1410 vs WKOX 1430 AM HD intereference

M.Casey map@mapinternet.com
Sat Jun 20 14:40:22 EDT 2015

I think that both of you are correct.

AM HD, as it is presently implemented, does not really work. Yes, in a 
maximum skywave area for WBZ (about 300+ miles west) last fall, traveling 
south from Rochester, NY to Harrisburg, PA, at night, the WBZ AM HD signal 
came in many times and held, but only to a maximum of less than 2 minutes. 
And, on that trip, most of the time HD would not decode while WBZ's skywave 
analog signal was very listenable. Farther out, in an area of eastern NC 
that I regularly travel to, WBZ, about 600 miles northeast, is often the 
strongest station on the dial at night, but HD decoding is rare.

I've heard the same about DRM, at least in some ways, being a better system, 
but that means that similtaneous analog is not possible--not a practical 

And it makes sense that a full power all-digital signal like what was used 
in the WBT test would work via skywave, but again the same problem as 
DRM--analog FM would not be possible.

Ironically, even though TV are much more expensive, I believe, It would be 
much harder on radio listeners to convert to all digital than it was for TV 
users. Radio is with us everywhere--cars, jobsite, beach, work, bedroom, 
bathroom, garage, walking & jogging--not so for TV.

The proposal for the changeover of TV CH 5&6 that was floated in 2008 has 
some good points. A scheme similar to the implementation of 1600-1700 band 
might work. An AM station gets a (Hybrid) IBOC FM HD channel in the 76-88 
MHz segment. The AM and FM both operate for a year. Then the applicant 
chooses one or the other. Eventually number of stations on the AM band 
declines and there could be some "refarming" of the AM band to lessen 
interference. Then, maybe some of the remaining regional and local AM 
stations could move to allow for a few new higher power (more than 50kw) AM 
stations to serve wide areas, rural areas, and help satisfy emergency 
broadcast needs.

It would be much easier on the listening public to add 76-88 MHz to new 
radios and use the current Hybrid IBOC HD system than to turn off analog 
which would require everyone to buy new all-digital radios.

These ideas have been around for more than 10 years. This could have been 
mostly completed by now. AM will still be around in 10, probably even 20 or 
30 years. Why not start with this 76-88 MHz idea now. Yes, some TV stations 
(just about all of those are very low power) would have to be refarmed right 

Here's an aside-- While eliminating Ch 5 & 6 TV in favor of FM Broadcast, 
Allow much higher power digital TV stations on channels 2, 3, 4, and 7-13 in 
order to restore TV service to the many folks in rural and mountainous areas 
like in central & northern New England that have LOST all, or nearly all TV 
reception since digital TV was implemented. Stations on channel 2, 3, or 4 
with decent power on big hills like Mt Mansfield, Washington, Ascutney, 
Greylock, or even Wachusett would help that situation. The TV stations 
located at Mt. Wilson in the Los Angeles, CA market that stayed on VHF have 
been permitted up to 4x the maximum power originally allowed for digital TV 
by the FCC.

Mark Casey

-----Original Message----- 
From: Scott Fybush
Sent: Friday, June 19, 2015 10:35 PM
To: boston-radio-interest@lists.BostonRadio.org
Subject: Re: 1410 vs WKOX 1430 AM HD intereference

On 6/19/2015 10:20 PM, Rob Landry wrote:

> If they do that, it should be DRM not HD Radio. DRM will work on
> skywaves; HD will not. Reports I've heard suggest DRM is just a better
> engineered system.

I've got over an hour of crystal-clear recorded audio from here in
Rochester during the WBT Charlotte all-digital testing that says
all-digital HD works via skywave.


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