A large water depth variable aperture acoustic wave oscillation array and acoustic wave landing point calculation method

Abstract

A large water depth variable aperture acoustic wave oscillation array and acoustic wave landing point calculation method, comprising a column (2), characterized in that: the lower end of the column (2) is vertically fixed on a hard bottom layer of a riverbed (1), an oscillator bracket (3) is fixed to the upper end of the column (2), a plurality of oscillators (4) are evenly spacedly mounted on the upper surface of the oscillator bracket (3), and the gap between adjacent oscillators (4) is an anti-silting groove (8). The present invention adopts an acoustic wave landing point calculation method, which ingeniously solves the problem of acoustic wave propagation in deep and complex water bodies affecting measurement accuracy, can accurately calculate the offset of the acoustic wave, and can adjust the position of the measuring ship according to the accurately calculated acoustic wave landing point position, so that the landing point position of the detection acoustic wave emitted by the depth sounder transducer is exactly located in the center of the oscillator array, and can achieve the best detection accuracy.

Description

Technical Field

[0001] The invention relates to a deep water acoustic wave measurement system, in particular to a deep water variable aperture acoustic wave oscillation array and an acoustic wave landing point calculation method, belonging to the technical field of acoustic wave detection. Background Art

[0002] At present, the absolute accuracy assessment method of water depth measurement is generally carried out indoors using a water tank simulation device, that is, a depth sounder is used to emit sound waves to the bottom of the water tank, and the water depth is measured by multiplying the propagation speed of sound waves in water by the time interval between the sound sounder transmitting and receiving the echo reflected from the bottom of the pool, and then the depth is compared with the known depth of the water tank to assess the absolute accuracy of the depth measurement. However, the traditional indoor water tank measurement and assessment method has great limitations. First, the water depth is limited by the depth of the water tank, which is generally no more than 20m, and it is difficult to measure and assess a greater water depth; second, the water tank is indoors, and it is difficult to simulate the complex working conditions in the field. For example, natural factors such as uneven riverbed bottom, siltation, and deep water conditions cannot be fully simulated; third, under natural conditions, changes in the vertical gradient of water temperature, pressure and salinity may cause changes in the speed of sound, which cannot be expressed by a fixed value. These factors make it difficult to evaluate the absolute accuracy of single-beam echo sounders in natural environments, and the only option is to use relative accuracy assessment, that is, repeated observations, resulting in relatively poor assessments, which will deviate greatly from the actual data under natural conditions.

[0003] In addition, the deep measurement method using traditional acoustic wave detection has not been able to solve the problem of sound waves propagating in deep and complex water bodies affecting measurement accuracy. Since sound waves are subject to the influence of temperature, pressure, salinity, etc. of different water layers in deep and complex water bodies, sound waves do not propagate in a straight line, but their propagation path is a relatively complex curve with "drift". Specifically, the speed of sound changes with the temperature in the water, and at the same time, it will be refracted between two water layers with different temperatures, changing its propagation direction. As the water depth increases, there will be various water layers with a certain thickness and water temperature. Every time the sound wave passes through the interface between two water layers, the sound wave will be refracted once. In addition, the influence of pressure and salinity differences at different depths in deep water bodies on the propagation of sound waves further increases the measurement deviation, which seriously affects the accurate detection of deep and complex water bodies. There has been a lack of a technical means with reasonable structure, easy installation and high detection accuracy to solve the above technical problems. Summary of the invention

[0004] The purpose of the present invention is to address the defects and shortcomings of the traditional deep measurement method of acoustic wave detection, which has not been able to solve the problem that the propagation of acoustic waves in great depths and complex water bodies affects the measurement accuracy. In natural environments, the measurement error is large, there will be a large offset, and it is impossible to meet the requirements of accurate detection and acquisition of scientific research data. The present invention provides a large-water-depth variable-aperture acoustic wave oscillation array and acoustic wave landing point calculation method with a reasonable structure, convenient installation, and repeated use, which cleverly solves the problem that the propagation of acoustic waves in great depths and complex water bodies affects the measurement accuracy, can accurately calculate the offset of acoustic waves, and has high detection accuracy.

[0005] To achieve the above-mentioned purpose, the technical solution of the present invention is: a large water depth variable aperture acoustic wave oscillation array, including a column, the lower end of the column is vertically fixed on the hard bottom layer of the riverbed, an oscillator bracket is fixed to the upper end of the column, a plurality of oscillators are installed at equal intervals on the upper surface of the oscillator bracket, and the gap between adjacent oscillators is an anti-siltation groove.

