A satellite radio is a special radio that receives signals broadcast by satellite. This allows the listener to follow a single channel no matter where he or she is because the signal's reach is not limited by station power (as long as there are no major obstructions in the line-of-sight between antenna and the satellite, such as a building). Curvature of the Earth limits the reach of the signal, but due to the high orbit of the satellites, 2-3 are usually sufficient to provide coverage for an entire continent.
United States
In the United States, two companies dominate satellite radio: XM Satellite Radio and Sirius Satellite Radio. A monthly fee is charged for both services (as of 2005 Sirius also offers a one time fee of nearly $500 valid for the lifetime of the equipment). Originally some XM music channels had commercials, while Sirius was commercial-free. As of March 2005 XM has 67 Commercial-Free Music Channels, 39 Channels of News, Sports, Talk & Entertainment, 21 dedicated Channels of XM Instant Traffic & Weather, 23 play-by-play sports channels and 1 premium channel. Sirius has 65 music-only channels as well as traffic and weather reports for major cities. XM operates on two geostationary satellites while Sirius uses three geosynchronous satellites. Both services are available mainly via portable receivers in automobiles, but both have many accessories so one can listen at home through one's stereo, with a portable boombox, or online through one's computer.
Local repeaters, on the same satellite frequencies, enable XM and Sirius's signals to be available even if the view of the satellite is blocked, for example, by skyscrapers in a large town.
Some critics of the service have expressed concerns that satellite radio will lead to a decline in the number and variety of local radio stations and programming and greater concentration of mass media in the hands of fewer companies, and a loss of jobs in the radio industry.
As of April 1, 2005, XM claimed 3.7 million subscribers, and Sirius claimed 1.1 million.
One critical factor for the success of satellite radio is the deployment of in-car recievers. Both Sirius and XM have attempted to convince carmakers to equip vehicles with their reciever. As of 2005, the following manufacturers offer satellite radio as original equipment:
Britain
In Britain, satellite radio is delivered by Sky Television, as part of their satellite television service. As of June 2004, there were around ninety radio stations on the Sky Digital service. Unlike in the US, where satellite radio is seen as a way of gaining additional choice, in Britain, most major radio stations also simulcast on satellite radio. Reception is currently limited to stationary receivers, and is not available in automobiles.
See also: Digital audio broadcasting
Canada
On November 1, 2004, the Canadian Radio-television and Telecommunications Commission began hearing applications for Canada's first satellite radio operations. Three applications have been filed: one by Standard Broadcasting and the CBC in partnership with Sirius, one by Canadian Satellite Radio in partnership with XM, and one by CHUM Limited.
CHUM's application is for a subscription radio service delivered through terrestrially based transmitters rather than directly by satellite (although satellites would be used to deliver programming to the transmitters). The CHUM service is all-Canadian; the other two applications propose to offer a mix of Canadian-produced channels and existing channels from the American partner services.
A small grey market already exists for Sirius and XM receivers in Canada.
Asia, Africa and most of Europe
Worldspace has its own satelites covering most of Europe, Asia and Africa. The signal can be received by specialised Worldspace receivers. A lot of the programs are only available to subscribers.
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