What if analog FM radio ended in the United States?

hdradio_stockEver since IBOC, or HD Radio, debuted locally in 2006, I always wondered what would happen if the analog radio dial shut down and was replaced with full-power IBOC signals.


Although I have expressed distaste with HD Radio in the past, I thought it’d be interesting to predict what would happen to the DXing hobby if the unthinkable happened and the United States had a ‘digital radio transition,’ much like the country did in 2009 for digital television.

IBOC technology, which according to various reports broadcasts a digital radio station on the ‘sidebands,’ or adjacent frequencies of participating FM radio stations, ruined (or at least curtailed) the hobby for many.  A station running IBOC on 95.5 FM would actually be broadcasting its analog signal on 95.5, while its digital signal would be broadcasted on 95.3 and 95.7 FM.  An HD Radio would pick up either sideband, where available, and decode it on 95.5 FM, allowing the listener to enjoy a digital signal.

But what if U.S. radio broadcasters flipped the switch one day and only broadcasted digital, full-power HD Radio signals?

Obviously, the initial reaction to a full analog FM shutdown would be that millions of existing analog radios would be rendered useless.  The government would likely need to have a coupon program or similar initiative as they did with the 2009 DTV transition to allow customers to purchase HD Radios or converter boxes for existing analog radios.  Likewise, electronics manufacturers would have to churn out new HD Radio models and converter boxes that would likely have the capability of converting IBOC signals to analog (i.e. if you tune in 95.5 on an old analog radio, it would, with the converter box, pick up 95.5-HD1.  Or, the converter box could be its own radio and it’d modulate a signal to a common frequency, much like an mp3 player FM modulator.

Based on reports, HD Radio signals currently operate at something close to 10% power of the parent station (10kw for a 100kw analog signal).  Some are slightly more powerful.  Understandably, these weaker signals do not have the same coverage area as their analog counterparts.  For example, I’m 56 miles away from Baltimore and although I can get their analog FMs clearly, digital reception is only received with tropospheric enhancement.  I’d predict that full-power IBOC would likely cover the same area as a stereo analog FM signal can reach, with some limitations, as expected.

The actual frequency of FM stations could change with an all-digital radio band.  Although I have no evidence to back this up, I predict the FCC would allow radio stations from the same city to be closer to each other on the RF spectrum than currently allowed with analog.  This could mean new radio stations in town, or an increased chance for DXing opportunities.

Stations that never adopted the technology would also have to pay up and become digital-only broadcasters.  This could cause a huge problem outside of major cities where the technology is not in use.  Although the majority of local FM signals run IBOC, many small market stations I pick up (most, I’d say) don’t currently have HD Radio broadcasts.  Some complete markets, such as Myrtle Beach as of 2012, have not a single FM signal broadcasting HD.

For a DXer, having an all-digital FM band would drastically change the way we receive radio stations.  Overall, I predict less FM DXing as a whole, as many signals are currently identified through weak propagation that I know a digital signal wouldn’t survive.  However, since IBOC does propagate fairly often via strong tropo and sporadic E, I would guess that DXers would see a huge increase in the amount of positive logs received during a given DX opening, given the call letters that always display on the screen of a tuned IBOC radio.

Having an all-digital band would likely render the IBOC sidebands of an analog FM station — something that DXers largely despise due to these signals ruining analog radio on the same frequency often impossible — useless.  Therefore, broadcasters could broadcast one, full-power signal instead of two low power sidebands.  For example, a post-transition 95.5 FM IBOC signal would have NO transmission at all on 95.3 and 95.7 FM.  These adjacent frequencies would, once again, be open for DXing.  This would, by default, allow more ‘DXable’ frequencies.

Devoid of DX conditions, a digital FM band would likely only bring in signals 0-60 miles away.  Stations in the 45-60 mile range would probably have frequent dropouts without enhancement, making continuous listening impossible or unpleasant.  But what DXers could do is leave an IBOC radio on an empty frequency and, with the use of a webcam or other similar device, capture pictures of any IBOC decodes on-screen.  This would come in handy with meteor scatter and sporadic E openings.  I’m sure a radio could be rigged to continuously scan for HD signals and, with the help of a computer program, log every IBOC signal received within a 24 hour period, allowing DXers to get maximum results while away from their radio.

Granted, IBOC has not been too popular in recent years.  In my rant on HD Radio, I mentioned how several of my local Washington, DC FM stations have ended their IBOC broadcasts in recent years, while others turn the digital signals off or on at random in recent years with no rhyme or reason.  My predictions are unlikely to come to fruition due to many factors, including lack of adoption of IBOC technology by broadcasters, consumer trends and the growing popularity of internet-based music providers.  I’m also sure there’s likely some limitation to the existing technology where a new digital radio standard would have to be adopted before DXers could enjoy a full-digital FM band without adjacent frequency hash.

I honestly predict analog radio would exist in some form for at least another 20 years, if not longer.  However, the radio business is definitely changing and more listeners are gravitating toward new technologies that could pose a threat to the continuation of the DXing hobby.  As a young DXer, I hope DXing exists 30-40 years from now in a comparable form to its current incarnation, but who knows what the future will bring.