We all have our favorite radio stations that we preset into our car radios, flipping between them as we drive to and from work, on errands and around town. But when you travel too far away from the station, the signal breaks up and fades into the background. Most radio signals can only travel about 30 or 40 miles from their source. On long trips, you might have to change radio stations every hour or so as the signals fade in and out. And it's not much fun scanning through static trying to find something -- anything -- to listen to. 

Sirius and XM Radio each offer more than 100 channels of continuous, crystal-clear music without commercial interruption. Satellite radio is similar to the specialty radio channels available on digital cable and satellite TV. In  2007, XM Radio and Sirius Radio announced that they planned to merge into a single satellite radio company. XM and Sirius are both in debt, and a merger could quickly solve that problem. The merger could also lead to lower prices and more programming choices for consumers About 8 million people subscribe to XM Radio, and more than 6 million people tune into Sirius Radio. 

All satellite radio broadcasts are digital to ensure high quality. The source of the broadcasts is a number of small studios typically located at a company's main office, where hundreds of thousands of CDs are stored.

Play lists, built by programmers, for themed channels are filled with appropriate tracks. Even this initial step in the broadcast process differs from conventional radio, where a disc jockey selects and plays cuts from CDs all day long.

The play lists are uploaded to a computer, which in turn transmits them to satellites orbiting more than 20,000 miles above Earth. The music, in the form of a digital signal is then sent down to listeners here on planet Earth. A variety of obstructions like tall buildings and mountains can weaken the signal therefore satellite radio providers operate a number of terrestrial repeaters, which bounce back the airwaves and reinforce the signal. 

Just like traditional radio and digital cable, satellite broadcasts are categorized into music genres. So, if you only want to listen to golden oldies, all you have to do is select the proper channel. Satellite radio offers a very wide range of channels dedicated to comedy, sports, news, talk, and entertainment. There are also weather and traffic channels available for major U.S. cities. 

Sirius and XM Radio provide services in the United States. In the United Kingdom, it’s Sky Television as most British radio stations are now available via digital signal. Canadians can receive American signals, but whether it's legal for them to do so is still a gray area. The Canadian government is currently evaluating Regions of South America, Europe, Africa, and Asia are now covered by a company called WorldSpace.

You can expect to pay around $100 US for a satellite receiver. When selecting a receiver, you'll be able to choose between portable devices and tuners that can be plugged into existing sound systems. There are also receivers designed specifically for automobiles.  One neat feature is that receivers always display the song title, artist and genre of music playing.

Of course few things in life is free. After you buy a receiver, you will also be charged monthly service fees. Subscriptions run around $13 per month. Finally, an activation fee is required before you can enjoy this new service. Given all these expenses, it's up to you to decide what's more important to you: radio that's crystal-clear and commercial-free, or radio that's just free.

You can sign up for either Sirius or XM radio at each respective company's official site, where you can also purchase a receiver.

You can also enroll for the service at many home appliance and electronic retailers or car dealerships -- providing that a receiver comes with your new vehicle. Outlets that carry receivers will usually have the required paperwork for you to subscribe to the corresponding service. There is no contract involved, only a monthly subscription, which you can cancel at any time. 

Remember, along with the great sound and the absence of advertisements, satellite radio is uncensored. The FCC doesn't impose regulations on the content broadcast through this medium, so, just like on cable TV, every subject is fair game and no word is taboo.