Satellite Radio Technology Cruising

Don’t touch that dial. Thanks to something new in the air, you might not have to channel surf in your car ever again.

Where radio radically changed the way the world received news and information in the 1920s and ’30s, satellite radio promises to extend the range of what its proponents say will be virtually static-free programming to anywhere in the continental United States. Aiming to offer more than 200 new ad-free channels, two companies are hoping their new satellite radio services will do for radio what DirecTV does for television … but in both the home and the car. (DirecTV is an investor in XM Radio.)

“The goal is to offer customers new choice and diversity … and open up the radio market to new national, creative channels,” said Vicki Stearn, a spokesperson for XM Radio, based in Washington.

XM Radio and New York-based Sirius Satellite Radio plan to roll out their competing new services sometime next year. Programming will include nearly all formats from sports to talk to weather to music — classical, rock&roll, jazz, you name it. The subscription-based services will deliver commercial free shows, which should follow you wherever you roam because though both companies will sell home receivers, their prime target is the car. And while the satellite technology is not new per se, getting a steady signal to hit a small antenna that’s constantly in motion is a fresh technical challenge.

“The moving vehicle part of it isn’t as challenging as … getting the signal to a small antenna,” said Stearns.

Not Your Father’s Radio

Satellite distribution of radio and television programming is standard in the broadcast world. Networks such as ABC, CBS and NBC uplink programs daily to satellites so that affiliate TV and radio networks can downlink them for transmission to local audiences. Such signals to and from a satellite are scrambled or encoded and can only be unscrambled or decoded with the correct equipment.

XM and Sirius Radio will work similarly. Each will beam a combination of original and syndicated programming to orbitting communications and terrestrial satellites, which will send out signals to the satellite radio receivers. These receivers, somewhat akin to AM/FM tuners, are made up of two parts: an “active” antenna and a receiving module.

The antenna is active because it basically looks for available signals to pick up from satellites it recognizes. When it finds them, it amplifies them, filters out any accompanying noise and interference, and then sends them to the receiver, where most of the real work is done.

En route to the receiver, the signals are converted from analog to digital. Once in the digital realm, they are analyzed for quality, and then processed and combined to produce the best digital “image” of the sound. The receiver also decrypts the signals and finally converts them back to analog audio, which can be sent to the radio’s speakers so you can hear it.

Two Companies, Two Methods

The receiving end is virtually the same for both companies, but the satellite configurations are different: XM Radio will use two satellites, and Sirius will use a combination three.

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