Synchronization of Signals Transmitted Over Power Lines

A transmitter having: an oscillator to generate a clock signal and synthesize frequencies for modulating a message to generate first signals to a first direct current power line, and a control circuit to adjust timing of the first signals in synchronization with second signals transmitted in a second direct current power line disposed in a vicinity of the first direct current power line, by synchronizing phase of the first and second signals or by transmitting the first and the second signals in separate time windows.