Powerline pulse position modulated transmitter apparatus and method
A transmitting controller is connected to a powerline and on command places a reference signal and a series of signal pulses in the powerline at a series of signal timing positions related to zero voltage crossing points so that the signals pulses are substantially in the powerline temporal quiet zone near zero crossing. The signal pulses are produced from a pair of capacitors and switches which are each sequentially charged a first polarity from the powerline and is discharged in the powerline at the opposite polarity so that the powerline voltage at the time of the pulse is additive to the pulse voltage. The receiving controller is connected to the powerline and has a filter circuit therein which filters away the powerline AC signal and noise to leave the reference and signal pulses. The signal pulses are compared to the position of starting reference pulses to determine in which signal timing position the pulses have occurred.
1. A powerline pulse position modulated system communication method for remotely controlling a load, comprising the steps of:
providing a transmitting controller with a connection to the powerline;
said transmitting controller incorporating a transmission circuit including a switch in series with a capacitor in series with an optional inductor, said switch, capacitor and inductor connected or coupled to line and neutral of the powerline in a single or three phase system or to a first and a second phase line in a three phase system;
sensing zero voltage crossing time in the powerline;
sensing a load control command causing the creation of a powerline control message consisting of one or more data pulses placed in predetermined signal timing positions related to the zero voltage crossing time;
each of said pulses generated by the discharging of a said capacitor by said switch in a half cycle of the powerline that is opposite in polarity and following a half cycle in which said capacitor finished charging;
providing a receiving controller with a connection to the powerline;
sensing by said receiving controller the zero voltage crossing time in the powerline;
sensing by said receiving controller the one or more data pulses; and
actuating the load depending upon in which of said predetermined signal timing positions the data pulses occurred.
2. The method of claim 1 wherein said transmitting controller employs a rectifying device connected in parallel with said switch to provide charging of said capacitor.