A data transmission system includes a sender, at least one receiver, a sender controller, and a receiver controller. The sender controller receives an AC signal from an AC power source via a first AC input port, receives data from the sender via a first data port, and processes the received AC signal according to the received data, and outputs a processed AC signal via a first AC output port. The receiver controller receives the processed AC signal from the sender controller via the second AC input port, powers the at least one receiver using the processed AC signal via the second AC output port, and converts the processed AC signal to corresponding data and transmits the data to the at least one receiver via a second data port.