Receiving and transmitting combined synthetic aperture sonar echo simulation method, system and device

Abstract

The invention discloses a receiving and transmitting combined synthetic aperture sonar echo simulation method, system and device, and relates to the technical field of image processing. The sonar echo simulation method comprises the following steps: calculating the accurate propagation time of a signal from emission to reception according to the emission distance between a sonar at a signal emission moment and a single target and the receiving distance between the sonar at an echo signal reception moment and the single target; and according to the two-dimensional coordinate of the single target, the calculated transmitting distance, the calculated receiving distance and the calculated two-way distance of the signal, carrying out time delay processing on the transmitted modulated broadband signal to obtain an echo signal corresponding to the single target, and aiming at any other target in the space, carrying out time delay processing on the echo signal corresponding to the single target. After the two-dimensional coordinates corresponding to the targets are transformed, iterative calculation is carried out according to the steps, echo signals corresponding to any other target in the space are obtained, coherent accumulation is carried out on the echo signals of all the targets in the time domain, then demodulation is carried out, and baseband echo signals are obtained.

Description

Technical Field

[0001] This invention relates to the field of image processing technology, and in particular to a method, system, and apparatus for simulating composite aperture sonar echoes, wherein the sonar echo simulation method can accurately simulate composite aperture sonar echo signals. Background Technology

[0002] Synthetic aperture sonar (SAR) is a high-resolution imaging device that provides underwater acoustic images "comparable to optical images," which is beneficial for underwater engineering applications such as underwater search and rescue, underwater small target detection and identification, underwater mapping, and underwater geological exploration. Transceiver-based SAR sonar uses a single array element to simultaneously transmit signals and receive echoes, making it relatively simple. However, traditional SAR sonar simulations assume the sonar is stationary during signal transmission and reception, ignoring the distance the sonar travels along the azimuth during transmission and reception. In reality, a SAR sonar in operation maintains constant linear motion, not a stationary position. When the target is close, the azimuth distance traveled by the SAR sonar during transmission and reception has a relatively small impact on the echo simulation. However, when the target is at a distance, it will cause inaccurate calculation of the receiving distance, leading to inaccurate calculations of Doppler phase and range migration, and ultimately resulting in inaccurate simulated echoes. In reality, before the actual transceiver synthetic aperture sonar system is developed, the simulated echo is the sole source of all signal processing methods, including imaging algorithms, image processing algorithms, and interferometric signal processing algorithms. It plays a crucial supporting role in the development of the entire signal processing software within the system. Using inaccurate echoes as input will prevent the developed signal processing software from effectively imaging distant targets, leading to degraded imaging performance and even defocusing. Therefore, it is essential to research echo simulation methods that approximate the actual motion conditions of a transceiver synthetic aperture sonar system. This will provide the signal processing software development with realistic input echoes, which has significant practical implications for improving the imaging performance of distant targets. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a method for simulating the echo of a combined transceiver synthetic aperture sonar, which can accurately simulate the echo of a combined transceiver synthetic aperture sonar when it moves along the azimuth during signal transmission and reception. The sonar echo simulation method includes the following steps: S1. Calculate the transmission distance between the transceiver synthetic aperture sonar and the single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the single target at the time of signal transmission. S2, calculate the receiving distance between the transceiver synthetic aperture sonar and the single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the target at the time of echo signal reception. S3. Calculate the precise propagation time of the signal from transmission to reception based on the transmission distance between the combined transceiver synthetic aperture sonar and the single target at the time of signal transmission and the reception distance between the combined transceiver synthetic aperture sonar and the single target at the time of echo signal reception. S4. Based on the two-dimensional coordinates of a single target, the transmission distance between the transceiver synthetic aperture sonar and the single target at the time of signal transmission, and the reception distance between the transceiver synthetic aperture sonar and the single target at the time of echo signal reception, calculate the two-way distance traversed by the signal, perform time delay processing on the transmitted modulated broadband signal, and obtain the echo signal corresponding to the single target. S5. For any other target in space, after transforming the two-dimensional coordinates of the target, perform iterative calculations according to the above steps to obtain the echo signal corresponding to any other target in space. S6 performs coherent accumulation of the echo signals of all targets in the time domain, and then demodulates them to obtain the baseband echo signal.

