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111 information. That enables the sonar to exceed widely recognised standards for feature detection bathymetric data point uncertainty, the company says. For bathymetry, it can operate at frequencies centred on 520 and 850 kHz, while for sidescan imaging operations it can use frequencies centred on 230, 520, 850 and 1600 kHz. Weighing 21.4 kg, the ‘ultra-lightweight’ version of the sonar measures 77 cm long, 33 cm wide and 34 cm high. The company also works with Norbit, which offers a range of light and compact wideband multi-beam sonar (WBMS) systems for bathymetry from USVs in shallow water. Its iWBMSh, for example, is a high-end turnkey system designed to operate in all conditions, including rough seas and under bridges. It features an integrated IMU and an NRTP client, which is a means of communicating differential GPS corrections to a GPS receiver. It features an 80 kHz bandwidth over a frequency range from 200 to 700 kHz and a nominal operating frequency of 400 kHz. Software capabilities include processing frequency modulated and continuous wave signals, several backscatter modes and a multi-detect capability that enables real-time detection of objects in the water column as well as on the seafloor. It also has an integrated sound velocity probe. With a sensor head assembly measuring 348 mm long, 227 mm high and 236 mm wide, the sonar provides swathe widths from 5 º to 210 º , along with a range resolution of better than 10 mm and between 256 and 512 beams. The EM 2040 is an established family of MBES sensors from Kongsberg, with the EM 2040P MkII for example representing the latest standard demonstrated on USV platforms. Available as a 200-700 kHz system, it enables the operator to choose the best frequency for the application, according to Kongsberg, such as 300 kHz near the bottom, 200 kHz for deeper waters and 400-700 kHz for very high resolution inspection. It also offers a 600 kHz wide area mapping mode in which it can achieve a swath width from 100 º to 120 º , while 700 kHz provides the sonar’s highest resolution within a swathe width of 30 º , the company says. It can also generate multi-frequency backscatter to improve characterisation of the seafloor. By changing frequency modes as it scans, it can provide backscatter from up to five frequencies in a single pass, Kongsberg says. Its large bandwidth enables a sample rate of up to 60 kHz, the company adds, and its ability to use very short pulses improves range resolution. For its shortest pulse, which lasts just 14 µs, Kongsberg quotes a raw range resolution of 10.5 mm. In terms of angular coverage in the 200-300 kHz range, the company gives a figure of up to 170 º . Accurate water temperature measurement is critical to the interpretation of sonar data, and RBR, which makes thermistor strings, is another of the sensor companies with which IM Solutions works closely. Thermistors are semiconductor Uncrewed Systems Technology | October/November 2022 The Torqeedo podded electric thrusters are high-torque, gear-driven units (Courtesy of IM Solutions/Christophe Le Potier) The EdgeTech 6205 S2 is one of a number of multi-beam sonars that can be mounted underneath the IM 3000’s hull, with access to sensors through the moon pool (Courtesy of EdgeTech)