Sidelobe cancellation method for extracting auxiliary channel array elements in electronic countermeasure

Abstract

The invention belongs to the field of electronic countermeasures, and particularly relates to a sidelobe cancellation method for extracting auxiliary channel array elements in electronic countermeasures. The method comprises the following steps: step 1, determining the number of main channel array elements, array element spacing, the number of auxiliary channels and the position of each auxiliary channel array element in a main channel; step 2, according to the antenna parameters, calculating antenna directional diagrams of the main channel and the auxiliary channel; and step 3, comparing amplitude values under the same azimuth angle and pitch angle, and the like. According to the invention, the problem that the target signal is attenuated is effectively improved.

Description

Technical Field

[0001] The invention belongs to the field of electronic countermeasures, and in particular relates to a sidelobe cancellation method for extracting auxiliary channel array elements in electronic countermeasures. Technical Background

[0002] Sidelobe cancellation technology is one of the primary means of radar anti-interference. In principle, by receiving interference signals through auxiliary channels and constructing Wiener filters, interference signals entering the main channel from the sidelobes can be effectively suppressed. However, in practice, target signals from the mainlobe direction of the main channel are often mixed into the auxiliary channels, causing target signals to be attenuated. Eliminating target signals in the auxiliary channels poses a practical engineering challenge for sidelobe cancellation.

[0003] Phased array radar is one of the mainstream radar types in modern times. When sidelobe cancellation processing is used in phased array radar, auxiliary channel array elements are sometimes not set up separately, and auxiliary channel array elements are extracted from the main channel array elements. In this way, target signals are inevitably present in the auxiliary channels.

[0004] In the sum and difference beam angle measurement of the phased array radar, the difference beam will form a null at the center of the main lobe, effectively suppressing the main lobe target signal. Inspired by this, a similar method can be used to process the auxiliary channel array element echo to obtain auxiliary channel echo data that significantly attenuates the main lobe target signal. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention provides a sidelobe cancellation method for extracting auxiliary channel elements in electronic countermeasures. The present invention includes selecting the number of main channel antenna elements, rationally designing the number of auxiliary channel elements, generating auxiliary channel data, DBF, and sidelobe cancellation.

[0006] The technical solution of the present invention is: a sidelobe cancellation method for extracting auxiliary channel array elements in electronic countermeasures, characterized in that the method comprises the following steps:

[0007] Step 1: Determine the number of main channel array elements, the array element spacing, the number of auxiliary channels, and the position of each auxiliary channel array element in the main channel;

[0008] Step 2: Calculate the antenna patterns of the main channel and the auxiliary channel according to the antenna parameters;

[0009] Step 3: Compare the same azimuth and elevation angles and the amplitude values ​​within the step;

[0010] Step 4: During the working process, the step of receiving echo data;

[0011] Step 5: Process the received data of each array element of the auxiliary channel to synthesize an auxiliary channel data matrix that can be used for sidelobe cancellation;

[0012] Step 6: Perform DBF processing on the main channel data.

[0013] Step 7: Perform sidelobe cancellation.

[0014] The beneficial effect of the present invention is that several groups of suitable auxiliary channel array elements are selected from the main channel antenna array elements, azimuth difference beamforming and elevation difference beamforming are performed on the received data of the auxiliary channel array elements, amplitude selection processing is performed on the results of the azimuth difference beamforming and elevation difference beamforming, and the target signal in the main lobe direction of the main channel in the auxiliary channel signal is attenuated, so that the auxiliary channel antenna radiation pattern forms a null notch in the main lobe direction of the main channel, effectively improving the difficulty of attenuation of the target signal in the main lobe direction after sidelobe cancellation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Layout diagram of antenna array elements for main and auxiliary channels.

[0016] Figure 2 is the auxiliary channel antenna pattern.

[0017] Figure 3 Antenna pattern for the main channel.

[0018] Figure 4 This is the DBF output result after suppressing the interference.

[0019] Figure 5 This is the sidelobe cancellation result after suppressing the interference.

[0020] Figure 6 This is the DBF output result after adding false target interference.

[0021] Figure 7 This is the sidelobe cancellation result after adding false target interference.

