[BC] IBOC Interference to 1st-adjacent FMs

[Kent Winrich]

Hopefully we can keep this a reasonable discussion.....

I have not had the chance to drive the area you describe.  There is another
example that I have driven.  WDRV - 96.9 Chicago, and WWDV 97.1 Zion, IL.
The stations are directional (and simulcast), WWDV more so than WDRV.  WDRV
is on the Amoco tower in the Loop.  The stations are 73 kM apart.

WDRV:
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM69531.html

WWDV:
http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM97092.html

The overlap is in the highly regarded northern suburbs.

Though I have not taken the time to pull out test equipement or the like (I
like to get through Chicago as fast as I can), I have tried a number of car
radios... some HD, some not HD.

I have not heard any "buzz" or hiss on the main channels.  I have, however,
seen the HD signal drop.  There is an area Buffalo Grove, where both
stations at analog only.  Of course the HD2s are gone as well.

Kent Winrich





On 3/23/07, Mark Humphrey <mark3xy at gmail.com> wrote:
>
> To anyone in the New York-Philadelphia area interested in evaluating
> the impact of IBOC on first-adjacent short spaced FM stations, you'll
> find a real-world case near Trenton, NJ:
>
> WUSL 98.9 in Philadelphia (Roxborough antenna farm) is only 85 km
> (52.9 mi) from WAWZ 99.1 in Zarephath, NJ, which transmits from a
> ridgetop near Somerville.  Both are full Class B facilities with no
> protection to one another, spaced at about half the normally-required
> distance, and both are currently running IBOC.
>
> >From these coverage maps, you'll see how far their predicted service
> areas overlap. Practically all of Mercer County, NJ and Bucks County,
> PA fall within the overlap area:
>
> WUSL:
> http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM274154.html
>
> WAWZ:
> http://www.fcc.gov/fcc-bin/FMTV-service-area?x=FM667957.html
>
> Most of the other Philadelphia Class B stations have a first-adjacent
> neighbor on the Empire State Building in New York City, but the
> spacing between these pairs is about 82 miles so the problem is not as
> severe.
>
> Mark
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