Information system for an underwater vehicle for determining navigational information by means of sonar

Abstract

The invention relates to an information system for an underwater vehicle (20) for determining navigational information by means of sonar. The information system has the following features: - a plurality of waterborne sound transducers (24) which are located on a plane and are each designed to convert waterborne sound into an electric signal corresponding to the sound pressure and to convert an applied electric voltage into waterborne sound; - a sound transmission unit (26) which is designed to apply a transmit signal (34) to a first number (52) of the plurality of waterborne sound transducers (24) in order to transmit the transmit signal (34) in a directed manner by means of the waterborne sound transducers (24); - a sound reception unit (28) which is designed to scan the electric signal of a second number (50) of the plurality of waterborne sound transducers (24) in such a way that a directional focus is formed towards the direction in which the transmit signal (34) has been transmitted in a directed manner in order to receive reflections (48) of the transmitted transmit signal (36), wherein the second number (52) of waterborne sound transducers comprises a subset of the first number (50) of waterborne transducers, and wherein the second number of waterborne sound transducers is smaller than the first number of waterborne sound transducers; and - a signal processing unit (30) which is designed to determine the navigational information based on the reflections (48) of the transmitted transmit signal (36).

Description

[0001] Information system for an underwater vehicle for determining navigation information using sonar

[0002] Description

[0003] The invention relates to the further development of a Doppler-based navigation support system for an underwater vehicle, in particular a manned underwater vehicle, also referred to as a submarine. However, it has been found that some aspects can also be applied to other sonar systems.

[0004] A Doppler-based navigation support system, also known as DOLOG (Doppler Log) or DVL (Doppler Velocity Log), determines the current speed of the underwater vehicle based on the Doppler shift of a transmitted signal. For this purpose, the transmitted signal is transmitted at an angle other than 90° towards the seabed and its reflections are received. This type of transmission of the transmitted signal is also known as (transmitted) beamforming. The directed transmitted signal is called a beam. Due to the current speed of the underwater vehicle, the reflections are Doppler-shifted compared to the transmitted signal, i.e. they exhibit a small frequency shift from one another. However, the system used to date has some weaknesses or can at least still be optimized, so some aspects for improvement are highlighted below.

[0005] The object of the present invention is therefore to create an improved concept for sonar systems, in particular Doppler-based navigation support systems.

[0006] This object is achieved by the subject matter of the independent patent claims. Further advantageous embodiments are the subject matter of the dependent patent claims. Embodiments of a first aspect show an information system, in particular a Doppler-based navigation support system, for an underwater vehicle for determining navigation information using sonar. Navigation information includes, for example, the current speed of the underwater vehicle or a current depth above ground (also referred to as diving depth). The information system comprises a plurality of underwater sound transducers, a sound transmitting unit, a sound receiving unit, and a signal processing unit.

[0007] The waterborne sound transducers of the plurality of waterborne sound transducers are arranged in a surface. The waterborne sound transducers are each designed to convert waterborne sound into an electrical signal corresponding to the sound pressure and to convert an applied electrical voltage into waterborne sound. Hydrophones, for example, can be used as waterborne sound transducers. In particular, the surface in which the waterborne sound transducers are arranged is a flat, i.e., non-curved, surface. In a primary application orientation, the surface occupied by the waterborne sound transducers is arranged essentially horizontally, i.e., parallel to the bottom of a body of water. The waterborne sound transducers can thus emit the waterborne sound directed towards the bottom of a body of water.

[0008] The sound transmission unit is designed to apply a transmission signal to a first number of the plurality of waterborne sound transducers in order to transmit the transmission signal in a directed manner using the waterborne sound transducers. Such a method is referred to as (transmission) beamforming. In particular, the sound transmission unit can also generate the transmission signal. The first number of waterborne sound transducers is, for example, the total number of waterborne sound transducers in the plurality of waterborne sound transducers. The control of the waterborne sound transducers can, for example, be such that the transmission signal is applied to the waterborne sound transducers with different phases at the same time. The control of a plurality of planarly arranged waterborne sound transducers so that they transmit a transmission signal in a directed manner is also referred to as a phased array. The transmission signal is advantageously a time-limited signal and is therefore also referred to as a transmission pulse or ping.

[0009] The sound receiving unit is designed to sample the electrical signal of a second number of the plurality of water sound transducers in such a way that a direction is formed in the direction in which the transmission signal was directed. This creates a reception cone in which the water sound transducers have the greatest sensitivity. Such a method is also referred to as (reception) beamforming. In this way, reflections of the transmitted transmission signal can be received in a targeted manner. The second number of water sound transducers comprises a subset of the first number of water sound transducers and the second number of water sound transducers is smaller than the first number of water sound transducers. This means that the number of water sound transducers available for receiving the reflections of the transmission signal is smaller than the number of water sound transducers available for receiving the reflections.In particular, the second number of waterborne transducers is a proper subset of the first number of waterborne transducers.

