Satellite radio

Satellite radio is – according to article 1.39 of the International Telecommunication Union´s (ITU) ITU Radio Regulations (RR) – a Broadcasting-satellite service.

The satellite's signals are broadcast nationwide, across a much wider geographical area than terrestrial radio stations, and the service is primarily intended for the occupants of motor vehicles. It is available by subscription, mostly commercial free, and offers subscribers more stations and a wider variety of programming options than terrestrial radio.

Satellite radio technology was inducted into the Space Foundation Space Technology Hall of Fame in 2002. Satellite radio uses the 2.3 GHz S band in North America for nationwide digital audio broadcasting (DAB). In other parts of the world, satellite radio uses the 1.4 GHz L band allocated for DAB.

Satellite radio subscribers purchase a receiver and pay a monthly subscription fee to listen to programming. They can listen through built-in or portable receivers in automobiles; in the home and office with a portable or tabletop receiver equipped to connect the receiver to a stereo system; or on the Internet.

XM Satellite Radio

XM Satellite Radio (XM) was one of the three satellite radio (SDARS) services in the United States and Canada, operated by Sirius XM Holdings. It provides pay-for-service radio, analogous to cable television. Its service included 73 different music channels, 39 news, sports, talk and entertainment channels, 21 regional traffic and weather channels and 23 play-by-play sports channels. XM channels were identified by Arbitron with the label "XM" (e.g., "XM32" for "The Bridge").

The company had its origins in the 1988 formation of the American Mobile Satellite Corporation (AMSC), a consortium of several organizations originally dedicated to satellite broadcasting of telephone, fax, and data signals. In 1992, AMSC established a unit called the American Mobile Radio Corporation dedicated to developing a satellite-based digital radio service; this was spun off as XM Satellite Radio Holdings, Inc. in 1999. The satellite service was officially launched on September 25, 2001.

On July 29, 2008, XM and former competitor Sirius Satellite Radio formally completed their merger, following U.S. Federal Communications Commission (FCC) approval, forming Sirius XM Radio, Inc. with XM Satellite Radio, Inc. as its subsidiary. On November 12, 2008, Sirius and XM began broadcasting with their new, combined channel lineups. On January 13, 2011, XM Satellite Radio, Inc. was dissolved as a separate entity and merged into Sirius XM Radio, Inc. Prior to its merger with Sirius, XM was the largest satellite radio company in the United States.

Radio

Radio is the use of radio waves is to carry information, such as sound, by systematically modulating some property of electromagnetic energy waves transmitted through space, such as their amplitude, frequency, phase, or pulse width. When radio waves strike an electrical conductor, the oscillating fields induce an alternating current in the conductor. The information in the waves can be extracted and transformed back into its original form.

Radio systems need a transmitter to modulate (change) some property of the energy produced to impress a signal on it, for example using amplitude modulation or angle modulation (which can be frequency modulation or phase modulation). Radio systems also need an antenna to convert electric currents into radio waves, and vice versa. An antenna can be used for both transmitting and receiving. The electrical resonance of tuned circuits in radios allow individual stations to be selected. The electromagnetic wave is intercepted by a tuned receiving antenna. A radio receiver receives its input from an antenna and converts it into a form usable for the consumer, such as sound, pictures, digital data, measurement values, navigational positions, etc. Radio frequencies occupy the range from a 3 kHz to 300 GHz, although commercially important uses of radio use only a small part of this spectrum.

Sirius XM Holdings

Sirius XM Holdings is an American broadcasting company that provides three satellite radio services operating in the United States, Sirius Satellite Radio, XM Satellite Radio and Sirius XM Radio. The company also has a Canadian subsidiary called Sirius XM Canada, an affiliate company that provides Sirius and XM service in Canada. At the end of 2013, Sirius reorganized their corporate structure, which made Sirius XM Radio Inc. a direct, wholly owned subsidiary of Sirius XM Holdings Inc. Sirius XM Radio was formed after the U.S. Federal Communications Commission (FCC) approved the acquisition of XM Satellite Radio Holding, Inc. by Sirius Satellite Radio, Inc. on July 29, 2008, 17 months after the companies first proposed the merger. The merger brought the combined companies a total of more than 18.5 million subscribers based on current subscriber numbers on the date of merging. The deal was valued at $3.3 billion, not including debt. Through Q4 2015, Sirius XM has 29.6 million subscribers.

Satellite

In the context of spaceflight, a satellite is an artificial object which has been intentionally placed into orbit. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as Earth's Moon.

The world's first artificial satellite, the Sputnik 1, was launched by the Soviet Union in 1957. Since then, thousands of satellites have been launched into orbit around the Earth. Some satellites, notably space stations, have been launched in parts and assembled in orbit. Artificial satellites originate from more than 40 countries and have used the satellite launching capabilities of ten nations. About a thousand satellites are currently operational, whereas thousands of unused satellites and satellite fragments orbit the Earth as space debris. A few space probes have been placed into orbit around other bodies and become artificial satellites to the Moon, Mercury, Venus, Mars, Jupiter, Saturn, Vesta, Eros, Ceres, and the Sun.

Satellites are used for a large number of purposes. Common types include military and civilian Earth observation satellites, communications satellites, navigation satellites, weather satellites, and research satellites. Space stations and human spacecraft in orbit are also satellites. Satellite orbits vary greatly, depending on the purpose of the satellite, and are classified in a number of ways. Well-known (overlapping) classes include low Earth orbit, polar orbit, and geostationary orbit.