Soon, a network of geostationary satellites and ground-based repeating stations could change the way you listen to music, news, talk and weather on the radio. Two companies are set up to bring crystal-clear digital radio signals and extensive program variety to anyone with a satellite radio.

In the southwestern United States, XM Satellite Radio is already delivering 100 channels of music and talk for $9.99 a month. The downside of XM is that many of its stations are subsidized by commercials.

Sirius Satellite Radio will broadcast all of its music commercial-free but will charge a monthly fee of $12.95 a month, when it rolls out its service nationwide this month.

Both companies' systems are expected to offer complete coverage across the country, letting you drive coast to coast with no interruption in the audio signal. The digital signal eliminates static and background noise on music channels offering bluegrass, country and western, oldies, classical, blues and opera. News/talk programming includes the BBC, Bloomberg, C/Net, CNN, Discovery Channel, ESPN, The Weather Channel and several comedy channels.

Installing satellite radio is similar to putting in a conventional car stereo, except that a small antenna must be mounted on the roof or rear window, either magnetically or with adhesive. A wire runs from the antenna to a small receiver that can be hidden under a seat or in the trunk. Another wire runs from the receiver to the car radio. The cost starts at about $400.

Contact Sirius Satellite Radio Inc., 1221 Avenue of the Americas, New York, NY 10020, 212/584-5100, www.siriusradio.com or circle 198; or XM Radio, 1500 Eckington Place N.E., Washington, DC 20002, 202/380-4000, www.xmradio.com.