A highly robust hydrophone array direction finding system device and design method

Abstract

The present invention discloses a highly robust hydrophone array direction-finding system device and a design method. The direction-finding system consists of a hydrophone array, a 485 module, a main control module, a human-computer interaction display terminal, and a solar power supply module. On the system platform of the present invention, a hydrophone array with sparse and dense layout and stable and reliable performance is designed. The array has a stable differential common array structure and high continuous degree of freedom, and its accuracy is higher than that of traditional uniform linear arrays and sparse linear arrays. The system of the present invention can realize the direction of arrival solution for multiple underwater targets, and has high robustness and high direction-finding accuracy under random failures of array elements.

Description

Technical Field

[0001] The invention belongs to the field of array signal processing, and in particular relates to a hydrophone array direction finding system device and a design method using a ternary redundant array arrangement. Background Art

[0002] Direction of arrival estimation is a research hotspot in the field of array signal processing and is widely used in many fields such as sonar, communication, and radar. Passive sonar systems are of great value in underwater navigation, marine development, and seabed exploration. Passive sonar systems do not emit sound waves themselves, but receive the radiation noise generated by underwater targets or the sound signals actively emitted by the targets through the hydrophone array to perceive the underwater environment and estimate the direction of the target. In the sonar system, improving the array resolution and accurately measuring the target direction are the goals that need to be continuously optimized. To achieve the above goals, a key is to have a stable and reliable hydrophone array. A hydrophone array refers to an array in which multiple hydrophones are arranged according to certain rules according to performance requirements. Its basic form includes hydrophone linear arrays, which can be divided into uniform linear arrays and sparse linear arrays. Traditional arrays often use uniform linear arrays, but with the changes in actual needs and the development of marine engineering, the number of array elements of the hydrophone array is required to increase, and the array size is also increasing. Sparse linear arrays have been widely used due to their advantages in resolution and freedom.

[0003] Sparse linear arrays can often be used The length of the physical array element is The central continuous segment differential common array can theoretically estimate However, in practical applications, due to the complex and harsh underwater conditions, the quality of the array elements themselves or the aging of the array elements, the array elements of the hydrophone array are prone to failure. The array element failure usually destroys the differential common array structure of the sparse array, breaks the continuity of the virtual array elements, reduces the number of degrees of freedom, and causes the performance of the related DOA estimation method to degrade or even fail. Although the uniform linear array has high redundancy and low vulnerability, the number of estimable sources is very limited, and the other sparse linear arrays often sacrifice redundancy for high degrees of freedom. When the array element fails, the number of continuous degrees of freedom is reduced, which reduces the robustness of the array. The design of existing sparse arrays basically does not take into account the situation when the array element fails. Therefore, the robustness of the array under the failure of the array element needs to be further studied. It is necessary to design a hydrophone array with high robustness that can maintain a long central continuous differential common array under the failure of the array element. Summary of the invention

[0004] The purpose of the present invention is to provide a highly robust hydrophone array direction finding system device and design method using a three-element redundant array arrangement, aiming to solve the problems that the differential common array structure of the sparse linear array is easily damaged, the degree of freedom is sharply reduced, and the direction finding accuracy is reduced when an array element fails.

[0005] To achieve the above object, the present invention is implemented by the following technical solutions, including:

[0006] (1) Hydrophone array: Select the appropriate number of hydrophones according to actual needs, and use a ternary redundant array arrangement to mount them on the RS485 bus to collect target signals.

[0007] (2) 485 module, using SP3485 chip as the transceiver for 485 communication. This module is connected to the RX485 bus, and multiple hydrophone receiving nodes can be connected to its transmission line.

[0008] (3) Main control module, the core processor selects TMS series DSP processor TMS320F28335, sets the spatial smoothing MUSIC program to process the received data, and calculates the spatial spectrum and wave arrival direction. The main control module sends a trigger signal to the hydrophone through the RS485 bus to start or stop acquisition. When the hydrophone is in the data upload mode and starts to collect data, the main control module commands each hydrophone to upload data in turn in response.

