Patent ID: 7296358

Claim:
An apparatus for measuring and displaying a cant angle of a ballistic projectile launcher, said apparatus comprising: a housing mounted on a sighting device of a ballistic projectile launcher, the projectile launcher defining a cant angle in a y-z vertical plane and defining a launch angle in a x-y vertical plane, the y-z vertical plane being orthogonal to the x-y vertical plane; a microprocessor in communication with an electronic accelerometer, the microprocessor and the accelerometer disposed within the housing; and a vertical level indicator in communication with the microprocessor, wherein, the electronic accelerometer is adapted provide an accelerometer output signal that is proportional to displacement of the projectile launcher in the y-z vertical plane and independent of displacement of the projectile launcher in the x-y vertical plane, wherein, the microprocessor is adapted receive the accelerometer output signal and is further adapted to provide an illumination signal, the illumination signal being proportional to the cant angle and independent of the launch angle, and wherein, the vertical level indicator is adapted receive the illumination signal and is further adapted to provide an visual or audible signal to a user of the projectile launcher, the visual or audible signal having characteristics corresponding to the cant angle.