Bluetooth gets DSP audio boost

CSR soups-up headsets with extra processing power

Digital signal processors (DSPs) are making their way into almost everything, and now it's the turn of Bluetooth headsets.

Chip developer CSR has just started shipping BlueCore5-Multimedia, which includes a 64Mips DSP alongside Class II Bluetooth.

Since DSPs in gear like this are mainly used for audio processing, it is little surprise that CSR is also inviting software developers to port to the new chip.

"It's about audio and music - it enables audio functions more convincingly," said CSR spokesman Alan Woolhouse. "Ninety per cent of the applications our customers want to perform are audio-related."

Those audio functions include echo cancellation and noise reduction, he said, along with bass boost and 3D sound surround. It's the use of DSPs that enables headsets to work well without boom microphones, for example.

A DSP could also be used for transcoding, to convert MP3s into a format that's quicker to transmit over Bluetooth, or for tasks such as text-to-speech, reading out caller-ID instead of displaying it on a screen.

Woolhouse added that the new chip - which is CSR's fifth generation of Bluetooth silicon - also supports Bluetooth EDR (enhanced data rate) which gives a raw bandwidth of 3Mbit/s, or three times the original.

"Power consumption continues to improve as well," he said. "For example, for streaming music it was 95mW and is now 60mW. That means a 15 hour battery life could become 20 hours."

That's despite the chip having twice the DSP power of CSR's previous Bluetooth generation. Much of the power drop is because manufacture (by TMSC in Taiwan) has shifted to 0.13micron CMOS, Woolhouse said.

"No other chip vendor offers an integrated DSP," he claimed. "It's a huge disadvantage to have a two-chip solution - it's more power and more integration, which means more cost."

CSR claims that 97 per cent of all Bluetooth headsets use its silicon, as do phones, MP3 players, and car hands-frees. It said it expects products based on BlueCore5-Multimedia to go into production in the first quarter of 2007.

There's a saying that there are only two good times to buy technology - six months ago and in six months time. If you just bought a Bluetooth headset, you might not want to know that... ®

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