DE102022004977A1 - Platform for detecting underwater vehicles - Google Patents

Abstract

Platform (20) for detecting underwater vehicles (22) with a sensor (24) and a signal processing unit (26). The sensor (24) is designed to detect light and output a corresponding electrical signal (27). The signal processing unit (26) is designed to issue a recommendation based on the electrical signal (27) as to whether the electrical signal (27) contains components of bioluminescence in order to detect the underwater vehicle (22).

Description

The invention relates to the detection of underwater vehicles with sensors or sensor arrangements that differ from classic sonars that are currently used for the detection of underwater vehicles.

Depending on the configuration, classic sonars can emit (active sonar) and/or receive (active and passive sonar) water sound with frequencies between 50Hz and 100kHz. However, modern underwater vehicles are becoming increasingly quieter and hardly emit any water noise when traveling at slow speeds. This makes detection and location using passive sonar much more difficult. Locating using active sonar has the disadvantage that the sound transmitter is easy to detect. Locating the (particularly enemy) underwater vehicle using a (own) underwater vehicle is therefore not possible without revealing its own position. However, this is not exactly desirable.

The object of the present invention is therefore to create an improved concept for detecting underwater vehicles.

The task is solved by the subject matter of the independent patent claims. Further advantageous embodiments are the subject of the dependent claims.

A variety of concepts are now disclosed, which can be divided into three categories. The concepts in the first category deal with the detection of the underwater vehicle itself. The concepts of the second category and the third category each deal with the detection of the wake of the underwater vehicle, whereby the concepts of the third category exploit physical effects to detect the water eddies in the wake and the concepts of the second category would also work without water eddies. One sensor or a plurality of sensors is used per concept, which determines a physical quantity based on a physical effect. One physical effect is used per concept.

The sensors can be arranged individually or in any number and combination on a platform. In other words, it is possible to use a physical effect to detect the underwater vehicle. However, a plurality of physical effects can also be used in combination to detect the underwater vehicle. The more physical effects are used, the higher the probability of detecting the underwater vehicle. It is also possible to use the sensor(s) used together with a classic sonar, preferably a passive sonar. Furthermore, one embodiment finally discloses how one or more of the sensors of the second or third category can be attached to the (own) underwater vehicle as a platform for detecting the (in particular enemy) underwater vehicle. Furthermore, at least some of the concepts described can also be used to classify underwater contacts that have already been detected. That is, to determine their exact type. This is possible because different underwater vehicles produce an individual, type-dependent manifestation of the physical effect under consideration.

Category 1:

Embodiments of concept 1a (1st category, concept a) show a platform for detecting underwater vehicles with an underwater antenna and a signal processing unit. In this and the following concepts, a platform can be viewed as a surface platform, for example an autonomous or conventional watercraft or a floating buoy or an underwater platform, for example an autonomous underwater vehicle or a manned underwater vehicle (submarine) or a target-seeking torpedo or an underwater buoy become. The underwater antenna has a variety of water sound transducers. The water sound transducers of the large number of water sound transducers are designed to convert water sound into an electrical signal corresponding to the sound pressure. The signal processing unit is designed to receive the electrical signals from the water sound transducers and to detect infrasound emitted by the underwater vehicle in the water sound. Infrasound is generated, for example, by the propulsion engines of the underwater vehicle but also by the displacement of the water, the flow noise.

The idea of concept 1a is to detect water sound not only in the known sound range of classic sonars >50 Hz, but also in the infrasound range <15 Hz, in particular <10 Hz, preferably <7 Hz. In principle, water sound transducers, for example piezoceramic water sound transducers, can detect noise detect these frequencies. However, such low frequencies are filtered out in almost all modern sonar systems in order to improve the signal-to-noise ratio in the actual, higher-frequency useful band. There is also a lack of suitable signal processing. A big advantage of this concept is that it is underwater Equipment can also be detected if the water sound transducers are outside the wake of the underwater vehicle.

Embodiments show that the underwater antenna has a length of at least 50m, preferably at least 75m, at least 100m, at least 200m, at least 350m or at least 500m. These antenna lengths allow the detection of infrasound in water using a half-wave antenna.

Further exemplary embodiments show that the platform has an underwater vehicle and the underwater antenna comprises a towed antenna which is designed to be towed by the underwater vehicle. If an underwater vehicle is used to detect the (enemy) underwater vehicle, it is advantageous to use a towed antenna as the underwater antenna. This makes it possible to decouple the underwater antenna from the noise of the towing underwater vehicle. Furthermore, antenna lengths that are significantly larger than 100m can be realized and noises with frequencies less than or equal to 1 Hz can also be detected. For a half-wave antenna, this would mean an underwater antenna length of 750m or more.

It is also possible, for example, to use an antenna that is permanently mounted on the underwater vehicle, for example a side-view antenna, as an underwater antenna. Here, however, the length of the underwater antenna is limited by the length of the underwater vehicle.

In addition, it is possible to form an antenna from water sound transducers of the antenna permanently mounted on the underwater vehicle and the towed antenna in order to be able to realize even greater lengths of the underwater antenna. That is, in one embodiment, the underwater vehicle has at least one water sound transducer of the plurality of water sound transducers and the towed antenna has at least one water sound transducer of the plurality of water sound transducers, so that the underwater vehicle and the towed antenna each have a part of the underwater antenna.

In further exemplary embodiments, the signal processing unit is designed to carry out beamforming based on the infrasound in order to determine a direction in which the underwater vehicle is located. This makes it possible to determine not only the presence of the (enemy) underwater vehicle, but also its position.

Analogously, a method for detecting underwater vehicles is disclosed with the following steps: -converting water sound into an electrical signal corresponding to the sound pressure; -Analyzing the electrical signal to detect infrasound emitted by the underwater vehicle in the water sound.

Embodiments of concept 1b (1st category, concept b) disclose an underwater platform (20) for detecting underwater vehicles, comprising a magnetic anomaly detector (MAD) and a signal processing unit. The magnetic anomaly detector is designed to detect the earth's magnetic field and output a corresponding MAD sensor signal. The signal processing unit receives the MAD sensor signal and can detect a deviation in the earth's magnetic field by the underwater vehicle.

