All Digital AM Band? Um, maybe not.

[ThaDood]

Boomer found this one on the proposal of making the AM broadcast band in the USA all digital. https://www.radioworld.com/news-and-business/business-and-law/few-broadcasters-show-interest      Yeah, the idea doesn't excite me either.

[KaySeeks]

His biggest concern for the future of AM radio is the electric car. “A few manufacturers have already eliminated AM radios from their electric car models, and several more have made it clear they will not have AM radios in their future models,” he said.

“We have been told the cost to filter the interference to AM radio from the car gets into the hundreds of dollars per car,” Cooney said.

So mobile operation on the 160-meter band in a Tesla might not be too fun.

Just wondering if they have permission to spew all this electronic garbage.

[ChrisSmolinski]

Just wondering if they have permission to spew all this electronic garbage.

There is a all digital test station nearby in Frederick MD on 820 kHz. It spews so much junk that it completely blocks 810 and 830. There was a post in a Facebook AM radio group from one of the guys behind it, talking about how wonderful it was and how it doesn't cause interference. I posted some waterfalls showing it, and they completely ignored it. They're sold on the technology to "save" AM, and don't care about reality.

[ThaDood]

Yeah... Somehow, if All-AM-Digital was to become a reality, like it did in HDTV, (I still miss analog TV.), I don't see a D/A converter RX'ing digital signal, then re-TX'ing it on an analog FREQ. (Hi-hi...) Albeit, they kind of did with satellite radio going to Part #15 FM TX's. Give me AM Wide!!!

[Josh]

Just wondering if they have permission to spew all this electronic garbage.

There is a all digital test station nearby in Frederick MD on 820 kHz. It spews so much junk that it completely blocks 810 and 830. There was a post in a Facebook AM radio group from one of the guys behind it, talking about how wonderful it was and how it doesn't cause interference. I posted some waterfalls showing it, and they completely ignored it. They're sold on the technology to "save" AM, and don't care about reality.

Just imagine the mess when dx starts rolling in.

[KaySeeks]

Just wondering if they have permission to spew all this electronic garbage.

There is a all digital test station nearby in Frederick MD on 820 kHz. It spews so much junk that it completely blocks 810 and 830. There was a post in a Facebook AM radio group from one of the guys behind it, talking about how wonderful it was and how it doesn't cause interference. I posted some waterfalls showing it, and they completely ignored it. They're sold on the technology to "save" AM, and don't care about reality.

Fair enough but I was referring to spewing electronic noise inside and in the proximity of an electric car.

[JimIO]

Most of what's on the AMBCB should not even be listened too, fix that first!

[NJQA]

I’ve looked at the spectrum of the 820 kHz all digital station many times on SDR receivers here in Northern VA, and the energy is pretty well contained within +/- 5 kHz of center frequency.  It actually looks better than many analogue AM stations as far as not interfering with adjacent frequencies.

You need to look at the required FCC spectral mask.  As I recall, energy on adjacent frequency slots has to be 25 dB below carrier power.   If you have a 10,000 watt station, it could have almost 30 watts of energy on adjacent channels and still be legal.  If you live close to a station, it could certainly seem “wide”.  We have a local station here that seems “wide” but I hesitate to make that claim because even at 15 miles away, I might be seeing legal power levels.

[ChrisSmolinski]

Here's a waterfall I just took a few minutes ago of 820 kHz.  It falls within the required 25 dB below carrier power, but still causes considerable damage to adjacent channels. I understand the desire to make MW more appealing to the masses, but have a difficult time accepting this as progress 

[pinto vortando]

Not as wide as the hybrid mode but looks like it would still interfere with the adjacent channels.

[skeezix]

How does a digital signal sound? We've had some around here in the usual hybrid mode (AM + IBOC) and the digital stream sounds horrible- worse than a 1990's dial-up Internet stream. Assuming it can hold the lock.

On FM on HD1, it sounds fine. On HD2+, it sounds rather lacking.

[ThElectriCat]

Most of what's on the AMBCB should not even be listened too, fix that first!

This.
audio quality dosent matter if nobody listens to you.

[redhat]

The bit rate is identical for both hybrid and digital only modes, as such audio quality will be the same (I believe...could be wrong).  There was a big Hoopla at NAB this year in the Nautel Users Group as for the first time transmitted album art over one of the HD only AM's.....big deal.  People are going to keep beating the drum for HD as long as someone is padding pockets to do so.  On the AM side, even amongst supporters, interest is waning.  It just doesn't work well, and the installed receiver base even after 15 years just isn't there.  FM HD is doing well largely due to the translator boom, and the HD power increase now allowed by the FCC.

+-RH

[R4002]

The bit rate is identical for both hybrid and digital only modes, as such audio quality will be the same (I believe...could be wrong).  There was a big Hoopla at NAB this year in the Nautel Users Group as for the first time transmitted album art over one of the HD only AM's.....big deal.  People are going to keep beating the drum for HD as long as someone is padding pockets to do so.  On the AM side, even amongst supporters, interest is waning.  It just doesn't work well, and the installed receiver base even after 15 years just isn't there.  FM HD is doing well largely due to the translator boom, and the HD power increase now allowed by the FCC.

+-RH

Good point.  Most of the HD FM listeners, especially what I would consider your usual consumer or casual FM listeners, are listening to analog FM translators of FM HD radio subchannels.  In urban areas, the translators take on a life of their own and appear to most listeners as their own radio station.  The FM band where I live is a lot more crowded with all the HD translators.  I have a feeling most folks wouldn't listen to the -HD2 sub-channels if they weren't repeated on analog FM however. 

Shame about the electric cars removing AM receivers.  Doesn't the all-channel receiver act come into play here?  Maybe not.  FM only car radios?  Several friends of mine (who are big sports fans) listen to AM stations almost exclusively for sports coverage.  One of them regularly makes a 100+ mile drive and likes to listen to The Nationals baseball on AM radio.  Once I explained how skywave works, he actually tries to take drives at night so he can listen to Nationals games on WRVA on 1140 kHz or WFED on 1500 kHz all the way back and forth on these long drives.  Of course, daytime coverage of those two powerhouse stations is also excellent, but at night he can simply pick which one and not have to touch the dial for the whole trip, basically all the way across Virginia.

Significant portions of these drives are through rural areas with limited cellular coverage and limited local radio stations in both the AM and FM bands, especially when it comes to sports stations.

There are still folks who listen to clear-channel AM stations in their secondary/skywave service area.  What's going to happen if the mediumwave broadcast band goes 100% digital?

At least some of these listeners will probably stream the audio on their smartphones using 5G.

[redhat]

There are still folks who listen to clear-channel AM stations in their secondary/skywave service area.  What's going to happen if the mediumwave broadcast band goes 100% digital?

Skywave listening will then be a thing of the past, with very rare exceptions.  I very much doubt this will happen though, as the vast majority of stations do not have the budget to drop $20-100K on gear and antenna modifications to make digital work.  Add to that the lack of receiver penetration, coverage variability...it goes on and on.

+-RH