Patent ID: 9419835
Filing Date: 2016-08-16
CPC Classification: H04B,H04L,H04W

Claim Text:
1. A preamble detector for use with a power line communications (PLC) device operative to receive data in a PLC network using an Orthogonal Frequency Division Multiplexing (OFDM) modulation scheme, comprising: a delayed correlation detector configured to determine an initial estimate of a preamble start in a received PLC signal stream; and a cross-correlation detector configured to, responsive to a search range around the initial estimate of the preamble start, determine a final estimate thereof based on cross-correlating against a known preamble sequence that is indicative of a start of a PLC frame in the received PLC signal stream; wherein the received PLC signal stream includes a preamble portion operative according to a legacy PLC data transmission standard comprising IEEE 1901.2 standard and further wherein the preamble portion comprises 8 SYNCP symbols followed by a full SYNCM symbol and a half SYNCM symbol, each symbol including a plurality of OFDM samples; wherein the delayed correlation detector is operative to: select a sliding window that spans a known number of SYNCP and SYNCM symbols; move the sliding window over the received PLC signal stream one sample at a time and calculate, for each window placement, a set of delayed correlations based on a select correlation order; add absolute values of the delayed correlations together to obtain a total correlation value for each window placement over the received PLC signal stream; and apply a threshold against the total correlation values and select a sample index having maximum correlation as the initial estimate of the preamble start based on a maximization length parameter.