Towed sonar system and method capable of reducing flow noise dynamic extension

Abstract

The invention relates to a dynamic stretching towing sonar system and method capable of reducing flow noise, and the system comprises a towing winch which is disposed on a ship and is used for collecting and releasing a towing cable; the towing array sonar is connected with the towing winch through the towing cable; wherein the total length of the towing cable is 5-10 km, and the towing winch dynamically controls the retracting and releasing length of the towing cable in the sailing process of the ship. According to the invention, the winch provided with a longer trailing cable is used for dynamically and safely controlling and releasing the trailing cable, and the trailing sonar moves at a speed lower than the driving speed of the ship and is far away from the ship, so that the interference of flow noise and the noise of the ship is greatly reduced.

Description

Technical Field

[0001] This invention belongs to the field of underwater acoustic engineering technology, specifically relating to a towed sonar system and method that can reduce dynamic extension of flow noise. Background Technology

[0002] Common towed linear array sonars such as Figure 3 As shown, 1 is a winch fixed at the stern of the ship, used for deploying and retrieving the towed linear array sonar; 2 is the tow cable for load-bearing and signal transmission; 3 is the bow isolation section, used to reduce vibrations transmitted along the tow cable; 4 is the non-acoustic module between the bow isolation section and the acoustic section, used to reduce the impact of tugboat navigation noise and turbulence on the hydrophones; 5 is the hydrophone array, which is the sensing core of the towed linear array sonar and is used to receive acoustic signals; 7 is the tail rope section, usually connected to a brush or float at the tail, used to provide resistance, reduce array meandering, and ensure that the towed array is horizontally straight.

[0003] Conventional towed array sonar tow cables are typically within 1000 meters. When the towed array moves underwater, it is susceptible to noise from tugboats, as well as turbulence and cavitation noise generated by the interaction between the tow cable, cable, and sheath with the surrounding water flow. Especially when the ship is moving at high speed, the navigation noise and flow noise increase suddenly, and the detection performance of the towed array will deteriorate rapidly.

[0004] In other words, the biggest bottleneck for towed line arrays at present is the interference of flow noise and ship noise. When the ship is maneuvering at high speed, the flow noise of the towed line array will increase significantly, and the detection performance will deteriorate sharply. However, the maritime battlefield is constantly changing, and it is difficult to balance the ship's speed and detection performance.

[0005] Therefore, there is an urgent need for a new towed sonar system to break the strong coupling between flow noise and speed, and to create valuable low-noise detection conditions for the sonar system at critical moments. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a towed sonar system and method that can reduce flow noise and dynamically extend the sonar. When the ship is running at high speed, the towed cable is released dynamically and safely by a winch equipped with a long towed cable, and the towed sonar moves away from the ship at a speed lower than that of the ship, so as to greatly reduce the interference of flow noise and the ship's own noise.

[0007] The technical solution of the present invention is to provide a towed sonar system that can reduce the dynamic extension of flow noise, comprising:

[0008] A towing winch, installed on a ship, is used to retrieve and deploy tow cables;

[0009] A towed array sonar is connected to the towing winch via the tow cable;

[0010] The total length of the towing cable is 5-10km, and the towing winch dynamically controls the length of the towing cable during the ship's navigation.

[0011] It also includes a control unit, which is configured to:

[0012] Obtain the ship's real-time speed V2;

[0013] Receive or set a target towing speed V1, wherein the target towing speed V1 is less than the ship's cruising speed;

[0014] When preset conditions are met, the towing winch is controlled to release the towing cable at a cable-laying speed V3. The cable-laying speed V3 is determined based on the ship's sailing speed V2 and the target towing speed V1, so that the towed array sonar moves at a speed lower than the ship's sailing speed V2, thereby increasing the distance between it and the ship, thereby reducing the interference of flow noise and ship noise on the towed array sonar.

[0015] Preferably, the cable laying speed V3 satisfies the relationship: V3 = V2 - V1.

[0016] Preferably, the preset condition includes: the ship's sailing speed V2 is greater than the target towing speed V1.