[0006] Furthermore, the oscillator includes an oscillator outer shell, a watertight bulkhead and a watertight compartment. The oscillator outer shell is a closed long strip shell structure. The internal cavity of the oscillator outer shell is provided with a plurality of watertight compartments, and a watertight bulkhead is fixedly provided between two adjacent watertight compartments.

[0007] Furthermore, the oscillator is a long rectangular column structure, and the cross-sectional width of the oscillator is smaller than the width of the anti-siltation groove.

[0008] Furthermore, the outer shell of the oscillator is made of high-strength stainless steel plate.

[0009] A method for calculating the sound wave landing point using a large water depth variable aperture sound wave oscillation array comprises the following steps:

[0010] A. First, construction should be carried out during the low tide or dry season of natural water bodies. The construction location should be as close to the lowest water level as possible. Before construction, the bottom of the water body should be treated to remove surface silt and expose the hard bottom layer;

[0011] B. Then dig the foundation and install fixed columns so that the columns are closely connected to the hard bottom layer to form a solid overall structure;

[0012] C. Then, a fixed oscillator bracket is installed on the column, and a plurality of oscillators are installed at equal intervals on the upper surface of the oscillator bracket to form an oscillator array, and the spatial position of the oscillator array is accurately measured;

[0013] D. When the oscillator array is submerged in water and the water depth needs to be accurately measured, the survey ship is driven to the top of the oscillator array. The survey ship is equipped with an attitude sensor. The depth sounder transducer installed at the bottom of the survey ship or suspended directly below the survey ship transmits a detection sound wave to the oscillator array. After the detection sound wave reaches the oscillator array, it is oscillated and enhanced by the oscillator 4 and then sends an echo to the depth sounder transducer.

[0014] E. Then, starting from the lower surface of the depth sounder transducer, additional water layers are added. Combined with the sound velocity profile, the propagation time t and horizontal displacement y of the beam in each water layer are calculated according to the following sound wave landing point reduction algorithm, as follows:

[0015]

[0016] F. Then add up the propagation time t of each water layer and compare it with the one-way propagation time t to determine whether to add a new water layer.

[0017] (1) If but and is the depth and horizontal displacement of the sound wave landing point;

[0018] (2) If Then it is necessary to add a new water layer and repeat steps 1 and 2;

[0019] (3) If Then the time insufficient to penetrate the last water layer is obtained, the depth and horizontal distance of the water layer penetrated are calculated, and added to the original result;

[0020] G. Finally, the refraction offset of each water layer is superimposed using the principle of calculus to obtain a total offset. The position of the survey ship is then adjusted based on the total offset so that the landing point of the detection sound wave emitted by the depth sounder transducer on the survey ship can be exactly in the center of the oscillator array, thereby obtaining the strongest echo sound intensity and the most accurate maximum water depth measurement value.

[0021] In the step E, the attitude of the depth sounder transducer is observed and calculated by the attitude sensor, so as to calculate the incident angle of the emitted detection sound wave. Before the calculation, the sound velocity profile of the water area must be observed and obtained, and then the calculation is performed by the sound wave landing point calculation algorithm.

[0022] The calculation method and process of the offset in step G are as follows:

[0023] a. First, use a special instrument (sound velocity profiler) to lower from the water surface to the bottom of the water to measure the interface of water layers with different water temperatures, the thickness of water layers with the same water temperature ds1, ds2...dsn, and the sound speeds C1, C2...Cn of water layers with different thicknesses;

[0024] b. Secondly, calculate the time t1 and offset y1 when the sound wave penetrates the interface between the first and second water layers. α1 is the incident angle of the sound wave entering the first water layer; α2 is the refraction angle of the sound wave at the interface between the first and second water layers, then:

[0025]

[0026] c. Then, according to this algorithm, calculate the time t2 and the offset y2 when the sound wave passes through the interface between the second and third water layers. Keep adding water layers until it reaches the bottom of the water. Add up the total time T and the total offset Y when the sound wave reaches the bottom of the water;

[0027]

[0028]

[0029] d. Finally, by adjusting the position of the surface survey ship from the original coordinate (0,0) to the coordinate (0, -Y), the underwater variable aperture acoustic wave oscillation array can be accurately hit.

[0030] The beneficial effects of the present invention are:

[0031] 1. The present invention adopts an oscillator array fixed on the bottom of the water. The oscillator array is composed of multiple oscillators. Each oscillator is provided with multiple independent watertight compartments. The cavity oscillation effect is used to achieve a significant enhancement of sound wave reflection, which greatly improves the accuracy of deep water detection.

