Re: [IRCA] IBOC Hash trashes KSL

[Scott Fybush <scott@xxxxxxxxxx>]

Tim Hall wrote:

> For what it's worth, here in San Diego, we have two stations very close
> together:  KOGO-600 running IBOC, and XESS-620, the fraudulent Tijuana
> station which pretends to be in Ensenada, not running IBOC.  KOGO's daytime
> IBOC hash is enough to put a nasty squeal on top of XESS' signal on 620.  It
> will be interesting to see what happens when two or more legitimate stations
> start interfering with each other...
> 
> Although I'm prepared for the worst (a total AM apocalypse which renders the
> band useless for DXing, even in remote areas like national parks), I
> cautiously expect the actual outcome will be at least a little less horrible
> than that...

There are a huge number of "what if"s that will combine to tip the 
balance between "less horrible" and "total AM apocalypse," and I've 
covered many of them in previous posts (and in an article I'm working on 
right now for a future issue of DXN.)

The biggest question - and this will vary dramatically from station to 
station and from market to market - is to what extent incoming 
interference from first-adjacent skywave IBOC signals will damage local 
analog reception.

There are a fair number of AM stations that put enough signal over 
substantially all of their target local market that they won't be hurt 
by any imaginable adjacent-channel IBOC. Here in Rochester, WHAM 1180, 
with its 50 kW ND signal from just a few miles outside of town, is one 
of those. By the time you get far enough from the 1180 analog signal 
that it's weak enough to be overcome by IBOC from WWVA on 1170 or 
WOWO/WLIB on 1190, you're outside the area WHAM sells to.

WHAM's sister station on 1280, WHTK, is another story - it's got a 5 kW 
DA signal at night that's very good in the core of the market (I'll 
never hear any interference to it from my QTH, 2 miles north of the 
transmitter site in their main night lobe), but it falls off very 
quickly in some suburban areas that are still very much within the 
market. The question then becomes: who, if anyone, will be running IBOC 
on 1270 or 1290 that might interfere? Right now, nobody is - those 
channels are full of lots of low-power signals in the northeast, and the 
biggest 1290 is CJBK, which won't be going IBOC any time soon.

But then consider a couple of other locals: WLGZ on 990 sends a narrow 
2500-watt DA beam over Rochester from a site 15 miles or so west of 
town. It's so narrow that even though I'm only three miles south of 
downtown Rochester, I'm already on an edge of the lobe and already have 
trouble hearing the station clearly at night. If WMVP 1000 in Chicago 
turns on its IBOC 24/7, WLGZ stands to lose a big chunk of its nighttime 
audience.

Even worse off are stations like WYSL 1040 in Avon, 25 miles south of 
Rochester. It now has a huge, booming 20 kW day signal that's easily the 
second-best AM in the market - but at sunset, it drops down to just 500 
watts. That's still enough to mostly overcome WHO on-channel up here, 
but it will be hammered by WBZ when - and this one's a "when," not an 
"if" - 'BZ stops turning off IBOC at night.

Here's a real-life example of a station already feeling the pinch - WRKL 
910 New City NY, in Rockland County, 35 miles NW of Manhattan, which has 
depended over the last few years on its fringe signal toward NYC for 
most of its audience:

http://gullfoss2.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6518808409

It is important to note that the FCC still hasn't issued its full Report 
and Order implementing nighttime AM IBOC, which suggests strongly that 
the Commission still isn't sure how it's going to make good on its 
promise to address interference situations like that one.

And none of this, in turn, even touches on the reality that there are 
still a handful of AMs - WBZ and KGO, in the big markets, for instance, 
but also a lot of Midwesterners like KRVN and KFYR and WNAX - that do 
still depend on reaching a skywave audience at night for at least part 
of their revenue. Some of them know what they're in for. Others don't, 
or are in denial about the effect that skywave will have on the edges of 
their signals...which will make for some very interesting times ahead.

s
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