[0010] The signal processing unit is configured to determine the navigation information based on the reflections of the transmitted signal. For example, the signal processing unit can determine the speed of the underwater vehicle by determining a Doppler shift between the transmitted and received signal. It is also possible, for example, to determine the current depth of the underwater vehicle based on determined signal propagation times (and, for example, knowing the transmission angle).

[0011] The idea behind the first aspect is to generate a narrow beam of the transmitted signal using numerous underwater sound transducers. The more underwater sound transducers used, the narrower the transmitted beam becomes. This not only results in a concentration of the transmitted power, but also in an increase in the transmitted power. Both of these are advantageous for the transmitted beams, as the transmitted beam hits the most precise reference point on the seabed possible. The reference point is also referred to as the reflection point. This enables more precise determination of navigation information compared to a wider transmitted beam. However, a narrow received beam is disadvantageous for receiving reflections. For example, a slight roll or pitch movement of the underwater vehicle is sufficient to move the reflected transmitted signal out of the reception cone of the underwater sound transducers. A wide received beam is therefore advantageous here.This is achieved by using fewer waterborne sound transducers to carry out the directional formation, i.e. to form the receiving beam.

[0012] In exemplary embodiments, the area occupied by the waterborne sound transducers forms a polygon that approximates a circle. The sound transmission unit is designed to control the total number of waterborne sound transducers of the plurality of waterborne sound transducers. The second number of waterborne sound transducers are located in an area formed by, in particular, central reduction of the circular shape. This means that the second number of waterborne sound transducers also forms a polygon that approximates a circle. The second number of waterborne sound transducers can be arranged centrally within the first number of waterborne sound transducers.

[0013] In exemplary embodiments, the area occupied by the waterborne sound transducers of the plurality of waterborne sound transducers forms a polygon that approximates a superposition of two ellipses. In particular, the ellipses are arranged such that the two centers of gravity of the ellipses are congruent. Advantageously, the ellipses are perpendicular to one another. The sound transmitting unit can control the total number of waterborne sound transducers of the plurality of waterborne sound transducers (first number of waterborne sound transducers). The second number of waterborne sound transducers can be formed by a polygon that approximates a circle. This means that the second number of waterborne sound transducers can lie in a circular area. The second number of waterborne sound transducers can be arranged centrally in the first number of waterborne sound transducers.

[0014] Analogously, a method for determining navigation information for an underwater vehicle using sonar is disclosed, comprising the following steps: a) transmitting a directed transmission signal using a first number of a plurality of waterborne sound transducers; b) sampling an electrical signal from a second number of the plurality of waterborne sound transducers so that a direction is formed in the direction in which the transmission signal was transmitted; in order to receive reflections of the transmitted transmission signal, wherein the second number of waterborne sound transducers comprises a subset of the first number of waterborne sound transducers and wherein the second number of waterborne sound transducers is smaller than the first number of waterborne sound transducers; c) determining the navigation information based on the reflections of the transmission signal.

[0015] Embodiments of a second aspect show an information system for an underwater vehicle for determining navigation information. The information system comprises a plurality of waterborne sound transducers arranged in a surface, each of which is designed to convert waterborne sound into an electrical signal corresponding to the sound pressure and to convert an applied electrical voltage into waterborne sound. A sound transmission unit provides a transmission signal with four different phase positions and applies the transmission signal in the different phase positions to the waterborne sound transducers in such a way that the transmission signal is transmitted in a directed manner by means of the waterborne sound transducers (sequentially) in four predetermined different spatial directions and the vertical. This means that five directed transmission signals are transmitted by means of one transmission signal in four different phase positions.

[0016] A sound receiving unit is configured to sample an electrical signal from the waterborne sound transducers of the plurality of waterborne sound transducers after the transmission signal has been transmitted, such that a direction formation occurs in the respective directions in which the transmission signal was transmitted in a directed manner in order to receive reflections of the transmitted transmission signals. This means that, in the first aspect, (receive) beamforming is performed for each directed transmission signal. A signal processing unit can determine the navigation information based on the reflections of the transmission signal.

[0017] The idea behind the second aspect is to obtain as much reliable information as possible for the underwater vehicle through a clever arrangement of transmission signals. For example, the height of the underwater vehicle above the ground and thus the diving depth of the underwater vehicle can be determined directly from the vertical transmission signal. Using the four transmission signals transmitted in the spatial directions, it is also possible to determine the speed of the underwater vehicle vectorially, i.e. the direction in which the underwater vehicle is moving. Using four directional transmission signals also creates a certain redundancy, which makes it possible, for example, to detect an inclination of the underwater vehicle or unevenness in the waterbed and to mark this measurement as unreliable or to calculate out the influences.

