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wide range of vessels expected to carry or tow sonars, from destroyers to corvettes and Offshore Patrol Vessels (OPVs), Mr. McDonald says. There has been a move away from Hull-Mounted Sonar (HMS) because of poorer acoustic performance compared to Variable Depth Sonar (VDS), and there is an increasing 'off-boarding' trend, he said, where sensors are placed on small, untethered surface vessels, requiring small, high-capability sonars. Thales has also observed an increasing demand for sonar capabilities on smaller vessels, because of the focus on littoral waters. “Nations are expanding their fleets of patrol vessels and corvettes to defend their sovereign interests in territorial waters and Exclusive Economic Zones,” a spokesperson said. “Such a trend is driving demand for smaller vessels to detect and deter underwater threats.” Beyond the increasing number of ships expected to be equipped with a sonar in the future, there has been a shift in the areas where submarines typically operate, from the blue waters of the ocean to the brown waters of the littorals. When coupled with the increasing threat, this limits the ability of ‘passive’ sonar systems and boosts the demand for ‘active’ systems, particularly low frequency active systems (which typically operate in the one to seven kilohertz/KHz band). This is because “the littorals have much more background noise, wave slap, tropical rain, snapping shrimps and vessel traffic, plus you are more likely to have obstacles in the way like islands and underwater structures,” Mr. McDonald explained. This background noise, and the quietening acoustic signatures of submarines, makes their passive detection more difficult. As such, the focus of ASW sonar will mainly be on active systems, the spokesperson from Thales told AMR. The company has observed that VDS technology is becoming the trend in ASW; when combined with an HMS, this forms a ‘sonar suite’. While VDS is an increasing trend for sonar design, the company spokesperson said that key recent technological developments include reliable access to low frequency sonar transmissions, which allow longer detection ranges due to less propagation losses in the water column. The Thales spokesperson also pointed to major improvements in signal processing; this has enabled the compan to expand its Adaptive Beam Forming (ABF) processing from submarine sonars to surface ship sonars. Thales
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Thales’ CAPTAS-2 towed array sonar is intended for use on medium-sized vessels. The company’s CAPTAS family of sonars, which also includes the CAPTAS-1 and CAPTAS-4, has been sold to several countries © Thales
Atlas Elektronik’s Active Towed Array Sonar System has recently been sold to the Indian Navy, with deliveries beginning in 2016. The low-frequency system allows observation of the sub-sea environment at ranges of more than 32nm © Atlas Elektronik
said that ABF allows an increased detection range and bearing resolution, and boosts the sonar’s resistance to noises in the ocean.
European Suppliers Regarding products, Thales’ divides its sonar suites into three broad groups, depending on the size of the ship. Its major products for smaller vessels are the CAPTAS-1 (Combined Active and Passive Towed Array Sonar) VDS and the BlueWatcher HMS. For medium-size vessels, it offers the CAPTAS-2 VDS and the Kingklip HMS, and for larger vessels, the CAPTAS-4 VDS and the UMS 4110 HMS. The company has signed deals for its CAPTAS VDS family with several countries, including France and Italy, where the CAPTAS-4 is used onboard the Marine Nationale (French Navy) and Marina
| november 2015 |
Militare (Italian Navy) FREMM (Frégate Européenne Multi-Mission / Fregata Europea Multi-Missione) European multi-role frigates. The same nations are also buyers of the UMS 4110 HMS, as is Morocco which operates the system on its FREMM frigates. The Kingklip system counts Indonesia (‘Sigma’ class frigates), South Africa (‘Valour’ class frigates), Morocco (‘Sigma’ class corvettes) and the United Arab Emirates (‘Abu Dhabi’ class corvettes) among its customers. Thales is joined as a European sonar supplier by Atlas Elektronik which recently enjoyed success with its Active Towed Array Sonar System (ACTAS), signing a $45 million deal in December 2014 to produce six of the systems for the Indian Navy, with deliveries beginning in 2016. ACTAS operates in the low-frequency range, according to the company, and
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