A system for identifying phase transitions in phase-shift keying signals and frequency transitions in frequency-shift keying signals broadly comprises a memory and a computing element capable of: selecting a portion of the signal to analyze, wherein the signal comprises a plurality of data samples; applying a transform to the signal to obtain a frequency spectrum; determining a maximum frequency spectrum corresponding to a carrier frequency; determining a starting approximation value of a slope of the phase transition; calculating a bounded limit of slopes within which to search for the phase transition; selecting a plurality of lines, calculating a sum for the data samples associated with each of the lines; and based on the sum for the data samples, identifying a line that corresponds to a location of the phase transition.