[BC] IBOC Tentatively Identified as Interfering Signal

[Phil Alexander]

On 13 Aug 2006 at 8:46, Kent Winrich wrote:

> Does KLOS really care about covering SD?  Are they selling 
> ads there?  I highly doubt it.


Kent,

This is yet another rehash of a settled issue concerning IBOC.
Specifically, the loss of so-called "bonus" coverage is the point.
In this case, those who listen beyond the established contours are
complaining they are losing a service that has not been recognized
as service per se. The loss of this coverage was considered and
dismissed by the NAB, literally years ago. IBOC has some serious
problems, especially WRT deployment in the AM band, but this one
is not going to get further consideration from the FCC IMHO.

What may draw a further RM at some point is the combination of
radiation in the nulls of Class B stations' nighttime patterns
on the first adjacent frequencies causing interference to 
formerly NIF contours. That is a very real and very troublesome
possibility that is almost sure to result from poor pattern/phase
bandwidth and skywave propagation. One of the points that has been
overlooked is the older stations (the old Class II's III-a's) were 
designed to provide nighttime first adjacent protection and many 
of those arrays are still in service. Many probably lack the pattern
stability at the first adjacents to prevent IBOC IX to the first
adjacent azimuths, and skywave will do the rest. Ignoring physics
does have a downside.


---------------------------------------------
Phil Alexander, CSRE, AMD
Broadcast Engineering Services and Technology 
(a Div. of Advanced Parts Corporation) 
Ph. (317) 335-2065   FAX (317) 335-9037




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