FCC allocated 3.1 to 10.6GHz band as the spectrum of the Ultra-Wide Band Impulse Radio (UWB-IR) system. Besides for data communication applications, the spectrum has also been frequently reported for being used for radar application. To support its ranging capability, the radar usually adopts coherent detection architecture, whose demodulation process requires not only the phase or frequency of the received signals but also that of the transmitted signals. Correlation-function based pulse detection is one of mostly implemented techniques in a UWB-IR coherent radar system.