Satellite radio services transmit signals from ground stations to one or more satellites orbiting the earth. The satellite sends the signal back to a dedicated receiver on the ground. This is commonly found in cars and home stereos. The signal is sent from space, so it can reach entire continents. Ground repeaters boost the signal in urban areas where tall buildings can cause interference. Satellite radio is a popular alternative to terrestrial radio and other broadcast media, but the industry faces fierce competition. Satellite service providers include satellite services that use communications satellites to broadcast encrypted digital signals to vehicles, homes, and public places. Satellite service providers can cover a wider geographic area and offer more channels than terrestrial providers. As a result, satellite radio companies are weighing the importance of their services and their impact on radio. Listeners should be able to tune in to local stations via satellite radio services, but they have access to hundreds of stations offering a variety of musical genres. Broadcast system plans vary from company to company, but the systems have one thing in common.  

Satellite and Terrestrial Transmission

The Sirius system uses satellites that transmit in the range 2320-2332.5 MHz, while XM uses 2332.5-2345 MHz. Both systems use frequencies in the middle of their respective ranges and use terrestrial transmission to boost satellites in cities with tall buildings or areas with high interference.

Home, Car and Portable

Almost all cars include a satellite tuner in their radio, and they usually offer the service for free for a period of time before a paid subscription is required. For non-satellite radio, the portable unit connects to your car's audio system and home stereo. In older cars without external audio jacks, some portable units output an FM signal that is received by his FM tuner in the car. See DAB and DARS.