What is Satellite Radio?

satellite view of earth
Using either geostationary or geosynchronous satellites, satellite radio providers are able to offer coverage to entire continents. Service areas are mainly limited by the curvature of the earth. Photo © NASA Goddard Photo and Video

Satellite radio has been around for over a decade, but the technology isn’t as widely used or understood as traditional radio. The technology has some similarities to both satellite television and terrestrial radio. The formatting is identical to terrestrial radio broadcasts, but most of the stations are presented without commercial interruptions. However, satellite radio is subscription-based like satellite television.

These services also require specialized equipment just like satellite television.

The main benefit of satellite radio is that the signal is available over a much broader geographical area than any one terrestrial radio station could possibly cover. A handful of satellites are capable of blanketing an entire continent, and each satellite radio service provides the same set of stations and programs to its entire coverage area.

Satellite Radio in North America

There are two satellite radio options available in the United States and Canada, but both services are operated by Sirius XM. These were two separate companies until 2008, at which point XM Radio was purchased by Sirius. Since Sirius and XM use different technology, both services have remained available.

XM broadcasts from two geostationary satellites that reach the United States, Canada, and parts of northern Mexico. Sirius uses three satellites, but they’re in highly elliptical geosynchronous orbits that can provide coverage to both North and South America.

The difference in satellite orbits also affects the quality of coverage. Since the Sirius signal originates from a higher angle in Canada and the northern United States, the signal is stronger in cities that have a lot of tall buildings. However, the Sirius signal is also more likely to cut off in tunnels than the XM signal.

Satellite Radio in Your Car

There are about 20 million satellite radio subscribers in the United States, which represents about 17 percent of the households in the country. Since some households have more than one satellite radio subscription, the actual adoption rate is most likely lower than 17 percent.

One of the driving forces behind satellite radio has been the automotive industry. Both Sirius and XM have pushed automakers to include satellite radio in their vehicles, and most OEMs have at least one vehicle that offers one service or the other. Some new vehicles also come with a pre-paid subscription to Sirius or XM, which is a great way to try one of the services out.

Since satellite radio subscriptions are tied to individual receivers, both Sirius and XM offer portable receivers that a subscriber can easily carry from one place to another. These portable receivers are designed to fit into docking stations that provide power and speakers, but many of them are also compatible with specialized head units.

If you spend a lot of time in your car, a head unit that has a built-in satellite radio tuner can provide an excellent, unbroken source of entertainment on the road. However, a portable receiver unit allows you to take that same entertainment into your home or workplace.

In fact, there are a few viable ways to get satellite radio in your car.

Satellite Radio Elsewhere in the World

Satellite radio is used for other purposes in different parts of the world. In some parts of Europe, terrestrial FM are simulcast over satellite broadcasts. There are also plans for a subscription-based service that will provide radio programming, video, and other rich media content to portable devices and head units in cars.

Until 2009, there was also a service called WorldSpace that provided subscription-based satellite radio programming to parts of Europe, Asia, and Africa. However, that service provider filed for bankruptcy in 2008.

The service provider has reorganized under the name 1worldspace, but it's unclear whether the subscription service will return.