WBZ's historical signal in VT

Dan.Strassberg dan.strassberg@att.net
Sat Feb 16 15:23:32 EST 2008

There is NO MORE 750-mile nighttime-coverage radius for ND Class
As--if there ever was one! At one point, the FCC may have been talking
about such a radius but AFAIK, it was never codified. And then, around
the time of the Rio Treaty (late 80s?), the formulas for calculating
NIF contours were changed, reducing the protected radius to
approximately 500 miles. For illustration, take a look at the spacing
between WGN and WVOA (CP) DeWitt (Syracuse) NY. The distance between
the stations is only 610 miles. WGN's protected contour lies just east
of Buffalo, almost exactly 500 miles from the WGN Tx. You'd think that
WBZ, because it's directional to the west, would be protected over a
larger distance than all other US Class As (except WWL, which is also
directional). Well, maybe a little--but not anywhere near as much as
you might think. WNVR, a Class D licensed to Vernon Hills IL, about 30
miles west of the Loop, runs 120W-N into two towers that produce a
figure-eight pattern on a north-south axis with a deep minimum toward
Boston. Nevertheless, in Ontario, east of Detroit (and west of
Buffalo), WNVR causes interference to WBZ within WBZ's 0.5 mV/m 50%
skywave contour. This overlap is permitted by treaty because Class A
AMs' nighttime-skywave service is not protected outside of the borders
of the Class A's home country.

Bear in mind that, despite being only 30 or so miles from WNVR, the
lake-shore in Chicago proper receives a nighttime signal from WBZ that
was recently described in a posting here as being better than those of
all but a couple of Chicago's five 50-kW Class A AMs.

As for the hissing sound you mentioned that destroyed WBZ at night a
few hundred miles from Boston, it was most likely KDKA's IBOC but
could also have been WHO's IBOC (or maybe some of each).

Dan Strassberg (dan.strassberg@att.net)
eFax 1-707-215-6367

----- Original Message ----- 
From: "Martin Waters" <martinjwaters@yahoo.com>
To: <bri@bostonradio.org>
Sent: Saturday, February 16, 2008 1:36 PM
Subject: Re: WBZ's historical signal in VT

> --- "Peter Q. George" <radiojunkie3@yahoo.com> wrote:
>> Hi Don:
>> Part of the problem with WBZ's super signal at night
>> is..... it's super signal.  Let me explain.  If you
>> get WBZ during the day fairly well during the day,
>> chances are the signal will be fairly diminished at
>> night due to the "cancellation effect" of a
>> combination strong groundwave and strong skywave
>> fighting themselves out.  'BZ's nighttime signal
>> beyond about 200-250 miles out should be very strong
>> as there are no vestiges of the groundwave left.
>   There's also the stations-staying-on-too-late on
> 1030 kHz factor and the
> FCC-licenses-stations-to-stay-on-on-1030-kHz-at-locations-and-with-nighttime-powers-that-are-way-too-high
> factor.
>   About halfway between Hartford and Sturbridge on
> I-84 the other night, I was getting an in-and-out
> hissing skywave signal from somewhere that made WBZ
> unlistenable. That's certainly in the zone that gets
> groundwave and a little skywave from WBZ -- about 85
> miles from Hull. But that wasn't why it was
> unlistenable.
>    WBZ's putting the equivalent of 80 or 90 or 100
> kilowatts toward where I was. In the daytime, it comes
> in perfectly well -- weak by civilian standards, but
> more than listenable.
>    The 750-mile protection for the Class A stations
> is a joke. Insert my usual rant here. I'll spare you.
>    Meanwhile, have I told you how in the last few
> years I get skywave crap blotting out WCBS in
> Wallingford, Conn., where I'm betting I'm inside their
> 0.5 groundwave contour. Then there's WOR. Ohhh. Don't
> get me started. :))
>    The FCC pays no attention to actual physics and
> radio engineering when it licenses secondary stations
> on the Class A channels. It pays no attention to the
> cumulative effect of 10 or 20 little diddly skywave
> signals.
>    When the X-band was new, I had fun listening to
> the 1 kW night signals from California. That's the
> sort of signal that's out there murmuring behind the
> Class A stations all over the place.
>    Geez. I guess that was at least pat of my rant . .
> .

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