Apparatus, system, method and computer program product for detecting at least partially submerged objects

Abstract

An apparatus, a system, a method and a computer program product for detecting at least partially submerged objects are disclosed. The method comprises: obtaining muon rate data measured by one or more muon detectors configured to be positioned below a surface of a body of water; processing the muon rate data to detect a change in the muon rate; and outputting a result of the processing. The method further comprises determining a presence of an object in the body of water based on the change in the muon rate, wherein the object is an at least partially submerged object comprising a structure with higher or lower density than the surrounding water.

Description

[0001] APPARATUS, SYSTEM, METHOD AND COMPUTER PROGRAM PRODUCT FOR DETECTING AT LEAST PARTIALLY SUBMERGED OBJECTS

[0002] Technical Field

[0003] The present solution generally relates to an apparatus, a system, a method, and a computer program product for detecting at least partially submerged objects.

[0004] Background

[0005] Maritime situational awareness has interested law enforcement authorities for decades. Surface surveillance and underwater surveillance are used to find ships and other vessels, submarines, remotely operated underwater vehicles (ROUVs or ROVs), and unmanned underwater Vehicles (UUVs) as well as divers. Both active and passive methods are used in maritime surveillance. Examples of passive methods include passive sonar, magnetic anomaly detection, satellite surveillance and thermal detection. Examples of active methods include active sonar, radar such as synthetic aperture radar, and laser-based surveillance methods. Due to their limitations, many of these technologies can be circumvented and their detection performance may be sub-optimal.

[0006] Summary of the Invention

[0007] The scope of protection sought for various embodiments of the invention is set out by the independent claims. Various embodiments are disclosed in the dependent claims. The embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention.

[0008] According to a first aspect, an apparatus for detecting at least partially submerged objects is configured to obtain muon rate data measured by one or more muon detectors configured to be positioned below a surface of a body of water; process the muon rate data to detect a change in the muon rate, and output a result of the processing, wherein the apparatus is further configured to determine a presence of an object in the body of water based on the change in the muon rate, wherein the object is an at least partially submerged object comprising a structure with higher or lower density than the surrounding water.

[0009] The at least partially submerged object may be an at least partially submerged heterogeneous object.

[0010] The result of the processing may comprise a detection result, wherein the detection result is positive if a change indicating the presence of an object was detected in the muon rate, and otherwise the detection result is negative.

[0011] The apparatus may be further configured to trigger performing an action, such as outputting an alarm, in response to detecting a change in the muon rate indicating the presence of an object.

[0012] The apparatus may be further configured to transmit the result of the processing to a user device.

[0013] The apparatus may be further configured to receive a result transmission command from the user device; and transmit the result of the processing to the user device in response to receiving the result transmission command.

[0014] The apparatus may be further configured to transmit the result of the processing in response to detecting a change in the muon rate indicating the presence of an object.

[0015] The apparatus may be further configured to only transmit the result of the processing in response to receiving a result transmission command from the user device or detecting a change in the muon rate indicating the presence of an object in the body of water.

[0016] The apparatus may be further configured to maintain transmission silence until the apparatus receives a result transmission command from the user device or detects a change in the muon rate indicating the presence of an object in the body of water.

[0017] The muon rate data may comprise muon angle data, and the apparatus may be further configured to process the muon angle data to detect the change in the muon rate.

[0018] The one or more muon detectors may be configured to transmit the muon rate data to the apparatus.

[0019] The apparatus may be further configured to transmit a muon rate data transmission command to the one or more muon detectors, wherein the muon rate data transmission command triggers transmission of the muon rate data from the one or more muon detectors to the apparatus.

[0020] The one or more muon detectors may be configured to only transmit the result of the processing in response to receiving the muon rate data transmission command from the apparatus.

[0021] The one or more muon detectors may be configured to maintain transmission silence until receiving the muon rate data transmission command from the apparatus.

[0022] According to a second aspect, a system for detecting at least partially submerged objects, comprises the apparatus according and the one or more muon detectors configured to be positioned below a surface of a body of water.

[0023] The system may further comprise the user device.

[0024] According to a third aspect, a computer-implemented method for detecting at least partially submerged objects comprises obtaining muon rate data measured by one or more muon detectors configured to be positioned below a surface of a body of water; processing the muon rate data to detect a change in the muon rate, and outputting a result of the processing, wherein the method further comprises determining a presence of an object (102) in the body of water (104) based on the change in the muon rate, wherein the object (102) is an at least partially submerged object (102) comprising a structure with higher or lower density than the surrounding water.

