Patent ID: 7548579
Filing Date: 2009-06-16
Classification: H04L

Abstract:
1. A method of receiving a packet in an input signal stream of complex samples, wherein the packet includes a preamble and a data payload, said preamble including a plurality of first symbols repeated at a first predetermined interval, the method comprising: digitizing a signal to obtain complex samples of the signal; calculating successive autocorrelation values for pairs of the complex samples separated by the first interval, by conjugating one complex sample of the complex sample pair and multiplying the complex sample pair together after conjugation to form a complex conjugate product, and determining an angle approximation from the complex conjugate product; filtering the successive autocorrelation values to form a time-averaged autocorrelation signal; detecting when said time-averaged autocorrelation signal exceeds a predetermined first threshold; aligning sampling of the data payload to a symbol boundary within the packet in response to the detection; determining whether the data payload is encoded according to a first mode or a redundantly spread second mode; and decoding the data payload.