[0022] Figure 8 This is the sidelobe cancellation flow chart. DETAILED DESCRIPTION

[0023] The technical solutions provided by the present invention will be described in detail below with reference to specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0024] like Figures 1 to 8 As shown, the sidelobe cancellation method for extracting auxiliary channel array elements in electronic countermeasures of the present invention comprises the following specific steps:

[0025] Step 1: Determine the number of main channel array elements (the number of horizontal array elements is , the number of vertical array elements is ), array element spacing, number of auxiliary channels (the number of auxiliary channels is greater than or equal to the number of sidelobe interference), the position of each auxiliary channel in the main channel, the number of array elements for each auxiliary channel (the number of array elements in the horizontal direction is , the number of vertical array elements is ,Usually, the antenna arrays of the main channel and the ,auxiliary channel are two-dimensional rectangular arrays;

[0026] Step 2: Calculate the antenna patterns of the main channel and the auxiliary channel according to the antenna parameters;

[0027] Step 2.1, let the main lobe angle of the beam be , the pitch angle is (The main channel and auxiliary channel beams are pointed in the same direction), the number of horizontal array elements of the main channel is , the number of vertical array elements is , then the steering vector of the main channel in the direction of the main lobe of the beam is as follows: (1)

[0028] (2)

[0029] (3)

[0030] In the above formula, is the horizontal direction steering vector of the main lobe of the main channel beam, is the vertical direction steering vector of the main lobe of the main channel beam, is the main lobe steering vector of the main channel beam, is the ratio of the array element spacing to the wavelength of the transmitted signal. In the present invention, the spacing between adjacent array elements in the horizontal direction and the vertical direction is the same, and different sizes of horizontal and vertical array element spacings can also be used. is the horizontal direction array element number row vector of the main channel, , is the row vector of array element number in the vertical direction of the main channel, , and are the window function row vectors of the horizontal and vertical steering vectors of the main channel, To calculate the Kronecker Product of x and y, " is the dot multiplication symbol of vector or matrix, "j" is the imaginary unit, .

[0031] The azimuth range of the antenna scan line vector is , the pitch angle range row vector is (The main channel is consistent with the auxiliary channel), then the array manifold of the main channel is:

[0032] (4)

[0033] (5)

[0034] (6)

[0035] in, is the horizontal array manifold of the main channel, The array manifold in the vertical direction of the main channel, is the main channel array manifold, is the array element number column vector in the horizontal direction of the main channel antenna, , is the array element number column vector in the vertical direction of the main channel antenna, .

[0036] Main channel antenna pattern for:

[0037] (7)

[0038] in, To seek conjugation.

[0039] Step 2.2: The number of horizontal array elements in the auxiliary channel is , the number of vertical array elements is , then the azimuth difference beam steering vector of the auxiliary channel in the direction of the main lobe of the beam is as follows:

[0040] (8)

[0041] (9)

[0042] (10)

[0043] (11)

[0044] In the above formula, is the horizontal azimuth difference beam steering vector of the auxiliary channel beam main lobe, is the azimuth difference beam steering vector in the vertical direction of the auxiliary channel beam main lobe, is the auxiliary channel beam main lobe azimuth difference beam steering vector, is the intermediate parameter, is the horizontal array element number of the auxiliary channel, , is the row vector of the array element number in the vertical direction of the auxiliary channel, , and It is a row vector of window functions. Usually, the window function type of the auxiliary channel is the same as the window type of the main channel.

[0045] The array manifold of the auxiliary channel is:

[0046] (12)

[0047] (13)

[0048] (14)

[0049] in, is the horizontal array manifold of the auxiliary channel, is the vertical array manifold of the auxiliary channel, is the auxiliary channel array manifold, is the column vector of the auxiliary channel antenna horizontal array element number, , is the column vector of the auxiliary channel antenna vertical array element number, .

[0050] Auxiliary channel antenna azimuth difference beam pattern for:

[0051] (15)

[0052] The auxiliary channel pitch difference beam steering vector is:

[0053] (16)

[0054] (17)

[0055] (18)

[0056] (19)

[0057] in, is an intermediate variable, is the vertical pitch difference beam steering vector of the auxiliary channel, is the horizontal pitch difference beam steering vector of the auxiliary channel, is the auxiliary channel elevation difference beam steering vector, l is the auxiliary channel vertical antenna array element number, , is the row vector of antenna element number in the horizontal direction of the auxiliary channel, , and is the window function row vector.

[0058] Auxiliary channel antenna elevation difference beam pattern O is:

[0059] (20)

[0060] Antenna pattern of a single auxiliary channel for:

[0061] (twenty one)

[0062] in, Indicates that when the azimuth and elevation angles are the same, the larger amplitude is selected.

[0063] Step 3: Compare the same azimuth and elevation angles and The amplitude value within the main lobe, except for the range of The magnitude is greater than If the amplitude is greater than , proceed to step 4. Otherwise, increase the number of auxiliary channel array elements and repeat steps 1 and 2 according to the new setting value until the conditions are met.

