Help for VR sensor signal conditioning (variable reluctance signal conditioning)
Use a comparator with hysterisis. 

Hysterisis allows it to trigger in one direction on an input pulse but when that input pulse returns to "neutral" (or midrail or 0V whatever it is), the output of the comparator remains triggered until an opposite input pulse comes along and takes it past the opposite hysterisis threshold. Then the comparator output toggles to the other direction.

What I'm describing is reversing the effect of a high pass filter. Here's what a high pass filter does to a square wave: -



All my suggestion does is use thresholds to recreate the square wave from the differentiated signal caused by what is likely to be an inductive proximity sensor (they tend to differentiate the magnetic fields and produce this waveform). Here's what the differentiated pulse looks like superimposed on the original sq wave: -