Broadband multi-beam sonar array directivity test system and method

Abstract

The present invention provides a broadband multi-beam sonar array directivity test system and method, the system includes a first trolley, a second trolley and a slide rail; the first trolley includes a first lifting mechanism, a laser rangefinder, an FPGA and a PC, the first lifting mechanism is connected to a transducer to be tested and the laser rangefinder by transmission, the laser rangefinder is connected to the PC, and the transducer to be tested is connected to the PC through the FPGA; the second trolley includes a controller, a second lifting mechanism and an omnidirectional transducer, the controller is connected to the second lifting mechanism and the slide rail, the second lifting mechanism is connected to the omnidirectional transducer by transmission; the slide rail is connected to the second trolley by transmission. A broadband multi-beam sonar array directivity test system and method of the present invention can save more test time to measure more beams, and can perform gain compensation according to the current position, thereby reducing the error caused during the test to improve the test accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of beamforming result testing, and in particular to a broadband multi-beam sonar array directivity testing system and method. Background Art

[0002] As an important fishing instrument in marine fisheries, multi-beam fishing sonar uses the signal reflected by the sound waves after encountering the target to detect the position and size of the target. Beamforming is the core technology in the development of multi-beam fishing sonar, and multi-beam directivity test is an important part of verifying beamforming.

[0003] The existing methods for testing the directivity of sonar arrays mainly include: 1. Manual measurement, that is, when the transducer rotates a certain degree, the peak-to-peak value of the waveform received by the hydrophone or omnidirectional transducer is manually read from the oscilloscope. When the echo waveform is irregular, it is necessary to perform multi-point reading to obtain the average value and then record the value. After the transducer rotates one circle, the data is summarized and a beam diagram is drawn. The degree corresponding to the maximum peak point is found to be the current actual pointing angle, and then it is compared with the expected pointing angle to verify whether the two are consistent. This method is time-consuming and due to the fluctuation of the oscilloscope display and the interference of the external environment, the error caused by human eye measurement is large; 2. Automatic measurement of the directivity of large aperture arrays. Compared with traditional measurement methods, this method adds a narrowband filtering module and an autonomous matching module, which reduces the error caused by the fluctuation of the sound field environment, effectively reduces the influence of the test environment on the directivity results, and saves more manpower. However, when the test conditions do not allow the transducer to rotate, this method and the manual measurement method cannot complete the directivity test.

[0004] There are two main types of traditional directivity automatic measurement systems as shown in the figure below: Figure 1 The process method for manual measurement is Figure 2 Automates the test process for transducer arrays with narrowband autonomous matching modules. Summary of the invention

[0005] In view of the deficiencies in the above-mentioned prior art, the present invention provides a broadband multi-beam sonar array directivity testing system and method, which can save more testing time to measure more beams, and can perform gain compensation according to the current position, thereby reducing the errors caused by the testing process and improving the test accuracy.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a broadband multi-beam sonar array directivity test system, comprising a first trolley, a second trolley and a slide rail; the first trolley comprises a first lifting mechanism, a laser rangefinder, an FPGA and a PC, the first lifting mechanism is transmission-connected to a transducer to be tested and the laser rangefinder, the laser rangefinder is connected to the PC, and the transducer to be tested is connected to the PC via the FPGA; the second trolley comprises a controller, a second lifting mechanism and an omnidirectional transducer, the controller is connected to the second lifting mechanism and the slide rail, the second lifting mechanism is transmission-connected to the omnidirectional transducer; the slide rail is transmission-connected to the second trolley.

[0007] Preferably, the laser rangefinder is arranged above the transducer to be measured and facing the second trolley.

[0008] Preferably, the first trolley further includes a first wireless serial port, and the PC is connected to the first wireless serial port; the second trolley further includes a second wireless serial port, and the controller is connected to the second wireless serial port; the first wireless serial port and the second wireless serial port are communicatively connected.

