We developed a detect-and-avoid (DAA) method for single-carrier ultra wideband (SC-UWB) systems. The method is simple and pragmatic. It uses frequency domain equalization (FDE) and incorporates a tunable notch Alter. Using computer simulations, we evaluated both the probability of detecting a narrow band (NB) signal and the reduction of interference level caused by a UWB system to an NB system. The results show that the DAA detect a narrow band signal with a level of around -80dBm at a probability of more than 75%, and the small-size low-cost tunable notch filter reduces the interference by more than 20 dB.