[0025] According to a fourth aspect, a computer program product comprises computer program code configured to, when executed by at least one processor, cause an apparatus or a system to perform a method comprising obtaining muon rate data measured by one or more muon detectors configured to be positioned below a surface of a body of water; processing the muon rate data to detect a change in the muon rate, wherein the change indicates the presence of an object in the body of water; and outputting a result of the processing.

[0026] Brief Description of the Drawings

[0027] FIG. 1 illustrates detecting a submerged object in a body of water according to the invention; FIG. 2 is a flow chart illustrating embodiments of a method;

[0028] FIG. 3 is a block diagram illustrating embodiments of an apparatus and a system.

[0029] Detailed Description of the Invention

[0030] The following description and drawings are illustrative and are not to be construed as unnecessarily limiting. The specific details are provided for a thorough understanding of the disclosure. However, in certain instances, well-known or conventional details are not described in order to avoid obscuring the description. In this specification, reference to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. References to an embodiment can be, but are not necessarily, references to the same embodiment in the present disclosure.

[0031] The present disclosure relates to an apparatus, a system, a method, and a computer program product for detecting at least partially submerged, including floating and completely submerged, objects in a body of water. The objects may include underwater objects such as submarines, remotely operated underwater vehicles (ROVs), and the like. For improved detection performance, the objects may be at least 4 or 5 meters long along one dimension and / or be at a depth of 100 to 500 meters. The invention may be employed for many purposes, including border security and various naval applications. For example, the invention may be used as a (early) warning system or for monitoring activities near underwater pipelines used to store or transport substances (e.g., gas pipelines) and / or underwater optical or electrical cables. The muon detectors may be arranged along the cable or pipeline, e.g., in a ladder configuration.

[0032] The invention has applications in all bodies of water in which underwater surveillance is deployable. Herein the body of water does not need to imply any particular chemical composition, salinity, temperature, dimensions, or depth; hence, the body of water may contain, e.g., salt water, brackish water, or freshwater. The term body of water, therefore, incorporates, for example, oceans, open seas, coastal seas, sea bays, fjords, inland seas, lakes, rivers, and shallow epicontinental seas.

[0033] The invention is based on detecting cosmic- ray- induced muons, which are generated in the upper part of the Earth’s atmosphere. Such high-energy atmospheric muons are heavy, charged, electron-like particles with excellent penetration abilities through various materials. However, muons are known to attenuate depending on the density of the material the muons pass through. Therefore, cosmic-ray-induced muons may be employed to detect (at least partially) underwater objects having structures with higher or lower densities than the surrounding water. Such a structure may be, e.g., an engine, a battery, an empty space filled with, e.g., air, a wall structure, a metal structure, or the like. The object may comprise a structure that has a lower density than water, a structure that has a higher density than water, or a combination of both, i.e., the object comprises a first structure with a lower density than water and a second structure with a higher density than water. These structures attenuate muons at different rates than the surrounding water, which may be detected in one or a plurality of muon detectors placed below the object and / or to the object's side.

[0034] The objects may be heterogeneous, such as partially submerged or underwater vessels, including submarines, which may comprise elements such as empty air compartments, engine and propulsion systems, ballast tanks, structural components, and instrumentation and control systems, which may have different density properties.

[0035] The one or more muon detectors are to be placed below the surface of the water, e.g., within an underwater structure, an undersea tunnel, or the like. The muon detectors may comprise plastic scintillation detectors, gas-based muon detectors, drift chambers, micromesh gaseous structures, resistive plate chambers, multiwire proportional chambers, chemical nuclear emulsions, or muon detectors of any other suitable type. Detectors that are designed to withstand water, e.g., borehole muon detectors, are preferred to reduce the need for protective structures around the detectors. The detectors may be placed anywhere from right below the water surface to the bottom of the body of water or even below the bottom of the water (e.g., underneath the interface between the water and the seabed). An advantage of muon detectors placed deep in the body of water is that they are able to monitor a larger area or volume above the detector compared to detectors positioned at shallower depths, especially when also configured to measure muon angles. The detectors may be stationary or movable, by attachment to a vessel, to a buoy, to a structure via a cable, or the like. Furthermore, if the number of muon detectors is greater than one, the muon detector array geometry may be, but need not be, fixed, and their pattern or mutual distances may be, but need not be, respectively symmetric or equal. The invention may be implemented with active, or preferably passive muon detection. In an active implementation, a muon generator is included and configured to emit muons to the one or more muon detectors. In contrast, the passive implementation relies on naturally occurring muons.