[0009] A broadband multi-beam sonar array directivity testing method based on the broadband multi-beam sonar array directivity testing system of the present invention comprises the steps of:

[0010] S1: Determine whether this test is a horizontal or vertical directivity test;

[0011] S2: calibrating the transducer to be tested and the omnidirectional transducer according to the determination result;

[0012] S3: the laser rangefinder measures the distance h between the transducer to be measured and the omnidirectional transducer, and transmits the measurement data to the PC to save the data;

[0013] S4: inputting the current depth of the transducer to be measured, the effective distance of the second trolley or the effective range of the second lifting mechanism into the PC, and storing the data in a table. If the data input is unsuccessful, returning to step S2;

[0014] The second trolley and the second lifting mechanism return to the corresponding initial positions according to the requirements of the horizontal or vertical directivity measurement. If they cannot return to the origin, the process returns to step S2;

[0015] S5: Send the beam number to be measured to the FPGA. After successful loading, send a command through the first wireless serial port to make the second trolley and the second lifting mechanism start to move according to the horizontal or vertical measurement requirements, and the transducer to be measured starts to receive the echo signal. The echo signal is processed by the FPGA and then transmitted to the PC; the PC automatically saves the data processed by the FPGA as a text document;

[0016] S6: when the omnidirectional transducer stops moving, the text document is opened, and the data of the text document is converted into decimal and matched with the transmission pulse width, and the matched filtered data is extracted and smoothed according to the requirements;

[0017] S7: Perform distance compensation;

[0018] S8: Draw a beam diagram including a main lobe peak using the distance compensated data.

[0019] Preferably, in the step S2:

[0020] If the judgment result is a vertical directivity test, calibrate the transducer to be tested and the omnidirectional transducer to have the same x-axis coordinates and the same y-axis coordinates;

[0021] If the judgment result is a horizontal directivity test, the transducer to be tested and the omnidirectional transducer are calibrated to have the same y-axis coordinates and the same z-axis coordinates.

[0022] Preferably, the step S7 further comprises the steps of:

[0023] S71: Load the data in the table and calculate the angle range between the transducer to be tested and the omnidirectional transducer according to formula (1) to formula (4), as the horizontal axis of the directivity diagram:

[0024] If x<0, Alpha_h_min=-arctan(L / 2h) (1);

[0025] If x>0, Alpha_h_max=arctan(L / 2h) (2);

[0026] If z<0,Alpha_v_min=-arctan((Lh ′ ) / h) (3);

[0027] If z>0, Alpha_v_max=arctan(h ′ / h) (4);

[0028] Wherein, x represents the coordinate value of the second car moving on the x-axis. When x>0, the second car is in the same direction as the positive direction of the horizontal x-axis of the geodetic coordinate system, and when x<0, it is in the opposite direction to the x-axis. When it is a horizontal directivity test, L represents the total distance that the second car can move in the horizontal direction. If it is a vertical directivity test, L represents the total distance that the second car can move in the vertical direction. h represents the straight-line distance between the first car and the second car on the y-axis. Alpha_h_min and Alpha_h_max represent the horizontal angles between the second car and the first car calculated according to the Pythagorean theorem, and the two are of the same magnitude but opposite signs. z represents the coordinate value of the second car moving in the vertical direction. When z>0, the second car is in the same direction as the positive direction of the vertical z-axis of the geodetic coordinate system, and when z<0, it is in the opposite direction to the z-axis. Alpha_v_min represents the minimum vertical angle between the two cars calculated according to formula (3), and Alpha_v_max represents the maximum vertical angle between the two cars calculated according to formula (4). h ′ It indicates the vertical distance from the transducer to be tested to the extension line of the maximum value of the positive range of the omnidirectional transducer;

[0029] S72: Distance compensation is performed in combination with formula (5):

[0030]

[0031] Wherein, S represents the distance compensation value calculated according to formula (5), if it is a horizontal directivity test, l represents the current horizontal coordinate value of the second car; if it is a vertical directivity test, l represents the current vertical coordinate value of the second car.

