Patent ID: 8638834

Claim:
A method comprising: receiving at a wireless communication device energy in a frequency band and generating data representing samples of a received time domain waveform from the received energy; processing data for groups of samples of the received time domain waveform to transform the data representing the samples of the received time domain waveform to data for an intermediate domain signal that is in neither the time domain nor the frequency domain, wherein processing comprises, for portions of the energy received over a time period, partitioning the samples of the received time domain waveform into R plurality of groups, each group comprising a plurality of ordered samples, wherein R is a repetition frequency of a predetermined pattern, wherein the processing comprises processing i'th ordered samples from each of the plurality of R groups with a corresponding one of R transform modules each of size R such that each transform module outputs R complex values which across the plurality of transform modules make up the intermediate domain signal, where i is an index for ordered samples in each of the R plurality of groups; and analyzing the data representing the intermediate domain signal to determine whether a sequence having the predetermined pattern from a set of possible sequences is present in the received energy.