I’m working with a traditional VR (variable reluctance) sensor that is used to measure RPM and serve as an angular reference point of an engine. It produces one pulse once per revolution on an engine that is running at say 240 RPM (or 4 pulses per second). The amplitude of the sensor ranges from about 5 volts (peak to peak) to about 15 volts (peak to peak).
I’m trying to think of a relatively simple/elegant way of determining if the signal coming off the VR sensor is starting on the upslope and going positive first, then going negative, or vice versa. See drawing to get the idea.