A radar system has look-down/shoot-down capability if it can detect, track and guide a weapon to an air target that (as seen by the radar) is silhouetted against the ground. Problem and naming Airborne intercept radar relying exclusively on time domain radar techniques is effectively blind any time the radar's antenna is aimed towards the Earth's surface. That is because pointing the radar at the ground produces a large reflection. That reflection and the ensuing "cluttered" display overwhelms human operators and computing systems (see ground clutter). Radar systems of this type are essentially useless when pointed ‘down’ at the surface, with the zone of weakness near and below the horizon. This zone can be actively utilized by enemy combatants wishing to hide from radar tracking utilizing a technique known as terrain masking. Frequency domain signal processing combined with time domain signal processing, as in pulse-Doppler radar, is a way to eliminate that vulnerability. Look down Militaries require performance of airborne intercept radar under all aspects, including downwards. By using techniques to effectively remove clutter, human operators and computers can focus on targets of interest. This allows the radar system to "look down", and that eliminates the zone of weakness. Military air combat vehicles that lack this capability are blind to attack from below and along the line of the horizon. Shoot down Once the radar can "look down", it is subsequently desirable to "shoot down". Various weapons systems (including guns and missiles) are then employed against designated radar targets, either relying on the aircraft's radar employing the "look down" capability (as in semi-active radar homing) or the weapon's own active radar to resolve the indicated target (as in active radar homing). Concept The technical challenge encountered by airborne radar is discerning relatively small radar returns (e.g. other aircraft, targets) in the presence of large radar returns (e.g. terrain) when the radar is pointed at the ground, "looking down". The ground strongly reflects the radar energy while the target relatively weakly reflects the radar energy, creating confusing clutter on the radar screen. It is difficult or impossible to separate the radar image of low-flying aircraft from the surrounding ground clutter. Look-down/shoot-down radars have been enhanced with electronic programs that process the radar image and search for moving objects, which are detected by looking for Doppler shifts in the radar return. See moving target indication. The radar removes all stationary objects (e.g.