[0036] When an object or a plurality of objects pass(es) over the muon detector or a plurality of muon detectors, the muon rate detected by the detector(s) is altered, and the object(s) may be detected. The muon rate or muon counting rate expresses the number of muons passing through a given area (e.g., the cross-section of the muon detector volume) within a given time period. Muon rate therefore represents the number of muons detected by a particular detector per unit time. It is usually expressed in units of counts per second (cps) or events per second (eps). The muon counting rate through a one-square meter area may be called muon flux, usually expressed in units of muons per square meter per second (m-2s-1). The invention may be implemented using muon rate or muon flux data, with appropriate measures in the data processing to account for the choice of the unit.

[0037] FIG. 1 illustrates a scenario where a submerged object 102 is detected in a body of water 104 according to the invention. Muon detector apparatuses 120-122 comprising muon detectors are positioned below the water surface 124. The muon detector apparatuses 120 may be anchored, float freely, and / or move using an actuator such as an engine or the like. One or more of the muon detector apparatuses may be positioned at the bottom 112 of the body of water (muon detector apparatus 121) and / or below the bottom of the body of water (muon detector apparatus 122).

[0038] Muons produced by cosmic rays travel along trajectories 106-111 from above towards the bottom 112 of the body of water. The muons are attenuated in different amounts by different densities. Some of the muons, such as muons with trajectories 107 and 110, may decay before reaching any of the muon detector apparatuses 120-122. The muons that arrive at the muon detector apparatuses 120-122 are detected by the muon detectors of the muon detector apparatuses. The detections are measured as muon rate data representing detections over time.

[0039] The muon rate data may be transferred to an external unit 130 and / or to a user apparatus 140 for processing. The external unit 130 and one or more of the muon detector apparatuses 120-122 may also be directly coupled to each other or comprised in the same device. Connections between the muon detector apparatuses, one or more external units and one or more user apparatuses may be implemented with wired or wireless connections, such as cellular, satellite, acoustic, light-emitting diode (LED), laser-based, or fiber optic connections.

[0040] One or more of the muon detector apparatuses 120-122, the external unit 130, and the user apparatus 140, are configured to process the muon rate data measured by the muon detectors. The one or more muon detectors and the apparatus(es) configured to process the muon rate data together make up a system for detecting at least partially submerged objects in the body of water. The apparatus (or the system) performs a method for detecting at least partially submerged objects in the body of water, which is described in more detail below with reference to FIG. 2.

[0041] FIG. 2 is a flow chart depicting embodiments of a (computer-implemented) method for detecting at least partially submerged objects. The method of FIG. 2 comprises obtaining 200 muon rate data measured by one or more muon detectors configured to be positioned below a surface of a body of water; processing 202 the muon rate data to detect a change in the muon rate, wherein the change indicates the presence of an object in the body of water; and outputting 204 a result of the processing.

[0042] The present disclosure provides a solution to stealthily probe underwater objects for improving maritime situational awareness and surveillance. It is very resistant to disruptions and interference as cosmic-ray-induced muons are extremely penetrative particles traveling at almost the speed of light, and it is difficult to interfere with their trajectories. The present solution is able to withstand disturbances in the form of electric or magnetic fields, electromagnetic radiation, pressure, sound, radar signals, or the like.

[0043] FIG. 3 is a block diagram illustrating embodiments of an apparatus 100 and a system 150 for detecting at least partially submerged objects. The apparatus, which may be, e.g., one of the muon detector apparatuses 120-122, the external unit 130, or the user apparatus 140 of FIG. 1 , is configured to perform the method of FIG. 2 or any of its embodiments. In other words, the apparatus comprises means for performing the method of FIG. 2 or any of its embodiments. Referring again to FIG. 3, the means may comprise at least one processor 10, at least one memory 20 including computer program code 22, wherein the at least one memory 20 and the computer program code 22 are configured to, with the at least one processor 10, cause the apparatus 100 to perform the method of FIG. 2 or any of its embodiments. The apparatus 100 of FIG. 3 may further comprise a communication interface 40, comprising, e.g., a transmitter (TX), a receiver (RX), and / or a transceiver. The communication interface may be used for communication between the apparatus 100 and one or more (external) muon detectors 50 and / or a user device 60. The one or more muon detectors 50 and / or the user device 60 may be configured to communicate with the apparatus 100 using respective communication interfaces 51 , 61 that may be similar to the communication interface 40 of the apparatus 100 described above. As discussed in relation to FIG. 1 , the communication connections between the apparatus 100, the muon detectors 50, and the user device 60 of FIG. 3 may be implemented with wired or wireless connections, such as cellular, satellite, acoustic, LED, laser-based, or fiber optic connections.

