Spectrum sharing techniques are attractive because the frequency bands for radio systems are limited. The cognitive radio technique and Ultra Wideband (UWB) system with a Detection and Avoidance (DAA) function are strong candidates for spectrum sharing. This paper discusses the techniques for detecting emissions from primary systems and the frequency bands they occupy. The received primary signals are assumed to be the sum of the sinusoidal waves. The sinusoidal signal is detected and is iteratively subtracted from the received signal to minimize the evaluation function. The frequency, phase and amplitude of the sinusoidal signals are estimated using the evaluation function and Newton method. The miss-Detection Error Rate and False Alarm Rate are evaluated to show the effectiveness of the proposed detection technique. The performance of the proposed detection scheme is superior to the ordinary scheme using FFT.