[0032] The present invention adopts the above technical solution, so it has the following beneficial effects:

[0033] The first lifting mechanism is connected to the transducer to be tested and generally remains unchanged; the second lifting mechanism is connected to the omnidirectional transducer and is controlled by the controller. When the vertical directivity is measured, the lifting mechanism will move along the z-axis according to the controller's instructions; the laser rangefinder is used to measure the distance between the first trolley and the second trolley, and transmit it to the PC through the serial port line; when the transmission directivity test is performed, the transducer to be tested converts the electrical signal into an acoustic signal and sends it out; when the reception directivity test is performed, the transducer to be tested converts the received echo acoustic signal into an electrical signal and inputs it into the FPGA for processing; the FPGA is used to perform beamforming of the transmit or receive beam, as well as receive instructions from the PC and select and send down the test beam pointing angle; the PC is used to send down the corresponding instructions The command and subsequent data processing can save and call the value of the laser rangefinder, and the data collected by the network port can be stored and processed. Since the second car is in continuous motion and the network port collection is continuous, at least 80 data packets can be collected per second; the navigation speed of the second car is about 0.25° / s. If the two cars are 5m apart at this time, the time for the first pulse to arrive is 5 / 1500≈3ms, and this value is much smaller than the time required for the car to move one degree, so the continuous measurement of the network port will basically not cause angle errors; in subsequent processing, 80 packets will be extracted from the middle of the data as needed, and then the corresponding coordinates can be established according to the corresponding imported data, which solves the problem of incoherent traditional measurement. The controller is connected to the second wireless serial port to establish a connection with the PC, and is used to control the horizontal movement of the second car or the lifting of the second lifting mechanism after receiving relevant instructions. The omnidirectional transducer can be used to receive or transmit signals. If the transducer to be tested needs to be tested for transmission directivity, the omnidirectional transducer does not receive the transmission signal, and directly receives the received echo signal through the board and performs matching filtering; if the transducer to be tested is tested for receiving directivity, the omnidirectional transducer transmits narrowband or broadband signals according to the needs. The slide rail is used to connect the second trolley and drive the second trolley to move according to the controller instructions.

[0034] Compared with the traditional method, the test method of the present invention can save more test time and measure more beams, and can perform gain compensation according to the current position, thereby reducing the error caused by the test process to improve the test accuracy. The distance compensation step is added to make the measurement more accurate, and at the same time solve the problems of the traditional measurement method that it takes a long time, is limited to narrowband signals, and the expected pointing angle cannot be matched. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A flow chart of traditional manual testing of the prior art;

[0036] Figure 2 A traditional automated testing flow chart for existing technologies;

[0037] Figure 3A schematic diagram of the structure of a broadband multi-beam sonar array directivity test system according to an embodiment of the present invention;

[0038] Figure 4 It is a flow chart of a broadband multi-beam sonar array directivity testing method according to an embodiment of the present invention;

[0039] Figure 5 A schematic diagram of the horizontal test compensation distance calculation principle of an embodiment of the present invention;

[0040] Figure 6 This is a schematic diagram of the vertical directivity test compensation distance calculation principle of an embodiment of the present invention. DETAILED DESCRIPTION

[0041] According to the attached figure Figure 3 to Figure 6 , give the preferred embodiments of the present invention, and describe them in detail so that the functions and features of the present invention can be better understood.

[0042] See also Figure 3 to Figure 6 A broadband multi-beam sonar array directivity test system according to an embodiment of the present invention comprises a first trolley 1, a second trolley 2 and a slide rail 3; the first trolley 1 comprises a first lifting mechanism 11, a laser rangefinder 12, an FPGA 13 and a PC 14, the first lifting mechanism 11 is transmission-connected to a transducer 15 to be tested and the laser rangefinder 12, the laser rangefinder 12 is connected to the PC 14, and the transducer 15 to be tested is connected to the PC 14 via the FPGA 13; the second trolley 2 comprises a controller 21, a second lifting mechanism 22 and an omnidirectional transducer 23, the controller 21 is connected to the second lifting mechanism 22 and the slide rail 3, the second lifting mechanism 22 is transmission-connected to the omnidirectional transducer 23; the slide rail 3 is transmission-connected to the second trolley 2.

[0043] The laser rangefinder 12 is disposed above the transducer 15 to be measured and is disposed toward the second trolley 2 .

