[opendtv] Re: HDradio?

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
  • Date: Tue, 4 Dec 2012 15:58:02 -0600

Takashi Tome wrote:

> I'm looking for some info about HDradio, but I'm not finding
> anything useful, or new.

Hi Takashi. You can get useful information from the Ibiquity web site.

http://www.ibiquity.com/

There used to be two white papers on that site, one that describes how it works 
in the FM band and another describes the AM band design. In a quick look, I 
didn't see those papers there anymore. But maybe I didn't look in the right 
place.

> I'd like to have some info like:
>
> 1) How is HDradio signal strenght at real life?

Very good. I have a stereo HD Radio receiver at home, made by Sangean, and I 
have a tiny little portable receiver that I can use in the car. It plugs into 
the miniphone jack on the car radio (the one used often for iPods and such). I 
tried the radio in the car, even on the subchannels, and reception was very 
good. And it would be far better if they used HD Radio in non-hybrid mode, 
where signal strength could go much higher. But even as is, it works very well.

> 2) Does HD signal interfere on adjacent analog stations?

Not that I ever noticed. And that's part of the "problem." In hybrid mode, the 
digital signal uses the guard bands of the analog signal from that same 
station. That's why the digital signal strength has to be suppressed. If I 
remember correctly, in the FM band, it has to be a full 23 dB below that analog 
signal's ERP. Which is substantial.

> 3) How does HD perform at LPFM stations?

Don't know.

> 4) How happy are the users?

Personally, very happy with it. A decent number of car companies are starting 
to offer it, but mostly I listen to it at home. Audio quality is excellent, 
very much like very good FM analog. Which makes any AM station that uses HD 
Radio stunningly better than its analog signal. But of course, for AM, it is 
limited to daytime only. In hybrid mode in the AM band, it takes up an 
incredible 30 KHz of bandwidth. In non-hybrid mode in  the AM band, it takes up 
no more than 10 KHz, and it would definitely make the AM band useful again. As 
opposed to the band-limited, muffled garbage you get now on AM analog.

> 5) Did HD upped stations audience?

Don't know. It should have, clearly, but as usual in the US, CE companies seem 
to go after what is in the best interests of the monthly subscription schemes. 
So for example, GM cars offer satellite radio receivers as standard equipment 
(GM is part owner of XM Radio), and yet they seem totally incompetent at 
offering HD Radio even as an extra cost option. Odd that such a simple idea has 
escaped them for what, about 10 years now?

Bert

 
 
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