UNDERWATER COMMUNICATION AND HOMING SYSTEM

Description

[0001] The invention relates to a method for the targeted approach of an object to an underwater vehicle or for the remote control of an object, wherein the underwater vehicle should not reveal its position as far as possible.

[0002] Many methods for underwater communication and for securing underwater communication are known from the state of the art.

[0003] From postproceedings of the DWT conference, page 154ff, Underwater communication with special forces (https: / / www.researchgate.net / publication / 269873931_Schall_und_Schwingungen_Well en_und_Turbulenz_in_sensibler_Umgebung) modulation methods are known to operate underwater communication with maximum betrayal.

[0004] The use of sound for underwater communication is described in Acoustic Underwater Communication (https: / / www.net.in.tum.de / fileadmin / TUM / NET / NET-2011-07-1 / NET-2011-07-1_07.pdf).

[0005] Methods for intentional spectral spreading during data transmission are known from Spread Spectrum Modulation (http: / / www.dirubeze.de / funksysteme / skripte / DiFuSy / DiFuSy_SprSpec_WS0405.pdf).

[0006] These methods are suitable for securing communication. However, in order to enable a meeting between an object, for example and in particular a diver, and an underwater vehicle, for example and in particular a submarine, or to navigate to a defined target, or to maintain a defined distance, location information must be exchanged so that a meeting between the two units can take place while fully submerged. Visual navigation is practically unreliable underwater due to limited visibility and / or at night.

[0007] The simplest method, of course, is for the underwater vehicle to continuously transmit a signal for location. The object can easily navigate to the underwater vehicle. However, this also makes the underwater vehicle easily detectable by any third party. Therefore, this method is only possible in an operation at great risk.

[0008] On the other hand, it's possible for the object itself to locate the underwater vehicle using active sonar. However, this would reveal the object's position and require large amounts of energy from the object. Therefore, this method is also practically impractical.

[0009] An acoustic underwater communication is known from US 2016 / 0315717 A1.

[0010] A contactless underwater communication device is known from US 2012 / 0105246 A1.

[0011] DE 10 2013 000 671 A1 discloses communication between a person and a submarine via a data line.

[0012] From DE 20 2016 008 794 U1 a diving mask with a telecommunications device is known.

[0013] An emergency device for divers is known from US 2017 / 0 243 471 A1.

[0014] From FR 2 926 901 A1 a method and a device for recovering an unmanned underwater vehicle under water is known.

[0015] From DE 10 2012 008074 A1 a recovery method for recovering an underwater vehicle, a corresponding recovery device and a submarine with a corresponding recovery device are known.

[0016] The object of the invention is to provide a method in which the object and the underwater vehicle can meet in the submerged state without revealing the position to a third party, whereby the priority is given to the undetectable nature of the underwater vehicle.

[0017] This object is achieved by the method having the features specified in claim 1. Advantageous further developments emerge from the subclaims, the following description and the drawing.

[0018] The method according to the invention serves to meet at least a first object and an underwater vehicle at a meeting point underwater. The first object has at least one first communication device. The underwater vehicle has at least one first sound receiving device and at least one first sound transmitting device.

[0019] The procedure includes the following steps: a) agreeing on an underwater meeting point between the first object and the underwater vehicle, b) the first object moving to the underwater meeting point, c) sending a first signal through the first communication device of the first object, d) receiving the first signal through the first sound receiving device of the underwater vehicle, e) estimating the further movement of the first object with the current direction of travel, f) the first underwater vehicle selecting an action option selected from the list comprising: (1) remaining at the position if the current direction of travel of the first object leads to the underwater vehicle, (2) determining the direction of travel to be selected by the first object for the underwater vehicle to reach the meeting point and transmitting the direction information in a first second signal to the first communication device by means of the first sound transmitting device,if an active transmission is assessed as safe, (3) moving the underwater vehicle to a new meeting point determined from the estimated further movement of the first object, (4) deploying at least one surface communication device and waiting for surface contact to be made by the first object, (5) aborting the attempt to meet and removing the submarine if a meeting is assessed as unsafe, The process also includes the following steps: g) Selecting an action option by the first object selected from the list comprising: I Meeting with the submarine, or if a meeting with the submarine is not possible successfully, II Using wireless communication over water to contact the submarine and if this communication is not successful, or if the submarine is not successful III Abort, for example swimming or diving back to land.

