On 9/6/2010 9:49 AM, Geoffrey S. Mendelson wrote:
hwh wrote:
You don't want to hear the simple truth: no broadcast system can sound
properly at 40 or 48 kbps. Both Sirius and HD use rates like that, or
less. And therefore they sound bad. I've heard them both and yes: in
practice even on a rental car stereo they do not match the FM produced
by the same receiver and speakers.

That's a codec problem. With currently available codecs, you can get FM radio
quality with 64k with AAC (aka MP4 audio). This is roughly equivalent to
128k MP3, which is good enough for a car radio or tiny earphones, but not
CD or even CRO2 Dolby cassete quality.

Since I don't know what codec they use, I can't say what they need to increase
their bit rates to, but assuming they do (or could) use AAC, they would have
to cut their number of channels by as much as one third to compensate for
the higher bit rate.

It's a trade-off to be sure. But even now, every independent test of HD
Radio has shown the claims of improved sound quality over FM to be true.
Too many people don't understand that the proper Codec can provide
excellent quality audio at bit rates that digital radio employs.

The issue is also the definition of "CD Quality." In a vehicle, where
most radio listening is done, you're not going to be able to tell much
of a difference between HD Radio and CD unless your vehicle has a very
high end sound system. Similarly, FM Radio is often of poor quality in a
vehicle due to multipath. Drive on 280 from Cupertino until about San
Bruno, and the multipath is horrendous (though until stations increase
their HD power you can't get HD for much of that stretch at all).