[0032] 2. The oscillator array of the present invention is provided with an anti-siltation groove, which can prevent the sediment from accumulating on the upper surface of the oscillator and affecting normal use. At the same time, the oscillator has strong pressure resistance and will not be deformed under the action of water pressure and water flow, and can be used underwater for a long time.

[0033] 3. The present invention adopts a sound wave landing point calculation method, which cleverly solves the problem that the propagation of sound waves in deep and complex water bodies affects the measurement accuracy. It can accurately calculate the offset of the sound wave and adjust the position of the survey ship according to the accurately calculated sound wave landing point, so that the landing point of the detection sound wave emitted by the depth sounder transducer is exactly in the center of the oscillator array, and the best detection accuracy can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the overall structure of the oscillator array of the present invention.

[0035] Figure 2 yes Figure 1 Schematic diagram of the front structure.

[0036] Figure 3 It is a schematic diagram of the structure of the oscillator of the present invention.

[0037] Figure 4 It is a working principle diagram of the present invention.

[0038] Figure 5 It is a diagram showing the relationship between the sound wave landing point position and the hull position of the present invention.

[0039] Figure 6 It is a schematic diagram of the structure of the water layer in the algorithm of the present invention.

[0040] Figure 7 It is the sound wave echo signal diagram of the present invention.

[0041] In the figure: riverbed 1, column 2, oscillator bracket 3, oscillator 4, oscillator outer shell 5, watertight bulkhead 6, watertight compartment 7, anti-silting tank 8, survey ship 9, depth sounder transducer 10, oscillator array 11. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0043] See also Figures 1 to 7 The present invention provides a large water depth variable aperture acoustic wave oscillation array, comprising a column 2, characterized in that: the lower end of the column 2 is vertically fixed on the hard bottom layer of the riverbed 1, an oscillator bracket 3 is fixed to the upper end of the column 2, a plurality of oscillators 4 are evenly spacedly installed on the upper surface of the oscillator bracket 3, and the gap between adjacent oscillators 4 is an anti-siltation groove 8.

[0044] The oscillator 4 includes an oscillator outer shell 5, a watertight bulkhead 6 and a watertight compartment 7. The oscillator outer shell 5 is a closed long strip shell structure. The internal cavity of the oscillator outer shell 5 is provided with a plurality of watertight compartments 7, and a watertight bulkhead 6 is fixedly provided between two adjacent watertight compartments 7.

[0045] The oscillator 4 is a long rectangular column structure, and the cross-sectional width of the oscillator 4 is smaller than the width of the anti-siltation groove 8 .

[0046] The oscillator outer shell 5 is made of high-strength stainless steel plate.

[0047] A method for calculating the sound wave landing point using a large water depth variable aperture sound wave oscillation array comprises the following steps:

[0048] A. First, construction should be carried out during the low tide or dry season of natural water bodies. The construction location should be as close to the lowest water level as possible. Before construction, the bottom of the water body should be treated to remove surface silt and expose the hard bottom layer;

[0049] B. Then, excavate the foundation and install the fixed column 2, so that the column 2 is tightly connected with the hard bottom layer to form a firm overall structure;

[0050] C. Then, an oscillator bracket 3 is fixed on the column 2, and a plurality of oscillators 4 are evenly spaced on the upper surface of the oscillator bracket 3 to form an oscillator array 11, and the spatial position of the oscillator array 11 is accurately measured;

[0051] D. When the oscillator array 11 is submerged in water and the water depth needs to be accurately measured, the survey ship 9 is driven to the top of the oscillator array 11. The survey ship 9 is equipped with a posture sensor. The depth sounder transducer 10 installed at the bottom of the survey ship 9 or suspended directly below the survey ship 9 transmits a detection sound wave to the oscillator array 11. After the detection sound wave reaches the oscillator array 11, it is oscillated and enhanced by the oscillator 4 and then sends an echo to the depth sounder transducer 10.

[0052] E. Then, starting from the lower surface of the depth sounder transducer 10, additional water layers are added, and the propagation time t and horizontal displacement y of the beam in each water layer are calculated according to the following sound wave landing point reduction algorithm in combination with the sound velocity profile, as follows:

[0053]

[0054] F. Then add up the propagation time t of each water layer and compare it with the one-way propagation time t to determine whether to add a new water layer.

