Abstract: A message is transmitted on a subcarrier of a main carrier frequency of a radio station. The message is displayed simultaneously with the audible reproduction of the radio program. The message is capable of being displayed dynamically by having different portions thereof sequencing through the display device until the entire message is concluded and/or using a variety of possible display attributes, such as scrolling and flashing. One feature involves scanning the radio band for a station that carries the message. Scanning of a plurality of subcarriers at each station is also performed. One embodiment transmits the message during the "dead time" of other programming normally transmitted on the same subcarrier. The alphanumeric characters of the message are preferably converted prior to transmission into a signal with an average value of zero. The converted characters are decoded at the receiver.