[0034] 3) The wave speed is obtained by the cross-correlation function of the wave images at two consecutive moments:

[0035]

[0036] T is the radar antenna scanning period;

[0037] 4) Wave height W H The wave height is obtained from the two-dimensional energy spectrum of the wave image.

[0038] A radar wave monitoring device, comprising:

[0039] Radar, the radar is connected to the radar image analysis and processing module through a communication interface to collect sea wave images;

[0040] The radar image analysis and processing module is used to convert the two-dimensional wave echo image data from the spatial domain to the frequency domain for analysis and to calculate the wave elements.

[0041] It also includes a radar wave image measurement recorder, the radar is connected to the radar wave image measurement recorder through a communication interface, and the radar wave image measurement recorder is connected to the radar image analysis and processing module through the communication interface.

[0042] The radar image analysis and processing module includes a spatial filtering module, which is connected to the ocean wave pattern display module for displaying an ocean wave pattern diagram.

[0043] The radar image analysis and processing module is connected to the ocean wave real-time display module for displaying the ocean wave measured image.

[0044] The radar image analysis and processing module is connected to the storage module and the printing module.

[0045] The radar wave monitoring method and device of the present invention collect image data through radar, and realize data processing and calculation through computer, so as to realize systematization, numeration, visualization, businessization, networking, intelligence, unattended, real-time display, and fully automated radar wave monitoring of wave information, with an accuracy of up to ±10%. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the radar wave monitoring system of the present invention;

[0047] Figure 2 It is a flow chart of the radar wave monitoring method of the present invention;

[0048] Figure 3It is the PPI map of sea waves collected by radar;

[0049] Figure 4 It is the distribution diagram of wave energy spectrum in spatial domain;

[0050] Figure 5 It is the frequency domain distribution diagram of wave energy spectrum;

[0051] Figure 6 It is the wave height map calculated from the power spectrum;

[0052] Figure 7 is the wavelength map calculated from the power spectrum;

[0053] Figure 8 is the wave direction diagram calculated by the cross power spectrum;

[0054] Fig. 9 is the wave velocity diagram calculated by the cross-correlation function. DETAILED DESCRIPTION

[0055] The radar wave monitoring device of the present invention is as follows Figure 1 As shown, including:

[0056] The radar is connected to the radar wave image measurement recorder through the communication interface, and the radar wave image measurement recorder is connected to the radar image analysis and processing module through the communication interface to collect wave images. The radar adopts an X-band special sea measurement radar with an accuracy of ±10%.

[0057] The radar image analysis and processing module consists of three functional modules:

[0058] (1) Computer and radar wave image acquisition real-time control module to realize the control of radar image acquisition;

[0059] (2) Statistical processing of wave image data and its feature extraction module, which is used to convert the two-dimensional wave echo image data from the spatial domain to the frequency domain for analysis and to calculate the wave elements;

[0060] (3) Module for displaying, saving and transmitting ocean wave elements.

[0061] The module for statistical processing of ocean wave image data and its feature extraction includes a spatial filtering module for image preprocessing, which is connected to the ocean wave pattern display module for displaying the ocean wave pattern diagram. The module for statistical processing of ocean wave image data and its feature extraction is connected to the ocean wave real-time display module for displaying the measured ocean wave diagram. The module for statistical processing of ocean wave image data and its feature extraction is connected to the storage module and the printing module.

[0062] The radar wave digital image is collected and processed through spatial filtering to obtain the radar wave pattern diagram. The wave height, wave direction, period, wave speed and other wave elements are calculated through computer programs (two-dimensional spectrum analysis and data processing). The whole process from radar wave image data collection, statistical processing, feature extraction to the storage, display and transmission of the final calculation results is automated and completed automatically by computer control.

[0063] The radar wave monitoring method of the present invention is as follows Figure 2 As shown, the following steps are included:

[0064] S1: Ocean wave image acquisition, collecting ocean wave images through radar;

[0065] S2: Analysis and processing of wave image data, converting the two-dimensional wave echo image data from the spatial domain to the frequency domain for analysis. The wave radar echo signal can be regarded as a two-dimensional sequence in space. In order to extract the wave information (wavelength, wave height, wave direction, wave speed), the two-dimensional wave echo image data is converted from the spatial domain to the frequency domain for analysis.

[0066] First, raw filtering is required before calculating the wave data:

[0067] The wave data is first processed by the median filter, and the median of the pixel values ​​in the filter window is selected as the output. The mathematical formula is as follows:

[0068] g(x,y)=median{f(s,t):(s,t)∈Sxy}

[0069] Among them, g(x,y) is the pixel value of the filtered image at point (x,y),

[0070] f(x,t) is the pixel value of the original image at point (x,t),

[0071] Sxy is the filter window centered at (x,y).

[0072] Assuming that g(x,y) represents two-dimensional wave echo data, its two-dimensional Fourier transform can be expressed as:

[0073]

[0074] u, v represent wave numbers, u=0,1,2……N-1; v=0,1,2……M-1, j is the sequence unit;

[0075] Its two-dimensional energy spectrum (auto-power spectrum) is described as:

[0076]

[0077] represents the conjugate complex number of G(u,v);

[0078] The continuous scanning results of the wave data are obtained, and the cross-power spectrum is obtained by the following formula:

[0079]

[0080] G 1 (u,v),G 2 (u, v) are two continuously observed wave echo signals;

[0081] The autocorrelation function and cross-correlation function are obtained by inverse Fourier transform of the energy spectrum and cross-power spectrum respectively:

[0082] Autocorrelation function:

[0083]

[0084] Cross-correlation function:

[0085]

[0086] S3: Calculation of wave elements: Calculation of wave elements through the two-dimensional spectrum of wave radar echo and its correlation.