[0055] (1) If but and is the depth and horizontal displacement of the sound wave landing point;

[0056] (2) If Then it is necessary to add a new water layer and repeat steps 1 and 2;

[0057] (3) If Then the time insufficient to penetrate the last water layer is obtained, the depth and horizontal distance of the water layer penetrated are calculated, and added to the original result;

[0058] G. Finally, the refraction offset of each water layer is superimposed using the principle of calculus to obtain a total offset, and then the position of the survey ship 9 is adjusted according to the total offset, so that the landing point of the detection sound wave emitted by the depth sounder transducer 10 carried on the survey ship 9 can be exactly in the center of the oscillator array 11, thereby obtaining the strongest echo sound intensity and the most accurate maximum water depth measurement value.

[0059] In step E, the attitude of the depth sounder transducer 10 is observed and calculated by the attitude sensor, so as to calculate the incident angle of the emitted detection sound wave. Before the calculation, the sound velocity profile of the water area must be observed and obtained, and then the calculation is performed by the sound wave landing point calculation algorithm.

[0060] The calculation method and process of the offset in step G are as follows:

[0061] a. First, use a special instrument (sound velocity profiler) to lower from the water surface to the bottom of the water to measure the interface of water layers with different water temperatures, the thickness of water layers with the same water temperature ds1, ds2...dsn, and the sound speeds C1, C2...Cn of water layers with different thicknesses;

[0062] b. Secondly, calculate the time t1 and offset y1 when the sound wave penetrates the interface between the first and second water layers. α1 is the incident angle of the sound wave entering the first water layer; α2 is the refraction angle of the sound wave at the interface between the first and second water layers, then:

[0063]

[0064] c. Then, according to this algorithm, calculate the time t2 and the offset y2 when the sound wave passes through the interface between the second and third water layers. Keep adding water layers until it reaches the bottom of the water. Add up the total time T and the total offset Y when the sound wave reaches the bottom of the water;

[0065]

[0066] d. Finally, by adjusting the position of the surface survey ship from the original coordinate (0,0) to the coordinate (0, -Y), the underwater variable aperture acoustic wave oscillation array can be accurately hit.

[0067] See also Figures 1 to 5 The present invention uses an oscillator array fixed on the bottom of the water to amplify the acoustic echo, and cleverly uses the cavity oscillation effect to enhance the intensity of the reflected echo, thereby greatly improving the measurement accuracy. The oscillator array 11 used in this application is constructed during the low tide or dry season of the natural water body, and the construction location should be as close to the lowest water level as possible. Before construction, the bottom of the water body should be treated to remove the surface silt and expose the hard bottom layer to facilitate firm fixation.

[0068] The lower end of the column 2 is vertically fixed on the hard bottom layer of the riverbed 1, so that the column 2 is tightly connected to the hard bottom layer to form a solid overall structure. An oscillator bracket 3 is fixed to the upper end of the column 2. The oscillator bracket 3 can be fixed by welding. A plurality of oscillators 4 are evenly spaced and installed on the upper surface of the oscillator bracket 3. The plurality of oscillators 4 constitute an oscillator matrix 11. In view of the characteristics of high sand content and easy siltation in river water bodies under natural environments, in order to prevent silt from silting up on the upper surface of the oscillator 4 and affecting normal use, a certain gap is set between adjacent oscillators 4 in the present invention as an anti-siltation groove 8. The width of the anti-siltation groove 8 is greater than the cross-sectional width of the oscillator 4. The silt can fall from the anti-siltation groove 8, and the occurrence of siltation can be effectively avoided under the action of water flow.

[0069] The oscillator 4 includes an oscillator outer shell 5, a watertight bulkhead 6 and a watertight compartment 7. The oscillator outer shell 5 is a closed long strip shell structure, and the internal cavity of the oscillator outer shell 5 is provided with a plurality of watertight compartments 7. A watertight bulkhead 6 is fixedly provided between two adjacent watertight compartments 7, and the adjacent watertight compartments 7 are separated by the watertight bulkhead 6 to form a mutually independent cavity structure. The inner cavity of the watertight compartment 7 is filled with air, and the cavity oscillation effect is used to achieve a significant enhancement of the sound wave reflection, which is equivalent to setting a drum at the bottom of a deeper water area, greatly improving the accuracy of deep water detection.

