This and the sun killer missile from Generations made me wonder about something.
In the Cold War, we were used to being under the theat of missiles. So I figured that when growing up, the Feds and Klingons had warp capable drones that could accelerate very fast but would burn out. By the time TNG rolled out, we had merculite rockets. I assume Soren's drone would self-destruct from the strain after a few moments, but by then it had reached its target anyway.
So I am going to say the probe was placed in front of a starbases free floating communications array (a starbase isn't just a spacedock, but ground facilities under it, space elevators on the bottom, etc.)
This work scame before the soliton wave, but a modified torpedo drone type deal--was all that could be fired in this way--a one man subspace catapault of sorts.
In the old GEC, there was a Klingon version called venom lance or something.