Preamble detection with multiple receive antennas

A system comprising:

• a differential demodulation module configured to generate differentially demodulated signals by differentially demodulating received signals;
• a first summing module configured to generate a combined signal by adding the differentially demodulated signals, wherein the combined signal includes a plurality of symbols;
• and
• a second summing module configured to
• generate a plurality of sums for each of a plurality of derived preamble sequences, wherein the derived preamble sequences are derived from preamble sequences,
• wherein each of the derived preamble sequences includes a plurality of derived symbols,
• wherein one of the plurality of sums generated for one of the derived preamble sequences is a sum of (i) a first portion of one of the plurality of symbols of the combined signal and (ii) a second portion of one of the derived symbols of the one of the derived preamble sequences,
• wherein one of the derived symbols of one of the derived preamble sequences has a first binary value when a corresponding symbol and a symbol adjacent to the corresponding symbol in a corresponding one of the preamble sequences have opposite binary values, and
• wherein the one of the derived symbols has a second binary value that is opposite to the first binary value when the corresponding symbol and the symbol adjacent to the corresponding symbol have the same binary value.