Technology Behind Satellite Radios

The concept of satellite radio is such a remarkably one that one might wonder why it took so much time for the first space-based audio service to make its debut in the countries. It is very easy. It is simple on the surface. It is just taking music, news or a talk station, then beaming the signal up to a satellite, and overcoming the limitations of ground based transmitters whose signals generally drop off as distance increases. Next step is to make sure that the programming is more appealing than traditional radio stations and cut down on the number of commercials in exchange for a monthly subscription fee. As we go into the details then we come to know that satellite radio is a whole lot more complex than it seems on paper and it took cutting-edge technology to make the systems operated by satellite radio service providers. It took a number of years to develop the satellite radio systems. Engineers had to figure out how to squeeze dozens of individual channels into a relatively small amount of bandwidth and come up with reliable methods of beaming signals from thousands of miles in space to roving antennas smaller than tennis balls. Also inexpensive circuitry, or chipsets, had to be developed to enable receivers to decode the satellite signals, which are encrypted to prevent reception by non-subscribers. The satellite service providers are working on newer versions of their chipsets that will be smaller and use less power. The two main service providers follow different approaches different approaches, although the end result, from a lay person's point of view is the same.

Every lay man thinks it is just hundred channels of music, news, sports and other fare available virtually anywhere in the continental United States. The companies are trying to distinguish themselves with programming and attitude. Systems of XM satellite radio use two very powerful satellites floating in space directly above the equator. These spacecrafts are in geostationary orbit that is they appear from the ground to remain in fixed perches, because they move around the Earth at the same speed the planet is rotating. The satellites which are geostationary are used are commonly used for all sorts of space-based communications because they enable use of inexpensive, fixed antennas. Satellite TV and Internet systems are two examples of consumer-oriented technologies that use this type of satellite. As geostationary spacecraft are above the equator, terminals on the ground must have a decent view of the southern sky to receive signals from them. This proved to be a challenge for XM, since listeners in cars often pass by obstacles, such as buildings, foliage or hills, which can block geostationary satellite signals. The solution to this was a network of repeaters that is antennas on buildings and other sites that receive satellite signals from an optimally placed antenna and retransmit them. These repeaters are located primarily in built-up areas, where loss of the satellite signal is most likely to occur.

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