[0070] At the same time, the use of multiple watertight compartments 7 can not only prevent the entire oscillator 4 from failing due to a leaking part on the same oscillator 4, but also improve the echo reflection effect, and the reflectivity of the natural riverbed can be increased from 30%-50% to more than 80%. Generally, when the water depth is within 20 meters, 1-2 watertight compartments 7 are set in the same oscillator 4; when the water depth is 30 meters-50 meters, 3-5 watertight compartments 7 are set in the same oscillator 4; when the water depth exceeds 50 meters, 6-8 watertight compartments 7 are set in the same oscillator 4. The oscillator outer shell 5 is made of high-strength stainless steel plate, which needs to have a certain pressure resistance and will not deform under the action of water pressure and water flow. In addition, the oscillator 4 of the present invention can be set with different apertures according to different water depths and different parameters of the depth sounder transducer 10, that is, oscillators 4 with different cross-sectional sizes are set.

[0071] The technical principle and steps of the sound wave landing point calculation method using a variable aperture large water depth sound wave oscillation array of the present invention are as follows: First, construction is carried out during the low tide or dry season of the natural water body. The construction location should be as close to the lowest water level as possible. Before construction, the bottom of the water body should be treated to remove the surface silt and expose the hard bottom layer. Then, the foundation is excavated and fixed columns 2 are installed so that the columns 2 are tightly connected to the hard bottom layer to form a solid overall structure. Subsequently, a fixed oscillator bracket 3 is installed on the column 2, and at the same time, a plurality of oscillators 4 are evenly spaced on the upper surface of the oscillator bracket 3 to form an oscillator array 11, and the spatial position of the oscillator array 11 is accurately measured, thereby achieving high-precision positioning of the specific position of the oscillator array 11.

[0072] When the oscillator array 11 is submerged in water and the water depth needs to be accurately measured, the survey ship 9 is driven to the top of the oscillator array 11. The survey ship 9 is equipped with a posture sensor. The bottom of the survey ship 9 is equipped with a depth sounder transducer 10 or the depth sounder transducer 10 is suspended at the bottom of the survey ship 9. The posture sensor can observe and record the posture of the depth sounder transducer 10, thereby calculating the incident angle of the generated sound wave beam. Then the depth sounder transducer 10 emits a detection sound wave to the oscillator array 11. After the detection sound wave reaches the oscillator array 11, it is oscillated and enhanced by the oscillator 4 and then sends an echo to the depth sounder transducer 10.

[0073] Then, starting from the lower surface of the depth sounder transducer 10, additional water layers are added, and the propagation time t and horizontal displacement y of the beam in each water layer are calculated according to the following sound wave landing point reduction algorithm in combination with the sound velocity profile, as follows:

[0074]

[0075] F. Then add up the propagation time t of each water layer and compare it with the one-way propagation time t to determine whether to add a new water layer.

[0076] (1) If but and is the depth and horizontal displacement of the sound wave landing point;

[0077] (2) If Then it is necessary to add a new water layer and repeat steps 1 and 2;

[0078] (3) If The time insufficient to penetrate the last water layer is obtained, and the depth and horizontal distance of the water layer are calculated and added to the original result.

[0079] According to the algorithm, a model between the incident angle a, the one-way propagation time t, the depth d, the horizontal displacement y, and the sound speed C is established, and the penetration depth and horizontal displacement of different propagation times under the incident angle of each transmission beam can be calculated, so as to accurately calculate the landing position of the sound wave. Finally, the refraction offset of each water layer is superimposed using the principle of calculus to obtain a total offset, and then the position of the survey ship 9 is adjusted according to the total offset. Finally, the position of the survey ship 9 is adjusted according to the accurately calculated sound wave landing position, so that the landing position of the detection sound wave emitted by the depth sounder transducer 10 can be located exactly in the center of the oscillator array 11. At this time, the intensity of the sound wave reflection is the largest, and the best detection accuracy can be achieved.

[0080] The above content is a further detailed description of the present invention in combination with specific implementation methods. It cannot be considered that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, simple modifications and substitutions made without departing from the concept of the present invention should be deemed to belong to the scope of protection of the present invention.

Claims

1. A large water depth variable aperture acoustic wave oscillation array, comprising a column (2), characterized in that: The lower end of the column (2) is vertically fixed on the hard bottom layer of the riverbed (1); an oscillator bracket (3) is fixed on the upper end of the column (2); a plurality of oscillators (4) are evenly spaced on the upper surface of the oscillator bracket (3); the gap between adjacent oscillators (4) is an anti-silting groove (8); the oscillator (4) comprises an oscillator outer shell (5), a watertight bulkhead (6) and a watertight compartment (7); the oscillator outer shell (5) is a closed long strip shell structure; a plurality of watertight compartments (7) are arranged in the internal cavity of the oscillator outer shell (5); a watertight bulkhead (6) is fixedly arranged between two adjacent watertight compartments (7); the oscillator (4) is a long strip rectangular column structure; the cross-sectional width of the oscillator (4) is smaller than the width of the anti-silting groove (8).

