Diver Detection Sonar
Encyclopedia
Diver Detection Sonar systems are sonar
and acoustic location
systems employed underwater for the detection of divers and submerged swimmer delivery vehicles
(SDVs). The purpose of this type of sonar system is to provide detection, tracking and classification information on underwater threats that could endanger property and lives. Further, this information is useful only to the extent that it is made available to authorities in time to make possible the desired response to the threat, be it deterrent or defensive action. Subsurface threats are a difficult problem, because reliable detection is available to date chiefly by use of high-resolution active sonar or trained dolphins or sea lions.
The threat of an underwater terrorist attack is a concern to the maritime industry and port law enforcement agencies. Ports face a range of threats from swimmers, boat-delivered ordnance such as limpet mines and other forms of improvised underwater explosive devices.
DDS systems have been developed to provide underwater security for ports, coastal facilities, offshore installations, pipelines and ships. Due to the variety of life and objects that exist under the water, it is desirable that a DDS system be capable of distinguishing between large sea mammals, shoals
of fish; a ship's wake; a diver with an open circuit scuba set
and a stealth diver with a rebreather
.
DDS systems have been developed that can be mounted on the seabed
, on a pier
or on the hull
of a vessel. For complete port security
these systems are integrated with the surface surveillance
and security systems employed at ports, coastal facilities and offshore installations. Various systems provide specialized features to facilitate their use in port security systems including automatic detection features.
and long propagation
distance in turbid harbor waters relative to other means of sensing (electromagnetic waves
, visual light, temperature, magnetism
). The leading sonar technology for detecting and tracking underwater intruders is active, monostatic sonar, using principles of conventional beam forming in its signal processing. These sonars are now available from a number of different manufacturers who recommend their use for surveillance against underwater intruders, whereas, other sonar technologies, such as active multi-static or passive sonar, possibly with model-based signal processing, remain at best in the development stage so far as intruder detection is concerned.
against intruders wearing open-circuit breathing equipment. The coverage is
significant relative to the area of open water and to the possible entry points for
intruders in many harbours.
accounted for by environmental (sound propagation) conditions at the time (see
below).
they are recognizably false because they are of short duration and do not follow a
track.
not to be intruders—by large fish, or schools of fish, or marine mammals, for
instance—can usually be recognized by an experienced operator from the
contact’s behaviour, especially the evolution of their track, so these “false”
alarms are unlikely to be troublesome in practice. They furthermore provide
feedback about the functioning of the sonar and domain awareness.
simultaneously.
Were the Diver Detection sonar systems to rely strictly on the echograph generated by the sonar units overlaid on a navigation chart
, then a diver or SDV would appear as a relatively small moving shape that is refreshed with each transmission or ping of the sonar against a fluctuating background of sound clutter and reverberation
. The operator would have to recognize the shape and judge if it represents a threat calling for further action or not. This is problematic in that they would have to be highly trained sonar operators. For this reason, commercial DDS systems use automation to simplify the sonar display by suppressing the echograph and displaying only the chart and detection and tracking information.
purchased the first DDS system to be installed in a commercial oil terminal. http://www.energy-daily.com/reports/dsIT_to_Supply_First_Underwater_Surveillance_System_To_Protect_Oil_Platform_999.html
In December, 2008, Diver Detection Sonar (DDS) System sold to an undisclosed EMEA government. The system will be installed in an area with critical infrastructure, including a port and energy production facilities. http://www.asdnews.com/news/18699/DSIT_Solutions_Sells_Underwater_Site_Security_System.htm
March 4, 2009,A $1.7M order for an underwater security system, to be used by a large energy facility at an undisclosed location in Asia, to guard and protect the customer infrastructure from underwater intrusion and sabotage. http://www.nationalhomelandsecurityknowledgebase.com/cln/news/030409a.aspxhttp://www.prnewswire.com/news-releases/dsit-to-supply-energy-facility-with-underwater-site-security-61685022.html
March 12, 2009, Sale of multiple Diver Detection Sonar sensors, which will protect a strategic site against underwater intrusion. http://finance.dailyherald.com/freelunch.html/news/read?GUID=8818281http://ca.us.biz.yahoo.com/prnews/090923/ny80704.html?.v=1
May 25, 2009, US Navy orders additional Sonar systems http://www.rovworld.com/modules.php?name=News&file=article&sid=3242
Anti-frogman Techniques Anti-frogman techniques
DSIT Solutions Ltd.http://www.dsit.co.il
Diver Detection Systems on www.naval-technology.com http://www.naval-technology.com/contractors/sonar/kongsberg
White paper on new trends in diver detection systems (released April 2009) http://www.naval-technology.com/downloads/whitepapers/sonar/file634
Kongsberg Diver Detection Systems product information http://www.km.kongsberg.com/ks/web/nokbg0240.nsf/AllWeb/31A785B964682F57C12573DB004AFC3D?OpenDocument
Kongsberg Mesotech Inc. [www.kongsberg-mesotech.com]
Diver Detection Sonar's and the Protection of Underwater Pipelines http://www.wi-ltd.com/security/Maritime_Security/Diver_Detection/Diver_Detection_Sonar_Underwater_Pipeline
31 January 2008
[www.sonardyne.co.uk/Products/SonarImaging/sentinel.html]www.sonardyne.co.uk/Products/SonarImaging/sentinel.html
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...
and acoustic location
Acoustic location
Acoustic location is the science of using sound to determine the distance and direction of something. Location can be done actively or passively, and can take place in gases , liquids , and in solids .* Active acoustic location involves the creation of sound in order to produce an echo, which is...
systems employed underwater for the detection of divers and submerged swimmer delivery vehicles
Diver Propulsion Vehicle
A diver propulsion vehicle is an item of diving equipment used by scuba and rebreather divers to increase range underwater...
