HD Radio (Digital Transmission - Licensing)

[RF101]

This post involves HD radio , both the intellectual licensing and FCC authorization aspects

(1) Is there anything to prevent an FM station from running augmented HD mode only during core hours , for example 5am-midnight and downgrading to analog overnights? I would imagine if there are analog cross-mode translators, say for HD2 and HD3, they would have to drop carrier when the primary station reverts to analog..
(2) One piece of justification might be the often-observed situtaion where FMs drop back their stations to analog mode for up to several weeks when there's an HD exciter failure; a "regularly scheduled" downgrade should be viable.
(3) Would there be any violation on the "terms-of-service" front? For example, if the technology licensee say you have operate XX% of time in HD hybrid mode.

The reason for the inquiry is that HD transmission systems are power hogs - if your transmitter site is solatr-based, off-grid you'll need lots of battery banks to be in HD hybrid mode at 2 am .. Why bother?

 

[Kelly A]

(1) Is there anything to prevent an FM station from running augmented HD mode only during core hours , for example 5am-midnight and downgrading to analog overnights?

When you say "augmented HD mode", do me mean "enhanced", where extra occupied bandwidth inside the channel is allotted for the digital carriers? If a station is approved for IBOC (HD) mode, there are no restrictions on when you can operate in that mode. Running enhanced mode is allowed anytime, provided you stay within the total mask.

(2) One piece of justification might be the often-observed situtaion where FMs drop back their stations to analog mode for up to several weeks when there's an HD exciter failure; a "regularly scheduled" downgrade should be viable.

Shutting down your digital carriers for whatever reason is allowed without having to notify the Commission. If one or more of those streams are used to provide audio for a translator, then you'd have to request an STA to shut the translator down if the translator STL feed is down longer than ten days.

(3) Would there be any violation on the "terms-of-service" front? For example, if the technology licensee say you have operate XX% of time in HD hybrid mode.

No, HD carriers are considered part and parcel of your total carrier payload. It's like shutting down an SCA, or stereo. If you choose to shut the digital portion off, that's entirely up to the station.

The reason for the inquiry is that HD transmission systems are power hogs - if your transmitter site is solatr-based, off-grid you'll need lots of battery banks to be in HD hybrid mode at 2 am .. Why bother?

Not sure what you mean by being a power hog. Most modern solid state transmitters are sized, and have the bandwidth to provide digital and analog portions of the carrier with some headroom. I would assume if a station invests in the infrastructure to power a site with alternative power like solar or wind along with running HD too, they would size the power systems accordingly to include the small amount that HD carrier(s) requires.