The Frequency-Shift Keying signal possesses characteristics of multi-frequency. The carrier frequency and modulation frequency are not exclusive, so spectral leakage may occur after Fourier Transform. The reason of spectral leakage is discussed. The frequency domain interpolation algorithm is used to find the interpolation between the real frequency and the adjacent discrete frequency, then the interpolation is used to recover the true frequency of the signal. Based on the true frequency and the frequency domain characteristics, the parameters of Frequency-Shift Keying signal are detected. The results of the simulation indicate that this method can detect the carrier frequency and the modulation frequency of low frequency with the home-made 18 information FSK signal and the UM-71 FSK signal. The carrier frequency errors are less than 0. 2 Hz and the errors of modulation frequency of low frequency are less than 0. 03 Hz , which all meet the requirements.%移频键控信号具有载频和调制频率都不唯一的多频特性,在傅氏变换后有频谱泄露的问题.讨论了产生频谱泄漏的本质原因.采用频域内插算法求出真实频率和其相邻离散频点的插值,利用此插值恢复出信号的真实频率,结合移频键控信号的频域特性,检测其参数特征值.仿真结果表明:文中方法能够检测出国产18信息移频键控信号和UM-71移频键控信号的载频和低频调制频率,载频误差在0.2 Hz以内,低频调制频率误差在0.03 Hz以内.
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