[0044] In general, communication between the muon detector apparatuses 120-122, the external unit 130, and / or the user apparatus 140 of FIG. 1 , and between the muon detectors 50, the apparatus 100, and the user device 60 of FIG. 3 may be performed in several ways. For example, one or more of the above-mentioned devices may be configured to periodically transmit status information comprising, e.g., the muon rate data and / or the results of the processing. The transmission interval may be 1 day or 1 week, for example. Alternatively, or additionally, the transmission may be performed at random and / or upon request, as will be described in more detail herein.

[0045] Alternatively, or additionally to communicating with the external muon detectors 50 and the user device 60, the apparatus may comprise or be directly coupled to one or more muon detectors 52 and / or a user interface 62. The user interface 62 may comprise one or more output devices, such as one or more displays, one or more speakers, and / or one or more haptic output devices. Additionally, the user interface may comprise one or more input devices, such as one or more microphones, keyboards, touch panels, buttons, or switches. The user device 60 may comprise a similar user interface as the user interface 62 described above.

[0046] While the external muon detectors 50 have been described above together with the user device 60, and the muon detectors 52 together with the user interface 62, other combinations of the features shown in FIG. 3 are also possible, such as: the apparatus 100 with muon detectors 52, wherein the apparatus 100 is configured to communicate with user device 60; and the apparatus 100 with user interface 62, wherein the apparatus 100 is configured to communicate with muon detectors 50.

[0047] According to another aspect, a computer program product comprises computer program code 22 configured to, when executed by at least one processor 10, cause an apparatus 100 or a system 150 to perform the method of FIG. 2 or any one of its embodiments. The computer program product may refer to a software as shown in FIG. 3 that may include at least one selected from a computer program, computer code, computer script, computer macro, computer library, algorithm or user interface.

[0048] In an embodiment, the computer program product is embodied on a computer-readable medium 30. In an embodiment, the computer-readable medium 30 is a non-transitory computer-readable medium.

[0049] The system 150 of FIG. 2 comprises at least the apparatus 100 and the one or more muon detectors 50. In addition, the system may comprise other components such as the user device 60. The system may comprise, e.g., one or more power supplies, such as one or more batteries, solar panels, windmills, and / or mains power supplies, which are integrated into the apparatus, the muon detectors, and / or the user device, and / or as separate components of the system. The system may further comprise communication means such as cables connecting the components of the system.

[0050] Details of the method performed by the apparatus 100 (or system 150) are now described with reference to FIG. 2 and FIG. 3. Obtaining 200 (see FIG. 2) the muon rate data may comprise reading the muon rate data from a memory of the apparatus, such as from a database 24 (see FIG. 3) stored in the at least one memory 20. Alternatively, or additionally, the muon rate data may be obtained from the one or more muon detectors 50 via the communication interface 40 or directly from the one or more muon detectors 52 coupled to or comprised in the apparatus. The muon rate data may be transmitted via one or more intermediate devices; for example, the external unit 130 of FIG. 1 may receive the muon rate data from the muon detector of muon detector apparatus 120 and transmit it to the user apparatus 140 as shown in FIG. 1. In this case, the external unit may act as a modem, such as a cable modem, digital subscriber line (DSL) modem, satellite modem, mobile broadband modem, or the like, between the user apparatus 140 and the muon detector of muon detector apparatus 120. Yet alternatively or additionally, the obtaining may comprise measuring the muon rate data by the one or more muon detectors. In this case, the apparatus 100 (see FIG. 3) may comprise the one or more muon detectors 52.

