Abstract: Indicator apparatus for determining the miss distance of a projectile in relation to a fixed or moving target, comprising pressure-sensing transducers intended to sense the pressure wave generated by the projectile in at least four points, and means for generating corresponding electrical signals therefrom. The apparatus further comprises computer circuits, calculating the distance to the point of origin of the wave, i.e. the so-called "bang generation point", in response to the characteristics of the pressure wave. This distance has been called the "miss distance" in previously known indicator apparatus, but in accordance with the invention the miss distance is defined as the shortest distance between the projectile and target, and one object of the invention is to indicate this distance and the exact position of the projectile when it is at the miss distance from the target.