How I had gotten stop the signal was I did the SS Azure mission, then the Diplomatic Mission, then Hide and Seek, and that's when Starfleet finally gave me the Stop the Signal mission...I got to become a Klingon at level 5 with the completion of that mission. Otherwise you have to wait for 6th.
isnt "stop the signal" that broken quest that wants you to plant charges but you cant?
Its a multiple sector mission...scan the signal beacon, warp out, scan unknown object in nebula, beam to klingon base, retrieve data, help klingons kill an Undine. They let you live this time....all done.