i want to set up an airborne telemetry relay to allow me to maintain control a vehicle that is out of line of sight while doing search and rescue operations in rugged terrain. when doing a grid pattern in mountainous terrain often the searching vehicle is behind a hill or in a valley out of sight. what i want to do is install a second set of the 3dr telemetry antennas back to back on a second vehicle that would fly high above the search vehicle and relay the signal to the ground station to maintain tm contact. i am thinking a null modem between two antennas on the high flyer with one antenna linked to the search airplane and one antenna linked to the ground station would work. my question is - would that work? is there a better way to do what i want to do?