The idea of concept 1b is to detect a distortion of the earth's magnetic field caused by the (enemy) underwater vehicle, in particular the ferromagnetic materials such as steel installed in it. The effects on the earth's magnetic field are minimal, but measurable. The detection of underwater vehicles from the air using MAD sensors is known. This means planes or helicopters can fly over water and detect underwater vehicles using the MAD sensors.

Now the communication between the aircraft or helicopter and the underwater platform, for example an underwater vehicle, is not trivial. In this respect, it is advantageous, in order to create the situation picture for the underwater vehicle, that the underwater vehicle can also detect the (enemy) underwater vehicle. This method for detecting the (enemy) underwater vehicle has the great advantage that the magnetic signature of an underwater vehicle can only be reduced with great effort and therefore offers good detection options.

Embodiments show that the underwater platform has an underwater vehicle and a traction device. The traction means is designed to be pulled by the underwater vehicle, in particular a submarine. For example, a rope or a band or a combination of a rope or a band and a towed antenna is suitable as a traction device. The magnetic anomaly detector is arranged on the traction means, so that the magnetic anomaly detector is arranged remotely from the underwater vehicle during operation. For example, the magnetic anomaly detector can be arranged at the end of a towed sonar. This is advantageous because it means there is a very large distance between the magnetic anomaly detector and the underwater vehicle is created. The influence of your own underwater vehicle on the magnetic anomaly detector is thus reduced. This means (enemy) underwater vehicles can be detected more reliably. The magnetic anomaly detector preferably has a distance of at least 100m, preferably at least 250m, more preferably at least 500m, more preferably at least 1000m or more preferably at least 1500m.

Analogously, a method for detecting underwater vehicles is disclosed with the following steps: -Detecting the earth's magnetic field by means of a magnetic anomaly detector and outputting a corresponding MAD sensor signal; -Detecting a deviation of the earth's magnetic field by the underwater vehicle in the MAD sensor signal.

Category 2:

Embodiments of concept 2a (2nd category, concept a) show a platform for detecting underwater vehicles with a sensor and a signal processing unit. The sensor is designed to chemically analyze seawater and to output a proportion of at least one predefined substance in a corresponding analysis result. For example, the sensor can determine a concentration of the substance in the seawater. In the following embodiments, various suitable substances are described that indicate the detection of an underwater vehicle, in particular a manned underwater vehicle. Since devices and methods are described in categories 2 and 3 for detecting the wake of the underwater vehicle, it is advantageous in each of these concepts to take measurements with the sensor continuously, i.e. at least at intervals of less than 10, preferably less than 1 second, more preferably at intervals of less than 100 milliseconds. This enables the platform, in particular a movable platform, to move with the sensor in the wake of the underwater vehicle and, when the wake is left, to find it again as quickly as possible.

The signal processing unit is designed to determine, based on the analysis result, a deviation from a previous analysis result or a deviation from an expected analysis result in order to detect the underwater vehicle. A deviation, particularly a significant deviation, from a previous analysis result can indicate that the platform's sensor has moved into or out of the wake of the (enemy) underwater vehicle. A deviation from an expected analysis result can indicate, for example, that the sensor is in the wake of an underwater vehicle, even without having previously determined a reference value.

The idea of concept 2a is to detect chemical substances secreted by an underwater vehicle in the wake of the underwater vehicle and to conclude the presence of the underwater vehicle.

Embodiments show that the signal processing unit is designed to query the expected analysis result in a database based on a current position of the underwater platform. The database can be, for example, a nautical chart in which concentrations of the predefined substance are entered. In this way, regional differences in the proportion of the predefined substance in the seawater can be taken into account. This makes it possible, for example, to determine with greater accuracy whether the sensor is in the wake of an underwater vehicle or not, even without prior analysis results. In other words, the background level of the predefined substance can be determined so that an increased concentration can be determined based on the background level.

In a further exemplary embodiment, the sensor is designed to determine a proportion of zinc, nickel, copper, hydrogen or hydrocarbon as a predefined substance in the seawater. The signal processing unit is designed to compare the specific proportion of the predefined substance with a proportion of the predefined substance in a previous analysis result or with an expected proportion of the predefined substance in order to detect the underwater vehicle. The previous analysis result is preferably the analysis result of the last, i.e. immediately preceding, measurement.

Zinc is suitable as a predefined substance because underwater vehicles typically have sacrificial anodes containing zinc. The sacrificial anodes prevent, for example, the hull or other external parts of the underwater vehicle from rusting.

Nickel is suitable as a predefined substance because pipes such as cooling water pipes of underwater vehicles that come into contact with seawater typically contain nickel.

Copper is suitable as a predefined material because it is also used for pipes of underwater vehicles that come into contact with seawater. Likewise, copper is also used in antifouling paint to the underwater vehicle to protect against fouling and other contamination.

Hydrogen is suitable as a predefined substance because it is a waste product from oxygen production. For example, oxygen is needed for the crew to breathe. The proportion of hydrogen in seawater can be determined quickly and reliably, for example, using a pH value analysis of seawater as a chemical analysis.

In one embodiment, in addition or as an alternative to determining the proportion of zinc, nickel, copper, hydrogen or hydrocarbon as a predefined substance in the seawater, the sensor is designed to determine a proportion of a hydrocarbon, in particular diesel, in the seawater. The signal processing unit is designed to compare the determined proportion of hydrocarbon with a proportion of hydrocarbon in a previous analysis result or with an expected proportion of hydrocarbon in order to detect the underwater vehicle. In the case of diesel-powered underwater vehicles, it is possible to detect small amounts of diesel in the wake of the underwater vehicle, since the diesel tanks are typically open at the bottom. Seawater can therefore replace the diesel used in order to keep the change in the buoyancy of the underwater vehicle as low as possible. Although the majority of the diesel floats to the top due to its lower density compared to seawater, it cannot be avoided that small amounts of diesel mix with the seawater and thus end up in the wake of the underwater vehicle.

