Patent ID: 8542720
Filing Date: 2013-09-24
Classification: H04B,H04L

Abstract:
1. In a two-way automatic communications system used by an electrical utility in which outbound messages are sent from the utility to an end device and inbound reply messages are sent from the end device back to the utility, the respective outbound and inbound messages being sent and received over the utility's power distribution system, a method for enabling a transponder to distinguish an outbound message from an inbound message of the outbound and inbound messages transmitted elsewhere on the two-way automatic communications system, comprising: detecting a plurality of bits forming a preamble of the outbound message and extracting the plurality of bits, said detecting including detecting intermediate values included in a sequence of the plurality of bits in the preamble; computing a ratio of signal strength for bit locations in the preamble where one bit value is expected to the signal strength for bit locations in the preamble where another bit value is expected; and, accepting the plurality of bits as a valid preamble for the outbound message if the computed ratio exceeds a predetermined value.