[0064] The beneficial effect of steps 1, 2 and 3 is to generate an auxiliary channel antenna pattern that produces a null at the center of the main lobe of the main channel, such as Figure 2 As shown, Figure 3 This is the main channel antenna pattern, compared Figure 2 and Figure 3 If the sidelobe gain of the auxiliary channel antenna pattern is greater than the sidelobe gain of the main channel antenna pattern, then the number of main channel antenna array elements and the number of auxiliary channel antenna array elements are reasonably selected. The rationality of the selection of the number of main channel and auxiliary channel array elements is determined by the main channel and auxiliary channel antenna patterns.

[0065] Step 4: After determining the number of main channel and auxiliary channel antenna array elements, the antenna design is completed. During the working process, the echo data is received. The main channel array element receives the data matrix as follows: The number of rows in the matrix is ​​the number of main channel antenna elements, and the number of columns is the number of distance sampling units. According to the position of the auxiliary channel antenna elements, the data of each auxiliary channel is extracted. 、 、…、 ,in The number of auxiliary channels.

[0066] The beneficial effect of this step is to extract the corresponding auxiliary channel array data from the main channel data matrix, which is convenient for the subsequent sidelobe cancellation operation.

[0067] Step 5: Process the received data of each array element of the auxiliary channel to synthesize the auxiliary channel data matrix that can be used for sidelobe cancellation.

[0068] Step 5.1: The mth auxiliary channel azimuth difference beam data for:

[0069] (twenty two)

[0070] Step 5.2: mth auxiliary channel pitch difference beam data for:

[0071] (twenty three)

[0072] Step 5.3: The data that can be used for sidelobe cancellation on the mth auxiliary channel for:

[0073] (twenty four)

[0074] in, Indicates that the amplitude is larger according to the distance unit.

[0075] Step 5.4: Total sidelobe cancellation auxiliary channel data for:

[0076] (25)

[0077] The beneficial effect of this step is to attenuate the target signal in the main lobe direction of the main channel received by the auxiliary channel antenna array element, preventing the target signal in the main channel from being cancelled after the sidelobe cancellation. At the same time, the processed data of each auxiliary channel is integrated into the auxiliary channel data matrix, which is convenient for the subsequent sidelobe cancellation.

[0078] Step 6: Perform DBF processing on the main channel data and obtain the result for:

[0079] (26)

[0080] The beneficial effect of this step is to perform spatial domain filtering on the received signal of the main channel to form main channel data.

[0081] Step 7: Perform sidelobe cancellation

[0082] Step 7.1, calculate the autocorrelation matrix of the auxiliary channel data:

[0083] (27)

[0084] in, is the autocorrelation matrix of the auxiliary channel, is the number of distance sampling points, Performs the conjugate transpose of a matrix or vector.

[0085] Step 7.2: Calculate the cross-correlation matrix between the auxiliary channel data and the main channel DBF result:

[0086] (28)

[0087] in, is the cross-correlation matrix between the auxiliary channel data and the main channel DBF result.

[0088] Step 7.3, calculate the cancellation coefficient for sidelobe cancellation:

[0089] (29)

[0090] in, is the cancellation coefficient of sidelobe cancellation, Find the inverse of a matrix.

[0091] Step 7.4: The cancellation result of the main channel data is:

[0092] (30)

[0093] in, is the output result of sidelobe cancellation.

[0094] The beneficial effect of this step is to generate sidelobe cancellation coefficients, perform sidelobe cancellation processing on the main channel signal, cancel the sidelobe interference in the main channel, and retain the target signal at the mainlobe position.

[0095] Example 1: Determine the number of main channel array elements, array element spacing, and the number of auxiliary channels. The position of each auxiliary channel array element in the main channel is determined. The number of auxiliary channels is less than or equal to the number of interferences. Typically, the antenna arrays of the main channel and the auxiliary channels are two-dimensional rectangular arrays.

[0096] In this example, the number of horizontal array elements in the main channel is 18, the number of vertical array elements is 48, the ratio of the array element spacing to the transmitted signal wavelength is 0.5, the number of auxiliary channels is 4, and in each auxiliary channel, the number of horizontal array elements and the number of vertical array elements are 4. The antenna array elements of the four auxiliary channels are extracted from the four corners of the main channel antenna array. The specific antenna array element arrangement diagram is shown in the attached figure. Figure 1 .