In embodiments, the sensor is designed to carry out atomic absorption spectroscopy, laser-induced plasma spectroscopy, energy-dispersive X-ray spectroscopy or at least two of the aforementioned methods in order to chemically analyze the seawater. Using the aforementioned methods, it is possible to examine seawater for predetermined substances.

In further exemplary embodiments, the sensor is designed to output proportions of a plurality of predefined substances in the seawater. Alternatively, the platform comprises a plurality of sensors, the sensor being a sensor of the plurality of sensors, the sensors of the plurality of sensors being designed to chemically analyze the seawater and, in a respective corresponding analysis result, to include a proportion of a plurality of predefined substances in the to spend more water. In other words, a sensor or a plurality of sensors can determine proportions of different substances in the seawater.

In these exemplary embodiments, the signal processing unit is designed to determine, based on the analysis results, a chemical signature from the plurality of predefined substances as a deviation of the proportions of the predefined substances from a previous analysis result or a deviation from an expected analysis result in order to detect the underwater vehicle, in particular classify. In other words, the signal processing unit can estimate a natural occurrence of the predefined substances at the current position of the platform. The estimate may be based on a previous reading where the platform took a measurement outside the wake of a submersible. Additionally or alternatively, the estimate can be based on values from a database. For example, the database is in the form of a nautical chart in which concentrations of the predefined substances are entered at different positions.

Based on the chemical signature, more robust detection of the underwater vehicle is possible. It is also possible to classify the underwater vehicle using the chemical signature. For example, the types of underwater vehicles differ in the amount of diesel that is flushed out of the fuel tanks or in the length of the pipelines that are in contact with the seawater. This changes the chemical signature of the underwater vehicle.

Furthermore, the sensor or sensors are designed to determine an isotopic composition of the detected substance or substances in order to enable classification of the underwater vehicle. The isotope composition of, for example, diesel or the metals detected makes it possible to determine the origin of the substances. Based on the origin, an assignment to an underwater vehicle, in particular a nation to which the underwater vehicle belongs, is possible.

The analysis of the isotope composition in combination with the chemical signature of the underwater vehicle enables an even more precise classification of the underwater vehicle than is possible with the respective methods individually.

Analogously, a method for detecting underwater vehicles is disclosed with the following steps: chemical analysis of seawater in order to output a proportion of at least one predefined substance in an analysis result; - Determine, based on the analysis result, a deviation from a previous analysis result or a deviation from an expected analysis result to detect the underwater vehicle.

Embodiments of concept 2b (2nd category, concept b) show a platform for the detection of nuclear-powered underwater vehicles. The platform has a sensor and a signal processing unit. The sensor is designed to detect radioactive radiation and to output a corresponding radiation signal. The sensor can be a Geiger counter. It is advantageous here that manned underwater vehicles usually already have a Geiger counter on board. This can be mounted on the periscope, for example. With the Geiger counter, the crew can check before exiting whether the exit location is radioactively contaminated, for example by an atomic bomb. This Geiger counter can also be used underwater to detect radioactive radiation in the wake of the underwater vehicle. Additionally or alternatively, a separate sensor can also be mounted on the platform. Optionally, the sensor can be integrated in a pressure-tight housing that allows the radioactive radiation to pass through. At the relevant points where the housing is intended to allow radiation to pass through, the housing can be made of glass, for example, so that the radioactive radiation can penetrate into the housing. Gamma radiation in particular can penetrate glass.

The signal processing unit is designed to receive the radiation signal and to determine a deviation from a previous radiation signal or a deviation from an expected radiation signal in order to detect the underwater vehicle. The expected radiation signal may include or consist of terrestrial radiation at the location. The previous radiation signal may come from a measurement outside the wake of a nuclear-powered underwater vehicle near the current location.

The idea of concept 2b is to be able to detect nuclear-powered underwater vehicles such as nuclear submarines, even if they emit no or very little noise. Since nuclear-powered underwater vehicles inevitably emit at least small amounts of radioactivity, such as gamma radiation, this can be detected in the water.

In exemplary embodiments, the platform is designed as a (particularly stationary) underwater platform or at least includes the same. The underwater platform is arranged on the bottom of the water or attached to the bottom of the water, in particular the seabed. This means that the underwater platform can have a greater density than water and sink to the bottom of the water. The underwater platform can be attached there, for example anchored. Alternatively, the underwater platform can also be neutral in buoyancy or have a lower density than the surrounding (sea) water. In this case, the underwater platform can be attached to the bottom of the water, for example by means of a rope.

The underwater platform is preferably arranged in the fairway, for example in a narrow water passage, such as in a strait. This has the advantage of forcing underwater vehicles to pass close to the underwater platform. Furthermore, the underwater platform is then inevitably arranged in the vicinity of the underwater vehicle. It is thus possible to receive atomic radiation emitted directly from the underwater vehicle and thus to carry out a classification of the underwater vehicle, for example based on an isotope study of the radioactive radiation. Radioactive radiation can also be detected at greater distances, but then only indirectly via water molecules ionized by the radioactive radiation. This makes it possible to differentiate between nuclear or conventionally powered submarines, but not a more precise distinction.

Analogously, a method for detecting nuclear-powered underwater vehicles is disclosed, comprising the following steps: -detecting radioactive radiation and outputting a corresponding radiation signal; Determining a deviation from a previous radiation signal or a deviation from an expected radiation signal to detect the underwater vehicle.

Embodiments of concept 2c (2nd category, concept c) show a platform for detecting underwater vehicles with a temperature sensor and a signal processing unit. The temperature sensor is designed to detect a temperature with an accuracy of less than or equal to 0.1 °C, preferably less or equal to 0.5 °C, more preferably less or equal to 0.01 °C. This means that the temperature sensor is highly sensitive to temperature changes. The signal processing unit is designed to continuously obtain the temperature of the temperature sensor and to determine a rate of change of the temperature in order to detect the underwater vehicle.

The idea of concept 2c is to detect rapid temperature changes in the wake of the underwater vehicle caused by the Mixing of water layers triggered by an underwater vehicle results. This results in frequent, rapid changes in temperature. This means that a dynamic temperature change takes place. Furthermore, the underwater vehicle heats the surrounding water minimally. This results in a static temperature change. Both effects can be detected with a continuous temperature measurement.

