Abstract: Improvements in the detection of TWACS outbound message signals. A first improvement involves matching some (or all) of the intermediate points in an outbound preamble occurring between bits of the preamble currently being detected. This reduces the possibility of a false synchronization and therefore decreases the probability of missing outbound message signals. A second improvement is to require some or all of the known preamble bits to exceed a predetermined threshold where both the thresh-old and which bits are adjustable. An additional approach is using 4-8 additional buffers in a transponder to detect preamble patterns in the outbound message. Each half cycle of the outbound message waveform requires entering a bit only into the buffers active for the particular frame of reference in which the message is being transmitted, since only buffers for that frame of reference are employed. The process continues until all bits specified to be sent, based on the length of the outbound message, are extracted.

Abstract: Improvements in the detection of TWACS outbound message signals. A first improvement involves matching some (or all) of the intermediate points in an outbound preamble occurring between bits of the preamble currently being detected. This reduces the possibility of a false synchronization and therefore decreases the probability of missing outbound message signals. A second improvement is to require some or all of the known preamble bits to exceed a predetermined threshold where both the thresh-old and which bits are adjustable. An additional approach is using 4-8 additional buffers in a transponder to detect preamble patterns in the outbound message. Each half cycle of the outbound message waveform requires entering a bit only into the buffers active for the particular frame of reference in which the message is being transmitted, since only buffers for that frame of reference are employed. The process continues until all bits specified to be sent, based on the length of the outbound message, are extracted.

Abstract: A method of controlling the current level of an inbound signal (Si) used in a TWACS (two-way communication system) for an electrical distribution system. The inbound signal conveys operational information and data on the performance of the system. The method includes first measuring the current (I) of the inbound signal. This current measurement is performed for each of a predetermined number of successive inbound signals. The root mean square (RMS) value of the measured currents is then determined. Operation of a solid state device (SCR) used to generate the inbound signal is now controlled as a function of the root mean square value. A line current propagating through the electrical distribution system is now modulated with the inbound signal. The inbound signal occurs at a predetermined range of angles (X) within a line voltage cycle regardless of variations in the line voltage characteristics. This enables the inbound signal to be readily detected.