Re: [IRCA] Another perspective on AM IBOC, from the broadcasters' mailing list

["Craig Healy" <bubba@xxxxxxxxxxxxxxxxxxxx>]

>Very interesting. So it sounds (If I am correct?) that a
>communications receiver could be built to solve our IBOC
>issues? I asked that question a couple of times early on
>with the IBOC discussion along with a noise blanker to
>take it out and several responded saying it could not be
>done. So I dropped that thought. Well, maybe just maybe
>one of the receiver manufacturers could take this issue on. 

The receiver would have to distinguish between several different digital sources and several analog signals as well.  Picture my local on 1220 going IBOC at night.  The lower adjacent is the 50kw clear channel in Philadelphia on 1210.  There are many stations on 1230 nearby as well.  I doubt any receiver could make heads or tails of that mess except *very* near the transmitter site.  Add in the resultant digital skywave hiss on their analog signal and it's a nightmare.

It seems that the comments about a DSP receiver are predicated on a single clean signal and not real-world conditions.  The Winradio and other software defined receivers are darned close to what is described in terms of bandwidth and shape factor.  They are good, but hardly a panacea for tough conditions.  

Perhaps the question should be posed as to how a radio could deal with interference that could exceed the desired signal.  If someone truly could design an intelligent algorithm for the DSP that would negate interference, then they could name their price.  The SETI folks and numerous government agencies would elbow their way to the head of the line, I'm sure.  The fact that it hasn't happened is telling.  Maybe that can be developed someday, but not in the next five years.

Craig Healy
Providence, RI




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