[0018] In exemplary embodiments, the sound transmission unit is designed to control the underwater sound transducers in such a way that a first directed transmission signal is transmitted at an angle towards the front, a second directed transmission signal at an angle towards the rear, a third directed transmission signal at an angle to the left, a fourth directed transmission signal at an angle to the right, and a fifth transmission signal is transmitted vertically. The angles relative to the transducer surface can be identical in each case, although the spatial direction in which the transmission signals are transmitted, preferably towards the waterbed, changes in each case. By transmitting forwards and backwards, for example, a pitching of the underwater vehicle can be detected. By transmitting left and right, for example, a rolling of the underwater vehicle can be detected.

[0019] Similarly, a method for determining navigation information using sonar for an underwater vehicle is disclosed, comprising the following steps: a) providing a transmission signal with four different phase positions; b) applying the transmission signal in the different phase positions to each of a plurality of waterborne sound transducers in such a way as to transmit the transmission signal in a directed manner by means of the waterborne sound transducers in four predetermined different spatial directions and the vertical; c) scanning a sound receiving unit which is designed to scan an electrical signal from the waterborne sound transducers of the plurality of waterborne sound transducers after the transmission of the transmission signal in such a way that a direction is formed in the respective directions in which the transmission signal was transmitted in a directed manner in order to receive reflections of the transmitted transmission signals; d) determining the navigation information based on the reflections of the transmission signal.

[0020] According to a third aspect, a waterborne sound generator for providing a transmission signal for a sonar is disclosed. The waterborne sound generator comprises a signal input that provides an applied transmission signal. The transmission signal can be generated by a signal generator. A transformer can transform the transmission signal to a maximum transmission voltage. The transformer can have a plurality of taps on the output side to receive the transmission signal with additional transmission voltages and to provide the transmission signal with different transmission voltages. The waterborne sound generator can be part of a sound transmission unit of the other described aspects.

[0021] The idea behind the third aspect is to provide a waterborne sound signal that can simultaneously generate different sound pressures underwater when emitted by waterborne sound transducers. The different sound pressures are adjusted by the different transmission voltages of the transmission signal. In particular, it is possible to operate waterborne sound transducers individually or in groups, and to apply the transmission signal with the corresponding transmission voltage to different waterborne sound transducers or groups of waterborne sound transducers depending on their position or the desired resulting waterborne sound signal.

[0022] One embodiment describes such a scenario in which the underwater sound signal is to be generated using so-called shading. This reduces the side lobes of the emitted underwater sound signal. The underwater sound generator here is part of an information system for an underwater vehicle for determining navigation information using sonar. The information system comprises a plurality of underwater sound transducers arranged in a surface, each of which is designed to convert an applied electrical voltage into underwater sound. The underwater sound transducers are connected to the taps of the transformer in such a way that underwater sound transducers in the center of the surface are subjected to the transmission signal with a higher average transmission voltage than underwater sound transducers in the outer region of the surface. The effective value of the transmission signal, for example, is suitable as the average transmission voltage.

[0023] Similarly, a method for providing a transmission signal for a sonar is disclosed, comprising the following steps: a) generating a transmission signal; b) transforming the transmission signal to a maximum transmission voltage using a transformer; c) tapping the transmission signal at various taps of the transformer to obtain the transmission signal with additional transmission voltages; d) providing the transmission signal with various transmission voltages.

[0024] Embodiments of a fourth aspect likewise show a waterborne sound generator which, in addition to or as an alternative to the waterborne sound generator of the third aspect, can be part of a sound transmission unit of the other aspects. The waterborne sound generator comprises a first signal feed and a second signal feed, each of which is designed to provide an applied transmission signal. The applied transmission signal can be generated by a common signal generator or a separate signal generator for each signal feed. Mixed forms are also possible. The transmission signals can be identical in their course and differ only in their phase position. In general, the applied transmission signals can be phase-shifted from one another by, for example, 36° or 72°. In addition, a (particularly vertical) transmission signal with a different phase position can be present. The signal generator can optionally also be part of the waterborne sound generator.

[0025] Furthermore, a first input transformer is connected on the secondary side to the primary side of a first output transformer by means of a first transmission path in order to be able to transmit the first transmission signal from the first input transformer to the first output transformer. The first output transformer can optionally transform the transmission signal to a transmission voltage. A second input transformer is connected on the secondary side to the primary side of a second output transformer by means of a second transmission path in order to be able to transmit the second transmission signal from the second input transformer to the second output transformer. The second output transformer can optionally transform the transmission signal to a second transmission voltage.

[0026] The underwater sound generator now comprises a third signal feed, which is configured to provide an applied transmission signal and to feed it on the secondary side into a center tap of the first input transformer in order to couple the transmission signal of the third signal feed into the first transmission path. Furthermore, the signal feed can optionally provide a variation of the transmission signal, in particular the inverted transmission signal, and to feed it on the secondary side into a center tap of the second input transformer. Thus, the transmission signal of the third signal feed is coupled into the second transmission path.

[0027] A third output transformer is configured to receive the transmission signal of the third signal feed for feeding into a first primary-side contact of the third output transformer from a primary-side center tap of the first output transformer and the variation of the transmission signal for feeding into a primary-side second contact of the third output transformer from a primary-side center tap of the second output transformer.

