Abstract:A FFA and TFA based interception of LPI frequency hopping signal is presented in this paper. the algorithm can detect the frequency hopping signal effectively in low Signal to Noise Ratio (SNR); By selecting the range of the folding period and resolution properly, the parameters of frequency hopping signal such as hop duration, time offset and hop frequency can be estimated. Finally, simulation and performance analysis illustrate that the algorithm can intercept the frequency hopping signal under 0dB, and has better performance than the adaptive threshold detection.