Abstract: A system and method for transferring digital data via the sub-carrier of a commercial broadcast FM radio station. Digital data generated by an originating subscriber is shaped with substantially a raised cosine response in the time domain. The shaped signal is then pre-emphasized and used to frequency modulate (direct angle modulate) a sub-carrier. The sub-carrier in turn frequency modulates the carrier and the data is transmitted by the radio station along with its commercial program. A receiving subscriber detects the sub-carrier and decodes and displays the originated data.