[0051] The one or more muon detectors may be further configured to measure muon arrival angles. In this case, the muon rate data may further comprise muon angle data. By measuring the angle of arrival of muons, it is possible to remove noise or other artifacts that the raw muon rate data may contain as one can distinguish muons produced by cosmic rays from other types of radiation and reduce the impact of background radiation on the measurement. Alternatively, or additionally the arrival angles of muons may provide information on the location of the object and / or its direction of movement.

[0052] The muon rate data is processed 202 (see FIG. 2) by the apparatus 100 of FIG. 3 to detect a change in the muon rate. The change indicates the presence of an object in the body of water due to a change in density with respect to the surrounding water. Alternatively, or additionally, the change may occur over time when the object is introduced to or leaves the area above the muon detector(s). The change may therefore be a spatial and / or a temporal change.

[0053] The muon rate data may be processed using various statistical and computational techniques to extract relevant information about the measured muon rate and to understand the possible reasons for the changed or changing muon rate. Processing the muon rate data may comprise one or more of the following:

[0054] Data preprocessing is a technique used to remove noise or other artifacts that the raw muon rate data may contain. This may involve filtering the data or applying corrections to account for variations in detector efficiency. Detector efficiency corrections may be performed at the end of the processing, or as a part of the data analysis described below.

[0055] Data analysis is a technique used for analyzing the measured muon rate. The muon rate data is analyzed using statistical methods to extract relevant information, such as the mean muon rate, the muon energy spectrum, or the directional muon distribution. Some common methods used in muon rate analysis include maximum likelihood estimation, Bayesian inference, and Monte Carlo simulation.

[0056] Model fitting is a technique used for fitting the muon rate data to describe the underlying processes that generate the measured muon rate. This may involve modeling the muon production and propagation in the atmosphere and through the investigated media, as well as the interaction of muons with the detector or a plurality of detectors.

[0057] Error estimation uses statistical and / or systematic error estimation methods to estimate the uncertainties associated with the muon rate measurements and the model parameters. This allows for quantifying the accuracy and precision of the muon rate results.

[0058] Interpretation is a procedure for interpreting the muon rate results in the context of the questions being addressed (i.e., detecting the object in the body of water), such as the cause of the change in the measured muon rate data.

[0059] Other data processing methods suitable for detecting changes in the muon rate may be used alternatively or in addition to the above techniques.

[0060] In an embodiment, the muon rate data comprises muon angle data. In this case, the one or more muon detectors are configured to measure the muon angle data, i.e., the angles of arrival of the muons detected by the detector(s). The muon angle data may be processed as described above to reduce background noise, to determine a position and / or location of the object, and / or to determine the movement direction of the object, for example.

[0061] The apparatus may further use the location information of the one or more muon detectors to detect the change in the muon rate. The location information may be stored in the memory 22 of the apparatus 100, e.g., in the database 24. Alternatively, or additionally, the location information may be obtained along with the muon rate data. For example, the one or more muon detectors may comprise positioning (e.g., Global Positioning System, GPS) means, and provide their location information to the apparatus along with the muon rate data. This may be useful if the muon detectors are movable, freely floating, and / or moved by storms or underwater currents. The location information of the one or more muon detectors may be used to determine the position and / or location of the detected object.

[0062] The result of the processing is output 204 (see FIG. 2) by the apparatus 100 of FIG. 3. The result of the processing may comprise a detection result, wherein the detection result is positive if a change indicating the presence of an object was detected in the muon rate, and otherwise the detection result is negative. The result may be output via an interface, such as a software interface, an application programming interface (API), the user interface 62, and / or the communication interface 40. For example, the apparatus 100 may transmit the result of the processing to the user device 60, e.g., via the communication interface 40. Upon receiving the result of the processing, the user interface 62 of the apparatus 100 and / or the user interface of the user device 60 may output the result of the processing to a user via one or more of their output devices.

[0063] When the apparatus comprises the user interface, the apparatus may be the user apparatus 140 of FIG. 1. When the apparatus transmits the result of the processing to the user device, the apparatus may be, e.g., one of the muon detector apparatuses 120-122 or the external unit 130, and the user device may be the user apparatus 140 of FIG. 1.

