For about 5 months now I have had a XM capable radio in my car, I have not enabled the XM portion of it as of yet. I did research the XM website to find out about the audio quality, and as best as I can tell it says “CD like quality”. I emailed the XM support, and they told me exact specifications are “not public information”.
I am a semi intelligent person, and I just find it hard to believe that “CD like quality” is being pushed out digitally to sunscribers. A clean, non mp3’d audio track of 5 minutes long is pretty sizeable, 20MB or more, that rules out that aspect. I know there must be some type of compression going on, with decompression happening in the car, or they would have been doing this a long time ago with regular FM radio waves.
I estimate it is on the order of a 128kb stream, which is really not that great, and not at all CD quality. Then again, I can easily tell any mp3 from a original CD, no matter how high a bit rate it is encoded at. The lows are washy and the highys are flat, the whole thing is muted. I know some of you will argue XM is good, and that is probably true, I am interested in knowing the exact specification, as well as a link to where that spec is. I googled the FCC on it, as well as many other sites, and I can just not find info on the technology behind the service.