Sirius vs. XM

What is Sirius?

Sirius Satellite Radio was founded in 1990, and was the first satellite radio service to get an FCC license in 1997. But because of technical problems with its satellites, its first broadcast wasn't until July 2002, nearly a year behind XM. Since then, it has lagged behind its competitor in subscribers, although since 2007 it has almost always posted higher net subscriber gains and often looks to catch up with XM.

­Sirius broadcasts satellite radio from three satellites, which were launched in 2000 from the Baikonur Cosmodrome in the Republic of Kazakhstan. The satellites orbit the Earth in an elliptical constellation, between 15,200 and 29,280 miles above the Earth's surface.

The three solar-powered satellites follow one after the other, so when one passes out of the Northern Hemisphere, for example, another is right behind it to provide uninterrupted transmission. Two ground stations, one in Ecuador and another in Panama, are in constant contact with the satellites.

Sirius offers radios for four environments: car receivers that either work with your car's existing radio or replace it (ranging from $100 to $300), home receivers that work with your home stereo components (ranging from $150 to $2,200), dock-and-play receivers that can go from the car to the home (ranging from $40 to $150) and portable radios that act like MP3 players (ranging from $150 to $280).

Before the two companies merged, XM and Sirius went head-to-head signing radio celebrities, and the most famous -- or infamous -- of these was Howard Stern. With his never ending parade of strippers, porn stars and willing female fans, the shock jock has often been the target of the Federal Communications Commission (see How does the FCC police obscenity?). In 2004, Clear Channel Communications dumped his show over alleged indecency violations. Late that year, Stern announced that he was going to be moving to Sirius, where he was reportedly offered a five-year, $100 million contract. Whereas traditional radio falls under the watchful eye of the FCC, satellite radio has no such restrictions. Like HBO and other pay cable networks, it can air virtually anything, including obscenity, giving Stern virtually free reign in his new home. Whether lawmakers will vote to regulate satellite radio in the future is still unknown, but both XM and Sirius note which programs contain adult content and offer family packages at reduced prices that omit channels with potentially offensive material.

Other personalities that Sirius has on its list are a mix of controversial and universal appeal, including Martha Stewart, Lance Armstrong, Eminem and 50 Cent.