The FCC is asking what the industry thinks about how or if it should allow stations to go digital at night. In July, NAB submitted evaluations of tests conducted by Ibiquity Digital and the NAB Radio Board recommended to the commission that it allow nighttime IBOC operation.
Currently AMs are allowed to transmit a digital signal during the daytime hours and some stations already authorized for pre-sunrise and post-sunrise operation may go digital too. But AMs cannot go digital at night because when the commission first authorized IBOC, it didn't have hard data to prove or disprove whether there could be significant interference from digital AMs to analog neighbors at night, especially during nighttime skywave propagation conditions.
The NAB ad hoc engineering group working on nighttime digital said there might be interference created in some situations, but found it acceptable and noted the commission has the ability to address instances of unexpected levels of interference. It recommended the FCC authorize nighttime digital operation rather than requiring stations (especially those already digital during the day) to seek separate permission for nighttime digital.
The FCC seeks comment on authorizing AM nighttime IBOC with Special Temporary Authoritys, or STAs.
Public comments are due June 14 (MM-Docket 99-325.)