Underwater part protection systems.
Recently, more and more anti-terrorist security experts have been paying attention to the high potential danger of terrorist attacks against water infrastructure and water transport. The increasing number of cases of pirates seizing ships, including those using scuba divers, confirms these concerns. The United States, especially after the events of September 11, has been concerned with the problem of strengthening its water bodies, and the destruction in New Orleans, which was ultimately caused by the collapse of the dam, clearly shows the possible consequences of a «small» underwater explosion in the «right» place. All doubts disappear when it comes to the safety of dams, reservoirs, hydroelectric power plants or nuclear power plants. And the approaching Olympics in Sochi poses the most serious challenges in ensuring coastal security.The integrated water body security system consists of several subsystems:
1) airspace security subsystem – solved with the help of local radars;
2) surface water security subsystem – solved with the help of a set of standard tools: video surveillance, thermal imagers, radars;
3) a subsystem for ensuring underwater water area security. Consists of intrusion detection devices and devices, means and measures to counteract intrusion (including active ones).
The last aspect of security is the most complex, firstly, due to the high level of potential danger (swimmers-saboteurs are a very serious threat), and secondly, because it requires the use of specialized equipment.
The leaders in the development of underwater water area protection systems are England (an island), the USA and Israel. Let us consider the classes of equipment intended for this purpose.
An example of anti-intrusion devices are the developments of Westminster International LTD (England) — Underwater Security Net and TSS (Israel) — F-8000-Marinet. These systems are mesh barriers with controlled structural integrity.
The Underwater Security Net consists of underwater and above-water parts, which are supported by polyethylene pontoons with a diameter of 40 cm. The height of the above-water part is 1.8 m, which allows blocking surface vessels, as well as attempts to climb over the barrier. The lower edge of the underwater part of the net is fixed to the bottom with concrete blocks, specially taken measures do not allow removing the blocks or digging.
Fig. 1 — Underwater Security Net barrier
The network is a cellular structure with 16 x 16 cm cells, created from special ropes (5 mm in diameter), consisting of a steel shell, internal protective layers and single-mode optical fiber.
Fig. 2 — Network fibers
The network is divided into modules 5 m wide, which allows for easy replacement of damaged sections. The electronic unit located at the top of the network monitors the integrity of the optical fiber within one module and, in the event of a break, sends an alarm signal to the central post. Remotely controlled gates can be installed to ensure authorized passage of floating craft into the protected area.
Fig. 3– Underwater Security Net barrier with integrated gates
The connection between the network devices and the post can be fiber optic or using WLAN. Special software allows real-time monitoring of equipment and provides the location of the break with an accuracy of up to 5 m.
Fig. 4 — Barrier monitoring program
The F8000 Marinet equipment has a similar structure and characteristics, but a more complex network control algorithm is declared, allowing to recognize attempts to cut, tear, stretch, short-circuit or crush the network. At the same time, the processor provides for filtering of background noise caused by sea waves.
It should be noted that, despite the attractiveness of such devices, they can be effectively used only in the absence of strong currents that can carry large debris (logs, etc.), and operation is significantly complicated if the water area freezes in winter.
Underwater intrusion detection equipment is a dynamically developing class of equipment. Acoustic devices (sonars) are the most widely used. Their operating principle is similar to the principle of detecting objects using conventional radar, but ultrasound is used to scan the space (frequency range – 50–90 kHz). There are several design options for underwater sonars.
The Sentinel Intruder Detection Sonar (IDS) system by Sonardyne International Ltd and the Cerberus system by QinetiQ use cylindrical emitter units (44 cm by 33 cm for the IDS system) that are submerged in water to depths of up to 50 m. The system includes: the emitter units themselves, signal processing modules, central control panel equipment and software.
The emitters can be submerged in water from a ship, a pier, or can be permanently installed on the bottom on special supports.
Fig. 5– Cerberus (left) and Sentinel (right) emitting modules
The transmitter module generates ultrasonic beams, receives reflected signals, digitizes the received data and transmits them to the processing module, which decodes the signals, analyzes them and sends them to the central monitoring station equipped with computers with special software. The structure of the system is illustrated in Fig. 6.
