[BC] A new digital band

[Scott Fybush]

At 04:29 PM 10/23/2005 -0400, you wrote:
>------ At 11:42 AM 10/23/2005, Barry Mishkind wrote: -------
>
>>         This raises an interesting question:
>>         How does IBOC do in the ducting zones?
>
>Good question but I've only encountered one regular ducting situation - 
>Florida to Massachusetts years ago with TV. I would often receive Florida 
>stations with reasonably good quality in Cambridge, MA. The interference 
>was in the video, not audio. I've personally never encountered it anywhere 
>else. I didn't find it in FM probably because I had highly directional 
>antennas on rotors pointed West rather than South.

My friends in the TV/FM DXing community would beg to differ.

E-skip is a common phenomenon in the summer months not only in coastal 
areas but across most of the east and midwest. Pick a typical June or July 
afternoon, and it's more likely than not that I can sit in front of my TV 
here in Rochester and be watching channel 2 from Miami or 3 from Shreveport 
or Lexington, Nebraska, just to name a few typical targets. The incoming 
skip signals (typically from 1100-1500 miles away) regularly override the 
signals - video and audio - I normally see on those channels from Buffalo 
and Syracuse, 70-80 miles away.

E-skip is limited both in duration (it's usually a May-July phenomenon) and 
in frequency (usually limited to low-band VHF, with occasional incursions 
into FM and even more rarely into 2-meter territory).

Tropospheric ducting is another thing entirely. It's generally far shorter 
in distance (200-500 miles) and largely confined to coastal paths, but it's 
less seasonal and far less confined to a small band of frequencies. When 
WCVB-DT in Boston first fired up on channel 20, summertime ducting along 
the coast to New Jersey wreaked havoc on a public-safety operation down 
there that used the same frequencies. Such ducting openings can, in the 
worst cases (or, as the DXers would have it, the best cases), last for days 
on end, affecting everything from low-band V all the way up the dial to the 
top of the UHF spectrum. It's not at all uncommon for folks in Long Island 
to be hearing most of the Norfolk, Virginia FM dial - and vice versa - on a 
warm late-summer day. It's reasonable to think that such propagation could 
cut into the fringes of local IBOC reception.

s