Automatic Identification Method of Link4A

Accurate identification of Link4A is the premise of performing effective jamming. Based on instantaneous information identification algorithm, three key features, including two new ones, are extracted which are used to identify 2FSK modulation signal: the maximum value of the spectral power density of the normalized-centered instantaneous amplitude gamma_max, the mean of the absolute value of instantaneous frequency offset delta_f and the standard deviation of the absolute value of instantaneous frequency offset . Simulation result indicates that the success rate reach 91.8% at SNR=-10 dB about 2FSK modulation signal. Then estimating the code-width of the 2FSK modulation signal, and comparing it with the real Link4A parameter, simulation result also indicates that the success rate reach 100% at SNR=5 dB. So, this mean has a high success rate under low SNR condition, and it would have a favorable using foreground.