[0087] 1) Wavelength:

[0088]

[0089] dl is the radar range resolution, and the radar used in the present invention has dl=15m. N is the image data size, which can be selected from 256×256, 128×128, etc.;

[0090] 2) Wave direction:

[0091]

[0092] The actual wave direction cannot be obtained from the energy spectrum alone, but it can be identified through the cross-power spectrum of the wave radar images at two consecutive moments.

[0093] 3) The wave speed is obtained by the cross-correlation function of the wave images at two consecutive moments:

[0094]

[0095] T is the scanning period of the radar antenna, and in the invention, T is 2.4s. The wave velocity is obtained by the cross-correlation function of the wave images at two consecutive moments.

[0096] 4) Wave height W H The wave height is obtained from the two-dimensional energy spectrum of the wave image.

[0097] Figure 3This is a PPI wave image collected by radar (which has been enhanced). The striped waves can be clearly seen from it. Figure 4 It is a two-dimensional image wave energy spectrum spatial domain distribution diagram; Figure 5 It is the spectrum distribution diagram in frequency domain. Figure 6-9 What is shown is the result of radar wave image processing. Figure 6 is the wave height calculated from the power spectrum, Figure 7 Calculate the wavelength from the power spectrum, Figure 8 The cross power spectrum of two consecutive images is used to calculate the wave direction. Fig. 9 The cross-correlation function calculates the wave speed. It can be seen that the present invention can quickly provide accurate sea wave information. It realizes the systematization, numeration, visualization, businessization, networking, intelligence, unattended, real-time display, and fully automated radar sea wave monitoring with high accuracy.

[0098] The present invention is described by way of embodiments, and those skilled in the art will appreciate that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the protection scope of the present invention.

Claims

1. A radar wave monitoring method, characterized in that: The following steps are involved: S1: Ocean wave image acquisition, collecting ocean wave images through radar; S2: Ocean wave image data analysis and processing, converting the two-dimensional ocean wave echo image data from the spatial domain to the frequency domain for analysis; S3: Calculation of wave elements: Calculation of wave elements through the two-dimensional spectrum of wave radar echo and its correlation.

2. A radar wave monitoring method according to claim 1, characterized in that: In the step S2, Assuming that g(x,y) represents two-dimensional wave echo data, its two-dimensional Fourier transform can be expressed as: u, v represent wave numbers, u=0,1,2……N-1; v=0,1,2……M-1, j is the sequence unit; Its two-dimensional energy spectrum is described as: represents the conjugate complex number of G(u,v); The continuous scanning results of the wave data are obtained, and the cross-power spectrum is obtained by the following formula: G1(u,v) and G2(u,v) are two continuously observed wave echo signals; The autocorrelation function and cross-correlation function are obtained by inverse Fourier transform of the energy spectrum and cross-power spectrum respectively: Autocorrelation function: Cross-correlation function:

3. A radar wave monitoring method according to claim 1, characterized in that: In the step S2, The wave data is first processed by the median filter, and the median of the pixel values ​​in the filter window is selected as the output. The mathematical formula is as follows: g(x,y)=median{f(s,t):(s,t)∈Sxy} Among them, g(x,y) is the pixel value of the filtered image at point (x,y), f(x,t) is the pixel value of the original image at point (x,t), Sxy is the filter window centered at (x,y).

4. A radar wave monitoring method according to claim 1, characterized in that: In step S3, the wave elements are calculated by the two-dimensional spectrum of the wave radar echo and its correlation: 1) Wavelength: Dl is the radar range resolution, N is the image data size; 2) Wave direction: 3) The wave speed is obtained by the cross-correlation function of the wave images at two consecutive moments: T is the radar antenna scanning period; 4) Wave height W H The wave height is obtained from the two-dimensional energy spectrum of the wave image.

5. A radar wave monitoring device, characterized in that: include: Radar, the radar is connected to the radar image analysis and processing module through a communication interface to collect sea wave images; The radar image analysis and processing module is used to convert the two-dimensional wave echo image data from the spatial domain to the frequency domain for analysis and to calculate the wave elements.

6. A radar wave monitoring device according to claim 5, characterized in that: It also includes a radar wave image measurement recorder, the radar is connected to the radar wave image measurement recorder through a communication interface, and the radar wave image measurement recorder is connected to the radar image analysis and processing module through the communication interface.

7. A radar wave monitoring device according to claim 5, characterized in that: The radar image analysis and processing module includes a spatial filtering module, which is connected to the ocean wave pattern display module for displaying an ocean wave pattern diagram.

8. The radar wave monitoring device according to claim 5, characterized in that: The radar image analysis and processing module is connected to the ocean wave real-time display module for displaying the ocean wave measured image.

9. A radar wave monitoring device according to claim 5, characterized in that: The radar image analysis and processing module is connected to the storage module and the printing module.

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