One other thing, the signal on the rails doesn't change at all for forward or reverse! The DCC decoder handles all that. It reads the commands from the command station then the processor in the decoder does the work, it reads the command and will reverse polarity when it is instructed to reverse. A DCC decoder is nothing more than a digital communication device and digital computer. It reads commands, in a specified communication protocol from the rails, then performs an action (basically a small microcontroller then does the action). It also has the circuity to perform the actions, like voltage regulator for output voltage or logic to turn off/on lines like to lights, etc. One more note. Let me clarify some things. Essentially DCC is not AC, because it does not have a negative combined voltage between rails. It is a square wave (not sinusoidal) from 0 to the top voltage ( can vary by scale from 12v-24v). Essentially embedded in that power wave is digital bits sent as phase changes, similar to Modems and other digital communication. However, that power is there and can be measured. If you use an AC meter it will be off by about 10-12% due to square wave vs sine wave. You really need an RMS volt meter. However, the reason it's not important is LionChief engines use a bridge rectifier anyway to convert AC to DC voltage, so any sine wave or square wave will be smoothed out to DC by the loco, as it really runs on DC. Yes, it can be confusing by I'm 99% certain that DCC power is perfectly fine for LionChief and engines.
Ted
