Generally, vehicles can be equipped with satellite radio receivers as an alternative to, or in combination with, common traditional terrestrial radio receivers. Additionally, satellite radio receivers can be used in places other than vehicles, such as handheld devices. Generally, satellite radio systems are designed, such that the receiver receives a satellite radio frequency (RF) signal from a satellite and a terrestrial RF signal from a terrestrial repeater or a transponder, which typically provides system redundancy.
The current systems in operation in the U.S. generally use double redundant information to enable high signal availability to receivers.
These systems typically use time and space redundancy for the satellite signals, such that the signal is transmitted from two sources. Typically, in urban areas, terrestrial repeaters can provide a third signal source. Generally, such systems use different frequencies for the satellite signal and the terrestrial repeater signal. This architecture generally reduces the bandwidth efficiency of the system by one-third (⅓), while increasing overall availability.
Due to current European regulations, one European satellite radio system has proposed generally using three (3) frequency bands that are five mega-hertz (5 MHz) wide around 2170 MHz and 2185 MHz. Generally, such a system proposes using a single frequency network for satellite and terrestrial components, such that the satellite signal is the same frequency as the terrestrial signal.