Underwater Eyes - Systems Detect and Deter Underwater Threats

Wed, 06/29/2011

Henry Canaday, SOTECH Correspondent

Detection of underwater threats such as swimmers, mines and mini-submarines is receiving increased attention, and a number of U.S. and foreign companies offer systems to do the job. Sonar is the most common technique for detection, but it may have to be refined or complemented with other tools. Always crucial are the algorithms that distinguish threats from normal aquatic life based on the different characteristics of each. And command and control software must enable even inexperienced guards to quickly interpret results.

Most detection systems are static or travel with ships at sea. But one promising technology is a small robotic vessel that can spot potential threats and then do its own detailed investigation and, possibly, destruction of the threat.

Wesmar Defense Products makes sonar systems that can be dropped over the sides of ships, attached to the hulls of ships, or installed in shallow water to detect mines and divers. Unlike many other systems, Wesmar uses focused, directed energy to improve detection in shallow waters, or what Senior Manager Chris Choich calls “high-reverberation environments.” Choich explained that there is usually more noise in depths up to 20 meters because there is more activity at these depths and the focused-energy approach yields more accurate sonar images. Wesmar systems can scan for threats over 360 degrees and have a range of 1,000 meters under typical conditions in depths of 10 to 15 meters.

Wesmar systems have been used by the U.S. Navy and Coast Guard as well as foreign naval services. Its new MS3850 system, which incorporates more energy, has now secured its first foreign customer and is being offered to the U.S. Navy.

Divers are distinguished from other sea creatures by algorithms that interpret data on target strength, speed and course. Wesmar first developed diver-detection sonar for the 1984 Olympics. Its systems were also very successful in detecting divers that had been blowing up ships in the Sri Lankan civil war. Choich said, “We have been working at this for a long time. Divers tend to be predictable, swim at about 1.2 knots and come on a straight course.” Wesmar systems interpret target strength, which is a measure of how much sonar energy is returned by the target, in light of the ambient conditions.

Wesmar has a new WEB 850 system that can be sent down to any desired depth in a column of water, rather than mounted on tripods. The WEB 850 is contained in a bottle, simplifying installation and maintenance because it is anchored and does not require seabed preparation. Choich said that tripodmounted detectors may sink in mud and thus require frequent adjustment, which poses maintenance challenges and can reveal the location of devices to threatening parties. “We have more flexibility of installation than any other sonar detectors I know of,” he said.

The WEB 850 also has gyro-electric stabilization for the sonar array so it can still detect threats even if prevailing currents tilt the equipment. The new system can be installed in any depth of water up to 4,000 meters from shore by use of a transmit-and-receive cable. The WEB 850’s light weight and versatile installation mean it can be carried to remote locations and deployed quickly.

Wesmar is working on further product innovations. “We have a variable depth sonar [VDS] for mine hunting under development that uses our focused-sound energy technology for long-range detection,” Choich said. “The VDS can operate in a self-propelled or towed mode.”

Another new development is a submarine acoustic net (SAN). This is an active-passive system that includes a passive sensor array to detect very quiet targets such as mini-submarines. The passive array allows SAN to monitor waters without active sonar signals. “Because small submersibles use the reverberations in shallow waters to hide, they are moving in and out of many waterways at will,” Choich said. “SAN sonar sensors will be installed many miles from shore to provide a coastal detection network to minimize the threat posed by these small submersibles.”

DSIT Solutions makes the AquaShield to detect all types of divers, whether they are using open- or closed-circuit breathing devices, and all types of swimmer-delivery vehicles. The advanced sonar-based AquaShield has protected naval bases, energy terminals, commercial ports and other high-value assets from underwater threats. AquaShield offers very long-range detection for even the weakest of targets and can easily handle over 1,000 targets simultaneously.

Algorithms distinguish swimmers from non-threatening targets based on a target’s behavior underwater, explains DSIT Marketer Brandy Ben-Josef. “We also send teams for the installation who learn about the sea life in the area and enter this information into the system,” Ben-Josef noted. “And it can teach itself to distinguish threats.”

