Localization signal receiver for determining a sound pulse image

Description

[0001] The invention relates to an array of underwater sound receiving arrangements, wherein each underwater sound receiving arrangement comprises an underwater sound receiver, also called a hydrophone or sound transducer, a sound window that is permeable to sound waves so that an underwater sound receiver arranged behind the sound window can detect the sound waves, and a sound reflector that can reflect sound waves (onto the hydrophone). The array can also be referred to as a sonar system.

[0002] Sonar systems mounted in or on watercraft, particularly ships or submarines, currently have equidistant spacing between individual hydrophones to simplify the analysis of the individual hydrophone signals. In particular, beamforming is simplified when the hydrophones are arranged in a straight line. However, this has the disadvantage that the array can only be mounted on surfaces of the watercraft that have no or only slight curvature. At curved sections, hydrophones are attached to the watercraft using spacers to ensure they remain aligned in a straight line. Consequently, at points with significant curvature, the hydrophones are positioned a considerable distance from the watercraft. Furthermore, an arrangement around the bow of the watercraft, for example, is not possible.The sonar system is also mounted on the outer hull of the vessel and cannot be located entirely inside, meaning the sound windows are flush with the outer hull. This has the disadvantage, particularly in submarines, that turbulence occurs at points where the sound window separates from the outer hull. Turbulence generates sound waves, which are undesirable, especially in submarines, which are designed to operate as quietly as possible to avoid detection.

[0003] EP 2 469 507 A1 discloses an acoustic underwater antenna for mounting on a boat hull.

[0004] DE 10 2016 118 238 A1 discloses an underwater antenna for an underwater vehicle, wherein the underwater antenna comprises a reflector, several hydrophones and at least one bracket for attaching the underwater antenna to an underwater vehicle.

[0005] FR 2 769 372 A1 discloses a method for correcting the effects of parasitic antenna movements in a synthetic antenna sonar.

[0006] CN 109 031 258 reveals an asymmetric acoustic conformal array.

[0007] EP 0 654 953 A1 discloses an electroacoustic transducer arrangement for underwater antennas.

[0008] DE 10 2015 207 490 A1 discloses a rudder arrangement on an underwater vehicle.

[0009] DE 19 525 877 A1 discloses a method for suppressing structure-borne noise disturbances in an acoustic locating system.

[0010] The object of the present invention is therefore to create an improved concept for an array for receiving underwater sound, in particular sonar systems.

[0011] The problem is solved by the subject matter of the independent patent claims. Further advantageous embodiments are the subject matter of the dependent patent claims.

[0012] Exemplary embodiments show an array of underwater sound receiving arrangements for receiving underwater sound. The array comprises a plurality of underwater sound receiving arrangements. Each underwater sound receiving arrangement comprises an underwater sound receiver, a sound reflector, and a sound window, or a common sound window is provided. A first underwater sound receiving arrangement is arranged adjacent to a second underwater sound receiving arrangement, and a third underwater sound receiving arrangement is arranged adjacent to the second underwater sound receiving arrangement. The first and second underwater sound receiving arrangements are spaced a first distance apart, and the second and third underwater sound receiving arrangements are spaced a second distance apart, the first and second distances being different from each other.The underwater sound receiving arrangements each form an individual module. In other words, the underwater sound receiving arrangements, and in particular the corresponding underwater sound receivers, are not equidistant; that is, they are not equidistant from each other. The underwater sound receiving arrangements can be connected via a bus system to provide audio signals to an evaluation unit.

[0013] The idea is to create small, individual modules, each containing an underwater sound receiver, a sound window, and a sound reflector, and to arrange them in such a way as to conform to the shape of the watercraft. Currently, the modules each comprise multiple hydrophones, which does not allow for individualization of the array's shape. Using these small modules, the underwater sound receivers can, for example, be positioned within the outer hull of the watercraft, such as in the hull of a ship or within the hull of a submarine. The sound windows then seal the outer hull watertight and can thus withstand water pressure. The underwater sound receivers can then be located in a chamber behind the sound window. This chamber can be filled with water.However, the outer hull or the sound windows allow for water exchange between the water surrounding the vessel and the water inside the chamber. This ensures that sound propagation within the chamber is as similar as possible to sound propagation on the other side of the sound window.

[0014] In exemplary embodiments, the underwater sound receiving arrays are arranged along a curved line. This allows the shape of the sonar systems to be adapted to any desired shape. In particular, the line can have a curvature in a first direction and in a second direction. Due to the curvature in two directions, the array of underwater sound receiving arrays can extend in different directions within a single plane. The curvature in the first and second directions allows the line, i.e., the array of underwater sound receiving arrays, to have a path in three spatial directions.

