Abstract: Spectrum sensing techniques have gained much attention due to their capabilities to improve the utilization of the spectrum and lay the foundation of cognitive radio. In this paper, a new kind of modified energy detection algorithm is proposed for the application on S-band uplink electronic surveillance. In this scheme, first, the uplink signal of Unified S-band Telemetry Tracking and Control is derived from Matlab simulation which is a multi-modulation signal of PCM-BPSK-PM. Then, a new kind of modified method is proposed based on the study of classical energy detection algorithm which makes use of ratio threshold and the coefficient of kurtosis. Simulation shows that the proposed method offers better performances than classical energy detection method to a certain extent. At last, some filters are used to confirm the central frequency of the uplink signal which is unified S-band telemetry tracking and control signal. The simulation results show that the proposed method is able to offer low estimation errors.