MEOSAR is the new reference for Cospas-Sarsat system, relying on SAR payloads deployed on all GNSS constellations and MEOLUTs deployed worldwide.
The first two MEOLUTs (Florida, France) have been officially approved in 2016. However, first operational results have rapidly shown a performance degradation compared to LEOSAR when the beacon was moving. Since then, it evolved to take into account moving beacons, at first up to 2 m/s, and now up to 5 m/s (fast moving beacon in the near future).
Together with the addition of these requirements to better cope with beacon motion, it was necessary to define the way to test them in a controlled way, to support the commissionings and operational use. Up to now, 3 different means have been used: TURN-STYLE MECHANISM, DRONES or TESTS AT SEA.
The only identified alternative is to start with an initial common signal, and to transmit it to the satellites with different modifications for each beacon-satellite link. 
The objective of the study is to implement such feature using a Digital Beamforming Network (DBFN) array, which will adapt the beamforming so that only the target satellites will receive the needed shifted signal.