[0028] The idea behind the fourth aspect is to be able to transmit six transmission signals using two transmission links. The six transmission signals consist of two signals and their respective inverse signals from the first and second signal feeds, as well as the transmission signal and its variation from the third signal feed. This eliminates the need for transmission cables. This is particularly advantageous for underwater vehicles, as the cables must be routed through the hull to deliver the transmission signals to the underwater sound transducers. However, the openings in the hull should be kept as small as possible, so that every cable that does not need to be routed through simplifies the technical design of the underwater vehicle.Embodiments show that the first signal feed and the second signal feed exhibit the absence of the respective transmitted signal when the corresponding transmitted signal is present at the third signal feed. This means that the two transmission paths are fed either with the transmitted signal from the first or second signal feed, respectively, or with the transmitted signal or a variation thereof from the third signal feed. This is advantageous if no overlapping of the signals is desired.

[0029] Embodiments of the fifth aspect show a Doppler-based navigation support system for determining navigation information for an underwater vehicle using sonar. The navigation support system comprises a plurality of underwater sound transducers arranged in a surface, each of which is configured to convert underwater sound into an electrical signal corresponding to the sound pressure and to convert an applied electrical voltage into underwater sound. In a main operating state, the transducer surface is arranged horizontally. In particular, in the main operating state, the transducer surface points toward the waterbed.

[0030] A sound transmission unit is configured to apply a transmission signal to the underwater sound transducers of the plurality of underwater sound transducers, so that the transmission signal is transmitted substantially vertically. The transmission signal is transmitted substantially vertically, for example, when a main transmission power is transmitted perpendicular to the transducer surface. Thus, substantially vertical can mean that any pitch or roll movements of the underwater vehicle are disregarded.

[0031] The navigation support system further comprises a sound receiving unit configured to scan the plurality of waterborne sound transducers to obtain reflections of the transmitted signal. The scanning can be performed by performing (receive) beamforming in the direction from which the reflections of the transmitted signals arrive.

[0032] A signal processing unit is now disclosed which is designed to continuously determine depth information of the underwater vehicle based on the reflections of the transmission signal and to graphically output a course of the depth information on a display unit.

[0033] The idea behind the fifth aspect is to integrate the functionality of an echo sounder into the Doppler-based navigation support system. This makes it possible to dispense with a separate echo sounder. This, in turn, saves space and cables through the hollow body of an underwater vehicle.

[0034] In exemplary embodiments, the sound transmission unit is designed to emit a CW signal pulse (CW: continuous wave) as a transmission signal in order to determine the depth information. CW signal pulses are comparatively long and thus have a narrow bandwidth. As a result, they are less susceptible to interference from noise. The depth information can thus be determined very robustly. In addition or alternatively, a frequency-modulated signal pulse can be used to determine the depth information. This provides a sharper echo so that the contours of the waterbed can be better displayed. Optionally, it is possible to change the type of signal pulse per sequence, i.e. the temporal sequence of transmitted transmission signals, or in any other rhythm across multiple sequences. A sequence can have transmission signals directed vertically or at specific angles towards the waterbed.

[0035] Embodiments of a sixth aspect show a Doppler-based navigation support system for an underwater vehicle. The navigation support system comprises a plurality of waterborne sound transducers arranged in a surface, each of which is configured to convert waterborne sound into an electrical signal corresponding to the sound pressure and to convert an applied electrical voltage into waterborne sound. Furthermore, the navigation support system comprises a sound transmission unit configured to apply a transmission signal to the waterborne sound transducers of the plurality of waterborne sound transducers, such that the transmission signal is transmitted substantially vertically.

[0036] A sound receiving unit is configured to sample the electrical signals of the underwater sound transducers of the plurality of underwater sound transducers to obtain reflections of the (vertical) transmitted signal. A signal processing unit is configured to continuously determine depth information of the underwater vehicle based on the reflections of the transmitted signal. Furthermore, the sound transmitting unit adjusts a parameter of the transmitted signal depending on the current depth information.

[0037] The idea behind the sixth aspect is to adapt the transmission signal to the current conditions, particularly the depth of the underwater vehicle above the ground. This can affect, for example, the length of the transmitted signal. While the underwater sound transducers are transmitting the transmission signal, they cannot receive reflections. On the other hand, a long transmission signal reduces susceptibility to interference with noise, for example. Another parameter can be the amplitude. If a signal with too high an amplitude is transmitted when the waterbed is close, it can overload the receiving electronics. However, if the waterbed is far away, the energy of a transmission signal with a high amplitude is required to receive a reflection.