[0017] Preferably, the control unit is further configured to:

[0018] Receive or set the maximum safe drag depth H;

[0019] Based on the currently released tow cable length or the depth sensor signal from the towed array sonar, obtain or calculate the real-time depth h of the towed array sonar;

[0020] When the real-time depth h is greater than or equal to the maximum safe towing depth H, the towing winch is controlled to stop releasing or begin retrieving the towing cable.

[0021] Preferably, the target towing speed V1 is a preset fixed value, or a variable value that is input in real time by the operator according to the needs of the detection task.

[0022] Preferably, the control unit is configured to control the towing winch to retrieve the towed cable at a speed opposite to the direction of cable deployment when the ship's speed decreases or when towed array sonar recovery is required.

[0023] The present invention also provides a noise suppression method based on the above-mentioned towed sonar system, comprising the following steps:

[0024] While the ship is traveling at a speed of V2, a target towing speed V1 lower than V2 is determined;

[0025] The towing winch is controlled to release the towing cable at a release speed V3 determined based on V2 and V1, so that the towed array sonar moves at a water speed lower than V2 to move away from the ship and thus enter a low-noise detection window.

[0026] During the low-noise detection window, underwater target detection is performed using the towed array sonar.

[0027] Preferably, the cable laying speed V3 = V2 - V1.

[0028] As a preferred option, the following steps are also included:

[0029] Monitor the real-time depth h of the towed array sonar and compare it with the preset maximum safe tow depth H;

[0030] When the real-time depth h is greater than or equal to the maximum safe towing depth H, stop releasing the tow cable or start tow cable retrieval to control the towed array sonar depth.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] This invention breaks away from the fixed mindset of optimizing sensor design and arraying. From the perspective of towed system design and use, it changes the unchanging cable length design of towed sonar systems, allowing the towed sonar system to move away from the ship without remaining stationary. Instead, when the ship is moving at high speed, the tow cable is released at a safe speed by a winch equipped with a longer tow cable, allowing the towed sonar to move away from the ship at a speed lower than that of the ship, thereby greatly reducing interference from flow noise and the ship's own noise. Attached Figure Description

[0033] Figure 1 This is a flowchart of an embodiment of the present invention.

[0034] Figure 2 This is a schematic diagram comparing the flow noise of a conventional towed array and the towed sonar system of this invention.

[0035] Figure 3 This is a schematic diagram of a towed linear array sonar structure based on existing technology. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0037] A towed sonar system capable of dynamically extending with reduced flow noise includes a towed winch and a towed array sonar. The towed winch is mounted on a ship and is used to deploy and retrieve the tow cable. The towed array sonar is connected to the towed winch via the tow cable. The tow cable overcomes the technical biases in this field by being an ultra-long tow cable with a total length of 8 km, which is much longer than the 1 km or less of existing technologies. The towed winch dynamically controls the deployment and retrieval length of the tow cable during the ship's navigation.

[0038] Depending on the detection requirements, the towed sonar system also includes a control unit, which is configured as follows:

[0039] Obtain the ship's real-time speed V2;

[0040] Receive or set the target towing speed V1, where the target towing speed V1 is less than the ship's cruising speed;

[0041] When preset conditions are met, the control unit controls the towing winch to release the towing cable at a cable release speed V3. The cable release speed V3 is determined based on the ship's sailing speed V2 and the target towing speed V1, so that the speed of the towed array sonar relative to the water body is lower than the ship's sailing speed V2. This allows the sonar array to be moved away from the ship, thereby reducing the interference of flow noise and ship noise on the towed array sonar.

[0042] As one implementation method, the cable laying speed V3 satisfies the relationship: V3 = V2 - V1.

[0043] In this embodiment, the preset conditions include: the ship's sailing speed V2 is greater than the target towing speed V1.

[0044] The target drag speed V1 is a preset fixed value, or a variable value that is input in real time by the operator according to the needs of the detection task.