Embodiments show that the temperature sensor is designed to detect at least 90% of a temperature change of 0.1 ° C within a maximum of 5ms, preferably within a maximum of 2ms, more preferably within 1ms. This makes it possible to track the dynamic temperature change at the necessary speed.

In further exemplary embodiments, the signal processing unit is designed to carry out a statistical analysis of the temperature measurements over time in order to determine a deviation of the temperature from a usual temperature.

Analogously, a method for detecting underwater vehicles is disclosed with the following steps: -continuously detecting a temperature with an accuracy of less than 0.1 ° C; -Determining a rate of change in temperature to detect the underwater vehicle.

Embodiments of concept 2d (2nd category, concept d) show a platform for detecting underwater vehicles with a sensor and a signal processing unit. The sensor is designed to determine a refractive index of the water surrounding the platform and to output a corresponding electrical signal. The sensor includes or is, for example, a refractometer. The signal processing unit is designed to detect a change in the refractive index of the water surrounding the platform based on the electrical signal from successive measurements in order to detect the wake of the underwater vehicle.

The idea of concept 2d is to detect a changed refractive index in the wake caused by the underwater vehicle. The refractive index changes, for example, due to a change in the temperature of the (sea) water. But there are other factors that change the refractive index. For example, a change in salinity or chemicals in the wake. The salt content can vary due to the mixing of water layers.

Chemicals can enter the water from the underwater vehicle. The determination of the refractive index therefore represents both an alternative to the temperature measurement of concept 2c and a useful addition to enable more robust detection of the underwater vehicle through mixing water layers.

Analogously, a method for detecting underwater vehicles is disclosed with the following steps: -Continuously determining a refractive index of the water surrounding the platform and outputting a corresponding electrical signal; -Detecting, based on the electrical signal of successive measurements, a change in the refractive index of the water surrounding the platform to detect the underwater vehicle.

Embodiments of concept 2e (2nd category, concept e) show a platform for detecting underwater vehicles with a sensor and a signal processing unit. The sensor is designed to detect light and output a corresponding electrical signal. For example, the sensor is a photodiode or the sensor has the photodiode, or the sensor is or includes a, preferably electronic, light image sensor, for example a CCD sensor (charge-coupled device (German: charge-coupled component)) or the like. Ä.. The signal processing unit is designed to issue a recommendation based on the electrical signal as to whether the electrical signal contains components of bioluminescence. Depending on the time of day (especially at night) and, in the case of an underwater platform, also the diving depth (the greater the diving depth, the less light penetrates the platform), it may be sufficient to detect the mere appearance of light in order to be able to conclude that bioluminescence is present.

The idea of concept 2e is to detect bioluminescence triggered by the underwater vehicle. The underwater vehicle triggers this when it travels through an area in which special microorganisms such as algae live, which are stimulated by pressure and begin to glow.

In exemplary embodiments, the sensor is designed to detect spectral components of the light. This is possible, for example, if the sensor has a spectrometer. The signal processing unit is designed to use the spectral components to detect whether spectral components of bioluminescence are present in order to issue a recommendation as to whether the electrical signal contains components of bioluminescence. This is advantageous, for example, in a bright environment, for example during daylight or a full moon, in order to ensure bioluminescence despite the to be able to reliably detect bright surroundings. Advantageously, the sensor has a light image sensor in addition to the spectrometer in order to be able to analyze both the spectrum and the real light image.

In further exemplary embodiments, the sensor is designed to sequentially take light images of the environment of the platform in order to detect the light. The photographs are preferably recorded using an electronic sensor, for example a CCD sensor. Using the sequence of light images, it is possible to detect the onset of bioluminescence. A comparison with other parameters, such as the time or the current position, makes it possible to rule out other causes for the onset of lighting.

Further exemplary embodiments show that the signal processing unit is designed to process data that assigns an occurrence of living beings that luminesce under pressure to the locations for different locations. For example, the signal processing unit has access to a nautical chart in which luminescent living beings are mapped. The signal processing unit can then determine the occurrence of living beings that luminesce under pressure for the current location of the platform and take this information into account when issuing the recommendation as to whether the electrical signal contains components of bioluminescence. This means that if illumination is detected in an area in which luminescent organisms are known to exist, the probability that this is bioluminescence is significantly greater than in an area in which such organisms are not known or at least it is not known that luminescent living beings exist.

Analogously, a method for detecting underwater vehicles is disclosed with the following steps: -detecting light and outputting a corresponding electrical signal; -Issuing a recommendation as to whether the electrical signal contains components of bioluminescence in order to detect the underwater vehicle.

Category 3:

Embodiments of concept 3a (3rd category, concept a) show a platform for detecting turbulences caused by the wake of underwater vehicles. The platform includes a laser Doppler anemometer and a signal processing unit. The laser Doppler anemometer is designed to measure a flow property in the water surrounding the platform and to output a corresponding electrical signal. The laser Doppler technique is based on determining the Doppler shift of the scattered light of a moving object that is illuminated with laser light. Flow properties include, for example, whether the water flows calmly or turbulently, how fast the water flows or in which direction the water flows. The signal processing unit is designed to receive the electrical signal and analyze the measured flow property in order to detect the underwater vehicle.

The platform advantageously comprises a plurality of laser Doppler anemometers. By measuring using the laser, it is only possible to determine the speed and optionally the direction of the surrounding water at specific points. When using several laser Doppler anemometers, several points in a volume can be examined with regard to their flow speed and, optionally, direction. This makes it possible, for example, to recognize whether it is a turbulent flow or a linear flow.

The idea behind concept 3a is to detect turbulence in the water that indicates the wake of an underwater vehicle. Various techniques can be used for this. One of them is laser Doppler anemometry. This is based on the Doppler shift of scattered light from one or more laser beams generated by particles in the water.

