Welcome to the last week of the inductive encoder project (as a part of HTMSTMaA. Getting to a state of a working encoder took some pretty abominable debugging/hacks (see video below), but the results are promising and I am excited to integrate it into a motor driver.
From the data last week it was clear that my sensor was saturating with copper present (see how it flatlines on the low end in the screenshots from that week). To remedy this, I started by trying to simply increase the air gap between the coils and the copper target, but found that the coils were so sensitive to the increase in axial distance (axial sensitivity is tied very closely coil diameter) that the SNR penalty from increasing the air gap made this a non-factor. So instead what I needed to do was increase my pole count to the next multiple of 12 from 6, so 18. With a given Sin/Cos coil spacing (in this case for me it's 75deg). Jumping to 18 targets was slightly more than optimal, but I was able to resolve a much more sinusoidal signal after doing it, with plenty of resolution between the high and low copper-present peaks.