[0020] The underwater rendezvous point in step a) can be agreed upon in advance by both parties, for example, before the divers are dropped off. The underwater rendezvous point can also be chosen by a third party and communicated to both the submarine and the first object.

[0021] A meeting point, within the meaning of the invention, can be an area, for example, an area where visual contact is possible. The lateral extent of the area within a plane can also be selected to vary depending on the diving depth. Firstly, the diving depth can be more easily recorded and verified, making an unintentional change less likely for a diver. Secondly, divers typically require more time to change diving depth (decompression).

[0022] A rendezvous point can also be used to establish and, preferably, subsequently maintain a relative position. This is preferred, for example, if the first target is not a diver, but an object, such as an AUV (autonomous underwater vehicle). The risk that this object has been tampered with, for example, by attaching an explosive device, is high. Therefore, reboarding such an AUV is often avoided, as this poses an immediate danger to the underwater vehicle and its crew.

[0023] An underwater meeting point comprises at least four coordinates, three in space and one in time. These can also encompass a space or an interval; for example, a time interval can be agreed upon instead of a point in time.

[0024] The deployment of at least one surface communication device and the waiting for a surface contact by the first object (4) is particularly relevant in the event of an emergency if the primary submarine contact was not successful.

[0025] The control in step b) can be performed either by the first object itself, for example, if the first object is a diver propulsion vehicle. The control can also be performed, for example, by a diver who, for example, transports the first object.

[0026] The selection of the course of action in step f) occurs after estimating the further movement of the first object with the current direction of travel, taking into account the situation report and the geographical surroundings. The situation report includes, in particular, other watercraft, especially hostile watercraft. The geographical surroundings include, in particular, the water depth. The position at the time the first signal is sent and the direction of travel can either be determined directly from the signal received on the underwater vehicle or result from the evaluation of the sensors on the underwater vehicle. For example, the first object emits an acoustic signal. This acoustic signal can be emitted, for example with the help of signal spreading, in such a way that it is difficult for the unwitting observer to detect, but known to the underwater vehicle.This sound signal can contain the direction of movement. The direction of movement and speed can also be estimated based on the duration of the first signal and the resulting change in position of the first object. Furthermore, the first object can send out several first signals so that the direction and speed can be determined from the different positions at different times. The underwater vehicle receives this signal via its sound sensors and can decode the transmitted information. Furthermore, the underwater vehicle can determine the position of the first object based on its sound sensors. The course of action is then selected, preferably in order of probability, to avoid detection by a third party while still aiming to carry out the encounter.

[0027] Option (1) represents the ideal case and is chosen whenever possible. The first object moves toward the agreed meeting point.

[0028] Options (2) or (3) are selected if option (1) is not possible, for example because the first object is drifting due to an underwater current and will therefore miss the actual rendezvous point, or because the path is blocked and the actual rendezvous point cannot be reached. The option selected here is the one that best suits the current situation for the underwater vehicle. Both options (2) and (3) have the disadvantage compared to option (1) that they involve additional noise, which can be detected by an enemy and used to locate the underwater vehicle. With option (2), the underwater vehicle transmits the first, second signal.While the signal strength can be adjusted to the distance to the first object to keep the signal as weak as possible and thus reduce the probability of detection, it must be taken into account that anti-submarine warfare (ASW) units, such as ASW frigates, but also other submarines, often have a very sensitive sonar system, meaning the first, second signal can be received even from a much greater distance, potentially allowing the underwater vehicle to be located. Likewise, the process in step (3) generates noise. This noise can also be minimized by using a very low speed, but there is always a risk of detection.Therefore, for example, an active transmission can be classified as safe if, for example, all registered surface contacts are so far away, even assuming maximum sonar sensitivity, that they can no longer resolve and thus detect the first second signal. Surface contacts that have been identified so precisely that their sonar capabilities are known to the underwater vehicle, for example, a task force support vessel, which is known to be designed without its own sonar system for locating submarines, can be classified as less critical, and thus the active transmission can be classified as safe even in the presence of such an identified contact. In addition, with option (3), it must also be possible to approach the new meeting point, for example, the water depth must be sufficient.

