First-order sea clutter detection method based on least squares approximation
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A least squares and detection method technology, applied in the field of high-frequency ground wave radar detection, can solve the problems of inaccurate Bragg peak position and high false alarm rate, reduce interference such as spectrum splitting and high-frequency noise, improve accuracy, Solve the effect of inaccurate recognition
Active Publication Date: 2016-08-24
HARBIN INST OF TECH
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[0004] The present invention proposes a first-order sea clutter detection method based on least squares approximation in order to solve the problems of inaccurate Bragg peak position and high false alarm rate found in the prior art
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specific Embodiment approach 1
[0025] Specific implementation mode one: as Figure 8 As shown, the first-order sea clutter detection method based on the least squares approximation includes the following steps:
[0026] The original radar echo data undergoes two FFT operations and one DBF operation to obtain the azimuth-range-Doppler spectrum (ARD spectrum) of the echo data. The identification of the first-order sea clutter is to identify the position of the first-order Bragg peak on the ARD spectrum.
[0027] Step 1: From the operating frequency f of the radar 0 , get the theoretical Bragg frequency f B ;
[0028] Step 2: According to f obtained in step 1 B Delineate the noise area on each sea element, and obtain the threshold value of each sea element;
[0029] Step 3: According to the sea state data in the sea area detected by the radar, determine the maximum value V of the radial flow velocity of the ocean current m , and find the maximum value of the Bragg frequency offset Δf m ;
[0030] Step ...
specific Embodiment approach 2
[0048] Specific embodiment two: the difference between this embodiment and specific embodiment one is: obtain theoretical Bragg frequency f in the described step one B The formula is:
[0049] f B = ± 0.102 f 0 - - - ( 6 ) .
specific Embodiment approach 3
[0050] Specific implementation mode three: the difference between this implementation mode and specific implementation mode one or two is that: the threshold value obtained for each sea element in the step two is specifically:
[0051] The threshold for each sea element is N p and the sum of SNR, the N p is the base noise, and SNR (given according to the actual situation) is the set minimum signal-to-noise ratio.
[0052] In this algorithm, the Doppler frequency is in [-2f B ,2f B ] area is divided into noise area (the range of noise area can be adjusted according to the actual situation).
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Abstract
Disclosed is a first-order sea clutter detection method based on least squares approximation. The invention relates to a first-order sea clutter detection method, and aims to solve the problem that the found Bragg peak position is inaccurate and the false alarm rate is high in the prior art. The method comprises the following steps: calculating the theoretical Bragg frequency fB based on the working frequency f0 of radar, defining a noise zone on each sea element, and calculating the threshold of each sea element; detecting sea area sea state data according to the radar, determining the maximum radial velocity Vm of ocean current, and calculating the maximum Bragg frequency offset Delta fm; determining a search scope according to Delta fm and fB, determining a suspected point of the Bragg peak, confirming the threshold of the amplitude of the suspected point, and judging whether the current sea element is effective; for the effective sea elements, taking the neighboring points of an appropriate number of suspected points to form a point set, and acquiring the approximation function of the point set using a least squares approximation method; and finally, taking the peak point of the approximation function as a Bragg peak. The first-order sea clutter detection method is applied to the field of high-frequency ground wave radar detection.
Description
technical field [0001] The invention relates to a first-order sea clutter detection method and relates to the field of high-frequency ground wave radar detection. Background technique [0002] High-frequency ground wave radar can break through the limitation of the curvature of the earth and detect targets below the line of sight. There are often a lot of interference and noise mixed in the radar echo. The first-order sea clutter of high-frequency radar is one of the most important interferences in radar echoes. Its energy is often high and seriously affects the detection of targets. Sea clutter should be suppressed as much as possible; but on the other hand, sea clutter Waves contain a large amount of sea state information, and are the main detection objects of sea state inversion. The mechanism of sea clutter can be explained by the Bragg resonance principle, that is, when high-frequency electromagnetic waves irradiate rough sea surfaces, the electromagnetic waves will i...
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