[BC] IBOC Interference to 1st-adjacent FMs

[Mark Humphrey]

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