A method for broadband high-gain spherical array layout based on co-frame design

Abstract

This invention belongs to the field of spherical array layout design, and discloses a broadband high-gain spherical array layout method based on co-frame design, according to the upper limit f of the operating frequency of the closely packed spherical array. max Calculate the approximate element spacing d0 = (c / f max Step 2: Based on the array space, calculate the maximum diameter R, vertical height H, and vertical arc length L of the spherical array. H This invention addresses the problem of insufficient low-frequency gain caused by the limited installation space of spherical arrays. By using a design that combines a vector sparse spherical array with a scalar close-packed conformal array, it achieves high low-frequency gain, enabling it to have broadband high array gain with only a slight increase in the number of preprocessing channels, thus meeting the requirements for full-band detection.

Description

Technical fields:

[0001] This invention belongs to the field of spherical array layout method design, specifically relating to a broadband high-gain spherical array layout method based on co-frame design. Background technology:

[0002] Spherical arrays possess excellent two-dimensional detection capabilities and are a commonly used sonar and radar array configuration both domestically and internationally. While spherical arrays offer good gain in the mid-to-high frequency bands, their low-frequency gain is limited by installation space. When the target signal frequency is below 200Hz, even with a spherical array diameter of 7m, the maximum space is still smaller than the signal wavelength, rendering the array essentially a point element and unable to achieve effective directivity, leading to a sharp decline in low-frequency detection capability. The common method to improve low-frequency array gain is to increase the array aperture. However, this is problematic because acoustic arrays have limited installation space, and increasing the aperture of a spherical array, which is a volumetric array, would exponentially increase the number of array elements and the size of the pre-processing circuitry, resulting in a sharp increase in cost and difficulties in data transmission between array elements.

[0003] Using vector array elements in spherical array configuration is an effective method to improve the gain of low-frequency arrays. Theoretically, under the same configuration, arrays using vector array elements are 4.7 dB higher than those using scalar array elements. However, the number of pre-processing circuit channels required for vector array configuration is three times that of scalar array configuration. When the pre-processing circuit and data transmission capabilities have reached their limits, using vector array elements to completely replace scalar array elements in spherical array configuration is not feasible in engineering practice and is too costly. Summary of the Invention:

[0004] The technical problem to be solved by this invention is to provide a broadband high-gain array arrangement method for spherical arrays based on co-frame design. By co-frame design of vector sparse spherical array and scalar close-packed conformal array, scalar close-packed spherical array is used in the mid-to-high frequency band, and vector sparse spherical array is arranged with an element spacing of about half a wavelength corresponding to the upper limit of the low frequency band. This achieves high gain at low frequencies, enabling it to have broadband high array gain with only a slight increase in the number of pre-processing channels, thus meeting the detection requirements of the entire frequency band.

[0005] The technical solution of this invention is to provide a broadband high-gain array arrangement method for spherical arrays based on a co-architecture design. This method utilizes a vector sparse spherical array and a scalar close-packed conformal array in a co-architecture design, employing a scalar close-packed spherical array in the mid-to-high frequency band. It is assumed that the upper limit of the spherical array's operating frequency is f. max To avoid grating lobes in the beamforming of the spherical array, the horizontal and vertical element spacing of the spherical array should not exceed:

[0006] d0=(c / f max ) / twenty one)

[0007] Because the perimeter of each layer of elements in a spherical array is different, it is impossible to arrange them at perfectly equal intervals; therefore, an approximation of d0 is necessary. Let the vertical arc length of the spherical array be L. H The vertical number of layers in a close-packed spherical array is in This indicates rounding up. This array configuration can meet the upper limit requirement for lobe-less operation frequency.

[0008] Let the low-frequency band of the spherical array be [f Lmin f Lmax Calculate the half wavelength corresponding to the upper limit of the low-frequency band:

[0009] d1=(c / f Lmax ) / twenty two)

[0010] The sparsity of the vector sparse spherical array is obtained by calculating the ratio of the half-wavelength corresponding to the upper limit of the full-band operating frequency of the spherical array to the half-wavelength corresponding to the upper limit of the low-frequency band.

[0011]

[0012] in This indicates rounding down to the nearest integer.

[0013] Then, based on the close-packed spherical array, a vector sparse spherical array is formed by selecting one layer vertically every r layers and one array element horizontally every r elements, replacing the scalar hydrophones with vector hydrophones.

[0014] As a preferred option, in practical engineering applications, to facilitate engineering implementation, the close-packed spherical array can be designed in vertical segments, with the number of array elements in the vertical multi-layer array elements remaining the same, and some layers can be appropriately densified, which can facilitate the formation of scalar close-packed spherical arrays and sparse sampling of vector sparse spherical arrays.

[0015] Compared with the prior art, the present invention has the following advantages after adopting the above solution:

[0016] Compared to the conventional spherical close-packed array method of scalar array elements, this method effectively improves the low-frequency array gain of the spherical array while keeping the mid-to-high frequency array gain unchanged, thus enhancing the low-frequency detection capability, with only a slight increase in the number of preprocessing channels and output transmission pressure. Attached image description:

[0017] Figure 1 This is a schematic diagram of a scalar close-packed spherical array with a maximum diameter of 3.4m, an effective vertical height of 2.5m, and a maximum operating frequency of 7500Hz.

[0018] Figure 2 This is a schematic diagram of the design of a vector sparse spherical array and a scalar close-packed spherical array co-located in the low-frequency range of 0–1500 Hz and with a sparsity of 5.

