This paper discusses a dual-stage detection scheme composed of coarse detection stage and refined detection stage for the continuous detection operation of Ultra-Wideband (UWB) detect and avoid (DAA). The threshold factor for the probability of indefinite detection is first proposed and defined to combine the two stages. The proposed scheme focuses on the integration of two different detection schemes with different complexities in order to reduce total computational complexity. A Single-carrier Frequency Division Multiple Access (SC-FDMA) uplink system operating in a Time Division Duplex (TDD) mode is utilized to evaluate the proposed detection scheme. Simulation results indicate that the proposed scheme can make a tradeoff between the detection performance and the computational complexity by setting the probability of indefinite detection.