In exemplary embodiments, the laser Doppler anemometer is designed to measure the flow properties in a backscatter arrangement. This means that the detector for receiving the scattered light is arranged on the same side of the measuring volume as the associated laser (or the associated lasers in a two-beam measuring system). With the backward scattering arrangement, it is possible to design the transmitting optics in such a way that they simultaneously record the receiving optics, so that there is no need for complex adjustment between the transmitting and receiving units. However, the intensity of the scattering signal with this arrangement is an order of magnitude smaller than with the forward scattering arrangement. Nevertheless, backward scattering is particularly preferred for moving platforms, especially underwater vehicles. This makes it possible to operate the laser on the bow facing forward. Since the measurement volume is then located in front of the moving platform, the measurement will have little or no influence on the flow properties from the moving platform.

Analogously, a method for detecting turbulences caused by the wake of underwater vehicles is disclosed with the following steps: -Measuring a flow property in the water surrounding the platform using a laser Doppler anemometer and outputting a corresponding electrical signal; -Analyzing the measured flow properties to detect the underwater vehicle.

Embodiments of concept 3b (3rd category, concept b) show a platform for detecting turbulences caused by the wake of underwater vehicles. The platform includes a distance flow meter and a signal processing unit. The flow meter is designed to measure a flow property in the water surrounding the platform and to output a corresponding electrical signal. The signal processing unit is designed to receive the electrical signal and analyze the measured flow property in order to detect the underwater vehicle.

The idea of concept 3b is to detect turbulence in the water, which indicates the wake of an underwater vehicle.

In embodiments, the distance flowmeter includes an ultrasonic Doppler profile flowmeter (Acoustic Doppler Current Profiler - ADCP). Using reflected, emitted sound pulses, the distance and the Doppler shift can be used to detect the speed of scattering particles in the water. Typically, high-frequency sound pulses are used for this, in particular frequencies typically greater than 500kHz, preferably greater than 1MHz. Such frequencies cannot be detected by typical passive sonars, so the risk of being located by the emitted sound is low. Furthermore, such high frequencies are also strongly attenuated in water, so that the range is very short and is at most in the range of a few hundred meters.

Analogously, a method for detecting turbulences caused by the wake of underwater vehicles is disclosed with the following steps: measuring a flow property in the water surrounding the platform using a distance flow meter and outputting a corresponding electrical signal; -Analyzing the measured flow characteristic to detect the underwater vehicle.

Exemplary embodiments of concept 3c (3rd category, concept c) show a platform for detecting turbulences caused by the wake of underwater vehicles. The platform includes a thermal anemometer and a signal processing unit. The thermal anemometer is designed to measure a flow property, in particular a flow direction and/or a flow velocity, in the water surrounding the platform and to output a corresponding electrical signal. The thermal anemometer uses the cooling effect that the surface of a warm body experiences in a colder flowing medium as a measuring effect. The warm body is preferably heated electrically, so that a measurable change in the body's resistance occurs directly via the change in temperature of the body. The signal processing unit receives the electrical signal and analyzes the measured flow velocity in order to detect the underwater vehicle.

The idea of concept 3c is to be able to detect turbulences in the water, which indicate the wake of an underwater vehicle, even without water vortices or particles in the water. This can be done reliably using a thermal anemometer.

Embodiments show that the thermal anemometer has a hot film or a hot wire (or a combination of both). The hot-wire anemometer comprises at least two hot wires arranged perpendicular to one another. This makes it possible to determine a two-dimensional flow direction. However, both four hot films and three or four hot wires are preferably used per thermal anemometer. A three-dimensional flow direction can be determined with three hot wires arranged perpendicular to one another, and a backflow can also be determined using a fourth wire. Likewise, four hot film anemometers can be arranged on four sides of a body, for example a pipe, in order to be able to determine a three-dimensional flow direction including backflow. The hot film anemometer is advantageous when used on mobile platforms (e.g. underwater vehicles) or platforms that are directly in a water current, as it is robust and can withstand water resistance well.

In embodiments, the platform has a temperature sensor configured to determine a current temperature of the water surrounding the platform. The thermal anemometer is designed to adjust a current flow through a sensor element (ie, for example, hot wire or hot film) such that a measuring temperature of the thermal anemometer has a constant temperature compared to the temperature of the water surrounding the platform, regardless of the flow properties of the water. This procedure is also known as constant temperature anemometry. Becomes a reference sensor needed to determine the temperature of the water, sensors already installed on the platform, for example an underwater vehicle such as a submarine, or the temperature sensor according to concept 2c can be used.

Alternatively, the thermal anemometer is designed to ensure a constant current flow through the sensor element, so that the flow properties of the water are measured via the temperature change. This procedure is also known as constant current anemometry.

Analogously, a method for detecting turbulences caused by the wake of underwater vehicles is disclosed with the following steps: measuring a flow property in the water surrounding the platform using a thermal anemometer and outputting a corresponding electrical signal; -Analyzing the measured flow properties to detect the underwater vehicle.

Embodiments of concept 3d (3rd category, concept d) show a platform for detecting turbulences caused by the wake of underwater vehicles with a sensor and a signal processing unit. The sensor is designed to detect a magnetic field surrounding the sensor and to output a corresponding electrical signal. The signal processing unit is designed to receive the electrical signal and, based on successive measurements, to determine magnetic field changes due to turbulence in the wake of accelerated ions as a superposition of the static earth's magnetic field. Thus, it is possible to determine the entry into the wake of an underwater vehicle. The sensor is preferably designed to determine the magnetic field of the accelerated ions in at least two, in particular three, spatial directions. Here, the typical rotating magnetic field of the turbulence present there can also be determined in the wake of the underwater vehicle.

auf.The idea of concept 3d is to detect the ions naturally contained in seawater due to the salt content in the wake of the underwater vehicle. Because of their charge, the ions create a magnetic field when they move. However, this is superimposed in terms of magnitude by the earth's magnetic field, which makes the measurement more difficult. For this reason, the signal processing unit analyzes a time course of the magnetic field in order to detect a change in the magnetic field. In the wake of the underwater vehicle, a change in the magnetic field can only be measured with a multi-dimensional magnetic field sensor. The magnetic field sensor is therefore preferably part of an array of (preferably similar) magnetic field sensors. In the case of a mobile platform, for example an underwater vehicle, the magnetic field sensor or the array of magnetic field sensors is preferably arranged in front of the underwater vehicle. Furthermore, the magnetic field sensor has a detection threshold of preferably less than $20\frac{pT}{sqrt\left(H\mathrm{e.g}\right)}$

on.

