Satellite Radio

Satellite Radio or Subscription Radio (SR) is a digital radio that receives signals broadcast by communications satellite, which covers a much wider geographical range than terrestrial radio signals.

SR functions any place there is line of sight between the antenna and the satellite, given there are no major obstructions, such as tunnels or buildings. SR audiences can follow a single channel regardless of location within a given range.

Because the technology requires access to a commercial satellite for signal propagation, SR services are commercial business entities (not private parties), which offer a package of channels as part of their service—requiring a subscription from end users to access its channels. Currently, the main SR providers are WorldSpace in Europe, Asia and Africa, and XM Radio and Sirius in North America. All are proprietary and non-compatible signals, requiring proprietary hardware for decoding and playback. These and other services have news, weather, sports, and several music channels.

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Success So Far

As of March 20, 2006, XM has claimed "over 6 million" subscribers, while Sirius claimed "over 4 million".

One critical factor for the success of satellite radio is the deployment of in-automobile|car]] receivers. Both Sirius and XM have attempted to convince carmakers to equip vehicles with their receiver. As of 2005, the following manufacturers offer satellite radio as original equipment:

Provider	BMW MINI Rolls-Royce	Chrysler Dodge Mercedes-Benz Jeep	Ford Lincoln Mercury Volvo Land Rover Jaguar Mazda	GM Cadillac Chevrolet Buick Pontiac GMC Opel Vauxhall Saab	Honda Acura	Hyundai Kia	Nissan Infiniti	Porsche	Toyota Lexus Scion	VW Audi	Suzuki
Sirius	Y	Y	Y				Y	Y	Y	Y
XM				Y	Y	Y	Y	Y	Y		Y

Sirius has an exclusive contract for VW and Audi vehicles from 2007 through 2012. Those brands previously offered both services.

One of the challenges for satellite radio has been to move away from cars and into the homes of consumers. Several portable satellite radio receivers have been made for this purpose. XM satellite radio has developed the XM2go™ line of "walkman-like" portable receivers, such as the Delphi MyFi™, the Pioneer AirWare™ and Giant International's Tao™. Sirius has developed the Kenwood Portable Satellite Radio Tuner, Here2Anywhere and the Sirius S50 (although neither is a true portable in comparison to XM's XM2go: Here2Anywhere is a plug-and-play receiver, and the S50 must download programming from a home or car docking kit and cannot receive live programming on its own). While key agreements with car manufacturers are still being made, both companies have made the leap away from satellite radio only in the car and into the homes of consumers.

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Worldwide

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 September 2005, XM has:

• 67 commercial-free music channels
• 39 channels of news, sports, talk, and entertainment
• 21 dedicated traffic and weather channels
• 23 play-by-play sports channels

Sirius has:

• 65 music-only channels as well as traffic and weather reports for major cities.

XM uses fixed-location geostationary satellites in two positions, and Sirius uses three geosynchronous satellites passing over North and South America, to transmit the digital streams. The net difference is that the Sirius signal comes from a higher elevation angle in the northern part of the U.S., and even more so in Canada. (This higher angle makes Sirius' signal less likely to drop out on cities, but more likely to drop out in parking garages, gas stations, and other covered spaces.)

Both services are available mainly via portable receivers in automobiles, but both have many accessories so one can listen at home through a home stereo, with a portable boombox, or online through a personal computer. Both services now have some form of receiver that is completely portable. These units have added a new dimension to the use of portable satellite radio.

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. There are also concerns that the ability to transmit local channels on repeaters, which is currently prohibited by FCC regulation, is only a rulemaking proceeding away from being legalized and further threatening existing local broadcasters.

The footprint of both Sirius and XM is only the United States (including Alaska), Canada, and the upper third of Mexico; it does not cover Hawaii as satellite TV does.

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Asia, Africa, and most of Europe

WorldSpace has its own satellites covering most of Europe, Asia and Africa. The signal can be received by specialised WorldSpace receivers. Many of the programs are available only to subscribers.

