Like GPS, satellite radio systems require a clear line of sight (LOS) path from the satellite to the receiver antenna. Obstacles such as trees and tall buildings can interrupt broadcasts, leading to listener complaints. To address this problem, content is simultaneously broadcast with a time offset from two satellites, each at a different location in the sky.
In essence, the Sirius satellite radio system uses three independent transmission signals, two from satellites at any given moment and one terrestrial. Each contains an audio bandwidth of 4.4 Mbits/second.