AquaShield comes with its own command-and-control displays, which are fully automated. “You do not have to sit in front of it; it will send aural and visual alarms,” Ben-Josef emphasized. “All you have to do is recognize what is on the screen.” DSIT conducts two days of training on the complete AquaShield system, but Ben- Josef said a security person can use it almost immediately.

AquaShield can detect threats within a 3,000-meter diameter of coverage, providing plenty of time for response. It also enables investigation of targets using a special zoom display and has optional real-time data communication with the response team. Finally, the system is very sturdy, able to withstand an explosion of up to 0.2 kilograms of TNT only 5 meters away.

DSIT also makes a smaller, more mobile diver-detection system, PointShield. This system uses the same basic sonar technologies and discriminating algorithms as AquaShield. But it can be deployed off the side of a ship with its own arm, installed on a pier or mooring pile or set on the seabed on a tripod. One possible use is for protection of water intake areas for nuclear power plants where coverage of a huge area is not necessary. Ben- Josef said PointShield is also used by several military customers. “We are interested in offering it to the U.S. military,” Ben-Josef said.

PointShield’s range is only 500 meters but, like its big brother, it can handle up to 1,000 contacts simultaneously and can investigate targets using zoom display. Windows-based software with intuitive displays and menus includes multiple formats, target data and exclusion zones.

Ben-Josef emphasized two features of DSIT’s detection systems: range and reliable automatic detection. “Our sonar array is bigger and more powerful, giving you more time to respond,” she said. “It does not do any good to detect a threat if there is not time to respond.”

Furthermore, DSIT’s automatic detection, classification and alerts are extremely reliable. Ben-Josef said her company’s employees are ex-Navy personnel, many with sonar experience. “They test themselves against the devices in interpreting results. They lose to the devices most of the time.”

Safeguards Technology has been working on perimeter security since 1982. “We are seeing a growing trend to look for divers,” noted Sales and Marketing Vice President Yaron Getter. Safeguards is the distributor of DSIT’s detection systems to the nuclear industry in the United Sates. “We also do integration and installation,” Getter said. “You want it to connect to the command and control center, tie into the existing system, so you don’t have to look at different monitors.”

Getter cited DSIT’s own easy-to-use command and control features. “You don’t have to be an expert in sonar to understand it. Any educated person can understand whether there is an alarm or not.”

The Safeguards marketer calls DSIT detection the “best in the industry,” able to filter out non-threats by matching them against very unique diver patterns. “They have a huge database for comparison, and they can adjust for different environments. They have been working at this for a very long time.”

G-Max Security Tech makes the UPDS, a magnetic marine intrusion detection system that arranges sensors on a net that can be fixed on a river bed. The system will detect divers carrying weapons or other ferromagnetic materials at a maximum of seven meters, said Managing Director Yehuda Nachman.

UPDS provides coverage at the short distances over which sonar and other sensors do not work, Nachman explained. “Sonar cannot detect intruders very close to a wall, so you can also place our sensors there,” he said. Another G-Max system, the Marine- Sensor Net, is sensitive to any force attempting to cut the net. “Divers will be detected as well as a capsule penetrating the net,” Nachman said. UPDS can be combined with the MarineSensor Net.

G-Max provides a lot of protection for nuclear cooling towers and is the only technology authorized by the Russian nuclear power corporation Rosatom, according to Nachman. G-Max nets and magnetic sensors guard the intake and outlet connections between cooling towers and nearby lakes and rivers.

Unveiled in 2007, Sonardyne’s Sentinel intruder detection sonar can detect swimmers with either open- or closed-circuit breathing apparatus, propulsion devices and submarines. Richard Dentzman, business development manager for defense maritime security in the Americas, said algorithms distinguish these threats from aquatic life by characteristics including size and tracks. “An animal swims very differently than a person,” Dentzman noted. “And sharks do not have air bladders like humans do.”

Dentzman said Sentinel is one of only two systems that were developed from the ground up solely for detection of intruders. Many systems were initially developed for general sonar-imaging functions and then adapted for detecting intruders. The tight focus of Sentinel means it needs only 65 watts of power, about a third of the power needed by many other systems. And Sentinel has a very low false-alarm rate, Dentzman emphasized. “You can’t have a system that cries wolf, or operators may not pay attention.”

