Magnetic pickup speed sensor
What could be the meaning of &quot;8P&quot;, &quot;10P&quot; and &quot;16P&quot;? Are these the poles of the reluctor?

Standard spur gears are used as 'reluctors' with variable reluctance pickups, in order to generate sinusoidal output signals.
8P, 10P, 16P are not the number of poles of the reluctor. They signify its Diametral Pitch (the number of teeth per inch of its pitch circle diameter). Diametral Pitch is a measure of the size of its teeth (smaller the number, greater the size).
The graphs, for a pickup having a specific sensing diameter, show a drastic increase in output voltage with an increase in tooth size from 16P to 8P.
The unit of 'Surface Speed' of the reluctor, on the X-axis, is 'inches per second' (IPS).