16 - OTA, ATSC, and 8VSB
In order to get HDTV started in the early 90s, a specification was created by the Advanced Television Systems Committee, or ATSC. For compression over the air, it uses MPEG-2. The ATSC signal was created to fit inside the existing 6MHz TV channels.
For over the air transmission, the data stream is modulated using 8 level vestigal sideband, or 8VSB, which is an AM transmission.
Over The Air, or OTA, can be an important part of an installation of the primary video source is satellite. Up until recently, the satellite carriers have not been able to offer local HD stations, so a home will need an OTA antenna to tune in the local stations in HD. Most if not all of the HD satellite boxes have an ATSC tuner built in.
In most markets, the local HD stations are in the UHF band. There is nothing special about an antenna for OTA HD, but some of the directional UHF ones will work better. Small Yagis or double bow-ties with a reflector will do well in urban areas. Larger Yagis might be needed for distant stations. The effective range is slightly less than UHF analog stations, and nearby high rise buildings or overhead aircraft can cause dropouts due to multipath interference.