Ultrawideband Adopted For Wireless Surround
By Joseph Palenchar -- TWICE, 11/19/2007
SANTA CLARA, CALIF. — A company that developed wired HDMI switchers and distribution devices is turning to wireless ultrawideband (UWB) technology to distribute 5.1-channel surround sound to home theater speakers.
Radiient Technologies, founded in mid-2005, touts its Roomcaster technology as delivering audio to five full-range speakers and a subwoofer without any audio dropouts, which are caused by interference with other wireless devices. The technology also produces sound synchronized with the action on a TV screen.
Roomcaster can be built into speakers or into a UWB-receiver/amplifier combination that can be attached to the back of a consumer's existing speakers.
Several speaker companies will demonstrate the technology at January's International CES, and consumer products will be available in the third quarter, a spokeswoman said. Wireless range is currently up to 30 feet, she said.
In part, Roomcaster avoids interference with microwave ovens, cordless phones and wireless networks in the 2.4GHz, 900MHz, 1.9GHz, 2.4GHz and 5.8GHz bands because it operates in the 3.1-4.7GHz range, said Radiient president Jano Banks. Also to avoid dropouts, the company "built a streaming audio protocol on top of WiMedia UWB [standard], including UWB-specific quality of service (QoS) methods," he said.
The Roomcaster protocol also avoids lip-sync problems "by accurate time-management techniques" that "take advantage of the human audio-visual system's allowance of up to +/- 20ms of latency between video and audio before lip-sync issues are noticeable," he said. The protocol also synchronizes the sound coming out of multiple speakers in a 5.1-channel sound system.
"We had to invent a lot of technology on top of standard WiMedia UWB," he noted.
WiMedia is the name of an alliance formed to certify the interoperability of devices based on a Texas Instruments radio (physical layer) technology called MB-OFDM (multiband orthogonal frequency division multiplexing), and on a media-access controller (MAC) layer developed by the TI-led MultiBand OFDM Alliance (MBOA).
The MBOA standard allows for seven data rates ranging from 55Mbps to 480Mbps, depending on distance. A maximum data rate of 480Mbps is achievable at 2 meters. At 10 meters, it's a maximum 110Mbps.
In 2002, the FCC allocated spectrum in the 3.1GHz to 10.6GHz band for unlicensed use of wireless UWB devices.
UWB reduces power output by spreading RF energy over a broad swath of spectrum up to several GHz wide. Power levels of less than 200mW look like background noise to other wireless devices, including licensed wireless products such as cellular, MBOA members say.
UWB technology has already appeared in the home in the form of laptop PCs and docking stations and in USB hub and dongle solutions to connect peripherals to a PC.
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