[0044] The first car 1 also includes a first wireless serial port 16, and the PC 14 is connected to the first wireless serial port 16; the second car 2 also includes a second wireless serial port 24, and the controller 21 is connected to the second wireless serial port 24; the first wireless serial port 16 and the second wireless serial port 24 are in communication connection.

[0045] (1) First lifting mechanism 11, second lifting mechanism 22

[0046] The first lifting mechanism 11 is connected to the transducer 15 to be tested and generally remains unchanged; the second lifting mechanism 22 is connected to the omnidirectional transducer 23 and is controlled by the controller 21. When the vertical directivity is measured, the lifting mechanism will move along the z-axis according to the instructions of the controller 21;

[0047] (2) Laser rangefinder 12: used to measure the distance between the first trolley 1 and the second trolley 2, and transmit the distance to PC 14 through the serial port line;

[0048] (3) Transducer under test 15

[0049] When the transmission directivity test is performed, the transducer 15 to be tested converts the electrical signal into an acoustic signal and sends it out; when the reception directivity test is performed, the transducer to be tested converts the received echo acoustic signal into an electrical signal and then inputs it into the FPGA 13 for processing.

[0050] (4) FPGA 13: used to perform beamforming of the transmit or receive beam, and receive instructions from PC 14 and select and send down the test beam pointing angle;

[0051] (5) PC14

[0052] It is used to issue corresponding instructions and subsequent data processing. It can save and call the values ​​of the laser rangefinder 12, and store and process the data collected by the network port. Since the second car 2 is in continuous motion and the network port collection is continuous, at least 80 data packets can be collected per second; the navigation speed of the second car 2 is about 0.25° / s. If the two cars are 5m apart at this time, the time for the first pulse to arrive is 5 / 1500≈3ms, and this value is much smaller than the time required for the car to move one degree. Therefore, continuous measurement of the network port will basically not cause angular error; in subsequent processing, a certain number of packets will be extracted from the middle of the data as needed from 80 packets, and then the corresponding coordinates can be established according to the corresponding imported data, which solves the problem of incoherence in traditional measurements.

[0053] (6) Controller 21

[0054] The second wireless serial port 24 is connected to establish a connection with the PC 14 and to control the horizontal movement of the second trolley 2 or the lifting and lowering of the second lifting mechanism 22 after receiving relevant instructions.

[0055] (7) Omnidirectional transducer 23

[0056] It can be used to receive or transmit signals. If the transducer 15 to be tested needs to be tested for transmission directivity, the omnidirectional transducer 23 does not receive the transmission signal, but directly receives the received echo signal through the board and performs matched filtering; if the transducer 15 to be tested is tested for reception directivity, the omnidirectional transducer 23 transmits narrowband or broadband signals according to the requirements.

[0057] (8) Slide rail 3: used to connect the second trolley 2 and drive the second trolley 2 to move according to the instructions of the controller 21.

[0058] A broadband multi-beam sonar array directivity testing method based on the broadband multi-beam sonar array directivity testing system of the present invention comprises the steps of:

[0059] S1: Determine whether this test is a horizontal or vertical directivity test;

[0060] S2: Calibrate the transducer 15 to be tested and the omnidirectional transducer 23 according to the determination result;

[0061] In step S2:

[0062] If the judgment result is a vertical directivity test, the x-axis coordinates of the transducer to be tested 15 and the omnidirectional transducer 23 are calibrated to be the same and the y-axis coordinates are the same;

[0063] If the judgment result is a horizontal directivity test, the y-axis coordinates of the transducer to be tested 15 and the omnidirectional transducer 23 are calibrated to be the same and the z-axis coordinates are the same.