[0029] Option (4) is preferably chosen in cases where options (1), (2), and (3) are not available. This requires the underwater vehicle to be at least close to the water surface or to have surfaced. For example, the underwater vehicle can be at the deployment depth of the surface communication device. This makes it easier to detect both the deployment devices and its own contour, especially from the air. The risk of detection is therefore higher. This option should therefore only be chosen if there are no contacts within line of sight to the vessel's location or if visual detection is prevented, for example, due to weather conditions such as fog. It should also be taken into account that surface communication can also be intercepted by a third party and used to locate the underwater vehicle, which is now even close to the water surface.Therefore, option (4) is ruled out, especially if a maritime patrol aircraft, especially one with anti-submarine warfare capability, is nearby. Examples of maritime patrol aircraft include the P3 Orion or the Tu-142.

[0030] If options (1) to (4) have all been eliminated, only option (5) remains: abort. In this case, the underwater vehicle moves away and thus reaches safety. The first object must then decide for itself in step g) according to Option III how this abort will work after an unsuccessful attempt to hit the underwater vehicle.

[0031] This method minimizes the number and intensity of sound signals, thereby reducing the likelihood of detection by third parties. In particular, the underwater vehicle does not emit any sound unless the first object is within range. The first signal is emitted by the first object, not the underwater vehicle.

[0032] For the purposes of the invention, an object includes, for example, and in particular, divers. Other objects within the meaning of the invention also include, for example, diving aids, such as diver propulsion vehicles, or underwater vehicles, such as, for example, and in particular, autonomous underwater vehicles, unmanned underwater vehicles. The first object can be a device worn by a diver, for example, a device worn on the forearm.

[0033] The sound transmitting device can, for example, be a conventional underwater telephone.

[0034] The sound receiving device may, for example, be a sonar and / or underwater communication system of the underwater vehicle.

[0035] In particular, if the data received in step d) indicate that the meeting at the meeting point will take place as planned, option (1) is preferred.

[0036] If the data received in step d) shows that, for example, due to drifting due to currents, the first object is not heading for the meeting point as planned and the position allows for underwater communication, the underwater vehicle can transmit correction data to the first communication device of the first object using the first sound transmission device, according to action option (2).

[0037] Alternatively, the submarine can, according to option (3), move to a new, corrected rendezvous point without contact, if this is technically and safely possible. This eliminates the need for communication.

[0038] As a further alternative, the submarine can wait for contact to be made above water, according to option (4). The advantage is that this type of communication may, in individual cases, have a lower probability of detection. Furthermore, more information can be exchanged more quickly, which also reduces the probability of detection or at least the probability of detection.

[0039] As a last option (5), the submarine may need to withdraw. In this case, the first object, especially divers, must return to land.

[0040] This results in various possible scenarios for the first object according to a further development of the method according to the invention. Therefore, in step g), an action option is selected from the above-mentioned list.

[0041] The preferred option is of course to carry out the rendezvous, for example the (re-)picking up of divers by the underwater vehicle according to action option I. In this case, with options (1) and (3) of the underwater vehicle, the first object remains on its course to the agreed rendezvous point at option (1) or the point which the first object considers to be the agreed rendezvous point according to option (3). If the underwater vehicle sends information about a new rendezvous point in option (2), the first object heads for the new rendezvous point according to option I. If a rendezvous cannot be carried out successfully underwater, an attempt at surface communication is made according to action option II, regardless of whether the underwater vehicle has already selected option (4) or (5). If the underwater vehicle has selected option (4), the further course of action is coordinated according to option II.If surface communication can be successfully established, a new meeting point can be agreed upon, for example. Alternatively, it can be jointly determined via surface communication that a safe rendezvous is not possible and the rendezvous is aborted. If the first object determines according to Option II that surface communication is not possible, for example because the underwater vehicle has already selected Option (5), then the rendezvous is aborted according to Option III if a rendezvous was not successful or is foreseeable that it will not be possible to carry out a successful rendezvous. If the first object is a diver or is being transported by a diver, the diver can, for example, return to land. This return also includes situations where, for example, the diver has only operated in the water and not on land.This option may also include swimming to a neutral vessel or to an enemy vessel, although a short- or long-term return for the divers must be avoided to protect the underwater vehicle. If the first object is an unmanned underwater vehicle, the abort may involve scuttling the unmanned underwater vehicle. In the event of an abort, the underwater vehicle will withdraw and return, for example, to its base or a naval unit.

