2005 Annual Report - Radio Content Analysis

For the distance commuter or long-distance car traveler, satellite radio seemed too good to be true. Suddenly, with the right equipment, it was possible to listen to a single station - virtually uninterrupted - from Maine to California. This was in stark contrast to the limited broadcast power of over-the-air radio.

While the exact technology used by XM and Sirius Satellite Radio, the two U.S.-based satellite radio networks, is different, the basic concept is the same.

XM broadcasts through two Boeing HS 702 satellites, one called Rock and the other Roll. The two maintain a geo-stationary orbit, meaning that they orbit at the same rate as the rotation of the Earth and thus remain stationary with respect to their position above the Earth. Rock and Roll maintain an altitude of roughly 22,223 miles and sit at 85 and 115 degrees west longitude.

Sirius Radio does not use geo-stationary satellites. As the network's three satellites orbit the Earth, each spends an estimated 16 hours a day above the continental U.S.

In both cases, the satellite networks' ground stations send their signal to their satellites, where it is bounced back down to their own unique receivers on the ground either directly or via Earth-based transmitters (in areas where satellite signals might be blocked by buildings). The two networks use a different frequency for their broadcasts so that only their own receivers can unscramble their own signals.

In addition to the audio broadcast, XM and Sirius's signals also allow the networks' listeners to display such information as song title, artist, music type or station identity on their receivers.