[0064] S3: The laser rangefinder 12 measures the distance h between the transducer 15 to be measured and the omnidirectional transducer 23, and transmits the measurement data to the PC 14 to save the data;

[0065] S4: Input the current depth of the transducer 15 to be tested, the effective distance of the second trolley 2 or the effective range of the second lifting mechanism 22 in the PC 14, and store the data in the table. If the data input is unsuccessful, return to step S2;

[0066] The second trolley 2 and the second lifting mechanism 22 return to the corresponding initial positions according to the requirements of the horizontal or vertical directivity measurement. If they cannot return to the origin, they return to step S2;

[0067] S5: Send the beam number to be measured to FPGA13. After successful loading, send a command through the first wireless serial port 16 to make the second trolley 2 and the second lifting mechanism 22 start to move according to the horizontal or vertical measurement requirements, and the transducer 15 to be measured starts to receive the echo signal. The echo signal is processed by FPGA13 and then transmitted to PC14; PC14 automatically saves the data processed by FPGA13 as a text document;

[0068] S6: When the omnidirectional transducer 23 stops moving, the corresponding program (the present invention uses Matlab, but is not limited to this software) is used to open the text document, and the data of the text document is converted into decimal and matched filtered with the transmission pulse width, and the matched filtered data is extracted and smoothed according to the requirements;

[0069] S7: Perform distance compensation;

[0070] Step S7 further comprises the steps of:

[0071] S71: Load the data in the table and calculate the angle range between the transducer 15 to be tested and the omnidirectional transducer 23 according to formula (1) to formula (4), which is used as the horizontal axis of the directivity diagram:

[0072] If x<0, Alpha_h_min=-arctan(L / 2h) (1);

[0073] If x>0, Alpha_h_max=arctan(L / 2h) (2);

[0074] If z<0,Alpha_v_min=-arctan((Lh ′ ) / h) (3);

[0075] If z>0, Alpha_v_max=arctan(h ′ / h)(4);

[0076] Where x represents the coordinate value of the second car moving on the x-axis. When x>0, the second car is in the same direction as the positive x-axis of the earth coordinate system (e.g. Figure 5 When x<0, it indicates the opposite direction to the x-axis. When it is a horizontal directivity test, L indicates the total distance that the second trolley can move in the horizontal direction. When it is a vertical directivity test, L indicates the total distance that the second trolley can move in the vertical direction. h indicates the straight-line distance between the first trolley and the second trolley on the y-axis. Alpha_h_min and Alpha_h_max indicate the horizontal angle between the second trolley and the first trolley calculated according to the Pythagorean theorem, and the two are of the same magnitude but opposite sign. z indicates the coordinate value of the second trolley moving in the vertical direction. When z>0, the second trolley is in the same direction as the positive z-axis of the earth coordinate system (such as Figure 6 As shown in the figure, when z<0, it indicates the opposite direction to the z axis; Alpha_v_min indicates the minimum vertical angle between the two cars calculated according to formula (3), and Alpha_v_max indicates the maximum vertical angle between the two cars calculated according to formula (4); h ′ It indicates the vertical distance from the transducer to be tested to the extension line of the maximum value of the omnidirectional transducer in the positive range (such as Figure 6 shown).

[0077] S72: Distance compensation is performed in combination with formula (5):

[0078]

[0079] Wherein, S represents the distance compensation value calculated according to formula (5), if it is a horizontal directivity test, l represents the current horizontal coordinate value of the second car; if it is a vertical directivity test, l represents the current vertical coordinate value of the second car.

[0080] S8: Draw a beam diagram including the main lobe peak using the distance compensated data.

[0081] The present invention is described in detail above in conjunction with the embodiments of the accompanying drawings. A person skilled in the art can make various variations of the present invention according to the above description. Therefore, certain details in the embodiments should not constitute a limitation of the present invention, and the scope of protection of the present invention shall be defined by the scope of the attached claims.

