The FCC adopted rules for the digital operation of FM radio stations (known as HD Radio or the Ibiquity In Band On Channel system - IBOC for short) in 2007 and allowed the Media Bureau to amend those rules as technical developments warranted. In 2010, the Bureau authorized an increase in the power level of the digital portion of the FM signal by 6 db in all cases, and up to 10 db upon a showing that such an increase would not cause significant interference to adjacent channel stations (see our summary here). As the digital signal is carried on "sidebands" of the analog signal, which operate on part of a station's assigned frequency that is closer to adjacent channel radio stations, an increase in power on these sidebands has the potential for causing interference to closely spaced stations.....