Abstract: A modulation feature measurement and classification system for classifying a pulsed signal that includes a preprocessor, phase measurement system and modulation classifier. Preprocessor detects pulse starts and stops, measures pulse duration and converts the pulsed signal into digitized baseband in-phase/quadrature samples. Phase measurement system measures short chip counts, long chip counts, phase jump magnitudes, number of phase states, and polynomial coefficients for phase modulation of the pulsed signal. Modulation classifier determines modulation type based on the measurements using both rules-based and similarity-based classification methods.