GB2399169A

GB2399169A - Detecting the location of an underwater explosion

Info

Publication number: GB2399169A
Application number: GB0302677A
Authority: GB
Inventors: John Kingsley Swinburne; Robert Woods; Roderick Schipper
Original assignee: REEF MAN INTERNAT Ltd
Current assignee: REEF MAN INTERNAT Ltd
Priority date: 2003-02-06
Filing date: 2003-02-06
Publication date: 2004-09-08
Also published as: GB0302677D0

Abstract

A system for the detection and location of an underwater explosion includes a plurality of data acquisition units DAU which comprise hydrophones mounted in a buoy (see figs 1,3). Each buoy has a GPS receiver to determine its position. The buoys transmit digitised received sound wave data via radio to a data processing and recording centre located onshore. The data processing centre determines the location of the blast using the difference in arrival of the sound waves at the different buoys. The system finds application in detecting illegal blast fishing.

Description

1 2399169

BLAST FISHING DETECTION SYSTEM

The invention is a system that can localize a dynamite (or other) explosion under water. The sound waves from the explosion travel through the water and get picked up by the recording units, to be digitized and transmitted over a (wireless) network to an onshore computer. The raw data coming in from several recording units is then processed to find and determine the location of the blast.

This invention addresses the problem of dynamite fishing a practice which destroys coral reefs and the fragile ecosystems they support The practice is widely spread throughout the world and is in fact illegal in many countries. Government authorities and private agencies are presently relying on patrol boats and other visual methods to monitor and protect the reefs, methods which are archaic and highly inefficient. The invention will allow reefs to be electronically monitored on a 24 hour basis.

The object is to provide government authorities and private organizations involved in monitoring and protecting coral reefs the technological ability to continually monitor a reef or series of reefs to ascertain if dynamite fishing is being undertaken. If such fishing is taking place the geographic co-ordinates of the explosion are computed from the data received and can be relayed to the relevant authorities instantly, thus allowing the authorities to take the appropriate action.

Accordingly, this invention provides a method to detect and quickly determine the location of an underwater explosion. Specifically it is the combination of individual seismic recording systems and network radio's placed in a series of buoys. Each buoy will have several hydrophores connected to it, from which, by using the difference in arrival time of the sound waves from the blast, a direction of the sound relative to the buoy can be determined. Several buoys sited using GPS (Global Positioning System) technology, will be installed in a wireless network to optimize the accuracy of the blast location. This system allows for great flexibility and can be extended to any required size, the only limiting factor being the maximum transmitting distance between successive radios in the network. Once the data is received by the shore based recording centre the data is analysed and the co-ordinates of the explosion computed.

A preferred embodiment of the invention will now be described with reference to the accompanying drawings, Figure 1. Shows sketch of the buoy, hereon referred to as an RMI-Data Acquisition Unit (DAU), with a list of all its contents Figure 2. A possible network setup of the DAU's in the water and how they connect to the mainland.

Figure 3. Top view of buoy showing how things are located inside the DAUbuoys.

As shown in Figure 1 the DAU unit is comprised of a coastal buoy I which has installed in it an instrument tray 2 which contains the recording equipment, batteries and radio. A pipe 3 goes through the buoy through which the hydrophores cables are lead. The hydrophores 4 which are used for detecting the acoustic signal of the explosion are encased in a protective cage 5. The mast on top of the buoy supports the solar panels for recharging the batteries and the network radio antenna.

Figure 2, shows a simple network displaying how the DAU's (buoys) are linked to transmit the data back to the shore based recording center. The network can be extended indefinitely, the only limiting factor being the transmission distance between adjacent DAU's.

Figure 3, shows an open top view of the DAU showing the hydrophore cable hole 3, the instrument tray 2, and how the battery 9 the seismic recording instrument 10 and the radio 11 will be placed in the buoy.

On He detonation of an underwater explosion the acoustic signals are picked up by by the hydrophores 4, the analog signal is then digitized by the seismic recording instrument 10 and transmitted by the radio 11 to the shore based recording processing center. The fact that an acoustic signal has registered on the system indicates that an underwater explosion has occurred. Taking Figure 2 as an example, each of the DAU's would register the explosion and transmit the data to the shore based Recording Center. The shore based computer would then analyze the data and compute the time differences of the acoustic signal reaching each individual DAU, from this data the location of the explosion is computed and the data instantly passed on to the relevant authorities for appropriate action.

Claims

1. An underwater explosion detection system that detects and determines the exact position of the explosion using a series of data acquisition units and hydrophores housed in buoys and an onshore data processing/recording center.

2. A detection system as claimed in Claim 1 where the data acquisition units and the shore based computing centre are networked together using wireless network technology, the size and geometric configuration of the network only being limited by the line of sight between buoys.

3. A detection system as in Claim 1 and Claim 2 whereby the acoustic energy generated by an underwater explosion is detected by underwater hydrophores, the resulting analogue data then being converted into digital format by the data acquisition units and relayed via a radio network to the onshore recording center.

4. A detection system as claimed in any preceding claim in which the onshore recording center analyses the data received from the buoys, sounds an audio warning that an event has taken place and instantly produces a visual reference on a digitized map and also the geographic co- ordinates of the location of the explosion.