Optionally, the magnetic anomaly detector according to concept 1b is suitable as a magnetic field sensor array, provided it has sufficient measuring speed to detect the water eddies. However, with the magnetic field sensor array according to concept 1b, it should be taken into account that it is advantageously towed and thus the towing underwater vehicle also generates water vortices.

Analogously, a method for detecting turbulences caused by the wake of underwater vehicles is disclosed with the following steps: -detecting a magnetic field and outputting a corresponding electrical signal; -Determine, based on successive measurements, magnetic field changes caused by turbulence in the wake of accelerated ions as a superposition to the static Earth's magnetic field.

Embodiments of concept 3e (3rd category, concept e) show a platform for detecting turbulences caused by the wake of for detecting underwater vehicles with a bending sensor and a signal processing unit. The bending sensor is designed to detect turbulences in the water surrounding the bending sensor and to output a corresponding electrical signal. The signal processing unit is designed to receive the electrical signal and to detect the turbulences caused by the wake of the underwater vehicle based on the electrical signal from successive measurements. Turbulence caused by the wake of the underwater vehicle is characterized, for example, by the fact that it forms a track and can therefore be detected using a variety of measurements. Furthermore, if the turbulence can no longer be detected on a moving platform, it is possible to find the turbulence, i.e. the track, again by taking measurements in the vicinity of the last measurement location.

The idea of concept 3e is to be able to detect water currents using a highly sensitive bending sensor, based on the whiskers of seals.

In exemplary embodiments, the bending sensor has a curvature, in particular a win dung, preferably a large number of turns. For example, the bending sensor is helically shaped. It is possible for the sensory element to have this shape; alternatively, it is also possible for the bending sensor to comprise a carrier shape to which the sensory element is applied. This shape is advantageous in order to achieve a low inherent rigidity and thus enable a high sensitivity of the bending sensor.

In further exemplary embodiments, the bending sensor comprises a piezo element. The piezo element can be applied to the carrier shape of the bending sensor. Application is possible, for example, in the form of a coating or a film. Alternatively, the piezo element can be rod-shaped. This means that the bending sensor can do without a carrier shape. In a further alternative, the carrier shape can be based on the piezo element. Depending on the set sensitivity of the carrier shape, the pressure exerted by the carrier shape on the piezo element varies at the same water speed.

In addition to or as an alternative to the piezo element, the bending sensor can include a strain gauge. The strain gauge can be applied to the carrier form of the bending sensor. The bending sensor preferably has a plurality of strain gauges. This means that compressions and stretches of the carrier shape in different directions can be detected in the best possible way. The same principle can also be used with piezo elements applied to the carrier shape.

Further exemplary embodiments show the bending sensor, in particular the carrier shape of the bending sensor, with a length that is at least 20 times, preferably at least 50 times, particularly preferably at least 100 times as large as a thickness (i.e. a diameter with a round cross section) of the bending sensor. Such a design also enables the bending sensor to be highly sensitive.

In further embodiments, the bending sensor is one bending sensor of a plurality of bending sensors, wherein the bending sensor and a further bending sensor of the plurality of bending sensors have a maximum sensitivity at different swirl frequencies. The sensitivity of the bending sensors can be obtained, for example, via a material of the bending sensor, in particular a material of the carrier shape, different lengths of the bending sensor, in particular of the carrier shape, or different winding steepnesses of the bending sensor, in particular of the carrier shape.

Analogously, a method for detecting turbulences caused by the wake of underwater vehicles is disclosed with the following steps: -detecting turbulences with a bending sensor and outputting a corresponding electrical signal; -Detecting turbulence in the wake of the underwater vehicle based on the electrical signal of successive measurements.

Across concepts, a platform is understood as a mobile or (quasi) stationary, i.e. essentially stationary, platform. The platform is essentially stationary, for example, if it is connected to the bottom of the water, e.g. the seabed, by means of a rope. This means that the range of motion is limited to a predetermined level. For example, a buoy, in particular an underwater buoy, can be used as a substantially stationary platform. A mobile platform can have its own drive or be externally moved, for example pulled. An externally moving platform can be, for example, a towed antenna or another towed body. A self-propelled platform is, for example, a manned or unmanned (e.g. autonomous) underwater vehicle. Unmanned underwater vehicles also include underwater vehicles (torpedoes).

The advantage of an externally moved platform is that it does not require its own energy supply, but can be powered by means of a drag device, which has an electrical cable, for example. For example, an unmanned surface vehicle can pull a towed body under water and optionally supply it with energy.

In a use case, a platform may be used with one or any combination of the concepts described above. That is, the platform is, for example, equipped with different sensors that can detect the underwater vehicle in accordance with the concepts described above. The use of multiple concepts reduces the probability of false detection, i.e. a false negative or false positive detection result.

It is also possible to use several different or similar platforms that can communicate with each other or with a base station. The platforms can have a communication unit for this purpose. Using the communication unit, the platforms can at least send data packets and optionally also receive them.

The sensors preferably continuously record measured values. This makes it possible, for example In the concepts of categories 2 and 3, it is important to follow the wake, ie to detect in particular when a sensor is in the wake or outside the wake. With category 1 concepts, it is also possible to follow a route of the underwater vehicle to be detected.

Particularly for sensors in categories 2 and 3, it is advantageous to use a plurality of similar sensors (i.e. several sensors per concept) per platform. This makes it possible to determine a gradient of the substances or physical properties to be detected (category 2) or the turbulence (category 3). The direction of the gradient indicates in which direction the measured physical effect weakens and in which direction it becomes stronger. This means that the gradient can be used to determine in particular the direction in which the wake is left. For example, at least 3 or 5 sensors, e.g. straight (3) or arranged in a cross (5), are used for this purpose. Any other sensor arrays can of course also be used, which make it possible to detect a gradient in one, preferably two, spatial directions. The signal processing unit can determine the gradient.

