Distribution Control Systems, Inc.

Aclara Power-line Systems Inc.

Benjamin A Hammond

John B Hessling, Jr

David W Rieken

Quentin H Spencer

Dennis L Kelley

William J Davis

Michael R Walker, Ii

Krister Lagerstrom

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. A CRC is then performed for the message. Using this method eliminates the problem of inbound messages being detected as outbound messages, and the resulting 'blindness' of the transponder. It further makes the transponders less sensitive to noise which currently causes the transponder to detect a preamble when there is none, resulting in a valid outbound message being missed.

Detection of outbound message signals in a power line two-way communications system

A method for concurrently communicating over each phase of an electrical power distribution network (N). A first outbound signal (SO) is transmitted over one phase (AN-A) of a bus (S) by an outbound modulation unit. The unit is released as soon as the first outbound signal (SO) is transmitted so the unit can transmit a second outbound signal (SO) over a second phase (BN-B or CN-C) of the bus. The second outbound signal is transmitted concurrently with an inbound signal (IB) sent in response to the first outbound signal (SO). The unit is again released, as soon as the second outbound signal (SO) is transmitted, so the unit can transmit a third outbound signal (SO) over the third phase (BN-B or CN-C) of the bus. This third outbound signal is transmitted concurrently with a second inbound signal (IB) sent in response to the second outbound signal (SO). The method allows concurrent communications over all three phases of the network (N).

Concurrent phase communication in TWACS

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St. Louis, MO, United States of America

Benjamin A Hammond