HD Radio -- off/on? Why?

[Ferguson]

I noticed the HD Radio always greyed out, and (as the usual last resort) looked in the manual, and found that it was turned off.

OK, it's on. It works (one whole station when I did an FM Auto-store). Very nice sound actually, quite impressive but then again it was pretty impressive to begin with (I have the Premium Sound).

My question is this -- why would I turn it off?

I'm not complaining, I just am confused. There's no "AM off/on".

I saw some old threads about not having RTTI and HD, but that's not true, I just checked, I have both with it on.

What am I missing?

Incidentally, how does Satellite radio compare in quality to HD Radio, i.e. bandwidth/frequence response wise? I'm not much of an audiophile, just curious.

[xnsf]

my first guess would be that hd service is not "smooth" in all areas

when the system is not able to find an hd signal, it will automatically turn over to regular

some people may not like the transition between the two because all hd really does is make things louder (for all practical purposes in explanation). so it'll get louder, then it'll get softer, then louder, etc.

both satellite radio and hd radio are marketed as CD-quality or better

[JBHorner]

Do they really market satellite radio as CD quality?! That is a HUGE stretch, in my opinion. I have Sirius and XM. (In cars, portable, and desktop.) Sirius has a lower quality sound to me than XM. Neither one sounds like CD quality.

The compression is audible.

Joel

[BG624]

Originally Posted by JBHorner

Do they really market satellite radio as CD quality?! That is a HUGE stretch, in my opinion. I have Sirius and XM. (In cars, portable, and desktop.) Sirius has a lower quality sound to me than XM. Neither one sounds like CD quality.

The compression is audible.

Joel

That's correct, both Sirius and XM use very compressed signals so their sound is marginal. HD radio and CD's are far superior in sound quality.

[thisX5life]

Originally Posted by xnsf

my first guess would be that hd service is not "smooth" in all areas

when the system is not able to find an hd signal, it will automatically turn over to regular

some people may not like the transition between the two because all hd really does is make things louder (for all practical purposes in explanation). so it'll get louder, then it'll get softer, then louder, etc.

both satellite radio and hd radio are marketed as CD-quality or better

That's exactly it. I have HD on my E70, and it can be very annoying to have the HD-quality signal coming and going, which is inevitable at the moment because the digital HD signal is transmitted at a lower power level than the conventional analog signal. It's especially irksome with AM stations, where the HD audio is markedly different than conventional analog AM. It does't get louder or softer, but the frequency range (and thus the timbre of voices) changes drastically. Sometimes when I'm in an area where the strength of the HD signal is marginal, I switch the HD off to keep it from flipping in and out.

More HD Radio info here: http://en.wikipedia.org/wiki/HD_Radio

Leaving satellite radio out of it for the moment, neither AM nor FM HD radio is "CD quality" although the FM is substantially better than AM (from using higher bit rates). The HDC codec used in HD radio is "lossy," meaning that it throws away information contained in the source to achieve savings in size. The same is true of the MP3 and MP4 compression used in iPods and the like, although at high bit rates the difference may be inaudible to some listeners.

In any event, the interior of a moving car isn't a very good listening environment, and I find the HD radio quality to be a pleasant improvement over conventional broadcasts even though it's not in the same class with a CD or my iPod.