[0038] In embodiments, the sound transmission unit is configured to occasionally provide a control transmission signal instead of the transmission signal due to an unfavorable selection of the parameter. Based on reflections of the control transmission signal, the current depth information can be validated by excluding better depth information, or a sudden change in the depth information can be detected. This means that a transmission signal that is not optimized for the currently determined depth information can be deliberately transmitted as a control transmission signal in order to detect incorrect measurements or to validate the current depth information. The control transmission signal can be transmitted randomly or at regular intervals instead of the sound transmission signal. Advantageously, however, the sound transmission signal is transmitted more frequently than the control transmission signal.

[0039] In further embodiments, the signal processing unit is configured to automatically determine the depth information using an estimator, in particular a Kalman filter. In particular, the sound transmission unit is configured to feed the estimator with the reflections of the control transmission signal in order to automatically detect any deviating depth information that occurs.Similarly, a method for determining navigation information for an underwater vehicle using sonar with a Doppler-based navigation support system is disclosed, comprising the following steps: a) applying a transmission signal to underwater sound transducers such that the transmission signal is emitted substantially vertically; b) sampling an electrical signal from the underwater sound transducers to obtain reflections of the transmission signal; c) continuously determining depth information of the underwater vehicle based on the reflections of the transmission signal; d) adjusting a parameter of the transmission signal depending on the current depth information.

[0040] The following discloses general features of a Doppler-based navigation support system for an underwater vehicle. These features can be used individually or in any combination with the previously described Doppler-based navigation support systems. It should be noted that both the described underwater sound generators and the described information systems for an underwater vehicle can be part of Doppler-based navigation support systems. Similarly, an underwater vehicle with a Doppler-based navigation support system is also disclosed.

[0041] First, regarding nomenclature, it should be noted that the terms "resulting directed transmission signal," "directed transmission signal," and "resulting transmission signal" are used synonymously. These terms describe the waterborne sound signal emitted by the waterborne sound transducers (e.g., also referred to as a ping or more commonly referred to as a beam). The "transmission signal" refers to the corresponding electrical input signal of the waterborne sound transducers. Depending on the context, however, the term "transmission signal" is sometimes also used for the emitted waterborne sound signal.

[0042] The navigation support system comprises a plurality of waterborne sound transducers arranged in a surface, each of which is designed to convert waterborne sound into an electrical signal corresponding to the sound pressure and to convert an applied electrical voltage into waterborne sound. In the main operating state or in the main orientation of use, the transducer surface is arranged horizontally, i.e., parallel to the bottom of a body of water.

[0043] An optional sound transmission unit is configured to apply a sequence of transmission signals to each of the plurality of waterborne sound transducers, resulting in a sequence of at least four, optionally five, resulting directional transmission signals. In particular, the waterborne sound transducers can be applied with the same transmission signal, with the phase position of the transmission signal differing for different waterborne sound transducers or groups of waterborne sound transducers. Such a method is referred to as (transmission) beamforming.

[0044] Optionally, in the main application orientation of the underwater sound transducers, the resulting transmission signals are directed towards the waterbed in such a way that one reflection point is created on the waterbed for each resulting transmission signal and the totality of the reflection points of the resulting transmission signals on the waterbed, particularly when stationary, spans an area. With four resulting transmission signals, a quadrilateral, typically a square, is created on the waterbed. With five resulting transmission signals, a quadrilateral with a reflection point located in the area (e.g. in the middle) or even a pentagon can be created. The fact that the reflection points span an area excludes the possibility that the reflection points lie on a straight line. This consideration applies in particular when the underwater sound transducers are not moving, i.e. are stationary.Otherwise, the movement of the waterborne sound transducers while the sequence of the resulting transmission signals is generated will naturally lead to a relative movement of the reflection points to each other.

[0045] An optional sound receiving unit is configured to sample output signals from the waterborne sound transducers to obtain reflections of the transmitted signal. The sound receiving unit samples the output signals of the waterborne sound transducers in such a way that the sensitivity of the waterborne sound transducers to sound waves from the direction from which the reflection of a directed transmitted signal is greatest. This method is also referred to as (receive) beamforming. In particular, a directed transmitted signal is transmitted, and then the reception of the reflection is awaited until the next directed transmitted signal in the sequence of directed transmitted signals is transmitted.

[0046] An optional signal processing unit is now configured to determine navigation information based on the reflections of the resulting transmission signal. In particular, the signal processing unit can determine a Doppler shift between the two signals based on the reflections of the resulting transmission signals and with knowledge of the transmitted resulting transmission signal in order to determine the speed at which the underwater sound transducers are moving. Furthermore, it is possible to determine a distance to the waterbed in the direction of the reflection point of the directed transmission signal based on the travel time of the resulting transmission signal until its reflection is received. Knowing the angle at which the directed transmission signal is transmitted, depth information of the reflection point can be determined, for example.The depth information can be determined additionally or alternatively with a vertically transmitted resulting transmission signal, for example a fifth transmission signal.

[0047] It is possible to detect reflections in the sound receiving unit or the signal processing unit, i.e., to separate them from other noise. This can be done, for example, using a matched filter.

[0048] Furthermore, corresponding computer programs for the respective aspects are disclosed.

