This one is the closest to your hangout in the NE quadrant of the Neon District. Walk into the blue light and listen to Moya describe some strange signals she's picking up near you. Look on your mini-map and find the blue triangle that pinpoints your objective; it is just on the next building on top of a round structure.
Collect the Dead Drops[edit]
Head over and climb the tower. You'll have to circle around to find the ledges that allow you to climb up. At the top of the tower is a satellite dish. Approach the dish and press 
to collect the Dead Drop. It's an encrypted audio recording; Moya needs more of them to break the encryption.
Press 
to activate a Radar Pulse and watch your mini-map. A gray circle will surround the map and gradually fade out. The last section of the ring to fade indicates the direction of another Dead Drop. From the tower where you got your first Dead Drop, the map points south.
Of course, there are Reapers in your way. You'll have to make your way across the square to a trapezoidal building near the bend in the railroad tracks. Climb to the top, take out the Reapers and find the small satellite dish on top of a structure on the building. Press to collect the Dead Drop and then press to search for another.
The trail points SE. From the building you are on, find the wire at the SE corner and run across, possibly taking out a Reaper on the other roof. As you cross the roof, you'll see this next Dead Drop is guarded by a whole passel of Reapers, some with shields.
You'll need to trade shots from this roof. There's plenty of cover if you need it and an electrical source for healing. It's difficult with your limited powers, but try to get head shots on the Reapers with shields. Once the Reapers are down, jump across and climb up to the satellite. Collect the Dead Drop and your mission is over.