[0097] Example 2: Calculating antenna patterns of the main channel and the auxiliary channel based on antenna parameters;

[0098] The azimuth angle of the main lobe center of the main channel is 0 degrees, the elevation angle is 0 degrees, the azimuth scanning range is -60 degrees to 60 degrees, the elevation scanning range is -30 degrees to 30 degrees, the main channel and auxiliary channel array elements are added with Taylor windows, and the auxiliary channel antenna pattern is shown in the attached Figure 2 , the main channel antenna pattern is attached Figure 3After comparison, the auxiliary channel antenna pattern forms a notch null in the main lobe direction. Except for the main lobe, the amplitude values ​​of the auxiliary channel antenna pattern in other directions are greater than the amplitude values ​​of the main channel antenna pattern. The number of main and auxiliary channel array elements selected in Example 1 meets the requirements.

[0099] Embodiment 3: Processing the received data of each array element of the auxiliary channel to synthesize an auxiliary channel data matrix that can be used for sidelobe cancellation;

[0100] For convenience, simulation data is used for verification. The transmitted signal is a linear frequency modulation signal with a pulse width of 200μs, a bandwidth of 2MHz, a pulse repetition period of 2ms, a target distance of 100km, an azimuth angle of 0 degrees, and an elevation angle of 0 degrees. It is aligned with the center of the main lobe. Two groups of interference are added respectively. The first group of interference is suppression interference, and the second group of interference is false target interference. The azimuth angles of the two groups of interference are both 21 degrees, and the pitch angles are both 7.5 degrees, which are consistent with the direction of the first side lobe of the main channel.

[0101] Embodiment 4: Processing the received data of each array element of the auxiliary channel to synthesize an auxiliary channel data matrix that can be used for sidelobe cancellation;

[0102] According to the attached Figure 8 The auxiliary channel array element position shown extracts the echo signal of each auxiliary channel from the main channel array element echo matrix, performs azimuth difference beamforming and elevation difference beamforming processing on the echo data of each auxiliary channel respectively, adds Taylor window to all, and selects the amplitude of the azimuth difference beam data and elevation difference beam data of each auxiliary channel according to the distance unit to obtain a group of auxiliary channel data. Similarly, all auxiliary channel data are processed and synthesized into an auxiliary channel data matrix.

[0103] Example 5: Perform DBF processing on the main channel data;

[0104] The Taylor window function is added to the coefficient of the main channel DBF. In order to facilitate the observation of the target echo, the pulse compression processing is performed on the DBF result. The main channel DBF result of adding the suppression interference is shown in the attached figure. Figure 4 As shown in the figure, the target echo is submerged in the suppression interference. The main channel DBF result of adding false target interference is shown in the attached figure. Figure 6 As shown, due to the multiple peaks in the echo signal, the specific location and number of the targets cannot be determined.

[0105] Embodiment 6: performing sidelobe cancellation;

[0106] Use the DBF result (without pulse compression) to cancel the sidelobe, perform pulse compression on the data after cancellation, and add the main channel data to suppress the interference. The result of sidelobe cancellation is shown in the attached figure. Figure 5 As shown in the attached figure, the result of the main channel data sidelobe cancellation with false target interference is shown in the attached figure. Figure 7 As shown, through the attached Figure 4 and attached Figure 6 By comparison, it can be seen that after sidelobe cancellation, the interference signal is effectively suppressed and the target echo signal can be observed intuitively.

[0107] The above description is only the best specific implementation method of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

[0108] The contents not described in detail in the specification of the present invention belong to the common knowledge of professionals in this field.

