Method and apparatus for communication over electric power lines

An apparatus for transmitting intelligence in a direction from load to source over an electric power line having a voltage wave thereon and supplying current to at least one load said apparatus comprising:

• (1) means for adding to the load current on the line a recognizable pattern of signaling currents in synchronism with the power line voltage wave, said pattern of signaling currents representing at least a portion of the intelligence to be transmitted;
• (2) means for sensing the line current comprising the combined load and signaling currents on the line and generating in response thereto a corresponding pattern of signals having a characteristic which is a function of the sensed line current;
• and,
• (3) means for extracting the transmitted intelligence from the sensed line current, said means for extracting the intelligence including means for processing said corresponding pattern of signals in accordance with an algorithm which commences in synchronism with the pattern of signaling currents and which operates on the sensed line current in opposite senses at different positions along the voltage wave with the sense at any one of said positions being determined by the synchronism and with each element of intelligence in the pattern of signaling currents being inferred from the polarity of the signal resulting from said processing.

A method for transmitting binary intelligence over an energized, AC power line having at least one load thereon in the direction from load-to-source wherein, by prior arrangement, a transmitter and a receiver recognize the two cycles of the power line voltage sinusoid that define the pair of cycles used in the representation of each bit of intelligence, and wherein each bit of intelligence is represented in the form of discernible difference between samplings of current effected by integrating the current throughout corresponding intervals in each cycle of the compared pair with the sign of the difference denoting the one/zero value of the binary bit, said method comprising the steps of:

• (1) drawing signal current from the energized power line at a transmitting site to produce a signal waveform which is the same in the two cycles of the pair except within corresponding intervals contained within at least one preselected quadrant of the power line voltage sinusoid where the signal current is drawn for each such corresponding interval for only one of the pair of cycles;
• (2) integrating at a receiving site the total line current comprising the pre-existing load current and the signal current superimposed thereon throughout corresponding intervals in the pair of cycles to produce at least one set of integrated current samples;
• (3) determining the difference between the integrated current samples in said at least one set of integrated current samples for the pair of cycles;
• and,
• (4) determining the sign of the difference, said sign denoting the binary value of the bit.

An apparatus for transmitting binary intelligence over an energized, AC power line having at least one load thereon in the direction from load-to-source wherein, by prior arrangement, a transmitter and a receiver recognize the two cycles of the power line voltage sinusoid that define the pair of cycles used in the representation of each bit of intelligence, and wherein each bit of intelligence is represented in the form of discernible difference between samplings of current effected by integrating the current throughout corresponding intervals in each cycle of the compared pair with the sign of the difference denoting the one/zero value of the binary bit, said apparatus comprising:

• (1) means for drawing signal current from the energized power line at a transmitting site to produce a signal waveform which is the same in the two cycles of the pair except within corresponding intervals contained within at least one preselected quadrant of the power line voltage sinusoid where the signal current is drawn for each such corresponding interval for only one of the pair of cycles;
• (2) means for integrating at a receiving site the total line current comprising the pre-existing load current and the signal current superimposed thereon throughout corresponding intervals in the pair of cycles to produce at least one set of integrated current samples;
• (3) means for determining the difference between the integrated current samples in said at least one set of integrated current samples for the pair of cycles;
• and,
• (4) means for determing the sign of the difference, said sign denoting the binary value of the bit.