Sentinel can be used in a fixed installation, deployed over the side of vessels, lowered from docks or set up on tripods. Dentzman said its compact size makes it ideal for expeditionary and special forces. “It fits in the back of an SUV, and can be up and running in 30 minutes.”

The Sentinel was designed so it can be used by security guards with no special sonar or computer training. It can easily be connected to a camera for investigation of identified threats. It can also send range and bearing data through 4G wireless connections to aid investigation.

Sentinel detects intruders at up to 600 meters in typical conditions. Dentzman said detection can work at up to 900 meters in very favorable conditions but may be limited to 500 meters in worse conditions. The device itself tells operators its effective range in any given sea, so that reaction times can be accurately measured.

About 50 Sentinels are now in use by military or commercial customers. Military users include the Naval Undersea Warfare Center in Newport, R.I., and the Space and Naval Warfare Systems Center in San Diego.

Qinetiq Technology Solutions has “been in this space for many years with acoustic, optical and radio-frequency maritime sensors,” said Dr. Mark Hewitt, senior vice president for maritime and transportation. One important effort, funded by the Office of Naval Research, has been Blackfish for the detection, classification and interdiction of swimmers approaching naval vessels.

“We developed a Jet Ski with the top taken off that is a robotic, radio-controlled tele-operated system that has both optical and sonar sensors,” Hewitt explained. “First, Blackfish identifies with sonar all the targets in a larger area, and then the operator drives it over to check out specific targets with high-resolution sonar and optical sensors.”

Hewitt said Blackfish has been very successful in ONR tests. The vehicle can be used in ports or when ships are out of port and seek to detect approaching threats.

“One of the challenges of swimmer detection is that you must be able to interdict within a limited time, for example 15 minutes,” Hewitt stressed. Blackfish’s ability to classify threats and then move to check them out thoroughly helps here. “It has an underwater camera with lights and a camera on top that can pan, tilt and zoom.”

Blackfish can be operated in three modes. First, it can be teleoperated through manual controls. Second, it can do way-point navigation with a GPS. “You give it a patrol area, and it will patrol it automatically,” Hewitt explained. The third mode is a hybrid of teleoperation and way-point navigation.

These three modes help meet another challenge of underwater detection: economizing on the operator manpower need to run the systems.

As currently designed, Blackfish does not destroy targets. But Hewitt said it could be equipped with a suite of non-lethal deterrents. For example, it could issue a loud warning that the swimmer has been detected. Or a laser light could dazzle the swimmer. The vehicle could also be loaded with low-power grenades like miniature depth charges.

Reconfiguring Blackfish is easy because it can carry a payload of 150 kilograms and is highly modular, with the ability to swap out equipment very quickly.

Dual power enables Blackfish to meet the challenge of getting there fast and acting smart. The Jet Ski can do 40 knots in getting to the target. But it must be able to maneuver slowly to deal with a swimmer. So it is fitted with electric bow thrusters for maneuvering at slow speeds.

Complete detection systems must not only reach out to find the threats, but may have to inform widely dispersed security personnel. Reality Mobile software can distribute any image, from camera feeds to displays of sonar and magnetic sensors on central computer screens, to soldiers on PCs, laptops and personal devices, wherever they are. It thus enables sharing of detection results across a wide spectrum of locations and users.

Reality Mobile has long worked for the special warfare community and recently completed a field test of distributing images from unmanned aerial vehicles, noted Brian Geoghegan, executive vice president and chief product officer. “This is all about enabling the warfighter in remote locations to see the same images that are being seen at central control.”

Images can be obtained by IP, analog or cell phone cameras, captured from the screens of command and control centers or be any files of texts or pictures. These images can be sent over commercial or private networks, WiFi or Wide-Area Networks or any IP pathway. The images can then be viewed on smart phones, BlackBerries, Androids, iPhones and, soon, iPads.

If a soldier’s personal device has a camera, its images can also be shared with others on a secure network. Reality Mobile supports the NSA Suite B encryption standards that the Department of Defense is encouraging. If a threat requires seven or eight screens to monitor and assess, Reality Mobile can feed images from all these screens and users can view several simultaneously by re-sizing images on their screens.