Patent ID: 8238492

Claim:
A method implemented with a packet detector, comprising: segmenting, with a segmenter of the packet detector, a received signal; cross-correlating, with a cross-correlator of the packet detector, each segment with an expected signal; and correcting a phase of each correlated segment, with the cross-correlator, by de-rotation according to an expected phase offset due to assumed frequency offset, wherein the cross correlation as a function of frequency offset is: y ⁡ ( Δ ⁢ ⁢ f ) ≈  x ⁢ ( 0 ) + ∑ n = 1 K - 1 2 ⁢ ( x ⁡ ( - n ) + x ⁡ ( n ) ) · cos ⁢ ( 2 ⁢ π · Δ ⁢ ⁢ f · Δ ⁢ ⁢ t · N K · n ) + j · ( x ⁡ ( - n ) - x ⁡ ( n ) ) · sin ⁡ ( 2 ⁢ π · Δ ⁢ ⁢ f · Δ ⁢ ⁢ t · N K · n )  2 wherein Δf is the assumed frequency offset correction, K is the number of segments, N is a number of samples, Δt is an inverse of sampling clock frequency, and x is the cross-correlation of each segment.