2. The variable aperture deep water acoustic wave oscillation array according to claim 1, characterized in that: The oscillator outer shell (5) is made of high-strength stainless steel plate.

3. A method for calculating the acoustic wave landing point using the large water depth variable aperture acoustic wave oscillation array as claimed in claim 1, comprising the following steps: A. First, construction should be carried out during the low tide or dry season of natural water bodies. The construction location should be as close to the lowest water level as possible. Before construction, the bottom of the water body should be treated to remove surface silt and expose the hard bottom layer; B. Then, excavate the foundation and install the fixed columns (2) so that the columns (2) are tightly connected to the hard bottom layer to form a solid overall structure; C. Then, an oscillator bracket (3) is fixedly mounted on the column (2), and a plurality of oscillators (4) are evenly spacedly mounted on the upper surface of the oscillator bracket (3). The aperture of the oscillator (4) can be adjusted according to the water depth and the amount of sand. The internal cavity of the oscillator outer shell (5) is provided with a plurality of watertight compartments (7), and a watertight partition (6) is fixedly arranged between two adjacent watertight compartments (7), thereby forming an optimal sound wave oscillation reflection effect, forming an oscillator array (11), and accurately measuring the spatial position of the oscillator array (11); D. When the oscillator array (11) is submerged in water and the water depth needs to be accurately measured, the survey ship (9) is driven to the top of the oscillator array (11). The survey ship (9) is provided with a posture sensor, and a depth sounder transducer (10) installed at the bottom of the survey ship (9) or suspended directly below the survey ship (9) emits a detection sound wave to the oscillator array (11). After the detection sound wave reaches the oscillator array (11), it is oscillated and enhanced by the oscillator (4) and then emits an echo to the depth sounder transducer (10); E. Then, starting from the lower surface of the depth sounder transducer (10), additional water layers are added, and the propagation time t and horizontal displacement y of the beam in each water layer are calculated according to the following sound wave landing point reduction algorithm in combination with the sound velocity profile, as follows: F. Then add up the propagation time t of each water layer and compare it with the one-way propagation time t to determine whether to add a new water layer. (1) If but and is the depth and horizontal displacement of the sound wave landing point; (2) If Then it is necessary to add a new water layer and repeat steps 1 and 2; (3) If Then the time insufficient to penetrate the last water layer is obtained, and the depth and horizontal distance of the water layer are calculated. And add it to the original result; G. Finally, the refraction offsets of each water layer are superimposed using the principle of calculus to obtain a total offset, and then the position of the survey ship (9) is adjusted according to the total offset, so that the landing point of the detection sound wave emitted by the depth sounder transducer (10) carried by the survey ship (9) can be exactly in the center of the oscillator array (11), thereby obtaining the strongest echo sound intensity and the most accurate maximum water depth measurement value; The calculation method and process of the offset are as follows: a. First, use a special instrument to lower from the water surface to the bottom of the water to measure the interface of water layers with different water temperatures, the thickness of water layers with the same water temperature ds1, ds2...dsn, and the sound speed of water layers with different thicknesses C1, C2...Cn; b. Secondly; Calculate the time t1 and offset y1 when the sound wave penetrates the interface between the first and second water layers. α1 is the incident angle of the sound wave entering the first water layer; α2 is the refraction angle of the sound wave at the interface between the first and second water layers. Then: c. Then, according to the algorithm, the time t2 and the offset y2 when the sound wave passes through the interface between the second and third water layers are calculated; the water layers are continuously accumulated until the water bottom is reached, and the total time T and the total offset Y when the sound wave reaches the water bottom are accumulated; d. Finally, by adjusting the position of the surface survey ship from the original coordinate (0,0) to the coordinate (0, -Y), the underwater variable aperture acoustic wave oscillation array can be accurately hit.

4. The method for calculating the acoustic wave landing point using a large water depth variable aperture acoustic wave oscillation array according to claim 3 is characterized in that: In the step E, the attitude of the depth sounder transducer (10) is observed and calculated by the attitude sensor, so as to calculate the incident angle of the emitted detection sound wave. Before the calculation, the sound velocity profile of the water area must be observed and obtained, and then the calculation is performed by the sound wave landing point calculation algorithm.

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