[0015] If the underwater sound receiving devices are arranged along a curved line, this constitutes a one-dimensional or single-row array of underwater sound receiving devices. However, a multi-dimensional or multi-row array of underwater sound receiving devices is also possible. In this case, the array comprises a plurality of curved lines along which the underwater sound receiving devices are arranged. Specifically, the underwater sound receiving devices then form a surface or a surface array. Adjacent curved lines within the plurality of curved lines can be equidistant. This is advantageous so that the (surface) array of underwater sound receiving devices can be adapted to the outer hull of the vessel.

[0016] In addition to adapting to the shape of the watercraft, the frequency response of the underwater sound receiver array (as small modules) can also be adjusted. The frequency response can be set, for example, by varying the distance between the sound reflector and the underwater sound receiver in different underwater sound receiver configurations. In other words, the distance between the underwater sound receiver and the sound reflector differs among the various underwater sound receiver configurations. By adjusting the distance between the sound reflector and the underwater sound receiver, the wavelength of the sound waves that superimpose constructively in the underwater sound receiver after prior reflection at the sound reflector and without reflection can be adjusted. The equivalent frequency of the sound waves that constructively superimpose is also referred to as the design frequency.

[0017] Furthermore, the size of underwater sound receivers can vary among the many different underwater sound receiving arrangements. For example, the resonant frequency of the underwater sound receiver is adjusted. While it is typically operated outside of its resonant frequency, it can be advantageous, especially at high design frequencies, to modify the size of the underwater sound receiving arrangement so that its resonant frequency is also increased, thus avoiding a resonant frequency close to the design frequency. At a higher resonant frequency, the sensitivity curve of the underwater sound receiver remains linear even at higher sound frequencies.

[0018] In practical applications related to underwater communication, it can also be advantageous to operate the underwater sound receiver near its resonant frequency. Underwater communication refers to the (targeted) exchange of data underwater using sonar. Near the resonant frequency, the underwater sound receiver then exhibits greater reception sensitivity. Furthermore, the non-linearity of the sensitivity curve is less relevant in the case of underwater communication, as a narrow, predetermined frequency band is typically used for data exchange. Signal processing is therefore still readily possible. However, with a broadband signal, such as that typically encountered in sonar-based positioning, signal processing would be significantly more difficult with a non-linear sensitivity curve like the one found near the resonant frequency.

[0019] A watercraft is further disclosed, comprising a body bounded by an outer shell, the outer shell being designed to be in contact with water, in particular salt or seawater. A multitude of underwater sound receiver arrangements are installed in the watercraft such that the sound windows allow a sound wave to enter the body, with the associated underwater sound receivers being arranged in the body between the sound windows and the associated sound reflectors. The sound windows can close an opening in the outer shell. This closure can be achieved by the sound windows being flush with the outer shell, i.e., by the sound windows being shaped to replicate the missing parts of the outer shell. Advantageously, the sound windows are shaped to form a smooth transition and not an edge with the outer shell.

[0020] In exemplary embodiments, the underwater sound receiver can extend around the bow of the watercraft. This is advantageous because it increases the range of sound incidence directions from which sound waves are detected. Furthermore, this allows the end-fire beam, an adjustable reception characteristic of the underwater sound receiver, to be used not only for high-frequency signals but also for lower-frequency signals. This is because the aperture of the underwater sound receiver is increased.

[0021] Furthermore, a method for adapting the array of underwater sound receivers to the vessel is presented. The method includes determining the vessel's acoustic impedance. This can be performed, for example, using the finite element method for a point grid within the available space in the vessel for the underwater sound receivers. This is followed by the optimization of the array's underwater sound receiver arrangement within the available space. The optimization process includes an analysis of the array's frequency response, linearizing the response through optimization.In other words, despite the non-linear shape of the underwater sound receiver arrangement, taking into account the behavior of the watercraft on the incident sound waves, i.e., the acoustic impedance of the watercraft, the frequency response in the application range can be approximated to a linear frequency response.

[0022] To linearize the frequency response, the arrangement of the underwater sound reception system can be varied. This means that the distance between the underwater sound reception systems or the underwater sound receivers themselves, and / or the distance between the sound reflectors and underwater sound receivers of the underwater sound systems, and / or the size of the underwater sound receivers can be varied. Furthermore, the depth of the underwater sound reception system, particularly of an underwater sound receiver, within the available installation space can also be varied. Optimizing one or more of these parameters can then lead to improved linearization of the frequency response.

