Patent ID: 7102490

Claim:
An apparatus for transmitting data to a distribution substation, wherein the distribution substation is configured to receive encoded data in a power signal on a distribution line in a power distribution network, the apparatus comprising: a transformer that includes a primary winding that is coupled to the distribution line and a secondary winding that is coupled between a first node and a second node; a half-bridge drive circuit that is configured to selectively assert a first drive signal and second drive signal in response to a control signal; a first driver that is coupled between a first power-supply node and a common node, wherein the first driver is arranged to couple the first power-supply node to the common node when the first drive signal is asserted; a second driver that is coupled between the common node and a second power-supply node, wherein the second driver is arranged to couple the common node to the second power-supply node when the second drive signal is asserted; and a resonant circuit that is coupled between the first node and the common node, wherein the resonant circuit has a natural resonant frequency in an audio frequency range, and wherein the half-bridge driver is arranged to selectively activate the first and second drivers such that the distribution line is modulated with a square-wave signal at a frequency that is associated with the encoded data.