Fig. 6 — Structure of the Sentinel system
The maximum distance between the transmitter and the signal processing device is 10 km (using a fiber-optic communication channel). Communication between the processing modules and the central station is via Industrial Ethernet or WLAN technology.
The emitter controls the space of 3600 around itself, while the range can reach up to 2 km in the horizontal plane. Emitters can be used individually or combined into a single system to protect extended lines (up to 10 in the IDS system). Various options for installing emitters are given below.
Fig. 7– Options for the location of emitters for the protection of water areas
The small dimensions and weight of the emitter module (35 kg) allow the system to be quickly deployed in case of non-stationary use (the stated readiness time is 30 minutes). To prevent detection of false objects due to the emitter swinging (in case of fastening on a cable), special measures have been developed to compensate for its own movement.
At the central post, the information received is collected and visualized using special software, and the state of the protected water area is displayed on the monitors. The software automatically monitors the water area, detects objects, analyzes their degree of danger, and attempts to identify them. If the detected object is recognized as dangerous, the system calculates its coordinates, speed, and direction of movement, dimensions, and draws a trajectory of movement. The software allows monitoring up to 60 objects at a time.
To eliminate false alarms, the threshold values of the parameters, upon exceeding which the object is recognized as potentially dangerous, can be set manually. Protection against extraneous signals that may occur in busy ports is also provided. The area map can be integrated with the GPS system and Google Earth.
Fig. 8– Monitoring program windows
Another type of emitters is used in the Driver Detector Sonar system by Westminster International LTD.
Fig. 9– Emitter of the Driver Detector Sonar system
In a sonar of this type, only the receiving and transmitting antennas are located underwater, all other equipment is raised above the water surface. The antennas rotate with a motor, monitoring the space with a radius of up to 2 km with a vertical viewing angle of up to 980. The units communicate with the central post using WLAN technologies. Special algorithms for signal processing and filtering extraneous signals allow achieving a virtually 100% probability of detecting dangerous objects.
The capabilities of the operator's workstation software are similar to those described above.
Westminster International LTD also offers solutions capable of drawing 3D images of the bottom and systems for protecting underwater pipelines (one sonar covers 1 km of pipeline).
Fig. 10 – 3D image of the bottom obtained using Pulsar-3D.
The disadvantages of all types of sonars include low sensitivity to objects moving in close proximity to the bottom at low speed. In order to eliminate this disadvantage, magnetometric detection devices are used.
Magnetometric detection devices record distortions of the Earth's magnetic field in the event of ferromagnetic substances being located near the sensitive element (cable). An example of a system built on a similar principle is the Neptune complex of JSC NPK Dedal.
Fig. 10 –Neptune Magnetometric Complex
Magnetometric systems are passive, i.e. the fact of their operation cannot be recorded. The systems are most often used at extremely shallow depths, where the operation of hydroacoustic equipment is impossible or difficult. The advantages include a high degree of reliability, since the system is insensitive to marine mammals. The disadvantages include high susceptibility to electromagnetic interference and the fact that they do not allow the registration of «diamagnetic» intruders (without metal objects — in practice, such an intruder is extremely unlikely).
Integrated water area security systems also include underwater video surveillance systems, including mobile ones (cameras are installed on controlled underwater robots). The cameras are not only waterproof, but also very sensitive, since illumination is ineffective in water, especially polluted water. For the same reason, underwater thermal imagers are rarely used — IR radiation is strongly absorbed by water.
An acoustic warning system allows you to tell underwater swimmers that they have been detected and are being followed, and an active counteraction system (usually acoustic) allows you to remotely neutralize violators.
Examples of global integrated systems for ensuring the security of water infrastructure facilities include UPSS (Underwater Port Security System), UIS (Underwater Inspection System), IAS (Integrated Anti-Swimmer System).
Thus, based on the analysis performed, we would like to draw the attention of domestic manufacturers and installers of systems to the wide possibilities of underwater security systems and call for the creation and use of such systems at Russian facilities.
In preparing the article, materials from the official websites of the above companies were used