(SDVs). The purpose of this type of sonar system is to provide detection, tracking and classification information on underwater threats that could endanger property and lives. Further, this information is useful only to the extent that it is made available to authorities in time to make possible the desired response to the threat, be it deterrent or defensive action. Subsurface threats are a difficult problem, because reliable detection is available to date chiefly by use of high-resolution active sonar or trained dolphins or sea lions.
The threat of an underwater terrorist attack is a concern to the maritime industry and port law enforcement agencies. Ports face a range of threats from swimmers, boat-delivered ordnance such as limpet mines and other forms of improvised underwater explosive devices.
DDS systems have been developed to provide underwater security for ports, coastal facilities, offshore installations, pipelines and ships. Due to the variety of life and objects that exist under the water, it is desirable that a DDS system be capable of distinguishing between large sea mammals, shoals
Shoaling and schooling
In biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...
of fish; a ship's wake; a diver with an open circuit scuba set
Scuba set
A scuba set is an independent breathing set that provides a scuba diver with the breathing gas necessary to breathe underwater during scuba diving. It is much used for sport diving and some sorts of work diving....
and a stealth diver with a rebreather
Rebreather
A rebreather is a type of breathing set that provides a breathing gas containing oxygen and recycled exhaled gas. This recycling reduces the volume of breathing gas used, making a rebreather lighter and more compact than an open-circuit breathing set for the same duration in environments where...
.
DDS systems have been developed that can be mounted on the seabed
Seabed
The seabed is the bottom of the ocean.- Ocean structure :Most of the oceans have a common structure, created by common physical phenomena, mainly from tectonic movement, and sediment from various sources...
, on a pier
Pier
A pier is a raised structure, including bridge and building supports and walkways, over water, typically supported by widely spread piles or pillars...
or on the hull
Hull (watercraft)
A hull is the watertight body of a ship or boat. Above the hull is the superstructure and/or deckhouse, where present. The line where the hull meets the water surface is called the waterline.The structure of the hull varies depending on the vessel type...
of a vessel. For complete port security
Port security
Port security refers to the defense, law and treaty enforcement, and counterterrorism activities that fall within the port and maritime domain...
these systems are integrated with the surface surveillance
Surveillance
Surveillance is the monitoring of the behavior, activities, or other changing information, usually of people. It is sometimes done in a surreptitious manner...
and security systems employed at ports, coastal facilities and offshore installations. Various systems provide specialized features to facilitate their use in port security systems including automatic detection features.
Evaluation of DDS Systems
In 2006, in a NATO report given by Dr. R. T. Kessel and R. D. Hollet at the NATO Undersea Research Center, it was stated that sonar gives by far the lowest cost per square meter of underwater coverage of all other means of surveillance (radar, video, visual). This is because sound waves have a low attenuationAttenuation
In physics, attenuation is the gradual loss in intensity of any kind of flux through a medium. For instance, sunlight is attenuated by dark glasses, X-rays are attenuated by lead, and light and sound are attenuated by water.In electrical engineering and telecommunications, attenuation affects the...
and long propagation
Wave propagation
Wave propagation is any of the ways in which waves travel.With respect to the direction of the oscillation relative to the propagation direction, we can distinguish between longitudinal wave and transverse waves....
distance in turbid harbor waters relative to other means of sensing (electromagnetic waves
Electromagnetic radiation
Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
, visual light, temperature, magnetism
Magnetism
Magnetism is a property of materials that respond at an atomic or subatomic level to an applied magnetic field. Ferromagnetism is the strongest and most familiar type of magnetism. It is responsible for the behavior of permanent magnets, which produce their own persistent magnetic fields, as well...
). The leading sonar technology for detecting and tracking underwater intruders is active, monostatic sonar, using principles of conventional beam forming in its signal processing. These sonars are now available from a number of different manufacturers who recommend their use for surveillance against underwater intruders, whereas, other sonar technologies, such as active multi-static or passive sonar, possibly with model-based signal processing, remain at best in the development stage so far as intruder detection is concerned.
Mature Diver Detection Sonar Technology
In the above mentioned study, conducted with the Italian Navy, it was found that diver or intruder detection sonar technology is mature inasmuch as:- It has demonstrated 360 degree coverage with detection ranges of 300 to 800 m
against intruders wearing open-circuit breathing equipment. The coverage is
significant relative to the area of open water and to the possible entry points for
intruders in many harbours.
