I am not sure I understand your question. I will try to explain how pulse generation works.

First, pulses can be generated by gobs of metal attached to various, unwanted, places on a pulley end disk or shell. A pickup magnetic head registers the flux increase as the sensor and gob get close. When the flux exceeds a set value a counter indexes the event and a timer counts till the next event. Knowing the distance between events, position of the event, and time between events a velocity can be calculated.

Second, pulses can be generated by a device called an analog or digital encoder.

I'll stick with the digital type. Metal or glass disks have very fine radial slots etched around the circumference to allow light to pass through, and an optical sensor will note the rise of a pulse event called the leading edge, followed by a fall of a pulse event, called the trailing edge (i.e. two pulses for the one slot). This can become a little fancier when two concentric slot groups populate the same disk. This is termed "quadrature" and the two rings of slots are called channels ("A" and "B" channels).

With quadrature we get 4 pulse counts and we can identify which channel occurs in specific sequence (i.e. A-A then B-B or A-B; A-B). With quadrature, noise immunity as well as pulse count increase aid in refining the signal accuracy and eliminate (filter) spurious noise such as walkie-talkies, motor contactor, bouncing contactors, and lightening RF signals et al. The noise filter is software programmed into the counting sequence. When the a channel is out of sequence, the information is discarded and the count starts over.

By counting the pulses and recording the time between pulses, we again can calculate speed of rotation and translate to belt speed and displacement.

There are many interesting technical considerations of these many devices which can be left to your imagination. ■