[0049] Preferred embodiments of the present invention are explained below with reference to the accompanying drawings. They show:

[0050] Fig. 1: a schematic representation of an underwater vehicle with a Doppler-based navigation support system; Fig. 2: schematic representations in a plan view (from below) of the underwater sound transducers, with Fig. 2a and Fig. 2b showing different embodiments;

[0051] Fig. 3: a schematic block diagram of a sound transmitting unit with a waterborne sound generator with five transducer strings in Fig. 3a and a schematic block diagram of an alternative transducer string in Fig. 3b.

[0052] Before exemplary embodiments of the present invention are explained in more detail below with reference to the drawings, it is pointed out 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.

[0053] Fig. 1 shows a schematic representation of an underwater vehicle 20 with an information system 22 or Doppler-based navigation support system 22. Hereinafter, the system 22 is referred to only as (Doppler-based) navigation support system 22. The differences to the information system are explained below, so that the description of the Doppler-based navigation support system can also be applied to the information system, with the exception of the distinguishing feature.

[0054] The Doppler-based navigation support system 22 comprises a plurality of waterborne sound transducers 24 arranged in a surface, a sound transmitting unit 26, a sound receiving unit 28 and a signal processing unit 30.

[0055] Sound transmitting unit 26, sound receiving unit 28, and signal processing unit 30 can be implemented in a processing unit 32, for example, a computer. A top view of the underwater vehicle is shown below the left side, and a bottom view of the waterborne sound transducer 24 is shown in the assembled state.

[0056] Dash-dotted line 33 indicates the selected section, ie, the position on the underwater vehicle 20. To the right below the underwater vehicle 20, a plan view of a waterbed 38 is shown in an area 35 in which emitted sound signals (referred to as resulting directed transmission signals 36) impinge on the waterbed 38.

[0057] The sound transmission unit 26 can each apply a sequence of transmission signals 34 to the waterborne sound transducers 24, resulting in a sequence of at least four resulting directed transmission signals 36. In the primary orientation of the waterborne sound transducers 24, the resulting transmission signals 36 are directed toward the waterbed 38 such that, for each resulting transmission signal 36, a reflection point 40a, 40b, 40c, 40d, 40e is created on the waterbed 38, and the totality of the reflection points 40 of the resulting transmission signals 36 spans an area 42 on the waterbed. A signal generator 43 and a waterborne sound generator 44 can be part of the sound transmission unit. The signal generator

[0058] 43 can provide the waterborne sound generator 44 with a generated transmission signal 45, which is processed by the waterborne sound generator 44 for use with waterborne sound transducers. The waterborne sound generator 44 can further comprise the transmission path of the transmission signal 34 between the sound transmission unit and the waterborne sound transducers. Furthermore, the sound transmission unit can also comprise electronics associated with the waterborne sound transducers, which provides the transmission signal 34 for the waterborne sound transducers 24. Optionally, the waterborne sound generator comprises

[0059] 44 also the signal generator 43 and / or the water sound transducers 24.

[0060] The sound receiving unit 28 can sample output signals 46 of the waterborne sound transducers 24 to obtain reflections 48 of the resulting transmission signal 36. The signal processing unit 30 can determine navigation information based on the reflections 48 of the resulting transmission signal. The reflections 48 can already be separated by the sound receiving unit 28 from an overall sound signal, which may, for example, also contain background noise and further waterborne sound. Alternatively, the reflections 48 can also be contained in an overall sound signal. The information system and the Doppler-based navigation support system differ in that the navigation information in the Doppler-based navigation support system is determined based on a Doppler shift between the transmission signal and the reflection. In the information system, the determination of the navigation information is not linked to a specific measured variable.

[0061] Fig. 2 shows schematic representations in a top view (from below) of the waterborne sound transducers. Fig. 2a shows the arrangement already shown in Fig. 1, and Fig. 2b shows an alternative arrangement of the waterborne sound transducers on the available surface 50.

[0062] The waterborne sound transducers in Fig. 2a are distributed regularly or randomly on a circular area 50. The actual area occupied by the waterborne sound transducers is thus a polygon that approximates the circular area 50. Optionally, the sound transmitting unit can now use the waterborne sound transducers in a smaller, particularly circular, area 52 (= first number of waterborne sound transducers) to transmit the transmitted signal. The waterborne sound transducers in the larger area 50 (= second number of waterborne sound transducers) can be used to receive the reflections of the transmitted signal by the sound receiving unit.