A large number of radio stations are available free-to-air on geostationary satellites targeting Europe throughout the Ku band, but these require fixed dish installations and as a result, are impractical for use in vehicles. Reception is often tied to a satellite television decoder. Both analogue stations, as subcarriers in SÉCAM and PAL analogue satellite signals, and digital, as DVB-S streams and Astra Digital Radio subcarriers, are in use.

South Korea started S-DMB service in May 1, 2005.

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System Design

Satellite radio uses the 2.3 GHz S band in North America, and generally shares the 1.4 GHz L band with local Digital Audio Broadcast (DAB) stations elsewhere. It is a type of direct broadcast satellite, and is strong enough that it requires no satellite dish to receive. Curvature of the Earth limits the reach of the signal, but due to the high orbit of the satellites, two or three are usually sufficient to provide coverage for an entire continent.

Local repeaters similar to broadcast translator boosters enable signals to be available even if the view of the satellite is blocked, for example, by skyscrapers in a large town. Major tunnels can also have repeaters. This method also allows local programming to be transmitted such as traffic and weather in most major metropolitan areas, as of March 2004.

Each receiver has an electronic serial number (ESN)-Radio ID to identify it. When a unit is activated with a subscription, an authorization code is sent in the digital stream telling the receiver to allow access to the blocked channels. Most services have at least one "free to air" or "in the clear" (ITC) channel as a test, and some outside the U.S. have a few free programming channels, though this may end up being a loss leader tactic to lure more listeners until satellite radio gains more widespread use.

Most (if not all) of the systems in use now are proprietary, using different codecs for audio data compression, different modulation techniques, and/or different methods for encryption and conditional access.

Like other radio services, satellite radio also transmits program-associated data (PAD or metadata), with the artist and title of each song or program, and possibly the name of the channel.

Satellite radio vs. other formats

Satellite radio differs from AM or FM radio, and digital television radio (or DTR) in the following ways:

Radio format	Satellite radio	AM/FM	Digital television radio (DTR)
Monthly fees	$12.95 U.S. and up	None	Very low — DTR represents a small portion of the total monthly television fee
Portability	Available	Prominent	None — a typical set consists of a stereo attached to a set-top box
Listening availability	Very high — a satellite signal's footprint covers millions of square kilometers	Low to moderate — implementation of AM/FM services requires moderate to high population densities and is thus not practical in rural and/or remote locales	Very high1
Sound quality	Moderate2	AM: Very low FM: Low to moderate	High
Variety and depth of programming	Highest	Variable — highly dependent upon economic/demographic factors	High
Frequency of programming interruptions (by DJs or commercial advertising)3	Low to high — satellite radio features a mixture of commercial and non-commercial formats; most stations have DJs	Highest4	None to low — some DTRs have DJs
Governmental regulation	Low to none5	Yes — significant governmental regulations regarding content6	Low to none

¹ Except in the case of DTR distributed through digital cable services, for which availability is low.

² The sound quality with both satellite radio providers may not always be comparable to FM radio. This is because XM and Sirius must add many channels in the tight bandwidth limits the FCC has placed on both companies.

³ Some satellite radio services and DTR services act as in situ repeaters for local AM/FM stations and thus feature a high frequency of interruption.

⁴ Nonprofit stations and public radio networks such as CBC/Radio-Canada, NPR, and PRI-affiliated stations and BBC Radio are commercial-free. In the US, all stations are required to have periodic station identifications and public service announcements.

⁵ In the United States, the FCC regulates technical broadcast spectrum only. Program content is unregulated.

⁶ Degree of content regulation varies by country, however the majority of industrialized nations have regulations regarding obscene and/or objectionable content.

External Links

• How Satellite Radio Works
• Orbitcast.com - All Things Satellite Radio
• Digital Insurrection Satellite Radio Info
• Getting Satellite Radio One subscriber's easy how-to guide
• Digital Home Canada Canadian Satellite Radio Information and Discussion forums.

United States and Canada

• XM Satellite Radio XM Satellite Radio Company
• Sirius Satellite Radio Sirius Satellite Radio Company

Asia, Africa and Europe

• WorldSpace Satellite Radio WorldSpace Satellite Radio Company