[0009] (4) The human-computer interaction display terminal uses the C series color screen intelligent terminal LCD display of Jinpeng Industrial Co., Ltd. It has a 32-bit ARM processor and FPGA dual-core control architecture. The DSP chip is connected to the display screen through the serial port to realize terminal human-computer interaction and real-time display of data. Parameters can be set through the operation page, such as powering on and off the equipment, launching and retracting the hydrophone array, starting and stopping sampling, processing accuracy of the DSP processor, number of operations, etc., and the incident wave arrival direction of the target signal can be displayed.

[0010] (5) Solar power supply module uses solar panels to generate electricity. The solar charging management chip uses CN3791 to store electrical energy in batteries. It powers all other modules through voltage reduction and stabilization, thereby saving energy.

[0011] In order to improve the robustness and accuracy of the direction finding system of the present invention, a triple redundant hydrophone arrangement is designed, including the following steps:

[0012] (1) Use The basic unit representing the spacing between array elements is usually taken as half wavelength, that is, , represents the wavelength of the incident signal on the array.

[0013] (2) Set the total number of hydrophone array elements according to actual needs ,and ,Depend on , , , find the number of array elements of the three sub-arrays , and .

[0014] (3) Selection Hydrophones are spaced Arrange in a straight line to form subarray 1, select Hydrophones are spaced Arrange in a straight line to form subarray 2, select Hydrophones are spaced Subarray 3 is formed by linear arrangement, and the interval between subarray 1 and subarray 2 is , the interval between subarray 2 and subarray 3 is That is, the array element spacing set is

[0015]

[0016] The above is the calculation formula for the array element spacing set L.

[0017] (4) Arrange the three uniform linear arrays to form a ternary redundant sparse linear array. The position of each physical element in the hydrophone array can be expressed as:

[0018]

[0019] The above is the calculation formula for the array element position S.

[0020] The above ternary redundant matrix can be calculated by The virtual differential common array position of the array is obtained, and the differential common array of the array is continuous and hole-free, and the degree of freedom is For the differential co-matrix of the ternary redundant matrix, and The weight of the virtual array element at position is 1. and The weight of the virtual array element at position is 2, and the weight of the other virtual array elements at position The weights of the virtual array elements in are all greater than 2.

[0021] The remarkable progress and creative technical features of the present invention are: the technical route adopts a hydrophone array with a three-element redundant array arrangement with stable and reliable performance; the technical purpose achieved is: when the array element fails, the receiving array has a stable differential common array and a high continuous degree of freedom; the beneficial effects are: when the system of the present invention detects the direction of underwater targets, the system device and design method of the present invention have high robustness and high direction-finding accuracy; the problem of the differential common array structure of the sparse linear array being easily damaged, the degree of freedom being sharply reduced, and the direction-finding accuracy being reduced when the array element fails is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1This is a diagram of an actual scenario application of the present invention.

[0023] Figure 2 The present invention is a block diagram of the hydrophone array direction finding system.

[0024] Figure 3 It is a schematic diagram of the structure of the ternary redundant array of the system of the present invention.

[0025] Figure 4 Schematic diagram of the weight and element importance of the ternary redundant array of the present invention.

[0026] Figure 5 This is a comparison chart of the continuous degrees of freedom of the ternary redundant array of the present invention and other arrays as the failure rate changes.

[0027] Figure 6 This is a comparison chart of the root mean square error of the direction of arrival estimation of the ternary redundant array of the present invention and other arrays as a function of the failure rate.

[0028] Figure 7 This is a comparison diagram of the direction of arrival estimation error between the ternary redundant array of the present invention and other arrays under a certain failure rate.

