Patent ID: 8090057

Claim:
A system for ranging a receiver in a shared communications channel, comprising: a filter that receives a signal from the shared communications channel and outputs a Nyquist sample, wherein said signal includes: a ranging preamble containing a first sequence whose derivative is a zero autocorrelation sequence, a second sequence corresponding to a truncated first sequence, and a third sequence corresponding to said truncated first sequence; a preamble processor/ranging subsystem that receives said Nyquist sample from said filter, provides a first carrier frequency estimate based on said first sequence, and refines said first carrier frequency estimate to provide a second carrier frequency estimate, wherein said refining is based on said second sequence and said third sequence, wherein said first carrier frequency estimate is of a first accuracy, wherein said second carrier frequency estimate is of a second accuracy that is greater than said first accuracy; and a tracking subsystem that extracts data from said signal based on said second carrier frequency estimate.