[0004] Preferably, in step S1, it is assumed that the system starts at the origin of the coordinate system, and after... After a certain time, at a certain speed The coordinates of the moving synthetic aperture sonar in the azimuth direction are: The coordinate of the target in the range direction is 0, and the coordinate of the target in the azimuth direction is... The coordinates in the distance direction are ,calculate At time t, the transmission distance between the combined transceiver synthetic aperture sonar and a single target at the signal transmission time. for: .

[0005] Preferably, in step S2, it is assumed that the precise propagation time of the signal from transmission to reception is... With speed Motion-based synthetic aperture sonar with combined transmitter and receiver operates on the precise propagation time of signals from transmission to reception. The distance of the inner azimuth movement is At this point, the azimuth coordinates of the combined transceiver synthetic aperture sonar are: The receiving distance between the transceiver synthetic aperture sonar and a single target at the moment of echo signal reception. for: .

[0006] Preferably, in step S3, the precise propagation time of the signal from transmission to reception is calculated in step S3. The corresponding propagation distance is equal to the sum of the transmission distance calculated in step S1 and the reception distance calculated in step S2, so the established equation is: ,in Let represent the speed of sound in water. Solving the above equations, we obtain the precise propagation time of the signal from transmission to reception as: The precise expression is: .

[0007] Preferably, in step S4, the transmission distance between the transceiver combined synthetic aperture sonar and the single target at the signal transmission moment is: The receiving distance between the transceiver synthetic aperture sonar and the single target at the moment of echo signal reception is: The two-way distance traversed by the signal is obtained as follows: Assuming Indicates frequency modulation. This indicates the fast time corresponding to the distance direction. Indicates the carrier frequency; the transmitted wideband signal is a linear frequency modulated signal. Then the modulated transmitted signal is After delay processing, the echo signal is obtained. The expression is: ,in It represents the imaginary unit.

[0008] Preferably, in step S5, it is assumed that the coordinates of any other target in space in the azimuth direction are... The coordinates in the distance direction are The two-way distance traversed by the signal is calculated according to step S4 as follows: Correspondingly, the echo signal corresponding to this target is: .

[0009] Preferably, in step S6, the expression for coherent accumulation is: The total number of targets is Then, the coherently accumulated echo signal is demodulated, as expressed by: .

[0010] According to another aspect of the present invention, the present invention further provides a transceiver combined synthetic aperture sonar echo simulation system for performing echo simulation of transceiver combined synthetic aperture sonar, wherein the sonar echo simulation system comprises: The first calculation unit is used to calculate the transmission distance between the transceiver synthetic aperture sonar and the single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the two-dimensional coordinates of the single target at the time of signal transmission. The second calculation unit is used to calculate the receiving distance between the transceiver synthetic aperture sonar and a single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the target at the time of echo signal reception. The third calculation unit is used to calculate the precise propagation time of the signal from transmission to reception based on the transmission distance between the transceiver synthetic aperture sonar and a single target at the time of signal transmission and the reception distance between the transceiver synthetic aperture sonar and a single target at the time of echo signal reception. The echo signal acquisition unit is used to calculate the two-way distance traversed by the signal based on the two-dimensional coordinates of a single target, the transmission distance between the transceiver synthetic aperture sonar and the single target at the time of signal transmission, and the reception distance between the transceiver synthetic aperture sonar and the single target at the time of echo signal reception. It also performs time delay processing on the transmitted modulated broadband signal to obtain the echo signal corresponding to the single target. The iterative calculation unit is used to perform iterative calculations on any other target in space after transforming the two-dimensional coordinates of the target, and then following the steps above to obtain the echo signal corresponding to any other target in space. The coherent accumulation unit is used to coherently accumulate the echo signals of all targets in the time domain, and then demodulate them to obtain the baseband echo signal.

[0011] Preferably, it is assumed that the system starts at the origin of the coordinate system, and after... After a certain time, at a certain speed The coordinates of the moving synthetic aperture sonar in the azimuth direction are: The coordinate of the target in the range direction is 0, and the coordinate of the target in the azimuth direction is... The coordinates in the distance direction are The first computing unit calculates At time t, the transmission distance between the combined transceiver synthetic aperture sonar and a single target at the signal transmission time. for: .