[0029] In the figure: 1. Processing device, the processing device includes a main control module, a human-computer interaction display terminal, and a solar power supply module; 2. Hydrophone array; 3. Underwater target. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0031] Figure 1 The actual application scenario diagram of a highly robust hydrophone array direction finding system device of the present invention is given. The receiving hydrophone array of the system is arranged underwater, and the processing device is arranged on the detection ship on the surface. The hydrophone array receives the signal actively sent by the underwater target, connects to the main control module through the 485 module, performs data processing and transformation, calculates the underwater target direction, and transmits the result to the human-computer interaction display terminal.

[0032] Figure 2The block diagram of the hydrophone array direction finding system device of the present invention is given. The system includes a receiving hydrophone array, a 485 module, a main control module, a human-computer interaction display terminal, and a solar power supply module. The hydrophone array determines the required number of array elements according to the environment and requirements, arranges them in a ternary redundant sparse linear array, and connects them in a bus manner. The 485 module uses the SP3485 chip as the transceiver of the 485 communication and is connected to the RX485 bus. Multiple hydrophone receiving nodes can be connected to its transmission line. The main control module selects the TMS series DSP processor TMS320F28335 as the core processor, sets the spatial smoothing MUSIC program to process the received data, calculates the spatial spectrum and the wave direction, and the main control module sends a trigger signal to the hydrophone through the RS485 bus to start or stop acquisition. When the hydrophone is in the data upload mode and starts to collect, the main control module commands each hydrophone to upload data in turn in a response manner. The human-computer interaction display terminal uses the C series color screen intelligent terminal LCD display of Jinpeng Industrial Co., Ltd. It has a 32-bit ARM processor and FPGA dual-core control architecture. The DSP chip is connected to the display screen through the serial port to realize the terminal human-computer interaction and real-time display of data, and the parameters are set through the operation page, such as the power on and off of the equipment, the deployment and retraction of the hydrophone array, the start and stop of sampling, the processing accuracy of the DSP processor, the number of operations, etc., and the incident wave arrival direction of the target signal is displayed. The solar power supply module uses solar panels to generate electricity. The solar charging management chip uses CN3791 to store electrical energy in the battery, and the entire system is powered by voltage reduction and stabilization, thereby saving energy.

[0033] Figure 3 A structural schematic diagram of a ternary redundant array is given, and the construction of the ternary redundant array of the present invention is described in detail by taking 17 hydrophones as an example.

[0034] Step 1: Calculate the wavelength of the incident signal ,use The basic unit representing the spacing between array elements is taken as half wavelength, that is, .

[0035] Step 2: According to the total number of hydrophones And the relationship between the array element parameters , , , determine the number of array elements of the three sub-arrays , and In this embodiment, .

[0036] Step 3: Place 6 hydrophones at a distance of Arrange the 7 hydrophones in a straight line into subarray 1 with a spacing of Arrange the 4 hydrophones in a straight line into subarray 2 with a spacing of Arrange them into sub-array 3 in a straight line, and finally separate sub-array 1 from sub-array 2. , subarray 2 and subarray 3 are separated by Arrange in a straight line.

[0037] Step 4: Determine the location of each physical element in the hydrophone array

[0038]

[0039] Figure 4 The weight and element importance diagram of the ternary redundant array of the present invention is given when the number of hydrophones is 17. Figure 4 (a) It is known that the ternary redundant array takes into account both degrees of freedom and redundancy. For the differential common array of the ternary redundant array, except for the 4 virtual array elements on the left and right sides whose weights are less than 3, the weights of the remaining virtual array element positions are greater than or equal to 3. Figure 4 (b) It is known that except for the first and last array elements in the ternary redundant array, the importance of most of the other array elements is not high. The lower the importance of the array element, the less important the array element is. Even when the array element fails, the degree of change in the differential common array is also lower, which ensures the stability of the differential common array and improves the robustness of the array direction finding system of the present invention to a certain extent.