[0023] For a linear frequency response, the underwater sound receivers of the underwater sound reception system must be positioned at a distance from each other such that no maxima or minima occur in the reception sensitivity within the considered frequency range, or more precisely, for a selected frequency. This is achieved when the underwater sound receivers are spaced apart at a distance equal to half the wavelength of the selected frequency. In other words, the underwater sound reception system is optimized for a selected frequency range by choosing the appropriate spacing between the individual underwater sound receivers. This optimization results in a (nearly) uniform reception sensitivity for the underwater sound reception system within the selected frequency range.

[0024] In exemplary embodiments, the underwater sound receiving arrangement can be optimized not only for one frequency range, but for multiple frequency ranges. This is possible by forming groups of underwater sound receivers within the underwater sound receiving arrangement. Thus, a first group of underwater sound receivers can be optimized for a first frequency range, and a second group of underwater sound receivers can be optimized for a second frequency range. In the first group, the underwater sound receivers can have a first spacing from each other that corresponds to half the wavelength of a (center) frequency of the first frequency range, and in the second group, the underwater sound receivers can have a second spacing from each other that corresponds to half the wavelength of a (center) frequency of the second frequency range.

[0025] This is advantageous for selectively monitoring multiple frequency bands or filtering out individual (dominant) frequencies. Filtering out frequencies can be useful when a loud underwater sound source is masking a quiet sound source with a different frequency. The quiet sound source can then be detected by a group of underwater sound receivers if they are optimized for a similar frequency and the loud frequencies of the other sound source are sufficiently offset from the frequency(ies) of the quiet sound source.

[0026] Preferred embodiments of the present invention are explained below with reference to the accompanying drawings. These show: Fig. 1 : a schematic representation of the array for receiving underwater sound signals; Fig. 2 : a schematic representation of a watercraft with the array of Fig. 1 in a side view; Fig. 3 : a schematic perspective representation of the watercraft made of Fig. 2 ; and Fig. 4 : a schematic representation of the watercraft with a surface array of underwater sound receiving arrangements.

[0027] Before exemplary embodiments of the present invention are explained in detail below with reference to the drawings, it should be noted that identical, functionally equivalent or equivalent elements, objects and / or structures in the different figures are provided with the same reference numerals, so that the description of these elements shown in different exemplary embodiments is interchangeable or can be applied to one another.

[0028] Fig. 1 Figure 1 shows a schematic representation of an array 20 for receiving underwater sound. The array comprises a plurality of underwater sound arrangements 22a, 22b, 22c. The underwater sound arrangements 22 each have a sound window 24a, 24b, 24c, an underwater sound receiver 26a, 26b, 26c, and a sound reflector 28a, 28b, 28c. However, a common sound window may also be provided. The sound window belonging to one of the underwater sound receiver arrangements is then a section of the common sound window behind which the corresponding underwater sound receiver is located.

[0029] The array is designed to receive sound waves that (at least partially) impinge on the underwater sound arrays from the y-direction. This direction is referred to as the sound incidence direction. Viewed from the sound incidence direction, the underwater sound receiver of an underwater sound array 22 is located between the associated sound window and the associated sound reflector. The sound reflector can be designed to bundle incident sound waves and focus them onto the underwater sound receiver. For this purpose, the sound reflector can be concave (in the direction of the underwater sound receiver). The sound window can be convex on the side facing away from the underwater sound receiver. This increases its resistance to water pressure. Furthermore, it can correspond to the shape of the outer hull of a watercraft, so that the sound window fits into the shape of the outer hull. However, the sound window can also be flat or...It should be flat, i.e., not convex.

[0030] The second underwater sound arrangement 22b is located adjacent to the first underwater sound arrangement 22a and the third underwater sound arrangement 22c. A distance d1 between the first and the second underwater sound arrangement 22a, 22b differs from a distance d2 between the second and the third underwater sound arrangement 22b, 22c. Fig. 1 The distance d1 is smaller than the distance d2. The distance can be considered the distance between the centers or centers of gravity of the underwater sound receivers.

[0031] Furthermore, the distance d3, d4, d5 between the underwater sound receivers 26a, 26b, 26c and the corresponding sound reflectors 28a, 28b, 28c of the array can also be varied. The design frequency of the individual underwater sound receiver arrangements can be adjusted via this distance.