[0064] The result of the processing may be used to perform, or to trigger further actions to be performed by the apparatus or another apparatus. For example, the apparatus may be configured to trigger performing an action, such as outputting an alarm, in response to detecting a change in the muon rate indicating the presence of an object, i.e. , in response to a positive detection result. The action may be performed by the apparatus itself, and / or the apparatus may, e.g., send a command to a second apparatus that causes the second apparatus to perform the action. The second apparatus may be part of the system 150 of FIG. 3; for example, it may be the user device 60. Examples of the action to be performed include outputting the alarm via the user interface 62 of the apparatus and / or via the user interface of the user device 60, activating a further monitoring system to obtain more information about the object, dispatching a (underwater) vehicle to obtain more information of the object, and activating a defense system for protection against neutral, hostile, and / or unwanted (unmanned) objects, such as naval mines, or other objects that may present a danger to civilians. For example, the apparatus may be communicatively coupled (optionally via another device) to an explosive, and configured to trigger detonation of the explosive in response to detecting an unwanted object. This results in a controlled explosion to eliminate the unwanted object. When testing the operation of the invention, the object may evidently be a friendly or neutral “dummy” object that has been deployed, for example, by the user of the apparatus or system.

[0065] In an embodiment, the apparatus 100 is configured to receive a result transmission command from the user device 60 and transmit the result of the processing to the user device in response to receiving the result transmission command. Correspondingly, the user device 60 is configured to send the result transmission command to the apparatus 100 and to receive the result of the processing from the apparatus 100. The result transmission command may be sent, e.g., in response to a user input via one of the input devices of the user interface of the user device. In this embodiment, the apparatus may be the external device 130 or one of the muon detector apparatuses 120-122, and the user device may be the user apparatus 140 of FIG. 1. In contrast to the continuous or periodic transmission of results from the apparatus 100 to the user device 60 of FIG. 3, the embodiment allows for reducing data transmission by doing so when requested by the user device. This in turn leads to power savings and makes the apparatus more difficult to detect based on its transmission behaviour.

[0066] Alternatively, or additionally, the apparatus 100 may be configured to transmit the result of the processing in response to detecting a change in the muon rate indicating the presence of an object, i.e., in response to a positive detection result. Benefits similar to those described above, i.e., reduced power usage and reduced detectability, may be achieved. The need for the user or the user device 60 to query the results is also removed.

[0067] The apparatus 100 may be configured to only transmit the result of the processing in response to receiving a result transmission command from the user device 60 or detecting a change in the muon rate indicating the presence of an object in the body of water. This may improve the resistance of the data transmission to detection or probing attempts by reducing its predictability in comparison to continuous or periodic transmission of the results.

[0068] Further improvements related to the detectability and power use of the apparatus may be achieved when the apparatus 100 is further configured to maintain transmission silence until the apparatus receives a result transmission command from the user device 60 or detects a change in the muon rate indicating the presence of an object in the body of water. In the first case, the apparatus will remain silent and begin transmitting the result of the processing after it receives the result transmission command from the user device. In the second case, the apparatus will remain silent and begin transmitting the result of the processing after it detects a positive detection result. In both cases, the apparatus will maintain transmission silence again after it has transmitted the result(s) of the processing.

[0069] In an embodiment, the one or more muon detectors 50 are configured to transmit the muon rate data to the apparatus 100. Correspondingly, the apparatus 100 is configured to receive the muon rate data from the one or more muon detectors 50. In this embodiment, the apparatus may be the external device 130 or the user device 140 of FIG. 1. At least one of the one or more muon detectors is configured to transmit the muon rate data; all of the one or more muon rate detectors may be but need not be configured to transmit the muon rate data to the apparatus 100.

[0070] The one or more muon detectors may measure the muons using a trigger condition, which may comprise an energy threshold and / or a time window (e.g., 1 ps), for example. For example, when a particle (muon) that arrives at the detector provides a higher amount of energy than the threshold, a signal is registered. The signal may be stored in a non- transitory or transitory memory, and / or sent for processing. If the condition is not met, the detector may wait for more muons to arrive at the detector to achieve the required energy within the time window, and / or discard the detection.

[0071] The muon rate data may be transmitted continuously or periodically by the one or more muon detectors. Alternatively, or additionally, the apparatus 100 of FIG. 3 may be configured to transmit a muon rate data transmission command to the one or more muon detectors 50. The muon rate data transmission command triggers transmission of the muon rate data from the one or more muon detectors 50 to the apparatus 100; the one or more muon detectors 50 are configured to receive the muon rate data transmission command, and transmit the muon rate data in response to receiving the muon rate data transmission command.