[0012] According to another aspect of the invention, the invention further provides a computing device including a processor and a memory, wherein computer program instructions are stored in the memory, and the computer program instructions, when executed in the processor, cause the processor to perform a sonar echo simulation method, wherein the sonar echo simulation method includes the following steps: S1. Calculate the transmission distance between the transceiver synthetic aperture sonar and the single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the single target at the time of signal transmission. S2, calculate the receiving distance between the transceiver synthetic aperture sonar and the single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the target at the time of echo signal reception. S3. Calculate the precise propagation time of the signal from transmission to reception based on the transmission distance between the combined transceiver synthetic aperture sonar and the single target at the time of signal transmission and the reception distance between the combined transceiver synthetic aperture sonar and the single target at the time of echo signal reception. S4. Based on the two-dimensional coordinates of a single target, the transmission distance between the transceiver synthetic aperture sonar and the single target at the time of signal transmission, and the reception distance between the transceiver synthetic aperture sonar and the single target at the time of echo signal reception, calculate the two-way distance traversed by the signal, perform time delay processing on the transmitted modulated broadband signal, and obtain the echo signal corresponding to the single target. S5. For any other target in space, after transforming the two-dimensional coordinates of the target, perform iterative calculations according to the above steps to obtain the echo signal corresponding to any other target in space. S6 performs coherent accumulation of the echo signals of all targets in the time domain, and then demodulates them to obtain the baseband echo signal.

[0013] Compared with the prior art, the present invention has at least the following beneficial effects: Compared with the traditional transceiver synthetic aperture sonar echo simulation method, the sonar echo simulation method of the present invention takes into account the influence of the azimuth movement distance of the transceiver synthetic aperture sonar during signal transmission and reception, thereby making the simulated echo signal closer to the actual movement of the transceiver synthetic aperture sonar. This can provide the transceiver synthetic aperture sonar signal processing software with an input echo that is closer to the actual movement, which is beneficial to improving the imaging performance of distant targets. Attached Figure Description

[0014] Figure 1 This is a flowchart illustrating a preferred embodiment of the present invention for simulating the echo of a synthetic aperture sonar with a combined transmit and receive configuration.

[0015] Figure 2 This is a spatial geometry diagram between the transceiver synthetic aperture sonar and the target in the sonar echo simulation method of the preferred embodiment of the present invention.

[0016] Figure 3 The echo is simulated using traditional methods.

[0017] Figure 4The echo simulated by the sonar echo simulation method of the above preferred embodiment of the present invention.

[0018] Figure 5 This is to account for the phase error caused by traditional echo simulation methods that do not consider the motion along the azimuth direction during signal transmission and reception.

[0019] Figure 6 The range profile is obtained by imaging processing based on the range-Doppler imaging method applicable to conventional simulated echoes and by imaging processing based on the sonar echo simulation method of the present invention.

[0020] Figure 7 The image is an azimuth profile after imaging processing based on the range-Doppler imaging method applicable to conventional simulated echoes and after imaging processing based on the sonar echo simulation method of the present invention.

[0021] Figure 8 for Figure 7 Enlarged image.

[0022] Figure 9 This is a block diagram of a synthetic aperture sonar echo simulation system with combined transceiver and receiver according to another preferred embodiment of the present invention.

[0023] Figure 10 This is a block diagram of a computing device according to another preferred embodiment of the present invention.

[0024] In the picture: 100. Sonar echo simulation system; 110. First calculation unit; 120. Second calculation unit; 130. Third calculation unit; 140. Echo signal acquisition unit; 150. Iterative calculation unit; 160. Coherent accumulation unit; 200. Computing device; 210. Processor; 220. Memory; 230. Input device; 240. Output device. Detailed Implementation

[0025] Before detailing any embodiment of the invention, it should be understood that the invention, in its application, is not limited to the details of the construction and arrangement of the components set forth in the following description or illustrated in the following figures. The invention can have other embodiments and can be practiced or carried out in various ways. Furthermore, it should be understood that the wording and terminology used herein are for descriptive purposes and should not be considered limiting. The use of “comprising” or “having” and variations thereof is intended to cover the items set forth below and their equivalents, as well as any additional items. Unless otherwise specified or limited, the terms “installation,” “connection,” “support,” and “linkage,” and variations thereof are used broadly and cover both direct and indirect installation, connection, support, and linking. Moreover, “connection” and “linkage” are not limited to physical or mechanical connections or links.

