Apparatus and method to detect and locate underwater articles

Abstract

A device to assist tracking of lost objects 8 at sea comprising an acoustic transmitter unit 2 adapted to emit an acoustic ping within a frequency band between 24kHz to 32kHz at intervals, and means 3

Description

This invention relates to a system and device for underwater detection and location of lost items and articles, such a fishing equipment. More particularly, but not exclusively, the invention may be used to signal the position (marking a location) of an object drifting or lost at sea. The invention is useful and finds particular application to tracking lost or discarded fishing gear as well as tracking divers and other floating or semi-submerged equipment. Background Lost or discarded fishing gear, which becomes accidentally or inadvertently detached from markers or ships is often referred to as ‘ghost gear'. Ghost gear is a huge global problem; ghost fishing gear includes fishing nets, lobster and crab pots when equipment has become abandoned, lost, or otherwise discarded in oceans, lakes, and rivers. The term ‘abandoned, discarded and lost fishing gear (ADLFG) is a term now being referenced globally amongst government policy makers, fisheries protection, environmental agencies and other organisations. Ghost gear provides one of the deadliest forms of marine plastic debris. It also interferes with shipping, fishing activities as well as the environment. It is estimated that ghost gear makes up at least 10% of marine litter. Every year between 500,000 and 1 million tonnes of fishing gear is lost at sea, resulting in toxic plastic pollution and 338,000 tons offish and shellfish killed from ghost fishing. Marine pollution is reaching alarming levels, with thousands of plastic litter items reported to be found extensively across seas and oceans. In addition to the detrimental environmental impacts, it is estimated there is a $2.6 billion annual fishing gear replacement cost. Furthermore, ghost fishing gear can take hundreds of years to fully disintegrate and decompose into the marine habitat. It is an object of the invention to significantly reduce the ghost fishing gear being currently lost at sea in order to reduce environmental pollution. It is another object of the invention to assist in the recovery of ghost fishing gear which becomes detached form floating buoys or markers or from fishing vessels. Summary of the Invention According to a first aspect of the invention there is provided a device to assist tracking of lost objects at sea comprises an acoustic transmitter unit adapted to emit an acoustic signal / ping within a frequency band between 24kHz to 32kHz at intervals, a means to attach the device to an object, and a means to power the transmitter. In some embodiments the device includes a means to power the transmitter, such as a battery. In some embodiments a solar power component is attached to the transmitter unit. In some embodiments the solar power component is attached, directly or indirectly to the transmitter unit by a mechanical line, and / or electrical cable. In some embodiments the solar power component is attached to a float, optionally wherein the mechanical line or electrical cable is attached to the float. In some embodiments includes a further attachment means, adapted to be attached to a fishing net / fishing pot float or surface line. A means to attach weights and / or floats. The means to attach weights comprises a closable sac. Preferably the interval between acoustic transmissions is between 100 milliseconds seconds and 3 seconds. In some embodiments the signal comprises spread spectrum signalling waveform which may include varying amplitude pulses and varying shape duty cycles and pulse intervals. The device may include a wireless transmitter for transmitting a signal to a wireless receiver mounted on a vessel or craft. The wireless receiver is configured to determine, from the wireless transmitter, its range with respect to the vessel. The reason the wireless receiver does this is to determine if the wireless transmitter, and hence the equipment to which it is attached, are within a so-called geo-fenced region. Provided the distance between the wireless receiver and wireless transmitter remains within a predefined limit (of the vessel, which is typically a trawler), the location of the equipment to which the wireless transmitter is attached, is defined as safe and secure. If the range between the wireless transmitter and wireless receiver exceeds a predefined distance, then a processor determines that the equipment has broken loose and triggers an alarm. The processor may receive an alarm via a receiver supported on the equipment. The processor is configured to automatically switch on an acoustic receiver to commence location and / or activate the acoustic transmitter unit to commence tracking and retrieval of the lost equipment or object. In one embodiment the device is configured to automatically commence transmission from the acoustic transmitter unit when it strays from a predefined geo-fenced zone. The predefined geo-fenced zone may be defined by a predefined set of coordinates (for example for a fixed object such as a lobster pot) by using, for example a set of GPS coordinates, to define a geo-fenced zone; or by a specified range between the wireless transmitter and wireless receiver when the distance between device and vessel exceeds a predefined range. In another aspect of the invention there is therefore provided a system which includes a wireless transmitter for mounting on a vessel or craft; a wireless transceiver for permanent attachment or temporary connection to equipment; an acoustic transmitter for permanent attachment or temporary connection to equipment and an acoustic receiver which is housed in a vessel or seagoing craft, the wireless transceiver supplies a signal to a processor when a geo-fence zone is breached by the equipment and the processor switches on the acoustic transmitter to transmit an identity signal for detection by when activated by the acoustic receiver. Preferably the wireless transmitter is tethered to a float or buoy so that it remains above the surface of water in use and so is able to transmit a radio