For Want of a Nail (or a bypass capacitor)

Indeed, noise on the IMU power line was the problem: while hooking up a bench power supply to the IMU (to isolate the IMU power from the Overo), I found that one of the leads of the bypass capacitor on the Pinto board had come loose. After fixing the solder joint (this time with a good, solid mechanical connection), the problem is gone. First, a plot of ten minutes of roll_rate after the repair (note how the plot is symmetrical around zero, and way smaller than the bad plot from the last post:

Updated stats:

	Factory	Quad	Quad, after bypass cap repair:
Roll Mean:	-0.78432	-0.63128	-0.77224
Roll STD:	0.14276	0.55705	-0.18555
Roll Max:	-0.4	1.04	-0.20874
Roll Min:	-1.4	-2.6	-1.3
Roll Rate Mean:	0.000353	-0.00224	0.000337
Roll Rate STD:	0.331451	1.89036	0.61565
Roll Rate Max:	2.635684	4.458878	2.8152
Roll Rate Min:	-2.92217	-8.58552	-3.637

Much better! While I was at it, I noticed that there's another problem: about 10% of our IMU readings have bad checksums. That's enough for concern, and might explain why our stdev numbers are still not as good as reading the IMU through a factory cable.

Shorter wires, ferrite beads?