[0026] Furthermore, firstly, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting the invention. Secondly, the term "a" should be understood as "at least one" or "one or more," that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple. The term "a" should not be construed as a limitation on the quantity.

[0027] Figure 1 This invention illustrates a preferred embodiment of a synthetic aperture sonar echo simulation method. The specific steps of the sonar echo simulation method include: S1, calculating the transmission distance between the synthetic aperture sonar and the single target at the signal transmission time based on the two-dimensional coordinates of the synthetic aperture sonar and the two-dimensional coordinates of the single target at the signal transmission time; S2, calculating the reception distance between the synthetic aperture sonar and the single target at the echo signal reception time based on the two-dimensional coordinates of the synthetic aperture sonar and the target at the echo signal reception time; S3, calculating the reception distance between the synthetic aperture sonar and the single target based on the transmission distance between the synthetic aperture sonar and the single target at the signal transmission time and the reception distance between the synthetic aperture sonar and the single target at the echo signal reception time. S4. Calculate the precise propagation time of the signal from transmission to reception based on the two-dimensional coordinates of a single target, the transmission distance between the transceiver synthetic aperture sonar and the single target at the time of signal transmission, and the reception distance between the transceiver synthetic aperture sonar and the single target at the time of echo signal reception. Perform time delay processing on the transmitted modulated broadband signal to obtain the echo signal corresponding to the single target. S5. For any other target in space, after transforming the two-dimensional coordinates of the target, perform iterative calculations according to the above steps to obtain the echo signal corresponding to any other target in space. S6. Coherently accumulate the echo signals of all targets in the time domain, and then demodulate them to obtain the baseband echo signal. Through the above steps, compared with the traditional transceiver synthetic aperture sonar echo simulation method, the sonar echo simulation method of the present invention takes into account the influence of the azimuth distance of the transceiver synthetic aperture sonar during signal transmission and reception. As a result, the simulated echo signal is closer to the actual motion of the transceiver synthetic aperture sonar, which can provide the transceiver synthetic aperture sonar signal processing software with an input echo that is closer to the actual motion, which is beneficial to improving the imaging performance of long-distance targets.

[0028] Figure 2 The diagram illustrates the spatial geometry between the transceiver synthetic aperture sonar and the target. The azimuth direction represents the motion azimuth of the transceiver synthetic aperture sonar, and the perpendicular azimuth direction is the range direction. The black-filled hexagon represents the ideal point target, and the coordinates of this single target in the azimuth direction are... The coordinates in the distance direction are On the azimuth coordinate axis, circles represent the array elements of the combined transceiver synthetic aperture sonar. The combined transceiver synthetic aperture sonar moves at a constant velocity in a straight line along the azimuth direction. Assuming the origin is at system startup, the coordinate of the combined transceiver synthetic aperture sonar in the range direction is 0. After a certain time, at a certain speed The coordinates of the moving synthetic aperture sonar in the azimuth direction are: Therefore, it is possible to calculate At time t, the transmission distance between the combined transceiver synthetic aperture sonar and a single target at the signal transmission time. for: .

[0029] In step S2, it is assumed that the precise propagation time of the signal from transmission to reception is... So, in terms of speed Motion-based synthetic aperture sonar with combined transmitter and receiver operates on the precise propagation time of signals from transmission to reception. The distance of the inner azimuth movement is At this time, the coordinates of the combined transceiver synthetic aperture sonar in the azimuth direction are... The receiving distance between the transceiver synthetic aperture sonar and a single target at the moment of echo signal reception. for: .

[0030] In step S3, based on the precise propagation time of the signal from transmission to reception, the transmission distance calculated in step S1, and the reception distance calculated in step S2, an equation is established, and the precise propagation time of the signal from transmission to reception is precisely solved. The propagation distance corresponding to the precise propagation time of the signal from transmission to reception calculated in step S3 is necessarily equal to the sum of the transmission distance calculated in step S1 and the reception distance calculated in step S2. Therefore, the established equation is: ,in Let represent the speed of sound in water. By solving the above equation, the precise propagation time of the signal from transmission to reception can be obtained as follows: The precise expression is: .