signal to a remote wireless receiver. The invention will now be described, by way of example only, and with reference to the following Figures in which: Brief description of Figures Figure 1 shows a view of a basic example; Figure 2 shows a schematic block diagram of one embodiment of an acoustic transmitter unit; and Figures 3 and 4 shows alternative embodiments of the device. Detailed Description of Embodiments of the Invention Referring to the Figures a device, such as shown in Figure 1, according to the invention can be attached to a range of items, such as nets or lobster pots or crab pots, for underwater tracking, marking and location. Optionally the device and system may be used to track divers and other underwater equipment. The device comprises a state of the art, an ultra-low power acoustic locator device designed specifically to track and locate all types of fishing gear. The device comprises an acoustic transmitter with a clip or connector means to attach to fishing nets, lobster or crab pots or other items. The clip means may be temporarily (i.e. releasably) or permanently attachable to the object to which it is attached to and, may comprise a locking mechanism such as those found on padlocks, spring loaded attachment means with jaws. The clip or attachment means may comprise a loop with a locking mechanism such that one end has a notch which fits into a locking portion at another end, the locking portion is adapted to receive the end with the notch using spring loaded lock mechanism. Alternatively, one end of the loop may have deformable portion, such as one or more barbs adapted to slot into an orifice, with a gripping member at another end. In such configurations therefore, the acoustic device may be attachable to the object (fishing net) with zip tie type attachment means. Alternatively, the attachment means may be a carabiner. The acoustic transmitter ideally includes battery that is hermetically sealed within a watertight container which also contains the acoustic transmitter. Alternatively, power for the acoustic device may be provided by a solar element connected to the acoustic device by a short wire. Also envisaged is a power element that converts wave energy into electrical energy. In such systems a float may be provided connected by a line to the transmitter unit. For fishing nets and lobster pots with floats, the float may be discarded but there may be a second attachment means for attaching the end of the line with the solar panel to a fishing net / pot float. Figure 1 shows a view of a basic example of the device 1 including an acoustic transmitter unit 2. The unit 2 is connected to an attachment means 3 (here a carabiner) for attachment to an object such as a fishing net. Figure 2 shows a schematic block diagram of the acoustic transmitter unit 2 showing an acoustic antenna 6, connected to an internal amplifier / antenna drivers / associated electronic 3, control unit 4 and battery 5. The control unit is programmed, or otherwise adapted, to control the frequency of the acoustic transmissions which are often referred to as ‘pings’. A train of pulses of varying amplitude, duration and interval may be generated by the acoustic transmitter unit 2 so as to provide a unique identity for the acoustic transmitter unit 2. Acoustic detection equipment may be configured to detect only this unique identity or signature and this is ideally achieved using suitable digital filtering equipment which may be housed in a sonar detector device. Figure 3 shows an advanced embodiment of the device. Like reference numerals refer to the same components. Here a float 9 is also provided which is mechanically connected by line 10 to the device 1 and unit 2. The float includes a solar panel 7 which provides soar power to the unit 2. The float ensures the solar panel is on the surface, and on the air side. The solar panel is connected by electrical lead 11 to the unit 2 to power the unit or recharge the battery. The unit may include a weight 12 or preferably a means to attach a weight to keep the arrangement below the water. The latter is preferably to save manufacture and transport costs. The means to attach a weigh may be a (e.g. closable) sack where pebbles stones can be added. This keeps the cost and weight down in transport. Further the sack can be made and advertised as being made form retrieved ghost fishing nets itself. In yet preferred embodiments the design of Figure 3 may be amended such that the float is dispensed with but replaced with further attachment means (clip) 16 to attach to the float 15 of a fishing net 8 or crab / lobster pot. This is shown in Figure 4. The acoustic device is adapted to emit an acoustic “ping” or signal, within a frequency band between 24kHz to 32kHz. The ping may be sent out at regular intervals or as chirps or pulses to define a unique signature. The ping may be intercepted by known receiver systems etc and the location of the device determined by known techniques e / g / triangulation etc. The invention is straightforward to deploy and easy to use. Deployment and recovery are likewise straightforward. The range is typically operative from between 1 km to 5km from the vessel to the ghost gear being located. The device includes a long battery life of over 6 months; in listening mode the devices use very little power and transmit zero noise. It is also possible to collect additional marine science data such as depth and temperature of the water column and other data. The device comprises an acoustic modem which uses an ultralow power processor and electrical design. The battery life is between 6months to 12 months depending on cycle rate and how often a ping from the device is sent, Specifically, an acoustic ping is sent from the device within a frequency band between 24kHz to 32kHz. Preferably a spread spectrum signalling waveforms to achieve very short message bursts and this has been found to deliver high success rates in message delivery. It will be appreciated that variation may be made to the aforementioned embodiments without departing from the scope of the invention as defined by the claims. For example, optionally the invention may be deployed to track divers, diving equipment and other underwater equipment.

