Any of the VARA modes will run over FM link , during testing , with local station on 6 metres , who , was suffering from solar panel qrm , during the day, 'we found that switching to FM gave a significant speed improvement
VARA-FM , has ' No Afc' , as is not needed for fm link , as the recovered tone range is not affected by the transmission , Hence 'designated 'fm' But , variations on the theme , could be AM , or pilot tone ssb ? the FM mode has much higher tolerance to switching times , to accomodate repeater usage , so, yes , will be ideally suited for MARS usage ,
Considerable work was carried out , modifying the vara-hf mode to vara-sat , to use with the ao-100 satellite , providing a ping system, that measured the frequency off set and the link 'round' delay time.. the tests where posted to one of the amsat groups , not sure if the ground station remains active ?
nb: this version , could be used for any transmission path, I don't think there is a minimum delay ..