[0042] The order of the options for action of the first object I, II and III represents a clear ranking.

[0043] The instruction to approach the rendezvous point may include, for example, direction, depth, change in depth, movement distance and / or movement time at a constant speed, and waiting times when changing depth. Furthermore, the instruction may also include multiple steps for approaching the rendezvous point if this is required by currents, obstacles, the orientation of the underwater vehicle, or other influences, such as the detection radius of a third party.

[0044] If directional information of the first object is transmitted in step c) or if this directional information can be determined from the first signal received in step d) and if this directional information is already directed at the meeting point, for example the current position of the underwater vehicle, then communication is not necessary, the first object only has to maintain the position or course.

[0045] Likewise, in options (2) or (4), it may be necessary to determine the absolute geoposition of the first object from the first signal received in step d), provided that this, along with the absolute geoposition of the meeting point, is necessary to determine the direction of travel to be chosen. Absolute geoposition is understood to be an indication, for example, in latitude, longitude, and depth, that indicates the exact position.

[0046] In a further embodiment of the invention, step c) is repeated continuously, regularly, or irregularly. The first object can continuously transmit the first signal, but this is energy-intensive and reveals the position of the first object with the highest probability. A regular repetition of the transmission of the first signal by the first object simplifies the method, but the regularity increases the probability of detection. An irregular repetition can also occur, for example, through manual triggering and is thus quasi-random.

[0047] In a further embodiment of the invention, the direction of movement of the first object is additionally determined and only if there is a deviation between the direction of movement of the first object and a direction of movement necessary to reach the meeting point is this information transmitted according to action option (2) or (4).

[0048] The advantage of this embodiment is that the underwater vehicle can minimize the transmission of the first second signals or, if necessary, completely forgo communication, so that the probability of detection can be minimized.

[0049] Nevertheless, it may be advantageous to send regularly updated information in case of action options (2) or (4), since, for example, currents or other local changes in the environment may cause the first object to drift.

[0050] In a further embodiment of the invention, after successful communication in step a)II, a new meeting point is agreed upon and the first object and / or the underwater vehicle heads for the new meeting point.

[0051] In a further embodiment of the invention, between steps II and III, the first object contacts a third location via satellite communication and obtains further instructions. The third location can be, for example, an operations control center or the like. Subsequently, operational parameters can be adjusted if necessary.

[0052] In a further embodiment of the invention, the first object uses an antenna for above-water communication to use wireless communication in step a)II. For example, and in particular, the antenna for above-water communication is first extended for this purpose. This can, for example, be an antenna for above-water communication mounted on a buoy, which is then connected to the first object, for example, via a connecting line. This has two advantages. Firstly, the probability of detection is reduced due to the lower optical visibility. Secondly, however, and perhaps more importantly, it allows divers to remain at a single diving depth, thus eliminating the need to adhere to decompression stages and thus avoiding time losses.

[0053] In a further embodiment of the invention, wireless communication over water is optical communication. A non-directional light source can be used. Particularly after contact has been established, the optical transmission is directed. Examples of this include Morse code lights on ships with optical elements for the most parallel beam guidance possible, or communication via a laser.

[0054] In a further embodiment of the invention, no exact meeting point is agreed between the underwater vehicle and the first object, which would, for example, enable the first object to be recorded by the underwater vehicle. Rather, only an approximate meeting point or a target area or recording region is defined, which is selected such that communication should be possible in this target area, either by means of the first communication device or a surface communication device. The advantage of this embodiment is that even if the information about the target area is lost, the probability of detection for the underwater vehicle is low. If the first object is to be recorded by the underwater vehicle, a submarine, for example, can first guide the first object to the target area or the recording region in order to record the first object by the underwater vehicle.Thus, before step c), the first object moves into a receiving area without using the first communication device. For example, the underwater vehicle is located in a first waiting area near the planned approximate meeting point. The first object first identifies a first target area and, after reaching the first target area, begins the method according to the invention. The underwater vehicle can now either guide the first object directly to its current position or navigate to a meeting point itself and guide the first object to this meeting point. The underwater vehicle is particularly preferably at the meeting point without moving in order to avoid damage or injury to the first object caused by its own propulsion device.