For the detection of the underwater vehicle, the signal processing unit can use a sensor result or any combination of the sensor results of the concepts described above. The signal processing unit can carry out the detection using a computer-implemented classification. Well-known classifiers include the Bayes classifier or neural networks. Training data and evaluation data are required to train the classifier. These can be obtained, for example, by equipping one or preferably a plurality of platforms with one or more of the sensors of the concepts described and knowingly recording data both outside and inside the wake of various underwater vehicles. This is of course easier in peacetime, as the actual position of underwater vehicles can be detected, for example using active sonar. Furthermore, it is possible, at least for the boats of friendly navies, to drive the platform behind an underwater vehicle in test trips or to have it drive along stationary platforms.

A detection means that the platform determines that an underwater vehicle is nearby. Locating means that the platform determines at least one direction, preferably a position, i.e. direction and distance, of the underwater vehicle. Classify means that the platform recognizes which underwater vehicle it is. The classification can, for example, include the determination of one or any combination of the following findings: a friend-enemy distinction, an origin (nationality), a type of underwater vehicle.

Detection of the underwater vehicle is possible using the measurement result of one or more sensors of the concepts described. Locating the underwater vehicle in the Category 2 and Category 3 concepts is possible, for example, by tracking the wake. Classification can be made based on Category 3 concepts by examining the structure of the turbulence in the wake. For example, the spatial extent of the turbulence, i.e. a diameter of the wake, as well as speed or an average direction of rotation can enable a classification.

Conceptual exemplary embodiments that can be used with one or any combination of the concepts described above show an underwater vehicle, in particular a submarine, for detecting another underwater vehicle with a measuring head and a deployment device. The measuring head has a sensor. The sensor is designed to detect a feature of the underwater vehicle underwater. The measuring head is also designed to be extended from the dispensing device in such a way that the sensor is located in front of the underwater vehicle. A pipe, for example, is suitable as a dispensing device. The pipe can have guide means, for example guide grooves, on the walls.

The idea of these higher-level exemplary embodiments is to provide one or more sensors for an underwater vehicle that 1. are not exposed to contamination, for example from algae or mussels, when they are not in use and 2. are not influenced by turbulence from the moving underwater vehicle. The first advantage is achieved in that the measuring head can be extended from the dispensing device. The second advantage is achieved in that the measuring head for a measurement or a series of measurements is arranged in front of the underwater vehicle in the main direction of travel.

The deployment device can be designed to deploy unmanned underwater vehicles, in particular underwater moving bodies, from the underwater vehicle. The deployment device can be a torpedo tube. This is advantageous because torpedo tubes can also be deployed in existing the underwater vehicles and can therefore also be used to deploy the measuring head, at least if they are located near the bow. Retrofitting existing manned underwater vehicles is therefore possible.

The measuring head can also have a fixing means which extends into a pipe of the dispensing device and is connected to the underwater vehicle in order to fix the measuring head on the underwater vehicle. An example of how the fixation means can be designed is a telescopic rod.

Alternatively, the measuring head can be part of an unmanned underwater vehicle, in particular a remotely operated underwater vehicle. The unmanned underwater vehicle is designed to travel ahead of the underwater vehicle. The remotely operated underwater vehicle (ROV) can be controlled manually, automatically or semi-automatically from the deploying underwater vehicle. In the case of automatic or semi-automatic control, this can be set so that the remotely operated underwater vehicle follows the changes in direction of the deploying underwater vehicle, so that the remotely operated underwater vehicle travels ahead of the deploying underwater vehicle. The unmanned underwater vehicle can be connected to the deploying underwater vehicle by means of a communication cable in order to transmit the measurement results of the sensor(s) of the measuring head. The control cable for the remotely operated underwater vehicle can be integrated in the communication cable.

The unmanned underwater vehicle is preferably connected to the underwater vehicle by means of a traction device. The communication cable and/or the control cable can be integrated into the traction device. The underwater vehicle has a retrieval device which is designed to retrieve the unmanned underwater vehicle to the deployment device by means of the traction means. The retrieval device can retrieve the traction device, for example roll it up, and thus bring the unmanned underwater vehicle back to the deployment device. If the deployment device is designed as a pipe, the retrieval device can preferably bring the unmanned underwater vehicle back into the pipe. For this purpose, the pipe can be supplemented with an energy-absorbing funnel so that the unmanned underwater vehicle can be pulled into the pipe without damaging the underwater vehicle or the unmanned underwater vehicle.

Analogously, a method for detecting a further underwater vehicle with an underwater vehicle is disclosed with the following steps: - extending a measuring head from a deployment device of the underwater vehicle in such a way that a sensor of the measuring head is located in front of the underwater vehicle, the sensor being designed to be a feature of the underwater vehicle under water to detect.

• 1: eine schematische Prinzipdarstellung einer Plattform zur Detektion eines Unterwasserfahrzeugs in einer Blockdarstellung;
• 2: eine schematische perspektivische Darstellung eines Biegesensors entsprechend des Konzepts 3e; und
• 3: eine schematische Seitenansicht eines Unterwasserfahrzeugs mit einer Ausbringvorrichtung zum Ausbringen eines Messkopfs, der beispielsweise mit einem oder einer beliebigen Kombination der Sensoren gemäß einem der beschriebenen Konzepte bestückt sein kann.

Preferred embodiments of the present invention are explained below with reference to the accompanying drawings.

• 1 : a schematic diagram of a platform for detecting an underwater vehicle in a block diagram;
• 2 : a schematic perspective view of a bending sensor according to concept 3e; and
• 3 : a schematic side view of an underwater vehicle with a deployment device for deploying a measuring head, which can be equipped, for example, with one or any combination of the sensors according to one of the concepts described.

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

1 shows a schematic block diagram of a platform 20, in particular a manned or unmanned underwater vehicle, for detecting an underwater vehicle 22. The platform comprises a sensor 24 according to one of the concepts described above and a signal processing unit 26 according to one of the concepts described above. Sensor data or measured values can be transmitted from the sensor to the signal processing unit 26 via an electrical connection 27 in the form of an electrical signal. Conversely, for example, a regulated preamplifier can already be integrated in the sensor, which can transmit an amplification factor or similar via the electrical connection.

