This article from Radio World is a few months old but it seems NPR is not in love with the proposed 10% digital increase either and they were one of the early boosters of IBOC (maybe because they got a free ride?). Some are saying that this increase won't cause any problems on the FM band or that the problems would be minor, this study seems to indicate the opposite:
"WASHINGTON
NPR Labs says in its more than 260-page study of digital coverage and interference analysis it found the impact of a 10 percent digital power increase to analog service varied considerably.
At 10 percent IBOC transmission power, most stations would gain covered population, approximately equally analog indoor and portable and exceeding auto.
However, that gain would come at a steep price: an unqualified 10 percent increase in the IBOC power “is predicted to cause substantial interference to analog reception of a significant number of first- and second-adjacent” channels."
In addition, “While elevated sideband approaches are being contemplated by some in the radio industry,” states NPR Labs in the document, “the data developed in this study indicates substantial adverse analog interference tradeoffs would result at many stations from an unqualified increase to 10 percent sideband injection if all stations were transmitting at 10 percent injection.”
more at:
http://www.rwonline.com/article/66268
"WASHINGTON
NPR Labs says in its more than 260-page study of digital coverage and interference analysis it found the impact of a 10 percent digital power increase to analog service varied considerably.
At 10 percent IBOC transmission power, most stations would gain covered population, approximately equally analog indoor and portable and exceeding auto.
However, that gain would come at a steep price: an unqualified 10 percent increase in the IBOC power “is predicted to cause substantial interference to analog reception of a significant number of first- and second-adjacent” channels."
In addition, “While elevated sideband approaches are being contemplated by some in the radio industry,” states NPR Labs in the document, “the data developed in this study indicates substantial adverse analog interference tradeoffs would result at many stations from an unqualified increase to 10 percent sideband injection if all stations were transmitting at 10 percent injection.”
more at:
http://www.rwonline.com/article/66268