Abstract: For detecting DRFM deception jamming timely when both target echo and jamming signal are co-existent in a range-gate, a method is proposed based on the theories of signal detection and convex optimization. At first, jamming-signal error angle (JSEA) is used to measure the degree of similarity between the target echo and the superposition signal of the target echo and the range-gate pull-off (RGPO) signal, and the case of a time-delay version of the jamming signal is also considered. Then, a clairvoyant detector and a GLRT detector are developed. The detection performances of the detectors are got through simulation. The results show that the detectors can rightly detect the RGPO signal when the number of quantization bits of DRFM is small.