[0032] Furthermore, it is evident that one underwater sound arrangement, here the third underwater sound arrangement 22c, is arranged offset to the rear in the direction of sound incidence. The underwater sound receiving arrangements 22a, 22b, 22c are therefore arranged on a curved line. The curved line has a curvature in the same direction as the direction of sound incidence.

[0033] Fig. 2 Figure 1 shows a schematic side view of a watercraft 30. The watercraft 30 has an outer shell 32 that encloses at least part of the watercraft 30 where it is in constant contact with water during operation. An imaginary curved line 34 connects the underwater sound receiving arrangements, in particular the underwater sound receivers.

[0034] Fig. 3 shows a schematic representation of a section of the bow of the watercraft 30 from Fig. 2 in a perspective view. Here it becomes clear that line 32 can be curved in the x, y, and z directions. Even with just two changes in curvature, the line can have a path in three spatial directions. Thus, the array can completely adapt to the shape of the outer hull of the watercraft and even, as shown in Fig. 3 The underwater sound receiver arrangements 22c and 22d are shown, positioned around the bow of the watercraft. For the sake of clarity, no further underwater sound receiver arrangements are shown between underwater sound receiver arrangements 22c and 22d on the bow of the watercraft 30.

[0035] The configuration of the array, in particular the spacing d1 to d5 and the size of the underwater sound receivers 26a, 26b, 26c, can be determined specifically for each vessel. This can be done, for example, using a (computer) model of the vessel, where sound propagation is simulated, e.g., using the finite element method. By varying the aforementioned parameters, the array can be optimized for the vessel. In particular, the frequency response of the array can be linearized within a specific application range. This application range can be between 1 and 100 kHz, and especially between 2 and 80 kHz.In addition to the possibility of changing the spatial arrangement of the underwater sound reception systems or underwater sound receivers in order to linearize the frequency response, electronics that process the output signals of the underwater sound receivers can also linearize the frequency response, for example by means of delay elements.

[0036] In Fig. 2 und Fig. 3 Only one line is shown at a time, along which the underwater sound receiving arrays can be arranged. This forms a line array. If further arrays are added, for example below the [unclear text], [unclear text] Fig. 2 und Fig. 3 The arrays shown are arranged in a series of lines, along which underwater sound receiver arrangements can be lined up (see...). Fig. 4 Then an area array is formed. However, to adapt the area array to the outer hull of the vessel, the lines are typically not parallel. This means that distances between adjacent underwater sound receiver arrays arranged on different lines can vary.

[0037] This shows Fig. 4 A schematic representation of the watercraft 30. Shown are three lines 32, 32' and 32", on which the underwater sound systems 22a, 22b, 22c, 22a', 22b', 22c', 22a", 22b", 22c" are arranged. The underwater sound systems form a 3x3 array.

[0038] Although some aspects have been described in connection with a device, it is understood that these aspects also constitute a description of the corresponding process, so that a block or component of a device can also be understood as a corresponding process step or as a feature of a process step. Similarly, aspects described in connection with or as a process step also constitute a description of a corresponding block, detail, or feature of a corresponding device.

[0039] Depending on specific implementation requirements, embodiments of the invention can be implemented in hardware or in software. The implementation can be carried out using a digital storage medium, for example, a floppy disk, DVD, Blu-ray disc, CD, ROM, PROM, EPROM, EEPROM, FLASH memory, hard disk, or other magnetic or optical storage medium, on which electronically readable control signals are stored. These control signals can interact with, or interact with, a programmable computer system in such a way as to execute the respective method. Therefore, the digital storage medium can be computer-readable.Some embodiments according to the invention therefore include a data carrier which has electronically readable control signals which are able to interact with a programmable computer system in such a way that one of the methods described herein is carried out.

[0040] In general, embodiments of the present invention can be implemented as a computer program product with program code, wherein the program code is effective in carrying out one of the methods when the computer program product is executed on a computer. The program code can, for example, also be stored on a machine-readable medium. Other embodiments include the computer program for carrying out one of the methods described herein, wherein the computer program is stored on a machine-readable medium.

[0041] In other words, an embodiment of the method according to the invention is thus a computer program that includes program code for carrying out one of the methods described herein when the computer program is executed on a computer. Another embodiment of the method according to the invention is thus a data carrier (or a digital storage medium or a computer-readable medium) on which the computer program for carrying out one of the methods described herein is recorded.

[0042] Another embodiment of the method according to the invention is thus a data stream or a sequence of signals that represents the computer program for carrying out one of the methods described herein. The data stream or sequence of signals can be configured, for example, to be transferred via a data communication connection, such as the Internet.

