The QM2 modem/interface is intended for terrestrial transmission of ATSC HDTV transport stream at 19.39 Mbps. With 16QAM modulation, the occupied bandwidth is about 7 MHz. A T1/E1 wayside channel is also provided for an independent application such as an audio or data channel. In addition, an RS–232 interface is available for asynchronous data transmission at a data rate of less than 9.6kb.