[0031] In step S4, based on the two-dimensional coordinates of a single target, the transmission distance between the transceiver synthetic aperture sonar and the single target at the time of signal transmission, and the reception distance between the transceiver synthetic aperture sonar and the single target at the time of echo signal reception, the transmitted modulated broadband signal is delayed. The azimuth coordinates of the single target are... The coordinates in the distance direction are The transmission distance between the combined transceiver synthetic aperture sonar and the single target at the moment of signal transmission is The receiving distance between the transceiver synthetic aperture sonar and the single target at the moment of echo signal reception is: The two-way distance traversed by the signal is obtained as follows: Assuming Indicates frequency modulation. This indicates the fast time corresponding to the distance direction. Indicates the carrier frequency; the transmitted wideband signal is a linear frequency modulated signal. Then the modulated transmitted signal is After delaying the signal, the echo signal is obtained. The expression is: ,in Indicates the speed of sound in water. It represents the imaginary unit.

[0032] In step S5, for any other target in space, after transforming the target's two-dimensional coordinates, the echo signal corresponding to the other target in space is iteratively calculated according to step S4, where it is assumed that the coordinates of the other target in space in the azimuth direction are... The coordinates in the distance direction are The two-way distance traversed by the signal is calculated according to step S4 as follows: Therefore, the corresponding echo signal for this target is: ,in This indicates the fast time corresponding to the distance direction. Indicates the speed of sound in water. Indicates frequency modulation. Indicates the carrier frequency.

[0033] In step S6, the echo signals of all targets are coherently accumulated in the time domain and then demodulated to obtain the baseband echo signal. The expression for coherent accumulation is as follows: Here, the total number of targets is .

[0034] Then, the coherently accumulated echo signal is demodulated, as expressed by: ,in This indicates the fast time corresponding to the distance direction. Indicates the speed of sound in water. Indicates frequency modulation. Indicates the carrier frequency.

[0035] Assuming the tow speed of the combined transceiver synthetic aperture sonar (SAR) is 0.125 m / s, the aperture of its array elements in the azimuth direction is 0.08 m, the center frequency of the transmitted linear frequency modulated (LFM) signal is 150 kHz, the bandwidth is 10 kHz, and the pulse repetition frequency is 6.25 Hz, and assuming an ideal point target exists in the scene with an aperture coordinate of 10 m in the azimuth direction and a spatial coordinate of 111 m in the range direction, traditional echo simulation methods assume the SAR is stationary during signal transmission and reception. This ignores the distance the SAR moves along the azimuth direction during signal transmission and reception. The simulated echo signal is as follows: Figure 3 As shown, the sonar echo simulation method of the present invention fully considers the distance the transceiver synthetic aperture sonar moves along the azimuth direction during signal transmission and reception. The simulated echo signal is as follows: Figure 4 As shown, for the single point target set, Figure 5 Since traditional echo simulation methods do not consider the phase error caused by azimuth motion during signal transmission and reception, it is easy to see that the phase error introduced by traditional echo simulation methods is relatively large and cannot well approximate the actual motion of a combined transceiver synthetic aperture sonar. Therefore, the range-Doppler imaging method, which is suitable for traditional echo simulation, is still used to image the echo simulated by both the traditional echo simulation method and the sonar echo simulation method described in this invention. The resulting range profile is shown below. Figure 6 As shown in the figure, the echo simulated by the traditional echo simulation method and the echo simulated by the sonar echo simulation method of the present invention have basically the same focusing results in the range direction. That is to say, the sonar echo simulation method of the present invention, after accurately considering the distance of the synthetic aperture sonar moving along the azimuth direction during signal transmission and reception, does not cause a performance reduction in the range direction when using the range-Doppler imaging method suitable for traditional echo simulation. Figure 7 Based on the range-Doppler imaging method applicable to traditional simulated echoes, the azimuth profiles of the echoes simulated by the traditional echo simulation method and the sonar echo simulation method of the present invention are imaged. It can be clearly seen from the figures that the range-Doppler imaging method applicable to traditional simulated echoes cannot effectively handle the simulated echoes of the sonar echo simulation method of the present invention, which considers the distance traveled along the azimuth direction by the combined transmitting and receiving synthetic aperture sonar during signal transmission and reception. This results in insufficiently pronounced sidelobes in the echo processing results of the sonar echo simulation method of the present invention. Figure 8 for Figure 7The magnified view of the main lobe clearly shows that after processing the echo simulated by the sonar echo simulation method of the present invention using the traditional distance-Doppler imaging method for simulated echoes, the main lobe of the azimuth profile has a small offset in the azimuth direction, and there is no side lobe structure. This reflects that the sonar echo simulation method of the present invention takes into account the influence of the azimuth movement distance of the transceiver synthetic aperture sonar during signal transmission and reception, making the echo simulated by the sonar echo simulation method of the present invention closer to the real situation of the transceiver synthetic aperture sonar.