[0043] Another embodiment comprises a processing device, for example a computer or a programmable logic device, configured or adapted to perform one of the methods described herein.

[0044] Another embodiment comprises a computer on which the computer program for performing one of the procedures described herein is installed.

[0045] In some embodiments, a programmable logic device (for example, a field-programmable gate array, an FPGA) can be used to perform some or all of the functionalities of the methods described herein. In some embodiments, a field-programmable gate array can interact with a microprocessor to perform one of the methods described herein. Generally, in some embodiments, the methods are performed by any hardware device. This can be general-purpose hardware such as a computer processor (CPU) or method-specific hardware such as an ASIC.

[0046] The embodiments described above merely illustrate the principles of the present invention. It is understood that modifications and variations of the arrangements and details described herein will be obvious to other people skilled in the art. Therefore, it is intended that the invention be limited only by the scope of protection set forth in the following claims and not by the specific details presented herein by way of description and explanation of the embodiments. Reference symbol list:

[0047] 20 Array 22 Underwater sound receiving arrangement 24 Sound window 26 Underwater sound receiver 28 Sound reflector 30 Watercraft 32 Outer shell 34 Line

Claims

1. Array of underwater sound receiving devices (20) for receiving underwater sound, comprising: a plurality of underwater sound receiving devices (22), wherein an underwater sound receiving device (22) comprises an underwater sound receiver (26), a sound reflector (28) and a sound window (24), or wherein a common sound window is provided; wherein a first underwater sound receiving arrangement (22) is arranged adjacent to a second underwater sound receiving arrangement (22) and wherein a third underwater sound receiving arrangement (22) is arranged adjacent to the second underwater sound receiving arrangement (22); wherein the first and second underwater sound receiving arrays (22) have a first distance between them and wherein the second and third underwater sound receiving arrays (22) have a second distance between them, wherein the first and second distances differ from each other, characterized in that the underwater sound receiving arrays each form an individual module.

2. Array (20) according to claim 1, wherein the underwater sound receiving arrays (22) are arranged along a curved line (34).

3. Array (20) according to claim 2, wherein the line (34) has a curvature in a first direction and in a second direction.

4. Array (20) according to claim 3, wherein the line (34) experiences a course in three spatial directions due to the curvature in the first direction and the second direction.

5. Array (20) according to any one of claims 2 to 4, with a plurality of curved lines (34) along which the underwater sound receiving devices (22) are arranged.

6. Array (20) according to claim 5, wherein adjacent curved lines (34) of the plurality of curved lines (34) exhibit the absence of an equidistant spacing.

7. Array (20) according to any of the previous claims, wherein a size of the underwater sound receivers (26) of the plurality of underwater sound receiving arrays (22) differs from one another.

8. Array (20) according to any of the preceding claims, wherein a distance of the underwater sound receiver (26) from the sound reflector (28) of the plurality of underwater sound receiving arrangements (22) differs from one another.

9. Watercraft (30) comprising: a body bounded by an outer hull (32), wherein the outer hull (32) is configured to be in contact with water; the array (20) according to one of claims 1 to 8, wherein the plurality of underwater sound receiving devices (22) are installed in the watercraft (30) in such a way that the sound windows (24) allow a sound wave to enter the body, wherein the associated underwater sound receivers (26) being arranged in the body between the sound windows (24) and the associated sound reflectors.

10. Watercraft (30) according to claim 9, wherein the sound windows (24) close an opening in the outer hull (32).

11. Watercraft (30) according to one of claims 9 or 10, wherein the sound windows (24) terminate at the outer hull (32).

12. Watercraft (30) according to any one of claims 9 to 11, wherein the underwater sound receiving array (22) extends around a bow of the watercraft.

13. A method for adapting an array of underwater sound receiving arrangements (20) according to one of claims 1 to 8 for receiving underwater sound to a watercraft (30), comprising the following steps: determining an acoustic impedance of the watercraft; optimizing an arrangement of the underwater sound receiving arrays (22) of the array (20) for receiving underwater sound within an available installation space in the watercraft.

14. Method according to claim 13, wherein the optimizing comprises analyzing the frequency response of the array (20) for receiving underwater sound, wherein the frequency response is linearized by the optimizing.

15. Method according to one of claims 13 or 14, wherein the arrangement of the underwater sound receiving devices (22) comprises a distance between the underwater sound receiving devices (22) and / or a distance between sound reflectors and underwater sound receivers (26) of the underwater sound devices and / or a size of the underwater sound receivers (26).