IBOC stands for "in-band, On-channel" and is a way to hide digital
transmission inside an analog signal.  The "Digital Radio Mondiale"
which you hear on some frequencies on shortwave, including 3995 KHz
from Germany at night, is an all-digital broadcasting system.

I don't know the details of IBOC on FM.  I can tell you about it on
AM, because WTOP, 1500 KHz is now running this mode during daytime
hours.  Part of the digital information sounds like white noise 30 or
40 dB below the modulation, spread over the plus/minus 10 KHz region
from the carrier frequency.  Then there is a stronger digital signal
between plus/minus 10 and plus/minus 15 KHz of the carrier.
Effectively, during the day, WTOP now occupies the spectrum from 1485
to 1505 KHz.  And even though I should have a "full quieting" signal,
being 1 mile from the 50 KW transmitter, it sounds like I'm 20 miles
away because of the added on-channel noise.  I think IBOC is a bad
idea, at least on AM, but supposedly it can sound as good as FM.


On Mon, 21 Mar 2005 09:57:07 -0500, Lowell Miller wrote:

>O.K. What is iboc?
>I must not be on the cutting edge!
>73
>Lowell  W8QIY
>----- Original Message -----
>From: "Jeff Kenyon" <[log in to unmask]>
>To: <[log in to unmask]>
>Sent: Sunday, March 20, 2005 5:31 PM
>Subject: IBOC AM question
>
>
>> Hi everyone, I have been hearing a few things here and there about IBOC
>> digital on AM and some short-wave stuff, and I have a few stations around
>> the Detroit area that I think are using the IBOC.  This includes WWJ and
>> WCHB 1200 and our family life station WUFL, 1030.  Has anyone used a
>> receiver that will work with IBOC and what have your opinions been and do
>> you all have any suggestions as to what to invest in?

Some people think that the devil is in the details.  Actually, God is in the details.
Lloyd Rasmussen, Kensington, Maryland
home: <http://lras.home.sprynet.com/>
Work:  <http://www.loc.gov/nls/z3986>