Effects of Carrier Offset on the Classification of Binary Frequency Shift Keying Based onthe Product of Two Consecutive Signal Values

摘要

In this paper we propose a feature to distinguishrnfrequency shift keying modulation from amplitude shiftrnkeying and phase shift keying modulations in thernpresence of carrier offset. The feature is based on thernproduct of two consecutive signal values and on timernaveraging of the imaginary part of the product. First, thernconditional probability density functions of the featurerngiven the present modulation are determined. In order tornovercome the complexity of calculating the probabilityrndensity functions, the central limit theorem for strictlyrnstationary m-dependent sequences is used to obtainrnGaussian approximations. The classification threshold isrnbased on the minimization of the total probability ofrnmisclassification. Finally the paper studies effects ofrncarrier offset on the performance in the case of knownrnand unknown carrier offset.