The Phase-Code Orthogonal Frequency Division Multiplexing (PC-OFDM) signal was used in communication systems at first.When using as an external radiation source signal,it has the advantages of low interception,anti-interference and flexible waveform,and is an effective supplement to the existing civil external radiation source signal.In this paper,it is proposed to use the PC-OFDM signal as an external radiation source radar signal,and thus to extract the micro-motion characteristics of the low-altitude target with rotor blades.Firstly,the micro-motion echo model of bistatic radar is established based on PC-OFDM signal,and the parameterized expression of micro-Doppler is derived.To further solve the problem of difficult parameter extraction under low SNR conditions,a method for extracting micro-motion features based on stochastic resonance is proposed.The simulation verifies the feasibility and robustness of the method.