Systems and methods are described for increasing the effective dynamic range of a digital data stream in a software-defined radio receiver. In one system the sample rate of an analog to digital ("A/D") conversion process is adjusted dynamically to shift harmonic signal interference induced by the A/D conversion process to outside the channels of interest. In another system the sample rate of an A/D conversion process is constant and the frequency of a dynamically controlled local oscillator in a frequency translator is adjusted dynamically to shift harmonic signal interference induced by the A/D conversion process to outside the channels of interest.