Claims

1. A sidelobe cancellation method for extracting auxiliary channel array elements in electronic countermeasures, characterized in that: The steps of this method are as follows: Step 1: Determine the number of main channel array elements, the array element spacing, the number of auxiliary channels, and the position of each auxiliary channel array element in the main channel; Step 2: Calculate the antenna patterns of the main channel and the auxiliary channel according to the antenna parameters; Step 2.1, let the main lobe angle of the beam be , the pitch angle is , the number of array elements in the horizontal direction of the main channel is , the number of vertical array elements is , the steering vector of the main channel in the direction of the main lobe of the beam is as follows: (1) (2) (3) is the horizontal direction steering vector of the main lobe of the main channel beam, is the vertical direction steering vector of the main lobe of the main channel beam, is the main lobe steering vector of the main channel beam, is the ratio of array element spacing to the wavelength of the transmitted signal, is the horizontal direction array element number row vector of the main channel, is the row vector of array element number in the vertical direction of the main channel, and is the window function row vector of the horizontal and vertical steering vectors of the main channel, To calculate the Kronecker Product of x and y, " is the dot multiplication symbol of vector or matrix, "j" is the imaginary unit, ; The azimuth range of the antenna scan line vector is , the pitch angle range row vector is , the array manifold of the main channel is: (4) (5) (6) in, is the horizontal array manifold of the main channel, The array manifold in the vertical direction of the main channel, is the main channel array manifold, is the array element number column vector in the horizontal direction of the main channel antenna, is the array element number column vector in the vertical direction of the main channel antenna, Main channel antenna pattern for: (7) in, To seek conjugation; Step 2.2: The number of horizontal array elements in the auxiliary channel is , the number of vertical array elements is , the azimuth difference beam steering vector of the auxiliary channel in the direction of the main lobe of the beam is as follows: (8) (9) (10) (11) is the horizontal azimuth difference beam steering vector of the auxiliary channel beam main lobe, is the azimuth difference beam steering vector in the vertical direction of the auxiliary channel beam main lobe, is the auxiliary channel beam main lobe azimuth difference beam steering vector, is the intermediate parameter, is the horizontal array element number of the auxiliary channel, is the row vector of the array element number in the vertical direction of the auxiliary channel, and is the window function row vector, The array manifold of the auxiliary channel is: (12) (13) (14) in, is the horizontal array manifold of the auxiliary channel, is the vertical array manifold of the auxiliary channel, is the auxiliary channel array manifold, is the array element number column vector in the horizontal direction of the auxiliary channel antenna, is the column vector of the auxiliary channel antenna vertical array element number, Auxiliary channel antenna azimuth difference beam pattern for: (15) The auxiliary channel pitch difference beam steering vector is: (16) (17) (18) (19) in, is an intermediate variable, is the vertical pitch difference beam steering vector of the auxiliary channel, is the horizontal pitch difference beam steering vector of the auxiliary channel, is the auxiliary channel elevation difference beam steering vector, l is the auxiliary channel vertical antenna array element number, is the row vector of antenna element number in the horizontal direction of the auxiliary channel, and is the window function row vector; Auxiliary channel antenna elevation difference beam pattern O is: (20) Antenna pattern of a single auxiliary channel for: (21) in, Indicates that when the azimuth and elevation angles are the same, the larger amplitude is selected; Step 3: Compare the same azimuth and elevation angles and The amplitude value within the main lobe, except for the range of the main lobe, if The magnitude is greater than If the amplitude is greater than , proceed to step 4. Otherwise, increase the number of auxiliary channel array elements and repeat steps 1 and 2 until the conditions are met. Step 4: During the working process, the echo data is received. The main channel array element receives the data matrix as follows: , according to the position of the auxiliary channel antenna array element, extract the data of each auxiliary channel 、 、…、 ,in is the number of auxiliary channels; Step 5: Process the received data of each array element of the auxiliary channel to synthesize the auxiliary channel data matrix that can be used for sidelobe cancellation. Step 5.1: The mth auxiliary channel azimuth difference beam data for: (22) Step 5.2: mth auxiliary channel pitch difference beam data for: (23) Step 5.3: The data that can be used for sidelobe cancellation on the mth auxiliary channel for: (24) in, Indicates that the amplitude is larger according to the distance unit; Step 5.4: Total sidelobe cancellation auxiliary channel data for: (25) Step 6: Perform DBF processing on the main channel data and obtain the result for: (26) Step 7: Perform sidelobe cancellation Step 7.1, calculate the autocorrelation matrix of the auxiliary channel data: (27) in, is the autocorrelation matrix of the auxiliary channel, is the number of distance sampling points, Performs the conjugate transpose of a matrix or vector. Step 7.2: Calculate the cross-correlation matrix between the auxiliary channel data and the main channel DBF result: (28) in, is the cross-correlation matrix between the auxiliary channel data and the main channel DBF result; Step 7.3, calculate the cancellation coefficient for sidelobe cancellation: (29) in, is the cancellation coefficient of sidelobe cancellation, Invert the matrix; Step 7.4: The cancellation result of the main channel data is: (30) in, is the output result of sidelobe cancellation.

2. The sidelobe cancellation method for extracting auxiliary channel array elements in electronic countermeasures according to claim 1, characterized in that: In step 1, the antenna arrays of the main channel and the auxiliary channel are two-dimensional rectangular arrays.

3. The sidelobe cancellation method for extracting auxiliary channel array elements in electronic countermeasures according to claim 1, characterized in that: In step 1, the number of auxiliary channels should be less than or equal to the actual number of interferences.

4. The sidelobe cancellation method for extracting auxiliary channel array elements in electronic countermeasures according to claim 1, characterized in that: In step 4, the main channel array element receives the data matrix The number of rows is the number of main channel array elements, and the number of columns is the number of distance sampling units.

5. The sidelobe cancellation method for extracting auxiliary channel array elements in electronic countermeasures according to claim 1, characterized in that: In step 4, the antenna is processed according to the number of main channel and auxiliary channel antenna array elements in steps 1 to 3.

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