Inside GNSS Media & Research

MAY-JUN 2018

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Page 38 of 67 M A Y / J U N E 2 0 1 8 Inside GNSS 39 ■ beacon can receive an activation command sent via the Galileo Return-Link • continuous power supply by the air- cra and a 24-hour autonomy at 406 megahertz thanks to the internal and rechargeable battery • The shape, size and weight of this ELT(DT) are similar to the standard ELT's already commercialized. Moreover, the designed solution offers a strong robustness to possible attempts in tempering the system with: • robustness to GNSS spoofing: the beacon independent locat ion is computed t hanks to t he beacon signa l cha racterist ics, indepen- dently from the message content or availability of GNSS onboard the aircraft, and specific spoofing detectors are implemented together with the beacon internal GNSS to ensure that such attempt triggers the SAR transmission. e beacon can then start transmitting in case of GNSS unavailability (jamming) or unreliability (spoofing), and will then be localized by Cospas-Sarsat MEOSAR independent localization, which will then become the only remaining solution to localize the beacon. To increase the gain of this capability, the beacon transmission implements the Second Generation Beacon waveform, which provides a more accurate in-flight independent localization • t he ac k now le d g ment f rom t he ground under the responsibility of RCC to avoid fake cancellation of a manually triggered ELT, to avoid ill- intentioned cancellation. In addition, human factors have become more and more important in recent years in the design of aeronau- tical systems, and the GRICAS project took these studies into account and implemented a manual acknowledgment from the cockpit crew to be requested in case of automatic activation by avion- ics, before the avionics send the cancel- lation command to the beacon. Thus, the pilots can confirm they are back in control of the flight in addition of the flight dynamics criteria characterizing a normal flight situation. From the beacon point of view, the Cospas-Sarsat ELT(DT) designed for the GRICAS project to comply to the Auton- omous Distress Tracking recommenda- tions is identical to currently commer- cialized and operated ELT's in terms of electronic components, mechanical and functional interfaces (with an additional interface for the automatic activation). However, this new ELT with Distress Tracking functionality benefits from a new design fitting with aeronautical ADT requirements: • It implements the new modulation, called Second Generation, of the Cospas-Sarsat system specifically

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