I don't know if this question is related to DSP, but I'll give a chance.
Introduction: These days there are a Guitar Synthesizers which allow the guitarist to play another instruments like: brass, drums, strings, pianos and other guitar models from his guitar.
It possible to turn any guitar with the MIDI Pickup, that sends the all data that the synth needs. Now, from what I understand the pickup turns the guitar into MIDI one.
My question is how a signals like those that the guitar makes can be converted into MIDI instructions ?
There is a sampling before this conversion? I think that it should be, because if not. How the Synth will know in which level (volume) or duration to produce the sounds?