[0055] In a further embodiment of the invention, the first second signal has multiple frequencies. Splitting it into multiple frequencies makes it easier to hide the first second signal in background noise, thus reducing the probability of detection. One method for splitting it into multiple frequencies is, for example and in particular, signal spreading.

[0056] In a further embodiment of the invention, a plurality of frequencies and / or frequency combinations are available to the first object and underwater vehicle for transmitting the first, second signal. This has the advantage that both the underwater vehicle and the first object must select the identical selection from the plurality of frequencies and / or frequency combinations. This enables friend-or-foe recognition to a certain extent, since a first object must have this knowledge. Thus, it is not enough to capture the first communication device in order to approach the underwater vehicle without authorization. If an operator, for example a diver, is at the first object, manual selection is preferred, as this achieves two-factor authorization.

[0057] In a further embodiment of the invention, the first second signal contains exclusively alphanumeric data, i.e. simple data that can therefore be easily transmitted even over data channels with low data transmission rates. Likewise, a small amount of data can be transmitted more easily, making it difficult for an eavesdropping third party to recognize a data stream as a data stream at all. All of these options become easier the smaller the amount of data transmitted. In particular, the first second signal only contains relative information about the course correction, for example a horizontal and / or vertical angle for the course correction. This makes it necessary for a third party analyzing the data to also know the position and direction of the first object in order to be able to extrapolate the position of the underwater vehicle.

[0058] In a further embodiment of the invention, the strength of the first signal in step c) is adjusted to the expected distance from the underwater vehicle. By adjusting to the expected distance, the signal strength can be reduced to a minimum. This minimizes energy consumption. It also reduces the probability of detection, since a third party must be in the immediate vicinity.

[0059] In a further embodiment of the invention, the frequency of the first signal in step c) is adjusted to the expected distance to the underwater vehicle. The range can be reduced, for example, by using a higher frequency. This optimizes energy consumption. It also reduces the probability of detection, since a third party must be in the immediate vicinity.

[0060] In a further embodiment of the invention, the strength and frequency of the first signal in step c) are adjusted to the expected distance to the underwater vehicle. This combination, in particular, minimizes the probability of detection, since a third party must be in the immediate vicinity.

[0061] In a further embodiment of the invention, the modulation type of the first signal in step c) is adapted to the expected distance to the underwater vehicle.

[0062] In a further embodiment of the invention, the strength or frequency of the first second signal is adjusted to the distance and / or direction to the first object. Preferably, and technically simplest, the strength of the first second signal is adjusted to the distance to the first object. This can also reduce the detection clarity. When locating the first object, the underwater vehicle can adjust the strength of the first second signal relatively easily and reliably.

[0063] In a further embodiment of the invention, the frequency of the first second signal is adjusted to the distance and / or direction to the first object. Preferably, and technically simplest, the frequency of the first second signal is adjusted to the distance to the first object, for example, a higher frequency is selected for a shorter distance. This can also reduce the detection clarity. The underwater vehicle can adjust the frequency of the first second signal relatively easily and reliably when locating the first object.

[0064] In a further embodiment of the invention, the strength and frequency of the first second signal are adapted to the distance and / or direction to the first object. This allows the detection clarity to be further reduced. The underwater vehicle can adjust the strength and frequency of the first second signal relatively easily and reliably when locating the first object.

[0065] In a further embodiment of the invention, the modulation type of the first second signal is adapted to the distance to the first object in step (2)

[0066] In a further embodiment of the invention, the first signal contains time information or can be linked to time information. The time information can be used to easily and reliably determine the distance from the underwater vehicle to the first object. For this purpose, the time information can be encoded directly into the first signal. Alternatively and / or additionally, the first object can transmit the first signals at agreed times so that the underwater vehicle can assign an agreed time to each received signal in the first signal and thus link time information to the first signal. The time information can also be, for example, a defined pause in the first signal or a time-defined transmission of a reference signal on a different frequency.

[0067] In a further embodiment of the invention, the first signal contains additional information. For example, the first signal can contain a diver's remaining running time as additional information, for example based on breathing air reserves. Furthermore, for example, the first signal can also contain information for friend-or-foe recognition. Furthermore, for example, the first signal can contain emergency information, for example of a medical or technical nature.

