02 March 2008

mediumwave dx vs. hd radio

While trying to log mediumwave stations this year, I have encountered a new problem. The mediumwave band now contains harmful interference where once it contained AM stations. The introduction of HD radio on the AM broadcast band may be to blame.

I expect the occasional instance of adjacent channel interference. I may hear a strong signal on 1400 kHz, then hear remnants of that same signal when tuned to 1410 kHz. Compensating for this problem usually involves enabling the narrow filter on a radio, tuning further away from the interference source (such as going to 1412 kHz for example), or a combination of the two. With the noise that I'm now hearing surrounding some HD broadcasts, these methods are ineffective as the noise is overwhelming.

Here are the stations that I have logged, which have harmful noise on both adjacent channels (plus and minus 10 kHz). I'll also list stations that I logged back in 2006, but will likely no longer hear as a result of adjacent channel interference. Listening tests to confirm the presence of noise on the adjacent frequencies were performed with my Eton E5 on 02 March 2008.

• 740 KCBS: Sometime in 2008, KCBS began identifying itself as "KCBS and KCBS HD". An email exchange with the station reveals that their HD broadcast is running 24/7. 730 kHz and 750 kHz are now so noisy that no stations can be identified on these frequencies. So this eliminates 730 CHMJ (Vancouver, BC, Canada), 750 KHWG (Fallon, NV), 750 KOAL (Price, UT), and 750 KXL (Portland, OR).

• 910 KNEW: Their website says "Broadcasting in HD radio." This eliminates 900 CKMO (Victoria, BC, Canada), 900 KBIF (Fresno, CA), 920 KIHM (Reno, NV), 920 KVIN (Ceres, CA), and 920 KXLY (Spokane, WA).

• 960 KKGN: This station used to be KQKE until August 2007. Their website includes an "HD radio" logo. This will eliminate 950 KAHI (Sacramento, CA), and 970 KCMD (Portland, OR).

• 1050 KNBR: This is an odd one. KNBR is the callsign here for both 680 and 1050. The 680 frequency does not have adjacent channel interference on 670 and 690. I don't know why only 1050 would use HD. The only confirmation I have for my suspicion of an HD broadcast on 1050 is Wikipedia. Fortunately, I have not previously logged any stations on 1040 or 1060.

• 1310 KMKY: Oh great, Radio Disney with its numerous stations will use HD radio too? I could not find evidence of the HD broadcast on the Radio Disney website, but I found it on the iBiquity station list for California. This eliminates 1300 KCMY (Carson City, NV) and 1320 KCTC (Sacramento, CA).

5 comments:

PocketRadio said...

Yup, HD/IBOC jams on both AM and FM:

"HD Interference: Not Just For AM Anymore"

"Radio World Engineering Extra dropped a bomb this month with a very provocative cover story: 'What Are We Doing to Ourselves, Exactly?' Written by Doug Vernier, the man who authored the technical specifications for an ongoing Corporation for Public Broadcasting-sponsored HD Radio interference analysis, the report is the first of its kind to document interference between FM-HD stations around the country. Using anecdotal reportage, some sophisticated contour-mapping, and presumably 'early data' from the CPB study, Vernier's article conclusively proves how stations running in hybrid HD/analog mode can (and do) interfere somewhat significantly with not only themselves, but their neighbors on the FM dial."

http://diymedia.net/archive/1207.htm#122307

"Editorial: AM IBOC in Distress?"

"Citadel Director of Corporate Engineering Martin Stabbert embodied questions about the efficacy of full-time AM HD when he ordered all his AMs that had already converted to cease transmitting HD at night, using language that must have given Ibiquity officials heartburn. Separately and for different immediate reasons, Cox, in a “let’s wait and see” move, has tried HD on most of its AM stations but is taking it off the air day and night, once tested at each facility."

http://www.rwonline.com/pages/s.0044/t.9917.html

HD Radio is a farce:

http://hdradiofarce.blogspot.com/

bobyoung said...

This is a constantly updated list of AM IBOC stations which has pretty much ruined my DXing here in the NE US this year.

http://topazdesigns.com/iboc/station-list.html

So far it has pretty much been dying a slow death especially on AM so I'm just biding my time until it's history. There is an awful lot of money behind it however here in the US, logically it would have already been dead and buried if it were a normal new product but with many of the big conglomerates banding together it is being artificially kept alive. Digital radio has already come and gone in several European countries such as Germany is dying in canada and is on life support in the UK also so there is hope.

paul vincent zecchino said...

HD does one thing well, it jams. That's why moribund greedygut BigRadio loves it. HD jams competitors off the air and listeners into submisssion.

Or so BigRadio thought.

But listeners dislike jamming. They see it as a cynical ploy to short circuit the free market, ruin their airwaves, and limit their choices. Listeners rejected HD.


As the article notes, it's the same in the UK and Europe. No one wants this digital turkey. It stinks.

Why do BigKorpseorate kronykasters think they'll prevail? The 90s are over. The numbers are in. People are sick of 'carny shills', like HD. Bridge Ratings long ago demonstrated, the more listeners learn about HD, the more they reject it. What a loser.

Paul Vincent Zecchino
Manasota Key, Florida
03 March, 2008

Anonymous said...

i have to commend you for putting up the good fight.

when my parents spoiled me with the shortwave radio i wanted from Radio Shack, when i was about 11 or 12, it was like opening up to a whole new world.

whats happened in the past decade and a half?things have gone to utter shit. the vast majority of the high quality SW broadcasters from western europe simply up and left. string out a good long wire and youre left with some poor quality signals from south america or africa, for a few hours a night. oooh!

and AM/MW riddled with all this digi-crap..

i really wanted to finally upgrade my first SW radio into something better. was pricing E1's on ebay. checking out the new PL-600 from Tecsun. but i cant really justify it, with the only thing available in the US during the daytime is a bunch of religious wackos. if i want to listen to the weird shows on the Maine stations theyre available as podcast or torrent in much higher quality..

heres to hoping for a new golden age?

one thing i _am_ interested in would be SDR 'band chunks' from major metropolii shared over P2P, something like TVAnts/SopCast (high quality digital TV from around the world without a Cable). i'd love to be able to lsiten to the dozens of FM channels available in Beijing, without actually moving there..

cheers, and keep up the good fight. i have a feeling this IBOC stuff will last longer in the US just because of the justification of investment and wilingness to present some alternative to XM/Sirius..

weatherall said...

Thanks to everyone who expressed their opinions on this subject. I always enjoy reading your comments.