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All Digital FM HD Radio-12 Streams On One Carrier

Never say never. Some creative company may decide that their one licensed station can go "dark" as far as listeners are concerned if it means feeding a half dozen formats to translators instead.

Just the fact that Beasley was willing to take one of their full market FM's in Las Vegas and shut off analog for the digital demonstration during NAB, is saying something.
 
If I read the pre-show announcement right, they still had the analog FM signal running on KKLZ. They did take down the normal HD signals for the multiple channel HD demonstration.
 
When I saw the demo, it was digital-only mode. As expected, they had a combination of music and mono voice programs to make up the 12 streams. It seemed to work fine, although to be fair, I'm not sure whether anyone would run with this many streams.
 
When I saw the demo, it was digital-only mode. As expected, they had a combination of music and mono voice programs to make up the 12 streams. It seemed to work fine, although to be fair, I'm not sure whether anyone would run with this many streams.

Based on the fairly extensive presentation John Layer from NAB gave at the Public Radio Engineering Conference before NAB, here's how KKLZ and its testing partners were working things:

Right after CES in January, Beasley allowed KKLZ's analog to be completely turned off from midnight-5 AM for one week, which allowed for true all-digital testing to take place during those overnight hours. They experimented with a variety of configurations and transmission modes to see which ones worked with stock receivers and which (like the "MP5" mode) had some potential compatibility issues. When that was done, the analog was turned back on but the all-digital exciter was left in place at KKLZ's Black Mountain Henderson transmitter site in preparation for more demonstrations during NAB.

During daytime hours of NAB week, KKLZ's analog remained on, but its digital carriers were modified, extending out 300 kHz instead of 200 kHz from the center frequency to demonstrate the 12-channel "all-digital" system. For radios that could tune to "96.0," "96.2," "96.4" and "96.6" (I brought my Sony for that purpose), you'd see three HD subs per frequency, listed as "Channel 1," "Channel 2," all the way up to "Channel 12" on 96.6-HD3. Each "channel" was just a loop of a single song repeating; no IDs or anything. (The PAD showed "HDMA" as the calls for 96.0, "HDMB" for 96.2, etc.)

You can hear a conversation with David Layer, with some discussion of the demo/test, on my podcast...

https://www.fybush.com/podcast-017/
 
Do you really think listeners going to buy another radio

If this happens, alot of FM Radios will be affected, Not sure about AM

Someone in NAB really wants us to go All Digital FM
 
The existing HD receivers already available in most cars being sold today, are already capable of digital-only or current hybrid digital reception.
 
I'd hate to see my 40 year old Technics receiver go obsolete, but protecting a nearly 60 year analog stereo broadcast standard along with obsolete SCA channels is a huge waste of spectrum.

Perhaps the center of the 200 kHz channel could continue as analog, mono only with 15 kHz frequency response. Goodbye to the 19 kHz stereo pilot, and the dim little red LED stereo indicator on my receiver. Let the rest of the channel be dedicated to a more robust digital transmission system.
 
I'd hate to see my 40 year old Technics receiver go obsolete, but protecting a nearly 60 year analog stereo broadcast standard along with obsolete SCA channels is a huge waste of spectrum.

Perhaps the center of the 200 kHz channel could continue as analog, mono only with 15 kHz frequency response. Goodbye to the 19 kHz stereo pilot, and the dim little red LED stereo indicator on my receiver. Let the rest of the channel be dedicated to a more robust digital transmission system.

If something like that were to happen, I doubt anyone would even notice except us "radio nerds"! So many in-car radios already blend aggressively to mono when the signal strength drops that most people are *probably* listening to mono audio at least some of the time while driving and they aren't even actively aware of it.

Locally owned "Cat Country 98.7" WYCT in Pensacola recently upgraded their transmitter and switched on HD broadcasts and now their analog audio is 100% mono, albeit with the stereo pilot still there. There has not been a single complaint to them that I know of. The effect going from mono analog to stereo HD, however, is very noticeable. Further east of Pensacola, another country station — WAAZ in Crestview — ran straight-up mono for decades, too. They installed a stereo exciter several years ago but it wasn't until 2017 that they finally began true stereo broadcasts. Hard to believe in this day and age, but then this station also still signs off at midnight every night. I can't think of another 100 kW FM that does that.
 
Hard to believe in this day and age, but then this station also still signs off at midnight every night. I can't think of another 100 kW FM that does that.

If you think back to when stations in large numbers started to begin 24 hour operation it was in the earlier years of music radio... mid to late 50's and into the 60's.

Before that, stations depended on the network or transcriptions. It was hard to fill the overnight hours without those resources. In fact, until Petrillo's American Federation of Musicians lost much of its power, stations in even smaller markets could only play records in proportion to the amount of live music they programmed!

By the later 50's, equipment was more reliable, but not so much that it was as immune to failure as today's transmitters. One of the times when failure was more frequent was at the beginning of each day's broadcasts. There was nothing worse than having the transmitter not go on right at the beginning of morning drive... or in rural areas, at the start of the farm reports!

Daytimers had no recourse, but fulltime stations could simply stay on the air all night, and they would be sure that things were working at 5 AM or 6 AM when it was important. Sure, equipment might fail, but the "it won't turn on" problem was significantly reduced.

I had a case where my first FM would not go on in the morning when a critter had gotten into the box during the night, and shorted out a filter capacitor at 6 AM. Besides cleaning out the remains of the varmint, I immediately hired a board op for overnights and went 24/7. And that was back in the 60's!

But I have never been at a station that made any money in overnights.
 
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