Editing Broadcast television systems (section)

=== ATSC ===
{{Main|ATSC standards}}

The terrestrial ATSC system (unofficially ATSC-T) uses a proprietary [[Zenith Electronics|Zenith]]-developed modulation called [[8VSB|8-VSB]]; as the name implies, it is a vestigial sideband technique. Essentially, analog VSB is to regular amplitude modulation as 8VSB is to eight-way [[quadrature amplitude modulation]]. This system was chosen specifically to provide for maximum spectral compatibility between existing analog TV and new digital stations in the United States' already-crowded television allocations system, although it is inferior to the other digital systems in dealing with [[Multipath propagation#Interference|multipath interference]]; however, it is better at dealing with [[Electromagnetic interference|impulse noise]] which is especially present on the VHF bands that other countries have discontinued from TV use, but are still used in the U.S. There is also no [[hierarchical modulation]]. After demodulation and error-correction, the 8-VSB modulation supports a digital data stream of about 19.39&nbsp;Mbit/s, enough for one high-definition video stream or several standard-definition services. See [[Digital subchannel#Technical considerations|Digital subchannel: Technical considerations]] for more information.

On November 17, 2017, the FCC voted 3-2 in favor of authorizing voluntary deployments of [[ATSC 3.0]], which was designed as the successor to the original ATSC "1.0", and issued a Report and Order to that effect. Full-power stations will be required to maintain a simulcast of their channels on an ATSC 1.0-compatible signal if they decide to deploy an ATSC 3.0 service.<ref>{{cite web |url=https://www.fcc.gov/document/fcc-authorizes-next-gen-tv-broadcast-standard |title=FCC Authorizes Next Gen TV Broadcast Standard |website=Federal Communications Commission |date=16 November 2017 |access-date=2017-11-18}}</ref>

On cable, ATSC usually uses [[Quadrature amplitude modulation#Digital QAM|256QAM]], although some use [[16VSB]]. Both of these double the [[Network throughput|throughput]] to 38.78&nbsp;Mbit/s within the same 6&nbsp;MHz [[Bandwidth (signal processing)|bandwidth]]. ATSC is also used over satellite. While these are logically called ATSC-C and ATSC-S, these terms were never officially defined.