Muzzle position sensor

Claim 1

In a military vehicle having a main gun, improved means for detecting gun muzzle deflection comprising a pulsed infrared light beam source on the gun near the breech end of the gun; a reflector mounted on the gun muzzle to receive the light beam and reflect same back toward the breech; a detector (36) mounted on the gun near the gun breech in the path of the reflected beam, whereby the detector senses changes in the direction of the beam caused by muzzle deflection; said detector comprising a depletion-mode linear photodiode sensor having four output terminals U, D, R and L oriented, respectively, directly above, directly below, directly to the right, and directly to the left of the detector optical axis representing zero muzzle deflection; first amplifier means (44) connected to the U and D terminals to develop a first light detector signal (46) representing the difference between the U and D outputs, and a second reference signal (48) representing the sum of the U and D outputs; second amplifier means (50) connected to the R and L terminals to develop a third light detector signal (52) representing the difference between the R and L outputs, and a fourth reference signal (54) representing the sum of the R and L outputs; means (60) and (62) for dividing the first and third detector signals in two; a sample and hold unit (56) receiving each of the two light detector signals and two reference signals to produce time-staggered signals; a multiplexer (64) receiving the time-staggered signals for simultaneous transmission thereof; an automatic gain control receiving the multiplexed signals for adjusting the two light detector signals up or down inversely according to the absolute values of the second and fourth reference signals; and circuit means for applying the adjusted first and third detector signals as corrections to a main gun ballistic computer.