Apparatus and method for calculating muzzle velocity

摘要

Apparatus for measuring projectile muzzle velocity with an accuracy of +/-0.1% is mounted in an easily portable muzzle attachment. It operates in the following manner. A washer shaped permanent magnet is positioned on a projectile body. A position sensor containing two inductive coils is located inside the muzzle. When the projectile is fired, the magnet mounted on the projectile passes through the inductive coils, inducing a voltage in each coil. Each voltage is amplified and then fed into hysteresis and zero crossing comparators corresponding to each inductive coil. The zero crossing comparator detects when the induced voltage crosses zero. The hysteresis comparator will gate out any noise induced zero crossings. The two zero crossings are used to start and stop a digital counter which generates a velocity count signal that corresponds to the velocity of the projectile. Further noise interference rejection is obtained by encasing the muzzle extension in a magnetic metal.