A method of processing a digital radio broadcast signal includes: (a) determining a plurality of current correlation sample values representative of a time delay between samples in an analog audio sample stream and samples in a digital audio sample stream; (b) determining a current inversion status; (c) updating a delay history and an inversion status history; (d) checking the current correlation sample values for consistency with a first confidence threshold; (e) if consistency is found in step (d), determining if each of a first plurality of values in the delay history is consistent within a predetermined range of the current correlation sample values; (f) if consistency is found in step (e), determining if a value in the inversion status history is consistent with the current inversion status; and (g) if the consistency is found in step (f), allowing blending of an output to the digital audio sample stream.