NAB filed comments last week supporting the call by some broadcasters and manufacturers to allow broadcasters to transmit digital radio at much higher levels than currently allowed. The request asks for FM digital broadcasters to be allowed to increase digital power levels on a voluntary basis by up to 10 dB, which is the equivalent of an increase from one percent up to 10 percent of a station’s authorized analog power. The purpose of the increase is to improve digital signal coverage, including indoor reception, and to better replicate analog coverage.

NAB's comments supported the request, noting that the digital power levels initially were set at an extremely low level, but this evolving service now requires more power to extend coverage throughout analog service areas and boost reliability indoors and for new portable devices and HD Radio-equipped cell phones. NAB also pointed out that this is an opportune time for a power increase, to enable the 85 percent of stations yet to convert to build digital facilities only once.

iBiquity and CBS had earlier submitted studies to the FCC showing that the requested power increase will allow FM stations to improve digital performance with minimal risk of harmful interference to existing analog service. These results were generally confirmed by an independent analysis NAB commissioned from Hammet & Edison engineering consulting firm. However, NAB recognized that the proposed increase in power may create new instances of interference in certain situations, and supported the joint broadcasters' recommendation for expeditious Commission action to address instances of unexpected interference. NAB also supported the joint broadcasters' recommendation for limits on the digital power for "Super B" stations to avoid any of the potential interference to first adjacent stations highlighted in iBiquity's test program.

Other commenters expressed concern about potential interference, including National Public Radio, which said it is committed to improving HD Radio coverage by increasing authorized power, but it wants a managed power increase, to avoid increases in interference for some stations. iBiquity is said to be participating with NPR and others in looking at additional testing modeling for interference.

You can read NAB's comments here.