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76 T he Defence and Security Equipment International show is a major military exhibition held at London’s ExCel in odd-numbered years, and it attracts many unmanned platform, payload and subsystem manufacturers and suppliers. At the 2019 event, in September, GNSS-independent navigation systems, optronic sensors and robust comms systems caught our eye, as did new and updated unmanned helicopters, EOD ground robots and underwater vehicles. EMCORE showed its latest range of inertial measurement units based on its own fibre-optic gyros (FOGs) and quartz MEMS technology from its recently acquired subsidiary Systron Donner Inertial, emphasising improvements in cost, size, weight and power for navigation applications, particularly in GPS-denied environments. Taking the new EN-2000i for example, Dave Faulkner described it as a full- featured navigator that is similar in performance to current units that go into helicopters and jet fighters but is one- third the size, weight and power draw. It is a three-axis, closed-loop FOG using a patented transceiver that features fibre optic coil diameters optimised for high- precision navigation, which measure angular displacement, and three quartz- based accelerometers. In laser-based inertial systems, the length of the enclosed path around which the beams travel is critical to stability, he said, which is limited in ring laser gyros (RLGs) by the practical size of the device. However, fibre-optics allow a much longer path to be packed into a small space in a FOG. “With fibre gyros you can wind almost as much fibre as you want,” he added. “We have the potential to get to the strategic- grade navigation capability with ours.” He emphasised that FOGs compete directly with RLGs but offer greater bandwidth, making them better for December/January 2020 | Unmanned Systems Technology Peter Donaldson reports from this year’s defence and security show with highlights of some of the unmanned systems now on offer Fighting fit Navigation systems, advanced sensors, robust comms systems and innovative air, sea and ground vehicles all made appearances at DSEI 2019