how it works:
(quoted from Atlas forum)
"DCC (Digital Command Control) operates on a square wave alterating current
signal divided into a units called packets.
The packet consists of a header (a signal to tell the decoder that this is the
start of the packet), the body (basically the command), and a trailing set of bits
at the end of the packet.
Each time the voltage goes from 0 to + back past 0 to - and back to 0 is called a bit. The decoder basically ignores the trailing bits of the packet (there is no information there, just AC current) "
Power for the DC motor is rectified from the track AC voltage.
Presumably the header also includes the loco address, since multiple
locos can be operated simultaneously.