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Re: [IRCA] IBOC Hash AM vs FM OT question



Scott,

I never considered that the Sony uses DSP. That would make a huge difference. I guess in the city where the hash is stronger, the DSP cannot get rid of all of it, but out here, the hash is weak, so the DSP can just filter it out, if there is any. I was playing around with 88.3 a bit ago, as the strongest HD signal I get is 88.1 down by Newport. They are like 8500w, but is quite high. I never could detect the signal up here on the van radio, but the Sony locks it right in in HD. I never seem to get it in analog. Just the Ocean Park WA station, but once Newport locks, Ocean Park is totally gone.  In checking 88.3, there is just a very weak Portland (presumed). Some FM Dxers feel I should run a small amp, to slightly up the noise, as the receiver tends to mute extremely weak signals. I have not noticed that, as I get a lot of very weak stuff on many  channels. Often there are two or three mixing or trading places. 

Patrick Martin
Seaside OR
KGED QSL Manager

> Date: Wed, 20 May 2015 21:33:55 -0400
> From: scott@xxxxxxxxxx
> To: irca@xxxxxxxxxxxxxxxx
> Subject: Re: [IRCA] IBOC Hash AM vs FM OT question
> 
> On 5/20/2015 1:14 AM, Patrick Martin wrote:
> 
> > I guess nulling FM or AM hash is the same. I have tried to get "any"
> > hash at this location. To date I have still never detected any. Now,
> > it could be that the hash is so weak not the detect.
> 
> Something else to consider about "hash": you won't generally hear it 
> from the audio output of an HD radio. "Hash" is digital data being 
> received on an analog receiver, right? You hear it as static because the 
> analog receiver doesn't know what else to do with it. But an HD radio's 
> DSP *knows* what to do with it and knows not to pass it out as analog 
> noise, so it will either mute on the adjacent channel or even use the 
> DSP to do some really advanced filtering to pull out analog 
> adjacent-channel audio from right under the digital data.
> 
> 
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