Improving signal quality by sampling an intermediate frequency signal by an analog-to-digital converter (ADC) and determining spectral characteristic data of the output signal of the ADC, and processing the spectral characteristic data to identify blocking signals and blocking spur signals that interfere with any desired signals. An adjustment is made to the frequency of one or more oscillators to reduce the interference resulting from the blocking signals if a ratio of the desired signal level to the total interfering blocker spur level is below a threshold.