Patent ID: 7315588

Claim:
A method of detecting a communication signal in an environment with poor signal to noise ratio, the signal including a preamble comprising a plurality of frequency modulated Maximum Length Sequences (MLS's) of j symbols, j is a positive integer greater than 0, each and a predetermined period of pure carrier, comprising the steps of: (a) receiving a candidate signal (b) sampling a plurality of times for each symbol of the candidate signal (c) calculating a weighted frequency from successive samples of the symbols; (d) calculating a 1 st attribute of the candidate signal from the weighted frequencies; (e) calculating a 2 nd attribute of the candidate signal from the weighted frequencies; (f) comparing the magnitudes of the 1 st and 2 nd attributes to thereby determine whether a communication signal has been detected, wherein the weighted frequency is a weighted phase difference, wherein the sampling of the candidate figure determines real (Re) and imaginary (Im) components and the weighted frequency is calculated by the equation: f[n]=Re{z[n]}·Im{z[n− 1 ]}−Im{z[n]}·Re{z[n− 1]} wherein f[n] is the weighted frequency and z[n] is the candidate signal sample, and n is an integer.