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7 Platform one A new generation of transponder design can reduce the power consumption of transponders to integrate smaller UAVs into air traffic control (ATC) systems and avoid overwhelming the 1090 MHz frequency band (writes Nick Flaherty). “The challenge is keeping every aircraft safe when you have potentially tens of thousands of unmanned aircraft in the air,” said Tom Furey, CEO of Sagetech Avionics, the company behind the design of the MXS transponder. “Transponders have always been part of safe airspace management, and can certainly help assure the safety of unmanned aircraft as well.” There are concerns that the 1090 MHz band, used for ADS-B, will be overwhelmed as more UAVs start using airspace. “Normally a transponder transmits at its full output power, of 54 dBm, which can overwhelm the frequency spectrum if not managed correctly. Our MXS Mode-S transponder design can dynamically vary that power output from 57 dBm, which is 500 W, down to 9 dBm, which is less than 10 mW. “Reducing the power will limit the range of the transponder, but the transmission range needed to maintain safe distances between UAVs is much less than most manned aircraft since the speed and mass of the UAV are a whole lot less,” he said. “That 0.1 W output limits the range of the transponder, but the range required for UAVs is much less than for most manned aircraft, as the speed and mass of the UAV are a lot less,” he said. This variable power management could be used with modified air traffic control procedures to further protect against spectrum congestion. The existing Mode A and C ADS-B transponders are ‘all call’ broadcast systems; with Mode S they can interrogate individual aircraft and avoid overwhelming the band. “The technology exists today in both aircraft and ATC hardware, so reducing spectrum usage would simply be a matter of procedure,” he said. Sagetech’s CTO Matt Hamilton added, “Low Size, Weight and Power [SWaP] transponders are available now, and they can be installed on UAVs down to 20 lb [8 kg]. With reduced power output, and decreased use of Mode A/C interrogations, UAVs could safely integrate into air traffic control systems today. “Since much of a transponder’s real estate is determined by power output, lower power transponders could reduce SWaP further to provide longer flight endurance and allow for installation on even smaller platforms. “We have included the technology to not only control power but also to transmit various modulation schemes – PPM, MSK and PSK – over a wide frequency range, of 1030-1090 MHz. “The modulation schemes could also further reduce spectrum use by packing up to 16 times more data into a single ADS-B transmission. This technology can meet new phase-overlay requirements being considered for the next revision to ADS-B standards as well,” he said. Seegrid has developed an autonomous warehouse system that uses automatic charging (writes Nick Flaherty). Its GT10 Series 7 Plus vision-guided vehicle (VGV) has been redesigned to accommodate this. The VGV uses 10 cameras with stereo inputs that collect and interpret thousands of data points every second to create a 3D map of its environment. The map also feeds into machine learning algorithms that can be trained on the factory floor. The new version of the VGV uses auto- charge technology that is integrated into Seegrid Supervisor, the company’s fleet management software. This monitors the vehicle’s battery levels, automatically sends vehicles to charging stations, and schedules vehicles to return to production once a full charge is reached. The system can be retrained for different routes around the factory without the need for Seegrid engineers to identify the charging points and train the system. That allows the VGV to be deployed in minutes for different functions or shifts. The tow tractor on the new version also has a shorter mast structure to accommodate facilities with height restrictions. It comes as standard with auto- hitch capabilities, and adds reverse sensing. “The GT10 Series 7 Plus removes the need for human assistance to complete the hazardous task of battery maintenance,” said Jeff Christensen, Seegrid’s vice-president of product. Transponder can vary its output Warehouses’ auto-charge Airborne vehicles Ground vehicles Unmanned Systems Technology | April/May 2020 The MXS transponder is aimed at UAVs of more than 8 kg but is also being made smaller for those weighing less A new self-learning algorithm adds autonomous charging to factory systems