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55 calibration-free system, and shallow water and omnidirectional performance.” Anticipated applications include providing navigation and localisation in renewable energy inspections and marine civil constructions, down to depths of 995 m. The Gaps M5 measures 29 cm in diameter, like its predecessor, and is 52 cm tall – 11 cm shorter than the M7. Rather than relying on an external motion sensor to improve its accuracy beyond 0.5% of slant range, it incorporates an iXblue Octans Nano AHRS, using a FOG as an internal source of inertial data. “No calibration at sea is needed thanks to the internal FOG, making it easy to use and even more cost-effective,” Urvoas added. “The Gaps M5 also provides a web- based man-machine interface, allowing command & control from any computer connected on the same network. This is a key benefit if users want to install remote control on a USV.” The M5’s design features the same four 3D antennas as its larger predecessor, although it can operate using three if one is damaged by floating debris. iXblue also provides modular replacement legs as spare parts for ease of maintenance. The SeapiX-C is a real-time static sonar for high-precision marine works such as bathymetric surveys or monitoring underwater structures from stationary positions. It can be mounted on USVs, autonomous buoys or other vessels. It consists of two antennas, both of which can transmit and receive, and each of which consists of 64 elements for generating up to 256 beams per swathe, each beam having an aperture angle of 1.6 º . This enables it to scan a volume of 120 º /120 º without any moving parts for pan and tilt, with coverage of areas up to 10,000 m 2 at depths of 30 m. It operates at a frequency of 150 kHz and integrates a MEMS-based motion reference unit for further accuracy in 3D reconstructions, although it can also interface with the user’s choice of external INS or AHRS. “Construction sites with hydrographic vessels sailing around or divers inspecting the seabed can pose risks to human workers,” Yannick Le Doze noted. “The SeapiX-C’s scanning volume though means it can replace a hydrographic vessel or diver in some areas, decreasing those risks and speeding up the survey process. “It is available in a 70 kg stainless steel format for rough environments and permanent installation tested on fishing vessels, or in a 24 kg composite version for short operations and easy deployment.” Kongsberg Maritime announced the commercial availability of its EM 304 Mk II, a new multi-beam echo sounder developed for high-resolution oceanographic mapping at all ocean depths. It has also been engineered for greater swathe widths and wider frequency bands than its predecessors, the EM 304 Mk I and the EM 302. As Gunvor Hatling Midtbo told us, “While most of the ocean is not so deep as to require full ocean depth capability, the physics determine that you need to choose between an optimal resolution for most ocean depths or a lower resolution and the ability to reach all depths. “With our new wideband transmitter technology, however, the EM 304 Mk II allows you to maintain a higher resolution while still reaching the deepest parts of the oceans.” The EM 304 Mk II’s swathe width is 75% wider than the 6000 m width of the Mk I and EM 302, and its operating frequency ranges from 20 to 32 kHz. In dual-swathe mode it emits up 1600 beams per ping, with beams actively stabilised to ±10° pitch and yaw and ±15° roll. For missions directed towards the coldest parts of the ocean, the echo sounder’s transmit and receive transducers can be fitted with ice protection windows specially made to withstand crushing by ice when surveying in, say, the Arctic or Antarctic. Elwave told us about its unique ‘electric sense’ technology, which it uses for marine navigation and 3D surveys. “More than 10 years of research by the bio-robotics laboratory at the Institute of Mines-Telecom Atlantique went into electric sense,” explained Jean-Marie Lapasset. “Inspired by the sensing Oceanology International 2020 | Report Unmanned Systems Technology | February/March 2021 Kongsberg’s EM 304 MK II multi-beam echo sounder