[0068] In a further embodiment of the invention, the first second signal contains further information. For example, the first second signal can contain environmental information. Further, for example, the first second signal can also contain information to avoid the meeting point if, for example, a safe capture of the first object by the underwater vehicle at the meeting point is not possible. Further, for example, the first second signal can also contain information about the mission or instructions carried out by the first object. For example, the first second signal can also contain information that approaching the meeting point is assessed as safe.

[0069] In a further embodiment of the invention, the information of the first second signal is displayed on a display device of the communication device. This embodiment is particularly preferred for use by divers.

[0070] Of course, the communication device can already be used when the underwater vehicle deploys the first object. For example, and especially when multiple divers are deployed from an underwater vehicle, mission information can be updated via a first, second signal during the deployment process or immediately thereafter.

[0071] In a further embodiment of the invention, the method additionally comprises the following steps: A) Sending a second first signal by a second communication device of a second object, B) Receiving the second first signal by the first sound receiving device of the underwater vehicle, C) Determining the direction of travel to be selected by the second object to reach the meeting point, D) Transmitting the directional information in a second second signal by means of the first sound transmitting device to the second communication device, E) The second object is guided to the meeting point using the directional information.

[0072] Thus, both the first object and the second object can be guided to the meeting point.

[0073] It is possible for the first second signal and the second second signal to be transmitted on the same frequency or with the same frequencies. Thus, both second signals would be receivable by both objects. In this case, the directional information must also contain information about which object it is intended for. The advantage is that all information is available to all objects at all times.

[0074] It's possible that the first second signal and the second second signal are transmitted on the same frequency, but with different encodings. Thus, only the object with the correct decryption code can receive the information. This eliminates misinterpretation.

[0075] Alternatively, the first second signal and the second second signal can be transmitted at different frequencies. This allows for orthogonal communication, thus eliminating any mutual interference.

[0076] All of the further embodiments described above are analogously possible for the second object. The further embodiments can be independent for the first object and the second object.

[0077] Furthermore, other objects, for example three, four, five or more, can be guided to the meeting point accordingly.

[0078] Additionally, an object can also guide other objects. For example, in a group of divers, one diver may be equipped with a communication device. Other divers swim with this diver and follow the diver with the communication device to the rendezvous point.

[0079] An exemplary diver communication device for carrying out the method according to the invention is described below. The diver communication device can be portable electronics, for example, a device worn on a diver's forearm. However, the diver communication device can also be part of a diver transport vehicle or a mini-submarine. It can also be part of an autonomous underwater vehicle. The diver communication device has at least a first module with a sound transmitting device and a sound receiving device. The diver communication device also has a second module. The second module is designed for wireless communication above water. The diver communication device is thus suitable for carrying out the method according to the invention.

[0080] In a further embodiment, the second module comprises an antenna, for example and preferably an extendable antenna. For example, the second module comprises a buoy with an antenna connected via a connection, for example a wire. For example, the wire can also be detached after communication, thus allowing the buoy with the antenna to be abandoned.

[0081] In a further embodiment of the invention, the second module is designed for both radio communication and satellite communication.

[0082] The method according to the invention is explained in more detail below using an embodiment shown in the drawing. Fig. 1 Flowchart

[0083] In Fig. 1 the method according to the invention is shown.

[0084] First, in step a), a meeting point is agreed upon, for example, before the underwater vehicle drops off a diver or a group of divers. One of the divers wears a diver communication device according to the invention. After the mission carried out by the divers is completed, they return to the agreed meeting point in step b). However, since the divers may be swept away unnoticed, for example by currents, an initial signal is transmitted in step c), received by the underwater vehicle in step d), and from this, the further movement of the divers is estimated in step e). Depending on the result, various options for action arise.

[0085] If the divers are still on course to the rendezvous point, the underwater vehicle remains in position according to action option (1) and the rendezvous is carried out according to action option I.

[0086] If a deviation is detected and underwater communication is deemed safe, the underwater vehicle can instruct the divers according to action option (2). The divers can then adjust their course, and a successful rendezvous can be achieved according to action option I.

[0087] Alternatively, if a deviation is detected, the underwater vehicle can adjust its position according to option (3). This way, communication can be omitted and a successful rendezvous can still occur according to option I.

