"Automatic aiming device for an anti-tank gun (ANPP) and universal receiver for synchronous angle transfer, D.M. Mojeys, D.I. Maryanovskiy, B.M. Kagan.
The concept behind the new solution is that the barrel of the gun does not follow the target, but remains motionless in a plane, which is crossed by a moving target. In order to strike the target, the gun must fire before the target crosses this plane. The advance timing must be equal to the time that the target takes to reach the plane. The speed of the target was calculated by the ANPP, the distance was entered by a control panel. The ANPP determined the time to fire, and fired automatically.
45 mm model 1937 guns were equipped with the ANPP, and were used for direct fire at enemy tanks. The device consisted of an ANPP device, an actuator mechanism, and a connector cable. The use of this device did not require any changes to the gun, it just had to be connected to the gun with connector cables and the actuator mechanism."