“Roll,” one of XM Satellite Radio’s two satellites
        blasts off on a rocket in May, 2001, from a launch
        platform in the Pacific Ocean. The XM satellites
        were built by Boeing Satellite Systems.

he satellites operate sort of like a parrot—they "hear" the music beamed up from two different radio stations—one in Washington, DC and one in New York City—and then send it back to earth, but with an extra kick.

In techspeak, the satellites receive the signal being beamed up from Earth, change the frequency (or position within the electromagnetic spectrum) from the X-band, where Am/Fm radio lives, to the S-band, which is designated by the U.S. Government for satellite radio. Then, they re-transmit the signal back to earth where it is picked up by a special antenna mounted on the back of your car. Specially made chipsets inside the radio then take over.

The "souped-up" signal sent back from the satellites is strong but it can't leap tall city buildings or slink through tunnels while it is trying to find your car. This was one of the major technology hurdles that had to be overcome before static-free satellite radio music in cars could become a reality. How could they get the signal to manuever around or over huge obstacles like high rise office buildings? In flat areas, like farmlands, the signal travels freely.

Engineers eventually designed special antennas, called repeaters, to help the signal find its way around when there are buildings or structures that block the signal. These repeater antennas were installed on the rooftops of some tall buildings in areas where it is hard to receive the signal.

The repeaters give the signal another jolt, which enables it to whip around corners and slide through tunnels until it finds the 2-inch square trunk-mounted antenna on your car. More than a thousand repeaters are sitting on towers and on top of high-rise buildings in major cities across the U.S., just waiting to catch the next wave and send it your way.

The result of all this techno zigging and zagging is satellite radio, the first advance in radio technology since FM was introduced in the 1960s. Fortune magazine called one of the companies' radios

The Figure 8 orbit path and diagram showing
how the signal travels

There is another new twist, again made possible by the satellites. You can listen to the same music regardless of how far you drive. You never drive out of range as you do with AM/FM. In fact, you can drive the 3,000 plus miles across the country and still listen to the same channel. How is this possible? With regular AM/FM, the signal can't travel too far from the transmitting radio transmitter due to the curvature of the earth, so the signal is eventually lost. With satellite radio, the signal coming from the satellites blankets the entire country, so you never drive out of range.

Two companies have been working hard for the past 2-3 years to fine-tune the technology, launch the satellites and begin selling the satellite radio and antenna kits as well as the monthly service. (See Company Profile box.)

Necessity Was the Mother of Invention

ow did the idea develop for this new way to hear music? Like many other inventions, satellite radio started out as a way to solve a pressing problem: how to stop the spread of HIV. In the late 1990s, a company called WorldSpace was trying to disseminate information on AIDS and HIV in Africa.

They explored many options. Dropping leaflets from airplanes would not work because a majority of the people could not read. They could not use TV to get the word out because most people in the region did not own one. So the company turned to radio, which many people in that region used as a source of information.

The health information was digitized and beamed up to a satellite, which then rebroadcast it to fixed antennas near the radio stations on earth. It worked. Huge numbers of people were able to hear the important health messages very clearly on their radios.

Could this concept now be applied in other ways, specifically to car radios and ultimately to individual houses? Broadcasting from a satellite worked, but in this case, the signal had been directed to a fixed target--the radio station antenna. Broadcasting satllite radio to a moving target had never been done before. Could the technology be pushed even further to do just that?

This was the ultimate technological challenge that brought together visionary thinkers from the business world, rocket scientists with degrees in electrical and aerospace engineering, and creative DJs and program directors who were ready to push the music envelope in bold new directions. These were people who saw the potential for enhancing quality of life with a new form of musical entertainment and delivery of news. They knew it wouldn't be easy, and that a lot of hard work was required. But they would be at the epicenter of a revolution in the world of radio. That would be a thrill enough. . .what they would learn along the way was beyond the ionosphere. TechXtra interviewed some of them to give you a glimpse into their world.

(See Xtra Real People Profiles.)

Facing Your Fears

tart-up companies and the people who work for them face many challenges in launching a new technology and introducing a totally new product to the marketplace. In fact, satellite radio was a concept that had to wait for technology to catch up. But the business people and scientists who had the vision for satellite radio didn't stand around the soda machine waiting for the technology to come along magically—they experimented. They tried and failed. They identified the problem, fixed it, and tried again.

Rockets blew up before launch. Volcanoes erupted in Ecuador while earth stations were being built. Satellites flopped.

There were challenges on the business side as well. How would they store all the music necessary for 100 channels? Even the terrorist attacks of September 11th affected one of the companies. The date they were going to begin selling to the public in 2001: September 12. The product launch date was rescheduled for later that month.

One by one, the technical problems were solved and progress continued. The most powerful communications satellites in commercial use were eventually built. Chipsets that are buried inside the radio were refined enough to receive the satellite's signal. Repeaters of varying sizes were designed to deal with urban static.

XM Satellite Radio purchased a 22 terabyte computer to hold 1.5 million songs. It was the largest single customer order ever for IBM. Just how extraordinary is a

22 terabyte computer? Consider this: Most home PCs and laptops have 1 gigabyte of memory, or storage "space"; this computer has memory equivalent to that of 22,000 home computers!

Any one of these challenges could have caused the people involved to give up and find another job. But they did not. The scientists kept on experimenting while the business executives found the money to keep the research and testing going.

The technology is now in place, the program directors were hired and have developed their radio shows, and investors have provided the cash the companies need to operate for a while.

If not, guess what? The companies probably will figure out why and try again. That is what innovation is all about. After all, according to industry statistics, 95 percent of all Americans age 12 and up listen to radio every week—75 percent listen every day. Many of those people are also listening to CD players in their homes and cars and getting used to the high quality sound. Satellite radio is not free, but neither is cable tv and consumers have been willing to pay a monthly fee to have more choices on their tv screen. So it may only be a matter of time before consumers will be willing to pay a little extra to have a lot more choices in radio--and get rid of the snap, crackle and pop of radio static at the same time!

Meanwhile, if you're listening to satellite radio and your parents tell you to turn it off, you can honestly tell them that you are studying rocket science. And... you can explain to them how it all works.

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Editorial Advisory Committee

James Galante, 10th grade, Thomas Jefferson High School for Science and Technology
Jennifer Martino, PhD, science teacher, Governor Livingston High School
John E. Riley, Radiation Safety Officer, Agere Systems
Douglas A. Tyson, chemistry teacher, Benjamin Banneker Academic High School
Gary Ybarra, PhD, Director of Undergraduate Studies, Duke University