Contrary to popular belief, the radar mentioned in the this achievement is not the one you obtain by getting a 3 kill streak. On the map, there are 3 military style tents to the right of the bridge. Inside the central tent (across from the river) there is a console with a world map displayed on a glass screen.
You need to press X on that console, and doing so will cause the lights on it to turn from green to red. While the lights are red, you then need to kill all members of the enemy team.
Only the person who activates the console can go for the achievement. Once the light turns back to green, another player can activate the radar and attempt to meet the requirements.
Goodluck and happy hunting!
Edit: As reported by a few gamers that this achievement is a little buggy and could unlock if you activate the station and then get the first kill of the match.