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Press Release 94-35
Mary Ann Peto
(Bus: 216/433-2902)

NASA Lewis Decoder will Enhance Satellite Communications

CLEVELAND, OH -- NASA's Lewis Research Center, in partnership with Harris' Government Communications Systems Division, Melbourne, FL, has developed a high-speed error correcting decoder chip that improves the data integrity of satellite communication systems. The chip, which implements the powerful class of BCH (Bose-Chaudhuri-Hocquenghem) random error correcting codes, will play a role in NASA applications such as the transmission of remote sensing and astrophysics science data.

"Harris employed a novel decoding technique that enabled the encoder and decoder to be placed on a one-inch-square chip," explained NASA Technical Contract Manager Robert Jones. "This chip will enable data to be transmitted faster and more accurately. In most cases, this can reduce the need for frequent rebroadcast."

The Harris-NASA Lewis BCH chip will impact the high-end market where extremely high speed and throughput are essential. "The chip is capable of decoding information at 300 megabits per second, which is a factor of over 30 thousand times faster than a 9600 bits per second computer modem," said Jones. "It can also correct 3 errors in a block of up to 224 bits of information."

Errors in data occur when rain, fog and thermal noise corrupt the data before it reaches the receiver. If errors are not found and corrected, important data could be lost.

In addition to satellite communications, error-correcting decoders are found in a number of common electronic products such as CD players, computer memory chips, computer modems and magnetic disk recorders. They are also appearing in state-of-the-art fiber applications including: fiber optic communications, microwave line-of-site communications, digital television, digital audio and digital cellular communication. Jones added that all of these applications share two things: the importance of ensured data quality and the potential for data corruption from material imperfection or transmission interference.

While the chip may one day benefit NASA's space station missions, it is currently aimed at commercial applications that utilize real- time video or high volume data transmission. "The chip will benefit interactive multi-media, distance learning, telemedicine, broadcast video and multiple channels of broadcast audio by providing more usable and timely data while reducing the required data transmission costs," Jones said.

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