Usually this is a QAM tuner, since over-the-air broadcasts are either COFDM (DVB-T and ISDB-T) or 8VSB (ATSC-T).
In general, this device is usually a QAM tuner, since most over-the-air broadcasts utilize either COFDM (DVB-T and ISDB-T) or 8VSB (ATSC-T) transmission protocols.