Cognitive radios should have an inherent quality of sensing interference or the degree of interference in the operating spectrum and then an automatic capability of switching to a less interfering portion of the spectrum. The source of interference may be external or internal. The internal source is mostly the control or the peripheral circuits in the radio system. Consequently, platform noise has also to be taken into account while considering the receiver performance of radio receivers using controllers and intelligent interfacing. It, particularly, is reflected in channel dependent receiver performance. In this paper, a totally automatic technique has been described which can solve this problem by looking for that portion of the Radio frequency spectrum, where the interfering noise is less.