The cognitive radio system and method uses a wideband chirp signal for characterization of the spectra that a mobile radio may use. A cognitive radio base station broadcasts the low power reference wideband chirp signal with bandwidth covering the sensed spectrum. At the receiver, spectral resolution in the presence of white noise is achieved by cross-correlating the chirp signal with a locally generated copy of itself (i.e., matched filtering). A Fast Fourier Transform (FFT) is applied to the output of this matched filtering. The FFT output is fed to a decision circuitry, where a threshold value is set to decide the minimum amplitude of utilized frequencies. This process eases sensing computational complexity and improves the quality of sensing, thereby offering enhanced cognition at the cognitive radio receiver.