2 shows a schematic perspective view of the sensor 24 in an embodiment as a bending sensor according to concept 3e. A carrier form 28 is based here on a (sensor) layer 30 comprising a material that converts a pressure into an electrical output voltage. The material is in particular a piezoelectric material, for example lead zirconate titanate (PZT). The electrical output voltage can be tapped at the electrodes 32a, 32b.

As in 2 shown, it is optionally possible to produce the bending sensor 24 as an integrated component. For this purpose, the layer 30 can be applied to a semiconductor substrate 34. An optional cavity 36 can then be introduced, in particular etched, into the semiconductor substrate 34. By means of the cavity, not only a vibration of the carrier form 28 can be detected, but also a 3-dimensional movement, i.e. also a movement up and down in the illustration in 2 .

Furthermore, an electrical circuit 34a can be directly formed in the semiconductor substrate 34. This can be, for example, the signal processing unit or include data preprocessing. One or more further layers can be applied to the substrate, in particular between the substrate 34 and the layer 30.

3 shows a schematic side view of an underwater vehicle 20 as a platform. The underwater vehicle 20 includes a deployment device 38. By means of the deployment device 38, a measuring head 40 can be extended from the underwater vehicle in such a way that it is located in front of the underwater vehicle. The measuring head has a sensor to detect environmental information of the underwater vehicle. In particular, the sensor is a sensor of the concepts described above.

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 a component of a device is also to be understood as a corresponding method step or as a feature of a method step. Analogously, aspects that have been described in connection with or as a method step also represent a description of a corresponding block or detail or feature of a corresponding device.

The embodiments described above are merely illustrative of the principles of the present invention. It will be understood that modifications and variations of the arrangements and details described herein will occur 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 from the description and explanation of the exemplary embodiments herein.

List of reference symbols:

20

platform

22

Underwater vehicle to be detected

24

sensor

26

Signal processing unit

27

electrical signal (sensor signal)

28

Carrier shape

30

sensory layer

32

Electrodes

34

Substrate

36

cavity

38

Dispensing device

40

measuring head

Claims (13)

Platform (20) for detecting underwater vehicles (22) with the following features: a sensor (24) which is designed to detect light and output a corresponding electrical signal (27); a signal processing unit (26) which is designed to output a recommendation based on the electrical signal (27) as to whether the electrical signal (27) contains components of bioluminescence in order to detect the underwater vehicle (22). platform according to Claim 1 , wherein the sensor (24) is designed to detect spectral components of the light; wherein the signal processing unit (26) is designed to use the spectral components to detect whether spectral components of bioluminescence are present in order to issue the recommendation as to whether the electrical signal (27) contains components of bioluminescence. Platform according to one of the preceding claims, wherein the sensor (24) is designed to sequentially take light images of the environment of the platform in order to detect the light. Platform according to one of the preceding claims, wherein the signal processing unit (26) is designed to process data which assigns an occurrence of pressure-luminescent living beings to the locations for different locations; wherein the signal processing unit (26) is designed for the current location of the platform To determine the occurrence of living beings that luminesce under pressure and to take this information into account when issuing the recommendation as to whether the electrical signal contains components of bioluminescence. Platform (20) according to one of the preceding claims, wherein the platform has a sensor (24) which is designed to chemically analyze seawater and to output a proportion of at least one predefined substance in a corresponding analysis result (27); wherein the signal processing unit (26) is designed, based on the analysis result, to determine a deviation from a previous analysis result or a deviation from an expected analysis result in order to detect the underwater vehicle. Platform (20) according to one of the preceding claims, wherein the platform for detecting nuclear-powered underwater vehicles (22) has a sensor (24) which is designed to detect radioactive radiation and to output a corresponding radiation signal (27); wherein the signal processing unit (26) is designed to receive the radiation signal (27) and to determine a deviation from a previous radiation signal or a deviation from an expected radiation signal in order to detect the underwater vehicle. Platform (20) according to one of the preceding claims, wherein the platform has a temperature sensor (24) which is designed to detect a temperature with an accuracy of less than 0.1°C, wherein the signal processing unit (26) is designed to continuously receive the temperature (27) of the temperature sensor (24) and to determine a rate of change of the temperature in order to detect the underwater vehicle (22). Platform (20) according to one of the preceding claims, wherein the platform has a sensor (24) which is designed to determine a refractive index of the water surrounding the platform (20) and to output a corresponding electrical signal (27), wherein the signal processing unit (26) is designed to detect a change in the refractive index of the water surrounding the platform based on the electrical signal (27) of successive measurements in order to detect the underwater vehicle (22). Platform (20) according to one of the preceding claims, wherein the platform for detecting turbulences caused by the wake of the underwater vehicle has a sensor which is designed to detect the turbulences. Platform (20) according to one of the preceding claims, wherein the platform comprises an underwater antenna (24) which has a plurality of water sound transducers, the water sound transducers of the plurality of water sound transducers being designed to convert water sound into an electrical signal (27) corresponding to the sound pressure, wherein the signal processing unit (26) is designed to receive the electrical signals from the water sound transducers and to detect infrasound emitted by the underwater vehicle (22) in the water sound. Platform (20) according to one of the preceding claims, wherein the platform has a magnetic anomaly detector (MAD) (24) which is designed to detect the earth's magnetic field and output a corresponding MAD sensor signal (27); wherein the signal processing unit (26) is designed to receive the MAD sensor signal and to detect a deviation in the earth's magnetic field by the underwater vehicle (22). Platform (20) according to one of the preceding claims, wherein the platform is a submersible vehicle; wherein the underwater vehicle has a measuring head (40) in which the sensor (24) is arranged or the sensors (24) are arranged; wherein the underwater vehicle has a deployment device (38); wherein the measuring head (40) is designed to be extended from the dispensing device in such a way that the sensor (24) is located in front of the underwater vehicle (20). Method for detecting underwater vehicles with the following steps: detecting light and outputting a corresponding electrical signal; Issue a recommendation as to whether the electrical signal contains components of bioluminescence in order to detect the underwater vehicle.

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