[0040] Figure 5 A comparison chart of the average continuous degrees of freedom of the three-element redundant array of the present invention and six types of linear arrays, namely, uniform linear array (ULA), extended coprime array (ECA), complementary coprime array (CCA), maximum inter-element spacing constraint array (MISC), nested array (NA), and second-order super nested array (SNA2) is given when the number of hydrophones is 17. Figure 5 It can be seen that under random element failure, as the failure rate increases, the average continuous degree of freedom of each array gradually decreases. When the random failure rate is in the range of 0.08 to 0.3, the array of the present invention has the highest continuous degree of freedom. This is because the ternary redundant array itself takes into account both the degree of freedom and redundancy. Even if the array element fails, its differential common array can still maintain a long central continuous segment; while the other sparse linear arrays and uniform linear arrays mainly consider one of the indicators of freedom and redundancy, and have lower continuous degrees of freedom under element failure.

[0041] Figure 6The curves of the root mean square error of the DOA estimation of the three-element redundant array of the present invention and the other six linear arrays as a function of the failure rate are given. It is assumed that the number of hydrophones is 17, 13 of which are evenly distributed in The incident signal source is within, the signal-to-noise ratio is 5dB, the number of signal processing snapshots is 3000, the failure rate increases from 5% to 30%, 20000 Monte Carlo experiments are performed at each failure rate, and the spatial smoothing MUSIC algorithm is used to estimate the direction of arrival. Figure 6 It can be seen that within the entire range of failure rates from 0.05 to 0.3, as the failure rate increases, the estimation errors of each array become larger and larger, among which the array of the present invention has the best estimation performance. This is because the ternary redundant array has both redundancy and freedom, and still has a high continuous degree of freedom under random failures of array elements.

[0042] Figure 7 The error diagram of the direction of arrival estimation obtained by the direction finding system of the present invention based on the ternary redundant array is given when the failure rate of the hydrophone is 0.2, and the error curve of the direction finding using other arrays is also given. The incident signal source is 5dB, the signal-to-noise ratio is 5dB, the number of snapshots is set to increase from 500 to 3500, and 20,000 Monte Carlo experiments are performed. Figure 7 It can be seen that as the number of snapshots increases, the estimation accuracy of the direction of arrival of each array is improved, among which the estimation error of the direction finding based on the ternary redundant array of the present invention is the smallest and has the highest direction finding accuracy.

[0043] In summary, in underwater target detection, when a hydrophone has a random failure, the hydrophone array direction finding system device of the present invention has superior performance in determining the target direction and robustness.