Claims

02 12 241. A device to assist tracking of lost objects at sea comprises an acoustic transmitter unit adapted to emit an acoustic signal / ping within a frequency band between 24kHz to 32kHz at intervals, a means to attach the device to an object, a means to power the transmitter and a means to attach weights and / or floats, wherein the means to attach weights comprises a closable sack.

2. A device as claimed in claim 1 wherein the means to power the transmitter comprises a battery.

3. A device as claimed in claims 1 or 2 including a solar power component attached to the transmitter unit.

4. A device as claimed in claim 3 where the solar power component is attached, directly or indirectly, to the transmitter unit by a mechanical line and / or electrical cable.

5. A device as claimed in either claim 3 or 4 wherein the solar power component is attached to a float.

6. A device as claimed in any of claims 3 to 5 wherein the mechanical line or electrical cable is attached to the float.

7. A device as claimed in claim 3 to 6 including a further attachment means comprising a clip or connector to be attached to a fishing net / fishing pot float or surface line.8 A device as claimed in claims 1 to 7 where the interval between acoustic transmissions is between 100 milliseconds and 3 seconds.

9. A device as claimed in claims 1 to 8 wherein the signal comprises spread spectrum signalling waveform.02 12 2410. A device as claimed in claims 1 to 9 wherein the device includes a wireless transmitter for transmitting a signal to a remote wireless receiver.

11. A device as claimed in claim 10 wherein the wireless transm itter for transm itting a signal to a remote wireless receiver is mounted on a vessel or craft.

12. A device as claimed in claims 1 to 11 wherein the device is housed in a hermetically sealed housing.

13. A device as claimed in claims 11 or 12 wherein the wireless transmitter is tethered to a float or buoy so that it remains above the surface of water in use and so is able to transmit a radio signal to a remote wireless receiver.

14. A system which includes a device to assist tracking of lost objects at seas comprising an acoustic transmitter unit adapted to emit an acoustic signal / ping within a frequency band between 24kHz to 32kHz at intervals, a means to attach the device to an object, and a means to power the transmitter, means to attach weights and / or floats, wherein the means to attach weights comprises a closable sack, a wireless transmitter for mounting on a vessel or craft; a wireless transceiver for permanent attachment or temporary connection to equipment; and an acoustic receiver which is housed in a vessel or seagoing craft, the wireless transceiver supplies a signal to a processor when a geo-fence zone is breached by the equipment; and the processor switches on the acoustic transmitter to transmit an identity signal for detection by the acoustic receiver.

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