Re: Re:WGBH

["Dan Strassberg" <dan.strassberg@att.net>]

Well, to a first approximation--admittedly not all that accurate but
probably accurate enough for this discussion--the coverage radius is
directly proportional to the square root of HAAT. My understanding is that
if you double the HAAT at the same site and you need to hold constant a
specific contour (say 50 dBu or 60 dBu), you have to cut the ERP to 25% of
the value used at the lower height. I know that, rather than this simple
relationship, the FCC uses curves or more complicated equations, but I don't
have the curves or equations.

My recollection is that 'GBH-FM is moving from 98 kW @ 198m to 21 kW @ 323m.
Using my relationship, the height increase should necessitate a reduction to
37 kW, but the CP is for 21 kW. Thus, to make the move, the FCC required
'GBH-FM to, in effect, cut its power to 57% of its current value. The power
cut could be the result of moving to a location 10 or so miles northwest of
the current one and thus 10 or so miles closer to some existing station or
stations (or maybe because the new site is just a bit less than 10 or so
miles closer to the Canadian border). However, I think the change in
height-adjusted ERP is to correct a grandfathered condition that could be
maintained only if the station made no change in its operation.

The curious thing is that, according to the FCC's public FM database, WGBH
is now and will continue to be a Class B (not B1 and not C of _any_
subclass), yet the old power, which is equivalent to roughly 200 kW at 150m
(the nominal Class-maximum HAAT for Class Bs--that is, the HAAT above which
an ERP reduction is required) is about four times the maximum for a Class B.
The new power, though lower on a height-adjusted basis, is still equivalent
to more than twice that for a Class B.

--
Dan Strassberg, dan.strassberg@att.net
617-558-4205, eFax 707-215-6367

----- Original Message -----
From: Aaron 'Bishop' Read <aread@speakeasy.net>
To: <bri@bostonradio.org>
Sent: Monday, June 10, 2002 11:21 PM
Subject: Re:WGBH
.
> Is WGBH's move already granted?  I thought it was still pending...the
> freeze has been in place for several years now.  To answer your question,
I
> believe CP's are not frozen.
>
> I couldn't tell you off the top of my head whether the contours will be
the
> same.