[0045] When a ship is moving at high speed, if low-noise detection is required, the towing winch will continue to release the towing cable at the target towing speed v1 according to the real-time sailing speed V2. Thanks to the ultra-long towing cable designed in this invention, within a certain time window, the towed array sonar will move away from the mother ship at the water movement speed v3=v2-v1. At this time, the actual flow noise of the towed array (towed array sonar) and the noise of the ship itself will be much smaller than that of the traditional towed array system. In the ever-changing battlefield, maintaining low-noise detection for a few seconds is enough to locate enemy ships and change battlefield perception.

[0046] As shown in the table below, Table 1 lists the maximum continuous working time at several ship speeds and cable release speeds.

[0047] Table 1. Maximum continuous working time of the present invention at different ship speeds.

[0048]

[0049] From the above table, even when the ship is traveling at a high speed of 14 knots, the towed sonar system designed by the present invention pays out the cable at a speed of 4 m / s. The actual speed of the towed array relative to the water is only 3 m / s (6 knots). The influence of the noise of the ship itself and the flow noise on the sonar system can be significantly reduced. With tow cables of 5 km and 10 km, low-noise detection windows of up to 1250 seconds or 2500 seconds can be created, which is sufficient for the sonar system to conduct low-noise detection and tracking.

[0050] As an implementation method, in order to achieve dynamic safety control, the control unit is further configured to:

[0051] Receive or set the maximum safe towing depth H;

[0052] Obtain or calculate the real-time depth h of the towed array sonar according to the currently released cable length or the depth sensor signal from the towed array sonar;

[0053] When the real-time depth h is greater than or equal to the maximum safe towing depth H, control the tow winch to stop paying out or start retrieving the cable.

[0054] As an implementation method, when the ship speed decreases or the towed array sonar needs to be retrieved, the control unit controls the tow winch to retrieve the cable at a speed opposite to the cable-paying direction.

[0055] On the other hand, as shown in Figure 1 , the method for suppressing the noise of the towed sonar system of the present invention is as follows:

[0056] 1. The system starts, and inputs the target towing speed V1 and the maximum towing depth H of the towed array;

[0057] 2. The system uses Beidou to read the ship speed V2 by itself. If V2 < V1, output "The target towing speed setting of the towed array is incorrect", and the tow winch records the real-time released cable length l (the maximum cable length is L, l < L);

[0058] 3. The tow winch starts to pay out the cable at a speed of V3 = V2 - V1. The system calculates the cable length l and the real-time depth h of the towed array (or the depth according to the readings of the depth sensors in the array), and checks whether it is greater than the maximum towing depth H. If h > H, the winch stops paying out the cable and outputs "Warning: The depth of the towed array is too deep".

[0059] As an implementation method, when the real-time depth h ≥ the maximum safe towing depth H, stop paying out the tow cable or start retrieving the tow cable to control the depth of the towed array sonar.

[0060] As shown in Figure 2When the ship is traveling at a high speed of 16 knots, the present invention releases the cable at speeds of 2, 4, and 6 meters per second, respectively. Compared with conventional towed sonar that moves at the same speed as the ship, the noise of the 100Hz processing current is reduced by 10, 20, and 46 dB. As shown in Table 1, the continuous cable release time is 5000 seconds, 2500 seconds, and 1667 seconds for a cable length of 10 km. The towed sonar system of the present invention can obtain considerable noise suppression capability within a long time window, which is sufficient for the sonar system to perform low-noise detection and tracking.

[0061] As is well known, noise reduction in existing sonar systems relies on sensor (hydrophone) design and array formation technology limitations, making it difficult to achieve significant theoretical breakthroughs. Consequently, noise suppression performance remains stagnant. This invention breaks away from the fixed mindset of optimizing sensor design and array formation. From the perspective of towed system design and use, it changes the unchanging cable length design of towed sonar systems. This allows the towed sonar system to move away from the ship without remaining stationary. Instead, it can release the tow cable at a safe speed using a winch equipped with a longer tow cable while the ship is moving at high speed. This allows the towed sonar to move at a speed lower than that of the ship and move away from the ship, thereby greatly reducing interference from flow noise and the ship's own noise.

