Electronic velocimeter having an oscillator coupled coil for measuring projectile muzzle velocity

Claim 1

In an electronic velocimeter for measuring muzzle velocity of a projectile exiting the muzzle of a weapon along a given trajectory, comprising: p1 sensor means which includes; an annular conductive shield axially aligned in front of and spaced from said muzzle; a conductive coil insulated from and operatively mounted between said muzzle and said annular conductive shield, said conductive shield and said conductive coil each concentrically encircling said trajectory; oscillator means electrically coupled to said conductive coil, for generating electromagnetic radiations from said conductive oil, said oscillator means being inductively responsive to passage therethrough of said projectile, for producing localized eddy currents on a metallic surface of said projectile as said projectile moves through said conductive coil, said eddy currents inducing secondary electromagnetic fields which cause a loss due to change in impedance transformations of said conductive coil and modulates the amplitude of an output signal of said oscillator means to be proportional to the geometric shape of said projectile; timing means for shaping the amplitude of said output signal of said oscillator means and operatively connected for producing a timing signal representing the transit time for said projectile to pass through said sensor means, said timing signal varying inversely proportional to the length of said projectile divided by said projectile muzzle velocity, which includes; logic means for producing a single output pulse having a leading edge which coincides in time with a first point on said projectile as said projectile passes said sensor means and a trailing edge coinciding in time with passage of a second point on said projectile passing said sensor means.