[0063] Fig. 2b shows an alternative arrangement of water sound transducers that can be controlled as described with regard to Fig. 2a. This means that the sound transmitter unit can control the water sound transducers in the circular area 52 while the reflections are received by the water sound transducers in the area 50. In contrast to Fig. 2a, however, water sound transducers are omitted here. The water sound transducers are not arranged on a circular area 50 as in Fig. 2a, but form two overlapping ellipses 54a, 54b. To ensure comparability with the arrangement in Fig. 2a, area 50 and area 52 were each chosen to be the same size. This makes it clear that a considerable part of area 50 is devoid of water sound transducers. This is the area outside the ellipses.This arrangement is advantageous for underwater sound transducers of an information system or Doppler-based navigation support system that transmits resulting transmission signals in the direction(s) in which the ellipse(s) is / are arranged. In particular, in the described arrangement, the resulting transmission signal can be transmitted in four directions (and optionally additionally in the vertical direction). Fig. 3a shows a schematic representation of a sound transmission unit 26. The sound transmission unit is designed to control underwater sound transducers such that the underwater sound transducers transmit four resulting transmission signals and one resulting vertical transmission signal. In this respect, the underwater sound transducer 44 comprises five parallel transducer strands 60. Advantageously, the four transducer strands 60 for the resulting transmission signals are identical; the lowest transducer strand for generating the vertical transmission signal advantageously differs from the other transducer strands.The sound transmission unit comprises a signal generator 43 and a water sound generator 44. The signal generator 43 comprises a unit 56 for generating the transmission signal 34 (e.g., a function generator) and, in this case, three phase shifters 58. The transmission signal is thus present with four different phase positions.

[0064] The generated transmission signal 45 or the phase-shifted generated transmission signal 45' can be amplified by an optional transmission amplifier 60, for example, a low-noise amplifier (LNA). The transmission amplifier 60 can output the transmission signal and an inverted transmission signal. The output (or outputs) of the transmission amplifier 60 can provide the transmission signal for transmission to the water surge transducers. A corresponding transfer point can be referred to as a signal feed 62. The optional amplifier and the signal feed are part of an input stage 64 of the water sound generator 44. The input stage 64 can be arranged within the underwater vehicle. By means of a transmission path 66, the transmission signal can be transmitted to an output stage 68, in particular to an electronic unit assigned to the water sound transducers. The transmission path 66 can pass through a pressure hull of the underwater vehicle.

[0065] The transmission path 66 connects the secondary side of an input transformer 70 to the primary side of an output transformer 72. The output transformer can transform the transmission signal into an output voltage. The output transformer can provide the transmission signal to the waterborne sound transducers at the outputs AH. Likewise, the waterborne sound transducers can provide an electrical signal corresponding to the received waterborne sound at the outputs AH, so that the output transformer 72 transmits it via the transmission path to the input transformer 70. The input transformer can output the electrical signal via its primary side for further processing (e.g., for detecting reflections).

[0066] However, the lowest (fifth) converter string does not have a dedicated transmission path. To save cables, the first and second transmission paths are used for this purpose. Typically, converter strings 1-4 are inactive when converter string 5 is operating, and vice versa. Likewise, converter strings 1-5 are typically inactive for transmission when reflections are to be received.

[0067] It should be noted that the two upper transducer strings are optional, and the underwater sound generator also functions with three transducer strings, for example, if three different transmission signals (e.g., in two directions and the vertical) are to be transmitted. In the illustrated version with transducer strings for transmission signals in four directions and the vertical, the two remaining (upper) transmission paths can also be used for signal transmission. For example, it is possible to use them to transmit an outside temperature or other physical parameter from a sensor to the interior of the underwater vehicle. In particular, transmission can occur when both transmission paths are inactive.

[0068] The lower transmission signal can be fed into a center tap of the first input transformer on the secondary side. The inverted lower transmission signal can be fed into a center tap of the first input transformer of a further transmission path. This couples the transmission signals into the corresponding transmission channels. The transmission signals can be accessed from a primary tap of the corresponding output transformers. This way, the transformer windings are used as a simple wire. Likewise, the transmission of received waterborne sound can be initiated from a center tap.

[0069] Fig. 3b shows an example transducer string in an alternative embodiment. In contrast to the transducer strings in Fig. 3a, this transducer string has four outputs A, A', B, B'. The outputs are arranged at different taps on the transformer. This allows outputs A and B to provide the inverted signal. Outputs A' and B' each provide the signal from outputs A and B, respectively, with a lower amplitude. Additional taps between outputs A and B are possible. This allows shading to be realized when the underwater sound transducers transmit the transmission signals. For example, the signals with the largest amplitude can be transmitted by the underwater sound transducers arranged centrally in the array of underwater sound transducers. The further out a underwater sound transducer is arranged, the lower the amplitude of the transmission signal can be.

[0070] The waterborne transducers can be permanently connected to an output in all aspects. For example, eight groups of waterborne transducers can be formed, which in the example shown in Fig. 3a are permanently connected to outputs A to H. If shading is used, the groups can each have subgroups that are fed with lower-amplitude transmission signals from the outputs.