[0036] Reference Appendix Figure 9 According to another aspect of the present invention, the present invention further provides a transceiver synthetic aperture sonar echo simulation system 100, wherein the sonar echo simulation system 100 includes a first computing unit 110, a second computing unit 120, a third computing unit 130, an echo signal acquisition unit 140, an iterative computing unit 150, and a coherent accumulation unit 160. The first computing unit 110, the second computing unit 120, the third computing unit 130, the echo signal acquisition unit 140, the iterative computing unit 150, and the coherent accumulation unit 160 cooperate with each other, enabling the simulated echo signal to be closer to the actual motion of the transceiver synthetic aperture sonar, and providing the transceiver synthetic aperture sonar signal processing software with an input echo that is closer to the actual motion, which is beneficial to improving the imaging performance of long-distance targets.

[0037] Specifically, the first calculation unit 110 is used to calculate the transmission distance between the transceiver synthetic aperture sonar and the single target at the time of signal transmission, based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the two-dimensional coordinates of the single target at the time of signal transmission. The second calculation unit 120 is used to calculate the reception distance between the transceiver synthetic aperture sonar and the single target at the time of echo signal reception, based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the target at the time of echo signal reception. The third calculation unit 130 is used to calculate the precise propagation time of the signal from transmission to reception based on the transmission distance between the transceiver synthetic aperture sonar and the single target at the time of signal transmission and the reception distance between the transceiver synthetic aperture sonar and the single target at the time of echo signal reception. The echo signal acquisition unit 140 is used to calculate the two-way distance traversed by the signal based on the two-dimensional coordinates of a single target, the transmission distance between the transceiver synthetic aperture sonar and the single target at the signal transmission time, and the reception distance between the transceiver synthetic aperture sonar and the single target at the echo signal reception time. It then performs time delay processing on the transmitted modulated broadband signal to obtain the echo signal corresponding to the single target. The iterative calculation unit 150 is used to perform iterative calculations on any other target in space, after transforming the two-dimensional coordinates of the target, according to the above steps to obtain the echo signal corresponding to any other target in space. The coherent accumulation unit 160 is used to coherently accumulate the echo signals of all targets in the time domain, and then demodulate them to obtain the baseband echo signal. Compared with traditional synthetic aperture sonar echo simulation methods, the sonar echo simulation system 100 of the present invention takes into account the influence of the azimuth distance of the synthetic aperture sonar during signal transmission and reception, thereby making the simulated echo signal closer to the actual motion of the synthetic aperture sonar. This provides the synthetic aperture sonar signal processing software with an input echo that is closer to the actual motion, which is beneficial to improving the imaging performance of distant targets.

[0038] Reference Appendix Figure 10According to another aspect of the present invention, the present invention further provides a computing device 200, wherein the computing device 200 includes a processor 210 and a memory 220, wherein computer program instructions are stored in the memory 220, and the computer program instructions, when executed in the processor 210, cause the processor 210 to execute a sonar echo simulation method, wherein the sonar echo simulation method includes the steps of: S1, calculating the transmission distance between the transceiver synthetic aperture sonar and the single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the two-dimensional coordinates of the single target at the time of signal transmission; S2, calculating the reception distance between the transceiver synthetic aperture sonar and the single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the target at the time of echo signal reception; S3, calculating the reception distance between the transceiver synthetic aperture sonar and the single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the target at the time of echo signal reception; S4, calculating the reception distance between the transceiver synthetic aperture sonar and the single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the target at the time of echo signal reception; S5, calculating the reception distance between the transceiver synthetic aperture sonar and the single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the target at the time of echo signal reception; S6, calculating the reception distance between the transceiver synthetic aperture sonar and the single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the target at the time of echo signal reception; S7, calculating the reception distance between the transceiver synthetic aperture sonar and the single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the target at the time of echo signal reception; S8, calculating the reception distance between the transceiver synthetic aperture sonar and the single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the target at the time of echo signal reception; S S4. Calculate the precise propagation time of the signal from transmission to reception based on the two-dimensional coordinates of the single target, the transmission distance between the synthetic aperture sonar and the single target at the time of signal transmission, and the reception distance between the synthetic aperture sonar and the single target at the time of echo signal reception. Perform time delay processing on the modulated broadband signal to obtain the echo signal corresponding to the single target. S5. For any other target in space, after transforming the two-dimensional coordinates of the target, perform iterative calculations according to the above steps to obtain the echo signal corresponding to any other target in space. S6. Coherently accumulate the echo signals of all targets in the time domain, and then demodulate them to obtain the baseband echo signal. Through the above steps, compared with the traditional transceiver synthetic aperture sonar echo simulation method, the sonar echo simulation method of the present invention takes into account the influence of the azimuth distance of the transceiver synthetic aperture sonar during signal transmission and reception. As a result, the simulated echo signal is closer to the actual motion of the transceiver synthetic aperture sonar, which can provide the transceiver synthetic aperture sonar signal processing software with an input echo that is closer to the actual motion, which is beneficial to improving the imaging performance of long-distance targets.

