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59 provide an exact frequency reference.” When a GPS signal is available, it provides a reference signal to ‘discipline’ the oscillator in the clock, which means using a tracking loop to match the clock output signal to the GPS input signal. As satellite navigation signals are central to Spectracom’s work, the company has developed a range of GNSS simulators (the GSG product line) to mimic satellite signals, and tools for developing new products and to assess the effects of interference, including jamming. “You can create an interferer and simulate the effects of that on the GPS receiver, so it is really testing the robustness of your system,” Sasaki said. Ceramic bearings manufacturer CEROBEAR is new to the unmanned vehicles sector but has a firm foothold in sensor gimbals, which require thin bearings that accommodate low-speed precision movements. The company also offers advanced bearings for aerospace and industrial high-tech applications in general. The company’s general manager, aerospace Europe, Bernd Reuter, and aerospace project engineer Katharina Norta outlined the case for hybrid bearings, combining steel rings with ceramic ball or roller elements. The aerospace industry has shown some reluctance to use non-metallic materials in bearings because of concerns over the difficulty in detecting wear debris with magnetic plugs. However, Reuter stressed that such worries are misplaced. “It has been proved,” he said, “that the ceramic elements are not the weakest link of any bearing. If wear starts, you will always pull material out of the rings, which will then be detected.” Hybrid technology offers longer bearing life for applications in marginal lubrication conditions such as in helicopter transmissions, which must run for 30 minutes after lubrication failure. Reuter said CEROBEAR wants to extend this ‘run dry’ endurance to a matter of hours. He said bearings survive much longer after lubrication failure if they combine metal and ceramics, because the ceramics are chemically inert. “There are no free electrons on the outside of the atoms,” he explained. “And then you have no cold welding between the two materials.” Norta pointed out that in applications where there are extreme temperatures or out-gassing problems – in space, for example – ceramic and hybrid bearings can be run at low speeds and loads without lubricant. At higher speeds and loads, lubrication is advisable even for hybrid or ceramic bearings, she said, because without it there is direct contact between the race and the rolling element. “So failure is DSEI 2015 | Show report Unmanned Systems Technology | Dec 2015/Jan 2016 The Geo-PNT contains a GPS/GNSS receiver, an IMU and highly accurate clock CEROBEAR says hybrid steel-ceramic bearings offer longer bearing life in applications such as helicopter transmissions