- Reduced detection range and track fragmentation, when it occurred, could be
accounted for by environmental (sound propagation) conditions at the time (see
below).
- Random false alarms are rare (when the auto-detection is properly adjusted), and
they are recognizably false because they are of short duration and do not follow a
track.
- Non-random false alarms caused by genuine underwater contacts that happened
not to be intruders—by large fish, or schools of fish, or marine mammals, for
instance—can usually be recognized by an experienced operator from the
contact’s behaviour, especially the evolution of their track, so these “false”
alarms are unlikely to be troublesome in practice. They furthermore provide
feedback about the functioning of the sonar and domain awareness.
- The automatic algorithms are capable of detecting and tracking many contacts
simultaneously.
Were the Diver Detection sonar systems to rely strictly on the echograph generated by the sonar units overlaid on a navigation chart
Nautical chart
A nautical chart is a graphic representation of a maritime area and adjacent coastal regions. Depending on the scale of the chart, it may show depths of water and heights of land , natural features of the seabed, details of the coastline, navigational hazards, locations of natural and man-made aids...
, then a diver or SDV would appear as a relatively small moving shape that is refreshed with each transmission or ping of the sonar against a fluctuating background of sound clutter and reverberation
Reverberation
Reverberation is the persistence of sound in a particular space after the original sound is removed. A reverberation, or reverb, is created when a sound is produced in an enclosed space causing a large number of echoes to build up and then slowly decay as the sound is absorbed by the walls and air...
. The operator would have to recognize the shape and judge if it represents a threat calling for further action or not. This is problematic in that they would have to be highly trained sonar operators. For this reason, commercial DDS systems use automation to simplify the sonar display by suppressing the echograph and displaying only the chart and detection and tracking information.
Commercial use of DDS
In 2008, the Port of GdańskPort of Gdansk
The Port of Gdańsk is a seaport located on the southern coast of Gdańsk Bay in the city of Gdańsk, extending along the Vistula estuary Martwa Wisła , Port Channel and Kashubia Canal. It is one of the largest seaports on the Baltic Sea....
purchased the first DDS system to be installed in a commercial oil terminal. http://www.energy-daily.com/reports/dsIT_to_Supply_First_Underwater_Surveillance_System_To_Protect_Oil_Platform_999.html
In December, 2008, Diver Detection Sonar (DDS) System sold to an undisclosed EMEA government. The system will be installed in an area with critical infrastructure, including a port and energy production facilities. http://www.asdnews.com/news/18699/DSIT_Solutions_Sells_Underwater_Site_Security_System.htm
March 4, 2009,A $1.7M order for an underwater security system, to be used by a large energy facility at an undisclosed location in Asia, to guard and protect the customer infrastructure from underwater intrusion and sabotage. http://www.nationalhomelandsecurityknowledgebase.com/cln/news/030409a.aspxhttp://www.prnewswire.com/news-releases/dsit-to-supply-energy-facility-with-underwater-site-security-61685022.html
March 12, 2009, Sale of multiple Diver Detection Sonar sensors, which will protect a strategic site against underwater intrusion. http://finance.dailyherald.com/freelunch.html/news/read?GUID=8818281http://ca.us.biz.yahoo.com/prnews/090923/ny80704.html?.v=1
May 25, 2009, US Navy orders additional Sonar systems http://www.rovworld.com/modules.php?name=News&file=article&sid=3242
External links
Swimmer detection sonar AN/WQX-2AN/WQX-2
The AN/WQX-2 is a diver-detector sonar used in anti-frogman precautions. It is in service with the US Navy. It uses Kongsberg Mesotech components. It can detect divers up to 2400 feet away....
Anti-frogman Techniques Anti-frogman techniques
Anti-frogman techniques
Anti-frogman techniques are security methods developed to protect watercraft, ports and installations, and other sensitive resources both in or nearby vulnerable waterways from potential threats or intrusions by frogmen or other divers....
External links
AquaShield Diver Detection Sonar System http://www.dsit.co.il/products/diver_detection_sonar.aspDSIT Solutions Ltd.http://www.dsit.co.il
Diver Detection Systems on www.naval-technology.com http://www.naval-technology.com/contractors/sonar/kongsberg
White paper on new trends in diver detection systems (released April 2009) http://www.naval-technology.com/downloads/whitepapers/sonar/file634
Kongsberg Diver Detection Systems product information http://www.km.kongsberg.com/ks/web/nokbg0240.nsf/AllWeb/31A785B964682F57C12573DB004AFC3D?OpenDocument
Kongsberg Mesotech Inc. [www.kongsberg-mesotech.com]
Diver Detection Sonar's and the Protection of Underwater Pipelines http://www.wi-ltd.com/security/Maritime_Security/Diver_Detection/Diver_Detection_Sonar_Underwater_Pipeline
31 January 2008
[www.sonardyne.co.uk/Products/SonarImaging/sentinel.html]www.sonardyne.co.uk/Products/SonarImaging/sentinel.html