[0088] If these options are not available, for example because a rendezvous is not possible due to a deviation, the underwater vehicle can go to periscope depth according to action option (4), extend a communication device and wait. If underwater communication was unsuccessful, they will attempt to establish contact via wireless surface communication according to action option II. This can be done in particular by radio or optically. This is preferably done by a diver ascending a buoy with a radio antenna on a wire. This means that the divers do not have to change their diving depth, which means that decompression steps on surfacing can be dispensed with, especially if the divers are operating at great depths, for example. After successful communication, a rendezvous can then take place at a new rendezvous point according to action option I.Alternatively, it may be determined that a rendezvous is not possible due to the enemy situation, and the divers must reach safety independently of the submarine, according to Option III. This last option only remains if the attempt at surface communication fails, for example, because the transmission power of the first object is too low and / or high waves make communication impossible. Likewise, according to Option II, contact can be established, for example, via satellite communication, with an operations control center, from which the next course of action can then be determined.

[0089] If the underwater vehicle concludes that an encounter is impossible based on the enemy situation combined with an assessment of the divers' movements, it can also abort the attempt and withdraw immediately according to action option (5). The divers will then still attempt to establish contact according to action option II. However, this is doomed to failure due to the absence of the submarine, so ultimately only action option III, and thus their own safety, remains.

Claims

1. A method for at least a first object and an underwater vehicle to meet at a meeting point underwater, the first object having at least a first communication device, the underwater vehicle having at least a first sound receiving device and at least a first sound transmitting device, the method comprising the steps of: a) agreeing on an underwater meeting point between the first object and the underwater vehicle, b) the first object heading for the underwater meeting point, c) transmission of a first signal by the first communication device of the first object, d) reception of the first signal by the first sound receiving device of the underwater vehicle, e) estimating the further movement of the first object with the current direction of movement, characterized by: f) selecting an action option by the first underwater vehicle selected from the list comprising: (1) the underwater vehicle remaining at the position, provided that the current direction of movement of the first object leads to the underwater vehicle, (2) determining the direction of movement to be chosen by the first object in order to reach the meeting point by the underwater vehicle and transmitting the directional information in a first second signal by means of the first sound transmission device to the first communication device, provided that an active transmission is deemed to be safe, (3) moving the underwater vehicle to a new meeting point based on the estimated further movement of the first object, (4) deploying at least one surface communication device and waiting for the first object to make contact above water, (5) aborting the attempt to meet and removing the underwater vehicle if a meeting is deemed unsafe, g) selecting an action option by the first object, selected from the list comprising: I. meeting with the underwater vehicle, or if a meeting with the underwater vehicle is not possible, II. using wireless communication above water to contact the underwater vehicle and if this communication is not successful, or if this is not successful, III. aborting.

2. A method according to claim 1, characterized in that after successful communication in step II, a new meeting point is agreed and the first object and / or the underwater vehicle head for the new meeting point.

3. A method according to any of the preceding claims, characterized in that in addition, in step e), the direction of movement of the first object is determined.

4. A method according to any of the preceding claims, characterized in that between step II and III the first object contacts a third party via satellite communication and obtains further instructions.

5. A method according to any of the preceding claims, characterized in that, for using wireless communication in step II, the first object uses an antenna for surface communication.

6. A method according to any of the preceding claims, characterized in that the first object moves into an area of reception prior to step c) without using the first communication device.

7. A method according to one of the preceding claims, characterized in that the first second signal contains exclusively alphanumeric data.

8. A method according to any of the preceding claims, characterized in that the strength of the first signal in step c) is adjusted to the expected distance to the underwater vehicle.

9. A method according to any of the preceding claims, characterized in that the frequency of the first signal in step c) is adapted to the expected distance to the underwater vehicle.

10. A method according to any of the preceding claims, characterized in that the type of modulation of the first signal in step c) is adapted to the expected distance to the underwater vehicle.

11. A method according to any of the preceding claims, characterized in that the strength of the first second signal in step (2) is adapted to the distance to the first object.

12. A method according to any of the preceding claims, characterized in that the frequency of the first second signal in step (2) is adapted to the distance to the first object.

13. A method according to any of the preceding claims, characterized in that the type of modulation of the first second signal in step (2) is adapted to the distance to the first object.

14. A method according to one of the preceding claims, characterized in that the first signal contains a time information or can be linked to a time information.