[0019] Figure 3 The beam pattern at 7500 Hz is for a closely packed spherical array.

[0020] Figure 4 The beam pattern at 1500 Hz is for a sparse spherical array.

[0021] Figure 5 This is a schematic diagram showing the gain curves of a vector sparse spherical array and a scalar densely packed spherical array as a function of frequency (below 1500Hz). Detailed implementation method:

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0023] This invention provides a broadband high-gain spherical array deployment method based on co-frame design, as detailed below.

[0024] Step 1: Based on the upper limit f of the operating frequency of the closely packed spherical array max Calculate the approximate element spacing d0 = (c / f max ) / 2;

[0025] Step 2: Based on the array space, calculate the maximum diameter R, vertical height H, and vertical arc length L of the spherical array. H ;

[0026] Step 3: Calculate the number of vertical layers in the closely packed spherical array. in Indicates rounding up;

[0027] Step 4: Design the close-packed array elements for each layer of the rings. Where M i Let L be the number of elements in the i-th layer of the matrix. i Let be the circumference of the i-th layer of the annulus; to facilitate engineering implementation, the closely packed spherical array can be designed in vertical segments, with the number of array elements in each vertical multi-layer array remaining the same, and some layers can be appropriately densified;

[0028] Step 5, based on the low-frequency band of the closely packed spherical array [f Lmin f Lmax ] Calculate the half wavelength d1 corresponding to the upper limit of the low frequency band d1 = (c / f Lmax ) / 2;

[0029] Step 6: Calculate the ratio of the half-wavelength corresponding to the upper limit of the full-frequency operating range of the close-packed spherical array to the half-wavelength corresponding to the upper limit of the low-frequency range, thus obtaining the sparsity of the vector sparse spherical array. in Indicates rounding down;

[0030] Step 7: Based on the densely packed spherical array, the vector sparse spherical array selects one layer vertically every r layers and one array element horizontally every r elements, replacing the scalar hydrophone with a vector hydrophone, thus obtaining the design of the vector sparse spherical array and the scalar densely packed spherical array co-located.

[0031] like Figure 1 The diagram shows a scalar close-packed spherical array with a maximum diameter of 3.4m, an effective vertical height of 2.5m, and a maximum operating frequency of 7500Hz. It has 28 vertical layers and 2640 effective array elements. Figure 2 This is a schematic diagram of the design of a vector sparse spherical array and a scalar close-packed spherical array co-located in the low-frequency range of 0-1500Hz and with a sparsity of 5. The black dots in the diagram are vector hydrophones, and the total number of vector array elements is 112. Figure 3 , Figure 4 The images show the beam patterns at 7500 Hz for a densely packed spherical array and at 1500 Hz for a sparsely packed spherical array, respectively.

[0032] Figure 5 The graph shows the gain curves of vector sparse spherical arrays and scalar close-packed spherical arrays as a function of frequency (below 1500Hz). As can be seen from the graph, the gain of the vector sparse spherical array with co-frame design is 4.7dB higher than that of the scalar close-packed spherical array.

[0033] This invention addresses the problem of insufficient low-frequency gain in spherical arrays due to installation space limitations. It achieves high low-frequency gain by co-laying a vector sparse spherical array with a scalar close-packed conformal array, enabling broadband high array gain with only a slight increase in the number of pre-processing channels, thus meeting the requirements for full-band detection. Compared to conventional scalar array element spherical close-packing methods, this method effectively improves the low-frequency array gain of the spherical array while maintaining the mid-to-high frequency array gain unchanged, thus enhancing low-frequency detection capabilities, with only a slight increase in the number of pre-processing channels and output transmission pressure.

[0034] The above description only illustrates preferred embodiments of the present invention and should not be construed as limiting the scope of the claims. Any equivalent procedural modifications made using this specification are included within the patent protection scope of this invention.

Claims

1. A method for arranging a broadband high-gain spherical array based on a co-frame design, characterized in that: The method includes the following steps: Step one, according to the close-packed spherical array operating frequency upper limit f max , the approximate array element spacing d0=(c / f max ) / 2 is calculated; Step two, according to the arrangement space, calculate the maximum diameter R, vertical height H and vertical arc length L of the spherical array H ; Step 3: Calculate the number of vertical layers in the closely packed spherical array. in Indicates rounding up; Step 4: Design the close-packed array elements for each layer of the rings. Where M i Let L be the number of elements in the i-th layer of the matrix. i Let be the circumference of the i-th ring. Step five, according to the close-packed spherical array low frequency band [f Lmin f Lmax ], the upper limit of the low frequency band corresponding to the half wavelength d1 = (c / f Lmax ) / 2; Step 6: Calculate the ratio of the half-wavelength corresponding to the upper limit of the full-frequency operating range of the close-packed spherical array to the half-wavelength corresponding to the upper limit of the low-frequency range, thus obtaining the sparsity of the vector sparse spherical array. in Indicates rounding down; Step 7: Based on the densely packed spherical array, the vector sparse spherical array selects one layer vertically every r layers and one array element horizontally every r elements, replacing the scalar hydrophone with a vector hydrophone, thus obtaining the design of the vector sparse spherical array and the scalar densely packed spherical array co-located.

2. The method for arranging a broadband high-gain spherical array based on a co-frame design according to claim 1, characterized in that: To facilitate engineering implementation, the closely packed spherical array can be designed in vertical segments.

3. The broadband high-gain spherical array arrangement method based on co-frame design according to claim 2, characterized in that: Some layers of a closely packed spherical array can be encrypted.

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