is decelerated by aerodynamic drag projectiles are commonly designed to produce minimal drag as a result the deceleration in the axial direction is fairly low in addition there may also be components of vibratory motions present in the axial direction axially oriented piezoelectric based power generation units 100 can also be very insensitive to lateral accelerations which are also usually fairly small except for high spinning rate projectiles when impact occurs assuming that the impact force is at least partially directed in the axial direction the piezoelectric elements of the power generation units 100 experience the resulting input impact including the time of impact the impact acceleration level peak impact acceleration force and the total impact impulse as a result the exact moment of impact can be detected and or calculated by the processor 208 from the output of the power generation unit 100 in addition when desired lateral impact time level and total impulse may be similarly detected by employing at least one such piezoelectric based power generation unit 100 in the lateral directions noting that at least two piezoelectric power sources directed in two different directions in the lateral plane are required to provide full lateral impact information alternatively a single power generation unit 100 can be provided which is aligned offset from an axial direction so as to have a vibration component in the axial direction and.