Systems, methods, and other embodiments associated with using a preamble with at least two polarity transitions to communicate over a power line channel are described. According to one embodiment, an apparatus includes a transmitter configured to transmit a communication signal on a communication channel for communicating with a remote device. The communication channel is a power line channel that carries electric power transmissions. The apparatus also includes a transmission logic configured to control the transmitter to generate at least two polarity transitions in a preamble of the communication signal.