[0039] In one embodiment of the computing device 200 of the present invention, the memory 220 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may, for example, include random access memory (RAM) and / or cache memory. The non-volatile memory may, for example, include read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 210 may execute the program instructions to implement the function of the sonar echo simulation method of the present invention described above.

[0040] In one embodiment of the computing device 200 of the present invention, the processor 210 may be a central processing unit (CPU) or other form of processing unit with data processing capability and / or instruction execution capability, which can run the program instructions stored on the computer-readable storage medium to realize the function of the sonar echo simulation method of the present invention described above.

[0041] In one embodiment of the computing device 200 of the present invention, the computing device 200 may further include an input device 230 and an output device 240. The input device 230 may be, but is not limited to, a keyboard or a mouse, and the output device 240 may be, but is not limited to, a display, a speaker or a printer. The input device 230 and the output device 240 may be connected to the processor 210 via a bus system.

[0042] Those skilled in the art should understand that the embodiments described above and illustrated in the figures are merely illustrative of the invention and not intended to limit it. All equivalent implementations, modifications, and improvements within the spirit of this invention should be included within the scope of protection of this invention.

Claims

1. A method for simulating echoes from a combined transceiver synthetic aperture sonar, used to simulate echoes from a combined transceiver synthetic aperture sonar, characterized in that... The sonar echo simulation method includes the following steps: S1. Calculate the transmission distance between the transceiver synthetic aperture sonar and the single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the single target at the time of signal transmission. S2, calculate the receiving distance between the transceiver synthetic aperture sonar and the single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the target at the time of echo signal reception. S3. Calculate the precise propagation time of the signal from transmission to reception based on the transmission distance between the combined transceiver synthetic aperture sonar and the single target at the time of signal transmission and the reception distance between the combined transceiver synthetic aperture sonar and the single target at the time of echo signal reception. S4. Based on the two-dimensional coordinates of a single target, the transmission distance between the transceiver synthetic aperture sonar and the single target at the time of signal transmission, and the reception distance between the transceiver synthetic aperture sonar and the single target at the time of echo signal reception, calculate the two-way distance traversed by the signal, perform time delay processing on the transmitted modulated broadband signal, and obtain the echo signal corresponding to the single target. S5. For any other target in space, after transforming the two-dimensional coordinates of the target, perform iterative calculations according to the above steps to obtain the echo signal corresponding to any other target in space. S6 performs coherent accumulation of the echo signals of all targets in the time domain, and then demodulates them to obtain the baseband echo signal.

2. The method for simulating synthetic aperture sonar echoes using a combined transceiver setup according to claim 1, characterized in that, In step S1, it is assumed that the system starts at the origin of the coordinate system, and after... After a certain time, at a certain speed The coordinates of the moving synthetic aperture sonar in the azimuth direction are: The coordinate of the target in the range direction is 0, and the coordinate of the target in the azimuth direction is... The coordinates in the distance direction are ,calculate At time t, the transmission distance between the combined transceiver synthetic aperture sonar and a single target at the signal transmission time. for: .

