Determination of the modulation type of communication signals

Abstract

Efforts to develop algorithms that can identify the modulation type of a signal and determine whether that signal varies continuously or takes on a finite number of discrete states are detailed. The approach used for determining the modulation type of a signal is to: (1) extract statistics about the time variation of the amplitude, frequency, and phase of a signal, (2) combine these statistics into interpretable features, and (3) associate these features with a modulation type using a suitably defined modulation space and metric. The algorithms were validated by performing Monte Carlo simulations to determine the accuracy of the estimators. The amplitude, phase, and frequency estimators were evaluated by calculating the mean and the standard deviations of the error distributions. The accuracy of the amplitude estimator was virtually unaffected by the sampling rate. However, the noise added to the signal did have an effect on the estimator's accuracy. The frequency estimator was affected by both the sampling rate and the amount of additive noise. >