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Ultrawideband chip tackles video distribution

Posted: 01 Sep 2005 ?? ?Print Version ?Bookmark and Share

Keywords:fcc? general atomics? aspen? ultrawideband chip? multiband coalition?

With its FCC certification, General Atomics' Aspen becomes the third ultrawideband chip for data communications to win such approval, further enlarging UWB options for wireless video distribution.

General Atomics is one of four founding members of the Multiband Coalition, which has since melded with and taken the name of the wimedia alliance. Despite strong ties to the alliance, General Atomics chose a much simpler radio and MAC design using spectral keying instead of OFDM. The decision sprang from a need to get to market soonerat lower cost and with better functionality, said marketing director Jeff Harris.

"We're by no means trying to become another standard," Harris said, "but there are certain applications we'll handle better, such as streaming video." He said that the Aspen radio can achieve the required bit-error rate for video of 10eight at the stated rate of 80Mbps at 15m. "Video is our quality metric, but we have taken it out to 22m for non-quality-of-service applications," he added.

While still a multibanded approach, the "key" to the design is spectral keying, which Harris said will allow higher performance in the face of multipath reflections. "We have a low pulse repetition frequency (PRF) in that we transmit symbols and then have a quiet period to capture the multipath," he said.

The scheme uses five bands: three between 3GHz and 5GHz and two between 6GHz and 7GHz, with a notch for the 5GHz band. The bands are 520MHz wide and have center frequencies at 3.48-, 4.02-, 4.56-, 6.12- and 6.96GHz.

The transmission works by sending out 83.35ns pulses across all five bands almost simultaneously. The symbol information is contained in the order in which the five bands are received, "so you have five factorial combinations as to what the data is," said Harris.

The chip is implemented in a multichip module with a front-end manufactured in IBM's SiGe process and a digital baseband and MAC portion manufactured in a 0.18 process by Korea-based Dongbu Electronics Co. Ltd. "We use our own 'thin' MAC," said Harris. The output options are USB and a general-purpose FIFO for streaming media. The evaluation kit is available now, but it has a two-month waiting list, said Harris.

Despite the steady flow of novel UWB designs, only two other data-communication-oriented UWB radios had been FCC-certified before Aspen, said Steve Jones, an engineer in the FCC's Columbus labs. Aspen joins the PulsON 200 from Time Domain Corp. and the XS110 from Freescale Semiconductor Inc. for high-speed communications.

"These were all evaluation kits and are not what we expect to see in the consumer market," Jones added. Also, Time Domain and Multi-Spectral Solutions Inc. have had radios certified for tagging and location applications, said Julius Knapp, deputy chief of the FCC's Office of Engineering and Technology.

- Patrick Mannion

EE Times

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