Satellite Radios - Digital subscription radio at it's best!
Satellite radios, also known as subscription radios or SRs, are digital radio signals that are broadcasted by a communications satellite. It also covers a much wider geographical range than the worldly radio signals. It is at the forefront of the evolution of radio services it allows the listener to roam across the planet while listening to the same audio programming anywhere he goes. It generally shares 1.4 gigahertz L band with local digital audio broadcasting (DAB) stations elsewhere and uses the 2.3 gigahertz S band in North America. It is a type of direct broadcast satellite and is strong enough to not even require another satellite for reception. The signal is limited by the curvature of the earth, two or three are usually sufficient to provide coverage for an entire continent because of the high orbit of the satellites. Signals are available even if the view of the satellite is blocked, for example by skyscrapers in a large city because of the local repeaters similar to broadcast translator boosters.
Regular radio is transmitted through either AM (amplitude modulation) or FM (frequency modulation). Especially at night, amplitude modulation stations can broadcast their signal at a fair distance. It is not unusual to pick up amplitude modulation stations hundreds of kilometers away on a clear night. The only problem with an amplitude modulation band is that the quality of the signal is not as good as the frequency modulation. The signal doesn't travel far for a frequency modulation radio but it was developed to improved signal quality that’s why it offers a rich stereo sound. But with digital or satellite radios, the quality of the sound is near compact disc quality sound. A home stereo, hand held unit, or a compatible car radio receiver can pick up the signal the same way a television can pick up digital television channels. It also carries extra information while a song is playing, for example you can find out when the performer will be on tour in your area.
Satellite radios depend heavily on something called the line of sight. In other words, in order for the receiving mechanism on Earth to reach it, the satellite needs a clear view or at least mostly clear view of the receiving mechanism. The signal is affected by severe weather, dense forest, canopies, concrete buildings and overpasses. Telecommunication companies use multiple satellites to increase the coverage area. Some satellites are engaged in a geostationary orbit directly above the equator. Signal reception is extremely predictable because this type of orbit keeps the satellite in a fixed place in the sky. However, the signal has a greater likelihood of interference because the signal comes in on a relatively flat plane relative to the surface of North America. Some satellites, on the other hand, are deployed in a geosynchronous elliptical orbit. This means that the satellites move in a figure eight pattern over South, Central and North America. There are at least two orbiting satellites hovering above the area while the third goes silent and conserves power as it makes a round trip which is perfect for satellite radios.