[0072] The one or more muon detectors 50 may be configured to only transmit the muon rate data in response to receiving the muon rate data transmission command from apparatus 100. This may improve the resistance of the data transmission to detection or probing attempts by reducing its predictability in comparison to continuous or periodic transmission of the data.

[0073] Technical effects of reduced power usage and reduced detectability are also achieved when the one or more muon detectors 50 are configured to maintain transmission silence until receiving the muon rate data transmission command from the apparatus 100. As in the case of the apparatus 100 communicating with the user device 60, the one or more muon detectors 50 may be configured to maintain transmission silence again after transmitting the muon rate data.

[0074] The skilled person will appreciate that as with all detection systems, there is a possibility for error, including false positives and negatives. References to the change indicating the presence of an object in the body of water herein may therefore reflect a possible or probable presence of the object in the body of water. For example, a confidence threshold may be used to determine when a detected change is considered to indicate the presence of the object in the body of water.

[0075] If desired, the different functions discussed herein may be performed in a different order and / or concurrently with others. Furthermore, if desired, one or more of the above-described functions and embodiments may be optional or may be combined.

[0076] Although various aspects of the embodiments are set out in the independent claims, other aspects comprise other combinations of features from the described embodiments and / or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

[0077] It is also noted herein that while the above describes various embodiments, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications, which may be made without departing from the scope of the present disclosure as defined in the appended claims.

Claims

Claims1. An apparatus for detecting at least partially submerged objects, wherein the apparatus is configured to: obtain muon rate data measured by one or more muon detectors configured to be positioned below a surface of a body of water; process the muon rate data to detect a change in the muon rate; and output a result of the processing, characterized in that the apparatus is further configured to: determine a presence of an object in the body of water based on the change in the muon rate, wherein the object is an at least partially submerged object comprising a structure with higher or lower density than the surrounding water.

2. The apparatus of claim 1 , wherein the result of the processing comprises a detection result, wherein the detection result is positive if a change indicating the presence of an object was detected in the muon rate, and otherwise the detection result is negative.

3. The apparatus of any preceding claim, wherein the apparatus is further configured to: trigger performing an action, such as outputting an alarm, in response to detecting a change in the muon rate indicating the presence of an object.

4. The apparatus of any preceding claim, wherein the apparatus is configured to transmit the result of the processing to a user device.

5. The apparatus of claim 4, wherein the apparatus is further configured to: receive a result transmission command from the user device; and transmit the result of the processing to the user device in response to receiving the result transmission command.

6. The apparatus of any preceding claim 4-5, wherein the apparatus is further configured to:transmit the result of the processing in response to detecting a change in the muon rate indicating the presence of an object.

7. The apparatus of any preceding claim 4-6, wherein the apparatus is configured to only transmit the result of the processing in response to: receiving a result transmission command from the user device or detecting a change in the muon rate indicating the presence of an object in the body of water.

8. The apparatus of any preceding claim 4-7, wherein the apparatus is further configured to: maintain transmission silence until the apparatus receives a result transmission command from the user device or detects a change in the muon rate indicating the presence of an object in the body of water.

9. The apparatus of any preceding claim, wherein the muon rate data comprises muon angle data, and wherein the apparatus is configured to process the muon angle data to detect the change in the muon rate.

10. A system for detecting at least partially submerged objects, the system comprising the apparatus according to any preceding claim 1-9 and one or more muon detectors configured to be positioned below a surface of a body of water.11 . The system of claim 10, wherein the one or more muon detectors are configured to transmit the muon rate data to the apparatus.

12. The system of claim 11 , wherein the apparatus is configured to: transmit a muon rate data transmission command to the one or more muon detectors, wherein the muon rate data transmission command triggers transmission of the muon rate data from the one or more muon detectors to the apparatus.

13. The system of claim 12, wherein the one or more muon detectors are configured to maintain transmission silence until receiving the muon rate data transmission command from the apparatus.

14. A computer-implemented method for detecting at least partially submerged objects, the method comprising: obtaining muon rate data measured by one or more muon detectors configured to be positioned below a surface of a body of water; processing the muon rate data to detect a change in the muon rate; and outputting a result of the processing, characterized in that the method further comprises: determining a presence of an object in the body of water based on the change in the muon rate, wherein the object is an at least partially submerged object comprising a structure with higher or lower density than the surrounding water.

15. A computer program product comprising computer program code configured to, when executed by at least one processor, cause an apparatus or a system to perform the method of claim 14.

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