[0071] The disclosed (water) sound transducers are designed for use underwater, particularly in the sea. The sound transducers can convert water sound into an electrical signal (e.g., voltage or current) corresponding to the sound pressure, the water sound signal. Furthermore, it is possible for the sound transducers to convert an applied electrical voltage into water sound. The sound transducers can therefore be used as water sound receivers and / or as water sound transmitters. The sound transducers can comprise a piezoelectric material, such as a piezoceramic, as the sensor material. The sound transducers can be used for (active and / or passive) sonar (sound navigation and ranging, dl: sound navigation and ranging). The sound transducers are preferably not suitable for medical applications and are not used for medical applications.

[0072] Although some aspects have been described in connection with a device, it is understood that these aspects also represent a description of the corresponding method, so that a block or component of a device can also be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block, detail, or feature of a corresponding device.

[0073] The above-described embodiments are merely illustrative of the principles of the present invention. It is understood that modifications and variations of the arrangements and details described herein will be apparent to others skilled in the art. Therefore, it is intended that the invention be limited only by the scope of the following claims and not by the specific details presented in the description and explanation of the embodiments herein.

[0074] List of reference symbols:

[0075] 20 underwater vehicles

[0076] 22 Doppler-based navigation support system

[0077] 24 water sound transducers

[0078] 26 Sound transmitter unit

[0079] 28 Sound receiving unit

[0080] 30 Signal processing unit

[0081] 32 computing unit

[0082] 33 Position of the detailed view of the water sound transducers

[0083] 34 broadcast signals

[0084] 35 Area of ​​the water bottom

[0085] 36 resulting directional transmission signal

[0086] 38 Waterbed

[0087] 40 reflection points

[0088] 41 Main direction of movement of the waterborne sound transducers

[0089] 42 Area spanned by the reflection points

[0090] 43 Signal generator

[0091] 44 Water sound generator

[0092] 45 generated transmission signal

[0093] 46 output signals

[0094] 48 Reflections

[0095] 50 Area for the arrangement of the water sound transducers

[0096] 52 Area for the water sound transducer to transmit the transmission signal

[0097] 54 elliptical surface

[0098] 56 Unit for generating the transmission signal

[0099] 58 phase shifters

[0100] 60 transmitter amplifiers

[0101] 62 Signal input

[0102] 64 input stage

[0103] 66 transmission path

[0104] 68 output stage

[0105] 70 Input transformer

[0106] 72 Output transformer

Claims

Patent claims 1 . Information system for an underwater vehicle (20) for determining navigation information by means of sonar, having the following features: - a plurality of water sound transducers (24) arranged in a surface, each of which is designed to convert water sound into an electrical signal corresponding to the sound pressure and to convert an applied electrical voltage into water sound; - a sound transmission unit (26) which is designed to apply a transmission signal (34) to a first number (52) of the plurality of water sound transducers (24) in order to transmit the transmission signal (34) in a directed manner by means of the water sound transducers (24); - a sound receiving unit (28) which is designed to sample the electrical signal of a second number (50) of the plurality of water sound transducers (24) in such a way that a direction is formed in the direction in which the transmission signal (34) was directed in order to receive reflections (48) of the transmitted transmission signal (36), wherein the second number (52) of water sound transducers comprises a subset of the first number (50) of water sound transducers and wherein the second number of water sound transducers is smaller than the first number of water sound transducers; - a signal processing unit (30) which is designed to determine the navigation information based on the reflections (48) of the transmitted transmission signal (36).

2. Information system according to claim 1, - wherein the area occupied by the water sound transducers (24) forms a polygon which is approximate to a circle; - wherein the sound transmitting unit (26) is designed to control the total number of water sound transducers (24) of the plurality of water sound transducers; - wherein the second number of water sound transducers are located in an area which is formed by, in particular, centric reduction of the circular shape.

3. Information system (20) according to claim 1, - wherein the area occupied by the water sound transducers (24) of the plurality of water sound transducers (24) forms a polygon that approximates a superposition of two ellipses; - wherein the sound transmitting unit (26) is designed to control the total number of water sound transducers (24) of the plurality of water sound transducers; - wherein the second number of water sound transducers are located in a circular area.

4. Information system (20) according to one of the preceding claims, - wherein the area occupied by the waterborne sound transducers (24) of the plurality of waterborne sound transducers (24) is oriented substantially horizontally.

5. A method for determining navigation information for an underwater vehicle (20) by means of sonar, comprising the following steps: a) transmitting a directional transmission signal (36) by means of a first number of a plurality of water sound transducers; b) sampling an electrical signal from a second number of the plurality of waterborne sound transducers so that a direction is formed in the direction in which the transmission signal (36) was transmitted in order to receive reflections (48) of the transmitted transmission signal (36), wherein the second number of waterborne sound transducers comprises a subset of the first number of waterborne sound transducers and wherein the second number of waterborne sound transducers is smaller than the first number of waterborne sound transducers; c) determining the navigation information based on the reflections (48) of the transmitted transmission signal (36).

6. A computer program comprising instructions which, when executed by a computer, cause a first number of a plurality of waterborne sound transducers to emit a directional transmission signal and further cause the computer to carry out steps b) and c) of the method according to claim 5.

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