Editing Broadcast range (section)

==Digital versus analog==
Digital transmissions require less power to be received clearly than analog ones.  The exact figure for various modes depends on how robust the signal is made to begin with, such as modulation, [[guard interval]], and [[forward error correction]].  In each of these three factors, the [[caveat emptor|caveat]] is that a higher [[data signaling rate]] means a [[tradeoff]] with reduced broadcast range.  The [[hierarchical modulation]] used on [[Digital Video Broadcasting|DVB]] is a unique case, which reduces the range of the full-[[screen resolution|definition]] signal, in exchange for an increase in the usable range of the lower-definition part of the video.

Digital stations in North America usually are operated by the same groups as the analog side, and thus operate their own independent facilities.  Because of this, the FCC requires U.S. TV stations to replicate their analog coverage with their digital signal as well.  However, ATSC digital TV only requires about one-fifth the amount of power to reach the same area on the same channel as analog does.  For HD Radio, the figure is only one percent of the station's analog [[watt]]age, in part because it is an [[in-band on-channel]] method, which uses [[sideband]]s that must prevent interference to [[adjacent channel]]s, especially for older or cheaper receivers which have insufficient [[sensitivity (radio receiver)|sensitivity]] and/or [[selectivity (radio)|selectivity]].