[0062] Since current methods for reducing noise in towed sonar systems are all based on sensor and array process design optimization, they are limited by theory and technology, and their effects are difficult to compare with those of this invention.

[0063] Furthermore, since the towed array will move away from the ship when the present invention is implemented, the ship's noise will be greatly reduced. Therefore, compared with conventional towed sonar systems, the towed sonar system designed in this invention has a stronger noise suppression capability.

[0064] Therefore, compared with other methods to reduce the noise of towed sonar systems, this invention is simple and effective, with low cost of tow cable, relatively low cost of increasing tow cable length and winch modification, and can achieve greater flow noise and shipboard noise suppression effect with slight modifications to the existing towed array sonar system winch. It is inexpensive and effective.

[0065] The above description only illustrates preferred embodiments of the present invention and should not be construed as limiting the scope of the claims. Any equivalent procedural modifications made using this specification are included within the patent protection scope of this invention.

Claims

1. A towed sonar system capable of reducing flow noise during dynamic extension, characterized in that, include: A towing winch, installed on a ship, is used to retrieve and deploy tow cables; A towed array sonar is connected to the towing winch via the tow cable; The total length of the towing cable is 5-10km, and the towing winch dynamically controls the length of the towing cable during the ship's navigation. It also includes a control unit, which is configured to: Obtain the ship's real-time speed V2; Receive or set a target towing speed V1, wherein the target towing speed V1 is less than the ship's cruising speed; When preset conditions are met, the towing winch is controlled to release the towing cable at a cable release speed V3. The cable release speed V3 is determined based on the ship's sailing speed V2 and the target towing speed V1, so that the towed array sonar moves at a speed lower than the ship's sailing speed V2, thereby reducing the flow noise and ship noise interference experienced by the towed array sonar.

2. The towed sonar system with reduced flow noise dynamic extension according to claim 1, characterized in that, The cable laying speed V3 satisfies the relationship: V3 = V2 - V1.

3. The towed sonar system with reduced flow noise dynamic extension according to claim 1, characterized in that, The preset conditions include: the ship's sailing speed V2 is greater than the target towing speed V1.

4. The towed sonar system with reduced flow noise dynamic extension according to claim 1, characterized in that, The control unit is also configured to: Receive or set the maximum safe drag depth H; Based on the currently released tow cable length or the depth sensor signal from the towed array sonar, obtain or calculate the real-time depth h of the towed array sonar; When the real-time depth h is greater than or equal to the maximum safe towing depth H, the towing winch is controlled to stop releasing or begin retrieving the towing cable.

5. The towed sonar system with reduced flow noise dynamic extension according to claim 1, characterized in that, The target dragging speed V1 is a preset fixed value, or a variable value that is input in real time by the operator according to the needs of the detection task.

6. The towed sonar system with reduced flow noise dynamic extension according to claim 1, characterized in that, The control unit is configured to control the towing winch to retrieve the towed cable at a speed opposite to the direction of cable deployment when the ship's speed decreases or when towed array sonar recovery is required.

7. A noise suppression method based on the towed sonar system according to any one of claims 1 to 6, characterized in that, Includes the following steps: While the ship is traveling at a speed of V2, a target towing speed V1 lower than V2 is determined; The towing winch is controlled to release the towing cable at a release speed V3 determined based on V2 and V1, so that the towed array sonar moves at a water speed lower than V2 to move away from the ship and thus enter a low-noise detection window. During the low-noise detection window, underwater target detection is performed using the towed array sonar.

8. The noise suppression method according to claim 7, characterized in that, The cable laying speed V3 = V2 - V1.

9. The noise suppression method according to claim 7, characterized in that, It also includes the following steps: Monitor the real-time depth h of the towed array sonar and compare it with the preset maximum safe tow depth H; When the real-time depth h is greater than or equal to the maximum safe towing depth H, stop releasing the tow cable or start tow cable retrieval to control the towed array sonar depth.

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