Claims

1. A highly robust hydrophone array direction finding system device, characterized in that: include: (1) Hydrophone array: select the appropriate number of hydrophones according to actual needs, and mount them on the RS485 bus in a ternary redundant array arrangement to collect target signals; (2) 485 module, using SP3485 chip as the transceiver for 485 communication. This module is connected to the RX485 bus, and multiple hydrophone receiving nodes can be connected on its transmission line; (3) Main control module, the core processor selects TMS series DSP processor TMS320F28335, sets the spatial smoothing MUSIC program to process the received data, and calculates the spatial spectrum and wave arrival direction. The main control module sends a trigger signal to the hydrophone through the RS485 bus to start or stop acquisition. When the hydrophone is in the data upload mode and starts to collect data, the main control module commands each hydrophone to upload data in turn in response; (4) Human-computer interaction display terminal, using the C series color screen intelligent terminal LCD display of Jinpeng Industrial Co., Ltd., which has a 32-bit ARM processor and FPGA dual-core control architecture. The DSP chip is connected to the display screen through the serial port to realize terminal human-computer interaction and real-time display of data. Parameters can be set through the operation page, such as the power on and off of the equipment, the deployment and retraction of the hydrophone array, the start and stop of sampling, the processing accuracy of the DSP processor, the number of operations, etc., and the incident wave arrival direction of the target signal can be displayed; (5) Solar power supply module, which uses solar panels to generate electricity. The solar charging management chip uses CN3791 to store electrical energy in batteries and provide power to the entire system through voltage reduction and voltage stabilization; The hydrophone array determines the required number of array elements according to the environment and requirements, and is arranged in a ternary redundant sparse linear array and connected in a bus manner. The 485 module uses the SP3485 chip as the transceiver of the 485 communication and is connected to the RX485 bus, and multiple hydrophone receiving nodes can be connected to its transmission line; The main control module, the core processor selects the TMS series DSP processor TMS320F28335, sets the spatial smoothing MUSIC program to process the received data, calculates the spatial spectrum and the direction of arrival, and sends a trigger signal to the hydrophone through the RS485 bus to start or stop the acquisition. When the hydrophone is in the data upload mode and starts to collect data, the main control module sequentially commands each hydrophone to upload data in a response manner; The human-computer interaction display terminal adopts the C series color screen intelligent terminal LCD display of Jinpeng Industrial Co., Ltd. It has a 32-bit ARM processor and FPGA dual-core control architecture. The DSP chip is connected to the display screen through a serial port to realize terminal human-computer interaction and real-time display of data, and parameter settings are performed through the operation page, usually the power on and off of the equipment, the launch and retraction of the hydrophone array, the start and stop of sampling, the processing accuracy of the DSP processor, the number of operations, and the display of the incident wave arrival direction of the target signal; The solar power supply module uses solar panels to generate electricity, and the solar charging management chip uses CN3791 to store electrical energy in batteries, and power all modules through voltage reduction and stabilization; The connection relationship of the highly robust hydrophone array direction finding system device is as follows: the receiving hydrophone array of the system device is arranged underwater, the processing device is arranged on the detection ship on the water surface, the hydrophone array receives the signal actively sent by the underwater target, the hydrophone array transmits the received signal to the main control module through the 485 module, the main control module performs data processing and transformation, calculates the underwater target direction, and transmits the result to the human-computer interaction display terminal, and the solar power supply module supplies power to the entire system; The hydrophone array arrangement design adopts a ternary redundant array (TRA), which includes the following steps: ① d is used to represent the basic unit of array element spacing, which is usually taken as half wavelength, that is, d = λ / 2, where λ represents the wavelength of the incident signal of the array; ② Assume that the total number of hydrophone array elements is N, and N>14, according to N1=N2-1,N3=N-N1-N2, and the number of array elements N1, N2 and N3 of the three sub-arrays are obtained; ③ Select N1 hydrophones to be arranged in a straight line with a spacing of d to form subarray 1, select N2 hydrophones to be arranged in a straight line with a spacing of 3d to form subarray 2, select N3 hydrophones to be arranged in a straight line with a spacing of 2d to form subarray 3, and the spacing between subarray 1 and subarray 2 is d, and the spacing between subarray 2 and subarray 3 is 3d, that is, the array element spacing set is: The above is the calculation formula for the array element spacing set L; ④ Arrange the three uniform sub-arrays to form a ternary redundant array. The position of each physical array element in the hydrophone array can be expressed as: S={0,1,…,N1-1,N1,N1+3,…,N1+3N2-3,N1+3N2,N1+3N2+2,…,N1+3N2+2N3-2}d The above is the calculation formula of array element position S; By calculation Obtaining a virtual differential common array position of the array, wherein the differential common array of the array is continuous and hole-free, and the degree of freedom is 4N-1; For the differential co-array of the ternary redundant array, the weights of the virtual array elements at the positions [±(N1+3N2+2N3-2)] and [±(N1+3N2+2N3-3)] are 1, the weights of the virtual array elements at the positions [±(N1+3N2+2N3-4)] and [±(N1+3N2+2N3-5)] are 2, and the weights of the remaining virtual array elements in [-(N1+3N2+2N3-6), N1+3N2+2N3-6] are all greater than 2.

2. The method for designing a highly robust hydrophone array direction finding system according to claim 1, characterized in that: The ternary redundant array can maintain a stable differential common array and high continuous degree of freedom when the failure rate of each array element does not exceed 0.3.

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