[Chemist_Geek]

First, it would be *really* hard to vibrate a mass large enough to produce any non-trivial amount of gravity.

Then, how would one modulate the baseband? Or would we have to use CW?

[RightWhale]

how would one modulate

Mass has to move. Perhaps a rotating double star would give off CW strong enough to detect. Perhaps Jupiter is massive enough and close enough for the instrument to pick up something.