Patent ID: 7590209

Claim:
A system for identifying at least one phase transition in a phase-shift keying signal comprising a plurality of data samples corresponding to phase values, the system comprising: a memory operable to store computing device executable instructions; and a computing device operable to select a portion of the signal to analyze; apply a transform to the signal to obtain a frequency spectrum; determine a maximum frequency spectrum corresponding to a first carrier frequency; determine a starting approximation value of a slope of the phase transition; calculate a bounded limit of slopes within which to search for the phase transition; select a plurality of lines, each having a slope within the bounded limit and an initial value, wherein each line passes through at least one of the data samples; calculate a sum for the data samples associated with each of the lines; based on the sum for the data samples, identify a line that corresponds to a location of the phase transition; determine a second carrier frequency corresponding to a second non-transition portion after the phase transition; and calculate a magnitude of a change in phase by determining a vertical distance of the phase transition lying between the first carrier frequency, which corresponds to a first non-transition portion before the phase transition, and the second carrier frequency.