A system and method to provide continuity of service in a radio broadcasting system, wherein the radio broadcasting system includes at least one modem using the COFDM technique, and transmits N time-frequency cells modulated independently of one another. A number N.sub.1 of cells conveying digital audio signal S.sub.1 and a number N.sub.2 of cells conveying analog audio signal S.sub.2 are transmitted to a receiver. When the receiver cannot decode the signal in the N.sub.1 cells, the receiver replaces the digitized audio signal S.sub.1 with the analog signal S.sub.2.