HD Radio Stations: More Power, Please
By Mark Fleischmann July 2, 2008 — FM stations sending out over-the-air digital signals have a message for the Federal Communications Commission: We need a stronger signal.

So they're lobbying the FCC for permission to boost their signals and expand their audience. Otherwise, says their petition as quoted by TWICE, "a significant number of potential listeners are unable to benefit from digital broadcasts."

As FM analog listeners are probably aware, FM mono signals tend to be stronger than FM stereo signals. That's because the FM stereo broadcast standard was piggybacked onto a preexisting mono standard. So borderline stations that are unacceptably noisy in stereo often work well in mono. Currently, HD Radio digital coverage exceeds FM stereo analog coverage by 10 percent, but lags FM mono analog coverage by 20 percent. The petition aims to achieve parity between HD Radio and the more robust FM mono.

Interestingly, the signal itself is far less powerful in HD Radio. Digital signal strength (as opposed to coverage) is only one percent of analog signal strength. The HD Radio broadcasters want to increase that to 10 percent, though there may be interference issues between the digital and analog signals.

As an occasional auditioner of HD Radio, I can attest that in a borderline reception area like my sheltered Manhattan apartment—buried in the back of a three-sided courtyard—it's hard to get a signal. But when you do get a signal, it can be a pleasant surprise to discover multiple feeds coming from a single station. With some tweaks to expand its reach, HD Radio could win lots of new listeners.