Autopilot Voltage Follow-up

Some of you may recall that I ran some tests this summer to collect voltage data on Silence's autopilot. I finally got around to plotting the data this week, and there are some interesting results. This all began because I suspected that I had a power problem because the autopilot would randomly shut down and reset itself, and drop off course. It turns out that the problem was caused by a loose connector on the back of the control unit, but I didn't figure that out until after I had built a data logger and collected this data. In the diagram above you will see that we start out with the engine off and the autopilot in standby. Shortly afterward, the engine is turned on and you can see the voltage rise as the alternator charges the batteries. (The straight line represents a period for which there is no data as I stopped logging to save space on the SD card.) Next, with the engine on, I started the autopilot and you see the noise on the signal increase. Later, the same cycle is repeated, engine off, engine on, autopilot on, autopilot off, and then at the end, engine off, and power turned off.