New technology that would allow radio broadcasters to transmit to listeners directly from Earth-orbiting satellites has been demonstrated by researchers from NASA's Jet Propulsion Laboratory.
JPL engineers demonstrated direct digital radio broadcasting of compact disc-quality audio via satellite at a recent telecommunications conference in Buenos Aires, Argentina.
Under sponsorship of the Voice of America, the U.S. government's international broadcasting agency, JPL is developing a satellite radio receiver that will be turned over to industry for commercial development.
Fields that could benefit from direct satellite radio broadcast include international broadcasting, which currently uses shortwave radio bands at much lower sound quality, as well as broadcasting to remote areas not served by local stations.
"It will soon be possible to transmit high-quality audio via satellite to receivers no larger than today's car radios," said Arvydas Vaisnys, task manager of the JPL effort.
In the Argentina demonstration, JPL researchers used a NASA Tracking and Data Relay Satellite (TDRS) to beam down a compact disc radio channel in the S-band portion of the microwave spectrum to a digital receiver with an 8-centimeter (3-inch) circular antenna.
Traditionally, receiving signals from satellites has relied on the use of much larger parabolic dish antennas.
According to Vaisnys, the demonstration was made possible by the "power of modern digital compression techniques and other digital signal processing methods that permit reception in cars and inside buildings with antennas only several centimeters long or wide."
The demonstration used a digital compression method to produce a 256 kilobit-per-second stereo signal transmitted at a frequency of 2055 MHz.
"This frequency is close to the U.S. allocation of 2310 to 2360 MHz for satellite sound broadcasting, and is 600 MHz above the L-band allocation accepted by other countries in the western hemisphere," said Vaisnys.
"The successful demonstration clearly shows the feasibility of both frequency bands for satellite sound broadcasting."
The final prototype of the receiver that JPL is designing will be turned over to the Electronic Industries Association for testing during 1994.
Project funding and management for the JPL effort are provided by the Voice of America, with support from NASA's Lewis Research Center and NASA's TDRS Operations Office.
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