[BC] Real cases of IBOC interference wanted for research

[David L. Hershberger]

Hi Doug,

My zip code is 95959 and your program reports that KKOH's daytime signal is
2.94 mv/m. BUT, I'm actually about 6 miles east of town up in Tahoe National
Forest (closer to Reno). MWViewer reports that my daytime signal strength
should be 3.27 mv/m. That's based on my actual location rather than my zip
code.

Similarly, my signal strength for KNCO's nighttime pattern should be13.2
mv/m, according to MWViewer.

As for KXNT's nulls, Paul Smith's comments are germane and correct. The
nulls of a DA are only at the carrier frequency. It's not reasonable to
expect an AM array to maintain its null depth over three channels of
bandwidth. And that's a huge problem for AM IBOC and it explains why KNCO
gets trashed by IBOC. I don't think there's anything wrong with KXNT's
facilities. I think it's an IBOC problem, not a KXNT problem.

MWViewer reports that KCBC (770, IBOC affecting KKOH 780) should be 349 uV/m
here. But their IBOC sidebands sound disproportionately loud. Again, I think
it is DAs not working over three channels of bandwidth.

Dave


----- Original Message ----- 
From: "Doug Vernier" <dvernier at V-soft.com>
To: <broadcast at radiolists.net>
Sent: Wednesday, July 19, 2006 3:03 PM
Subject: [BC] Real cases of IBOC interference wanted for research


Dave,

If you provide your zip code the ZipSignal program will provide the signal
strength of KKOH at the zip code centroid.

http://www.v-soft.com/ZipSignal/default.htm

That way we can tell if the interference you hear is within the normally
protected signal contour.

Doug

-------------



Message: 14
Date: Wed, 19 Jul 2006 10:15:45 -0700
From: "David L. Hershberger" <dave at w9gr.com>
Subject: Re: [BC] Real cases of IBOC interference wanted for research
purposes
To: "Broadcasters' Mailing List" <broadcast at radiolists.net>
Message-ID: <00e601c6ab56$fbf9ff40$6500a8c0 at ATHLON64>
Content-Type: text/plain; charset="iso-8859-1"

Hi Doug,

I have two AM cases to report. First, KXNT 840 in Las Vegas apparently
sometimes "forgets" to turn off their IBOC at night. When this happens it is
usually on weekends. This trashes our adjacent local 5 kW AM station at
night (KCNO 830). Here are examples recorded two years ago:

http://www.w9gr.com/knco.mp3  (normal reception, no IBOC)

http://www.w9gr.com/kncoiboc.mp3  (IBOC on from Las Vegas)

Details of antenna patterns, my receive location, etc. are in my comments on
the FCC web page.

The second case is daytime interference. KCBC 770  in Riverbank (Modesto)
trashes KKOH 780 in Reno. My location is Nevada City, CA and I think I am
well within KKOH's protected contour. I don't have a recording of KKOH but I
could easily make one.

Dave Hershberger


Doug Vernier, Telecommunications Consultants
V-Soft Communications
Broadcast Propagation Software and Engineering Consulting
WWW.V-Soft.com
319 266-8402

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