Claims

1. A broadband multi-beam sonar array directivity test method based on a broadband multi-beam sonar array directivity test system. The broadband multi-beam sonar array directivity test system includes a first trolley, a second trolley and a slide rail; the first trolley includes a first lifting mechanism, a laser rangefinder, an FPGA and a PC, the first lifting mechanism is connected to a transducer to be tested and the laser rangefinder by transmission, the laser rangefinder is connected to the PC, and the transducer to be tested is connected to the PC through the FPGA; the second trolley includes a controller, a second lifting mechanism and an omnidirectional transducer, the controller is connected to the second lifting mechanism and the slide rail, the second lifting mechanism is connected to the omnidirectional transducer by transmission; the slide rail is connected to the second trolley by transmission; the laser rangefinder is arranged above the transducer to be tested and arranged toward the second trolley; the first trolley also includes a first wireless serial port, the PC is connected to the first wireless serial port; the second trolley also includes a second wireless serial port, the controller is connected to the second wireless serial port; the first wireless serial port and the second wireless serial port are connected in communication; The test method comprises the steps of: S1: Determine whether this test is a horizontal or vertical directivity test; S2: calibrating the transducer to be tested and the omnidirectional transducer according to the determination result; S3: the laser rangefinder measures the distance h between the transducer to be measured and the omnidirectional transducer, and transmits the measurement data to the PC to save the data; S4: inputting the current depth of the transducer to be measured, the effective distance of the second trolley or the effective range of the second lifting mechanism into the PC, and storing the data in a table. If the data input is unsuccessful, returning to step S2; The second trolley and the second lifting mechanism return to the corresponding initial positions according to the requirements of the horizontal or vertical directivity measurement. If they cannot return to the origin, the process returns to step S2; S5: Send the beam number to be measured to the FPGA. After successful loading, send a command through the first wireless serial port to make the second trolley and the second lifting mechanism start to move according to the horizontal or vertical measurement requirements, and the transducer to be measured starts to receive the echo signal. The echo signal is processed by the FPGA and then transmitted to the PC; the PC automatically saves the data processed by the FPGA as a text document; S6: when the omnidirectional transducer stops moving, the text document is opened, and the data of the text document is converted into decimal and matched with the transmission pulse width, and the matched filtered data is extracted and smoothed according to the requirements; S7: Perform distance compensation; S8: Draw a beam diagram including a main lobe peak using the distance compensated data.

2. The broadband multi-beam sonar array directivity test method according to claim 1, characterized in that: In the step S2: If the judgment result is a vertical directivity test, calibrate the transducer to be tested and the omnidirectional transducer to have the same x-axis coordinates and the same y-axis coordinates; If the judgment result is a horizontal directivity test, the transducer to be tested and the omnidirectional transducer are calibrated to have the same y-axis coordinates and the same z-axis coordinates.

3. The broadband multi-beam sonar array directivity test method according to claim 2, characterized in that: The S7 step further comprises the steps of: S71: Load the data in the table and calculate the angle range between the transducer to be tested and the omnidirectional transducer according to formula (1) to formula (4), as the horizontal axis of the directivity diagram: If x<0, Alpha_h_min=-arctan(L / 2h)(1); If x>0, Alpha_h_max=arctan(L / 2h)(2); If z < 0, Alpha_v_min = -arctan((L - h ′ ) / h)(3); If z > 0, Alpha_v_max = arctan(h ′ / h)(4); Wherein, x represents the coordinate value of the second car moving on the x-axis. When x>0, the second car is in the same direction as the positive direction of the horizontal x-axis of the geodetic coordinate system, and when x<0, it is in the opposite direction to the x-axis. When it is a horizontal directivity test, L represents the total distance that the second car can move in the horizontal direction. If it is a vertical directivity test, L represents the total distance that the second car can move in the vertical direction. h represents the straight-line distance between the first car and the second car on the y-axis. Alpha_h_min and Alpha_h_max represent the horizontal angles between the second car and the first car calculated according to the Pythagorean theorem, and the two are of the same magnitude but opposite signs. z represents the coordinate value of the second car moving in the vertical direction. When z>0, the second car is in the same direction as the positive direction of the vertical z-axis of the geodetic coordinate system, and when z<0, it is in the opposite direction to the z-axis. Alpha_v_min represents the minimum vertical angle between the two cars calculated according to formula (3), and Alpha_v_max represents the maximum vertical angle between the two cars calculated according to formula (4). h ′ It indicates the vertical distance from the transducer to be tested to the extension line of the maximum value of the positive range of the omnidirectional transducer; S72: Distance compensation is performed in combination with formula (5): Wherein, S represents the distance compensation value calculated according to formula (5), if it is a horizontal directivity test, l represents the current horizontal coordinate value of the second car; if it is a vertical directivity test, l represents the current vertical coordinate value of the second car.

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