Company : Polyamp AB

Category : Navy

Subcategory : Stealth, Signature Reduction and Materials

Key Products : Significance of Electromagnetic signatures in ships and submarines

Polyamp was founded in 1966, producing switch mode DC/DC converters. This has lead Polyampto develop the first digitally controlled degaussing loop coil amplifier in the world, in the year 1982. They are still fully operational in all RSwN vessels. During the 90s, Polyamp expanded its marketing to international markets. In the end of 90s, an exclusive license on Carbon Fibre sensors where acquired. Together with SWECADE system, Polyamp can now design, install and range any type of degaussing system.

Some of the products include underwater electric potential sensors, electromagnetic signatures on ships and submarines, magnetic signature management, magnetic sweep supplies etc.

Electromagnetic Signatures

Significance of Electromagnetic signatures in ships and submarines

The importance of Electromagnetic signatures in ships and submarines can't be ignored given the current defence scenario.

The magnetic signature has for a long time been successfully used as the trigger in torpedoes and moored mines. In subsequent years, the magnetic signature has been used in combination with another electromagnetic signature called Underwater Electric Potential UEP,which in proximity of the vessel has a similar trigging capacity as the magnetic field.

Sensors for these electromagnetic signatures can easily be used in underwater weapons and related countermeasures on-board naval vessels must therefore be a part of the vessels self-defence.

Degaussing systems

A Degaussing system minimizes the Magnetic influence of a vessel – or in other words – the magnetic signature. A Degaussing system is a challenge to design and install for a shipyard and understanding the need for the extra weight and power consumption.

The Degaussing system consists of cables along the hull in Vertical, Longitude and Transversal directions, producing counteracting magnetic fields in three directions. Those cables are powered by computer controlled coil amplifiers distributed around the ship. Depending on the design up to 90% of a vessels Magnetic influence can be suppressed on water depths where underwater weapons are effective.

Polyamp Systems Division specializes in the design, manufacture and supply of on-board Degaussing systems for ships and submarines. Polyamp offer customers complete turnkey systems package over the time from an agreed signature demand, via equipment delivery, to the signature fulfilment trials. Polyamp have experience from small non-magnetic hull ROV to the largest steel hull Navy vessel, the CVN77 as well as conventional submarines.

Signature Management

Magnetic Signature Management

Once a vessel is delivered and approved at the first magnetic ranging it needs to come back regularly to the range and fine tune its Magnetic signature. If not, the signature will deteriorate and be a hazard for the vessel and its crew, in case it enters lethal waters. In addition to this the MCMV activities will have to be longer as larger margins are needed, which result in delaying the Navy’s operational activities. That is also the reason for all vessels in a Navy to have well-conditioned on-board Degaussing systems that is continuously in operation.

Polyamp can provide multisensory measurement system based on the sensor platform UMISS©MkII that can be used to build an Open Sea fixed measurement range. Then the ships acoustic, magnetic, electric, pressure signatures can be measured and managed. The SWECADE software package integrates magnetic coil design with prediction, measurement and analyse with new degaussing value settings that are made very fast. All measured signatures are stored and supports the use of a structured documentation and reporting system. The SWECADE can handle the design and analyse of both non-magnetic and steel hull vessels.

The UMISS MkII can be configured as a transportable measurement system, with different methods to transfer data between the sensors and the operator. Double encrypted WLAN, underwater Ethernet and optical fibre cable solutions all available and proven. For use with a single UMISS MkII where SWECADE is not optimal a versatile alternative data acquisition system and analysing software is available.

Electric Potential Sensors

Underwater Electric Potential sensors

Underwater Electric Potential sensors UEP are produced by cathodic currents in the ship or submarine hull and also from propeller or other dissimilar metallic materials mounted on the hull and in contact with seawater. The UEP field structure is similar to the magnetic as it creates dipoles. The ELFE (Extra Low Frequency Electromagnetics) signal of electric field can detect a vessel at distances of nautical miles even in environments that is very difficult for acoustic methods. The Polyamp Carbon Fibre (CF) sensor is very robust and does not need any special care at shore or during deployment and even so, it is not the sensor but the amplifier (noise level) that decides the sensitivity of a measuring system.

Electromagnetic Sweep

Mine hunting is today focusing on forward looking methods and UAV and the legacy type of towed sweeps has not been designed for years. The smarter weapons are however requiring sweep sources with ship like dimensions. The state of the art sweeps on the market are based on floating electrodes with high current and power which gives magnetic field output but creates enormous UEP fields which a simple weapon sensor can classify as a mine sweep activities and shut-off the mine. Polyamp created the versatile MSS2000 power supply system for such electrode sweeps end of 1990-ties.

In 2013 Polyamp made a design study for a closed loop Electromagnetic Sweep that creates ship-like electromagnetic signatures for vessels of up to 150 m, which represent the majority of the worldwide Navies fleet. The power needed is a fraction of an electrode sweep which means that the power can be accommodated in a smaller RHIB or vessel of opportunity. Using several of those sweep systems will make efficient sweep operations using an MCMV as a mother vessel.

Contact Details

Polyamp AB
Tingsvägen 19, 8th floor
191 61 Sollentuna
Phone: +46 8 594 69300
Fax: +46 8 594 69305