Abstract: A combined data and power transmission arrangement has one or more power supplies and loads interconnected by a power transmission line, with transmitters and receivers for transmitting a digital data signal over the transmission line. The transmitter and receiver each include an inductor for providing a high impedance barrier to a data signal on the line, so as to isolate the data signal from the power supply and load. The receiver includes circuits for tracking the mid-point value of the data signal to produce a threshold value, and for comparing the threshold value with the data signal to produce an output signal. The threshold value is a controlled positive feedback signal derived from the output of the comparator by way of a positive feedback loop having a time constant approximately equal to the time constant of the transmitter.