Re: [IRCA] OK, What is "IBOC Hash"

["Bill" <wharms@xxxxxxxxxxx>]

Hi!	

	IBOC or In-band On-channel is a mode of transmitting digital audio over our 
current AM and FM bands.  iBiquity, a consortium of broadcasting companies is 
responsible for promoting this system. http://www.ibiquity.com/hdradio/

	Currently, certain stations are testing the use and impact of IBOC.  IBOC in 
the hybrid mode (analog and digital together) interferes with stations on adjacent 
channels.  The interference or digital hash is white noise. The hybrid mode will be 
used until all stations convert to digital only. In the digital only mode, the interference 
will occur to stations on the same frequency and also likely to stations on adjacent 
channels.  Up until now, virtually all of the testing has been done during the daytime.  
Here locally, WKDL on 730, which had been testing with IBOC, turned it off for a few 
days and now I see they turned it back on today. 

	The controversy of IBOC for DXers is how it will impact DXing.  It appears 
that because of problems with interference between stations, when all stations use 
IBOC it will limit the coverage of a station in most cases to a local area. This will 
likely be particularly onerous at night with skywave interference. With analog, audio 
from stations can still be heard mixing with each other. With digital, audio is only 
audible when the station is in the clear .  Additionally, even if the signal being 
propagated by skywave is in the clear, the audio will suffer drop outs because of 
fading.  There is also speculation about what will happen when the signal is 
subjected to power line noise as people drive around and lightning storm crashes.

	The bottom line is that IBOC, if implemented, will cause AM DXing to cease 
to exist as we know it now.  DXers and other interested parties have submitted 
comments to the FCC arguing against IBOC.  I understand that the deadline is past.  
I wonder if they would still accept comments for the record.

Bill Harms
Elkridge, Maryland
R8B
Homebrew K9AY
	
On 20 Jun 2004 at 14:53, Mdcalvert@xxxxxxx wrote:

> 
> I am a recent subscriber to the group and I don't know the acronyms and buzz 
> words.
> 
> What does "IBOC" stand for?
> 
> What is "hash" and why would one station have it on and another have it "turned 
> off."
> 
> Velly intelesting!
> 
> MDCalvert
> Oak Ridge, TN


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