An e-mail from ABC-Citadel corporate engineering has reportedly issued an order effective this morning to suspend AM In-band on-channel (IBOC) operations, according to Radio-Info.

The communication came from Citadel's Martin Stabbard, according to sources.

The order, effective immediately, is reportedly for all Citadel AMs running IBOC at night. While no reason was given for the order, it is believed that interference issues are the most likely factor.

IBOC is the method in which iBiquity utilizes to broadcast the HD Radio signal - using sidebands to transmit the digital data over AM/FM waves. But since wider channels are required, both the AM/FM implementations of the iBiquity system often cause interference with adjacent stations on the dial. As a result, lower power stations can become unlistenable if they have an HD Radio station on an adjacent channel.

[Radio-Info]
Thanks Karl!

UPDATE: Apparently Citadel/ABC's AM stations will suspend nighttime HD Radio transmission until they can do further work with iBiquity to reduce adjacent-channel interference. Radio-Info adds that, "the FCC allowed nighttime AM digital as of September 14 - and the complaints have mounted up."

The HD Radio camp is advertising that there are currently over 1,500 radio stations now broadcasting in HD (from its website, to press releases as well as in various other promotions)... but yet only 1,300 have filed with the FCC.

That's according to the Federal Communications Commission's Audio Division Chief Peter Doyle at least. And I'd say he's a pretty good authority on the matter.

At the NAB Radio Show last week, Doyle brought up the issue at a panel discussion, according to Radio Info.

"I keep hearing that 1500 stations are in HD, but only 1300" have filed the required notification with the Commission, said the FCC Audio Division Chief.

Doyle added, "if you're one of the 200, please let us know."

Funny how the NAB calls Sirius and XM's infractions with the FCC as "brazen" and that the companies "cannot be trusted" as a result. The NAB even calls for Freedom of Information Act requests to extract, and likely publicize, any of satellite radio's problems with the agency. But when it comes to their own requirements with the FCC, terrestrial radio conveniently ignores their own responsibilities.

How hypocritical is it for the NAB to scream about XM-Sirius repeater towers - ones that were voluntarily lowered - while there are 200 HD Radio stations that haven't filed with the FCC themselves?

Absoulutely ridiculous.

[Radio Info (PDF)]