16 September 2008
XM Radio is a brand of satellite radio which allows one to listen to hundreds of channels, anyplace where one can see the satellite in the sky. It blanks out if you go through a tunnel, under a lot of trees, or get too close to a steep hill in the wrong direction.
XM Radio is found mostly in cars. To use it indoors, you need an external antenna.
XM radio has hundreds of channels, but half of them are country, sports, disco, or traffic reports for places you've never been. Each traffic channel has a cursory weather forecast for each large metropolitan area, but even with all the channels, there is only one weather channel.
Just like cable TV, who care if it has 125 channels if there's nothing on? You'll have to give it a try and see if you can find channels you like; most people love XM radio.
I've used both XM and Sirius and find them identically bad in sound quality for the same reasons.
They use the same digital audio data reduction and compression technology as cell phones, so the sound quality is similar. XM Radio, just like Sirius, throws away most of the digital audio bits that make up your music so they can cram hundreds of channels down one satellite channel, much as your cell phone company uses this to cram thousands of phone calls into each cell site.
I can identify a familiar piece of music simply by hearing less than a one-second clip of the music, If I can hear a fraction of one chord, our ears are so advanced that it's easy for many people to recognize a song, or entire symphony, simply from the complex and unique timbre (color) of the sound. This is what makes music music.
The sound quality of XM Radio's severe data compression is so bad that these complex colors are lost. I can't recognize a song over XM until I've heard enough bars to recognize the lines, since I can't hear the timbres.
XM Radio sounds as if you're listening to a friend calling you on his cell phone's speaker phone while playing the music in his car.
XM Radio sounds like an old, garbled cassette tape. The sounds and instruments pop in and out.
To you more technical people, the severe data compression sounds like a multi-frequency noise gate set too high so it shuts off a lot of bands that it shouldn't. Bands keep popping in and out of squelch. This is one of the ways audio data rate reduction works.
Percussion and cymbals sound awful. They don't sound anything like music.
XM Radio depends on you already knowing how a song sounds so that your brain can fill in between all the missing sound. If you listen to a new piece, you'll probably not be able to hear much of it since many of the inner voices of more complex music is filtered out.
Oddly, of all popular music, the Salsa channel sounded the least bad. I have a sneaking suspicion that XM throws more bits at this channel, since XM radio sounds the worst on percussive sounds.
The three classical channels sound the best. On a mediocre car system like the standard radio of a Buick Enclave, the classical channels sounded just fine. I also have a sneaking suspicion that XM is dedicating a lot more bits to these channels. The dynamics sound reasonably intact, yay!
The Buick Enclave's radio has an excellent "CAT" button which lets you browse XM channels by category.
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