Radio Waves: November 6, 2020

Exploring all-digital AM radio

The FCC gave final approval last week allowing AM radio stations to transition to an all-digital broadcasting system, a variation of the currently-approved hybrid mode HD Radio standard used by most FM stations and a few AM stations nationwide.

The hybrid system was always intended as transitory in nature … it allows all AM radios to receive the same analog signal AM broadcasters have sent out for the past 100 years. But sandwiched on both sides of the analog signal is a digital component that, when received by a special HD Radio tuner, allows for increased fidelity and lower noise.

But there are problems with that hybrid mode: it causes interference to other nearby stations. The digital signal — limited in power to help reduce that interference — doesn’t travel as far as the analog signal, causing problems with reception. And the digital portion in hybrid mode is limited somewhat in fidelity. For those reasons, many AM stations just turned off the digital portion of their broadcast signals.

The all-digital MA-3 mode of the HD Radio system differs from the hybrid mode by removing the analog component completely. This gives more space for the digital signal, allowing for greater fidelity (in computer terms, it allows a higher bit rate). It also allows for the signal as a while to be more centered on a station’s broadcast frequency, reducing interference. And it allows the signal to be sent full-strength, for much better reception including long-distance reception.

In other words, all-digital AM has the potential to send high-fidelity audio at a distance as good as or even greater than current analog AM. And like FM, there is a possibility for special features including a second channel as is done with HD on FM. But this all comes at a great cost: just like analog television after the switch to HDTV, no traditional AM radios would be able to pick up the signal.

That would be a problem for a station like KFI (640 AM) or KNX (1070 AM), where analog listening allows a huge audience already. But what about a station toward the bottom of the ratings? Or one in which the signal doesn’t clearly reach an entire city? The potential here is immense.

Fortunately, every HD Radio sold since the standard was set in 2002 can receive all-digital AM (and FM, for that matter). Many people own HD Radios via their car audio systems and may not even know it; home audio tuners are less common, but still available. That gives all-digital AM a bigger head start than FM broadcasters had in the 1950s. If I owned an AM station, I would run test hours at night to prove the technology, and market the heck out of the system. 

And run a format you can’t find elsewhere that will attract attention.

Locally, no station owner except one has committed to all-digital AM. Saul Levine is ready to do it when he feels that there are enough HD Radios around to make the change feasible. No date has been set, but it can be easily assumed that KSUR (1260 AM) will be the first to do it.


You can still get your radio questions answered … just submit them to Ask a Recovering Program Director, in care of this column…. The former program director of The Sound (now KKLQ, 100.3 FM) Dave Beasing will be a periodic guest on the Radio Waves podcast I do with Mike Stark. 

Beasing should be joining us within the next few weeks and hopefully will make a monthly appearance at

Morning Mess

Have you had a chance to hear the Morning Mess on Amp Radio (97.1 FM)?  I’m curious what you think. Check out the show weekdays 6 – 10 a.m. if you have not already, and send your thoughts to me at the email address below.


“When I listen to all the mushy & boring traffic reporters on AM radio stations, I can’t help but remember the ‘traffic man’ who really told it like it was … that being Bill Keane of KNX. Nobody could match his wit and humor dealing with some of the idiots on the freeways; he could always come up with choice words to match misguided accidents or whatever.  

“On top of that how many people in his position have a star on the Hollywood Walk of Fame? It would be nice to hear an occasional recorded piece to fit in with contemporary traffic reports to educate current freeway flyers.

“RIP Bill Keane 1927 to 2020.” — Phil Solomon, Fountain Valley