What a difference two days makes. This SDR-IQ plot shows the entire 695-865 kHz wide band filled with the tell-tale white bands of IBOC digital hash. Compare to my previous post which showed a relatively open spectrum the first night of IBOC, Sept. 14 2007.
At 12:01 AM Eastern last night, full nighttime IBOC broadcasting began in the US on the medium wave band. Above is an example of the spectrum from the SDR-IQ receiver showing the digital hash from 700 WLW and 710 WOR extending to stations +/- 15 kHz from their carrier. On this band segment those two stations were by far the most notable IBOC signals. It's not certain whether any other stations were broadcasting on IBOC in that range last night.