3. The method for simulating synthetic aperture sonar echoes using a combined transceiver setup according to claim 2, characterized in that, In step S2, it is assumed that the precise propagation time of the signal from transmission to reception is... With speed Motion-based synthetic aperture sonar with combined transmitter and receiver operates on the precise propagation time of signals from transmission to reception. The distance of the inner azimuth movement is At this point, the azimuth coordinates of the combined transceiver synthetic aperture sonar are: The receiving distance between the transceiver synthetic aperture sonar and a single target at the moment of echo signal reception. for: .

4. The method for simulating synthetic aperture sonar echoes using a combined transceiver setup according to claim 3, characterized in that, In step S3, the precise propagation time of the signal from transmission to reception is calculated. The corresponding propagation distance is equal to the sum of the transmission distance calculated in step S1 and the reception distance calculated in step S2, so the established equation is: ,in Let represent the speed of sound in water. By solving the above equation, the precise propagation time of the signal from transmission to reception is obtained as follows: The precise expression is: .

5. The method for simulating synthetic aperture sonar echoes using a combined transceiver setup according to claim 4, characterized in that, In step S4, the transmission distance between the combined transmit / receive synthetic aperture sonar and the single target at the signal transmission moment is: The receiving distance between the transceiver synthetic aperture sonar and the single target at the moment of echo signal reception is: The two-way distance traversed by the signal is obtained as follows: Assuming Indicates frequency modulation. This indicates the fast time corresponding to the distance direction. Indicates the carrier frequency; the transmitted wideband signal is a linear frequency modulated signal. Then the modulated transmitted signal is After delay processing, the echo signal is obtained. The expression is: ,in It represents the imaginary unit.

6. The method for simulating synthetic aperture sonar echoes using a combined transceiver setup according to claim 5, characterized in that, In step S5, it is assumed that the coordinates of any other target in space in the azimuth direction are... The coordinates in the distance direction are The two-way distance traversed by the signal is calculated according to step S4 as follows: Correspondingly, the echo signal corresponding to this target is: .

7. The method for simulating synthetic aperture sonar echoes using a combined transceiver setup according to claim 6, characterized in that, In step S6, the expression for coherent accumulation is: The total number of targets is Then, the coherently accumulated echo signal is demodulated, as expressed by: .

8. A combined transceiver synthetic aperture sonar echo simulation system, used for echo simulation of combined transceiver synthetic aperture sonar, characterized in that, include: The first calculation unit is used to calculate the transmission distance between the transceiver synthetic aperture sonar and the single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the two-dimensional coordinates of the single target at the time of signal transmission. The second calculation unit is used to calculate the receiving distance between the transceiver synthetic aperture sonar and a single target based on the two-dimensional coordinates of the transceiver synthetic aperture sonar and the target at the time of echo signal reception. The third calculation unit is used to calculate the precise propagation time of the signal from transmission to reception based on the transmission distance between the transceiver synthetic aperture sonar and a single target at the time of signal transmission and the reception distance between the transceiver synthetic aperture sonar and a single target at the time of echo signal reception. The echo signal acquisition unit is used to calculate the two-way distance traversed by the signal based on the two-dimensional coordinates of a single target, the transmission distance between the transceiver synthetic aperture sonar and the single target at the time of signal transmission, and the reception distance between the transceiver synthetic aperture sonar and the single target at the time of echo signal reception. It also performs time delay processing on the transmitted modulated broadband signal to obtain the echo signal corresponding to the single target. The iterative calculation unit is used to perform iterative calculations on any other target in space after transforming the two-dimensional coordinates of the target, and then following the steps above to obtain the echo signal corresponding to any other target in space. The coherent accumulation unit is used to coherently accumulate the echo signals of all targets in the time domain, and then demodulate them to obtain the baseband echo signal.

9. The synthetic aperture sonar echo simulation system with combined transceiver configuration according to claim 8, characterized in that, Assuming the system starts at the origin, after which... After a certain time, at a certain speed The coordinates of the moving synthetic aperture sonar in the azimuth direction are: The coordinate of the target in the range direction is 0, and the coordinate of the target in the azimuth direction is... The coordinates in the distance direction are The first computing unit calculates At time t, the transmission distance between the combined transceiver synthetic aperture sonar and a single target at the signal transmission time. for: .

10. A computing device, characterized in that, It includes a processor and a memory, wherein computer program instructions are stored in the memory, and when the computer program instructions are executed in the processor, the processor causes the processor to perform the sonar echo simulation method as described in any one of claims 1 to 7.

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