Product category:
Communications ICs (Wired)
News Release from: Zarlink Semiconductor | Subject: ZL38004
Edited by the Electronicstalk Editorial
Team on 06 June 2006
Voice processors fix in-car and
speakerphone noise
Voice processing platform and embedded firmware deliver measurable sound quality improvements in high-noise environments.
Zarlink Semiconductor has expanded its voice processing product portfolio with a highly integrated, flexible and programmable solution for hands-free communication systems The ZL38004 voice processing platform and embedded firmware deliver measurable sound quality improvements in high-noise environments
This article was originally published on Electronicstalk on 7 Feb 2001 at 8.00am (UK)
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The ZL38004 voice processing platform is a complete solution integrating dual-channel codecs, Zarlink voice processor engine for acoustic echo cancellation and noise reduction, and complete firmware support for hands-free car kits (ZLS38500) and speakerphones (ZLS38501).
The new platform helps designers deal with complex noise situations, such as echo, background noise and double-talk that have traditionally plagued hands-free communication systems.
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Zarlink is demonstrating the ZL38004 voice processing platform at Globalcomm 2006 with speakerphone manufacturer Multisuns.
Zarlink's new voice processing platform is designed into Multisuns' ConferBase phone system.
Manufacturers are developing high-performance hands-free car kits that deliver superior voice quality in severe noise situations.
For example, hands-free car kits must deal with vehicle noise and acoustic echo created by direct coupling between the microphone and speaker and sound reverberation inside the car cabin.
Hands-free car kit manufacturers require voice processing solutions that deliver noise reduction, good double-talk and clipping compensation performance.
Cost and board space savings are also a concern, particularly as hands-free car kits are deployed in higher volumes.
To achieve good noise reduction, the ZLS38500 firmware distinguishes between voice and noise signals.
The firmware removes the noise from the total signal and preserves the integrity of the original speech signal.
Double-talk, when two people are speaking at the same time, commonly poses a problem for hands-free communication systems.
Good double-talk performance relies on the interaction between the AEC (acoustic echo canceller) and NLP (nonlinear processor).
The ZLS38500 firmware tracks changes in the echo path and continuously converges during double-talk and the NLP cancels the imperfections of the AEC.
Under severe noise conditions, for example a car driving at over 100km/h with the windows open, a good clipping compensation circuit is required.
The ZLS38500 firmware prevents the signal from being clipped, allowing the AEC to converge to echo and the noise reduction circuit to identify and reduce background noise.
Speakerphone manufacturers consider sound quality as a key differentiator, and prefer an integrated solution that reduces design cost.
Factors such as the quality of plastic enclosure used in the speakerphone design and the size of the room where the phone is used can also impact the quality of a voice processing solution.
The ZLS38501 firmware delivers exceptional full-duplex operation and good double-talk performance.
Most voice processing solutions deliver only half-duplex operation, meaning voice signals pass in only one direction.
During double-talk only the signal with the highest level is transmitted, resulting in interrupted conversation.
Most competing full-duplex solutions will also stop tracking the echo environment during double-talk.
The algorithm then has to readapt when double-talk ceases, resulting in an audible burst of echo.
In comparison, the ZL38004 voice processor algorithm is able to continuously converge and track changes in the echo path to support full-duplex operation.
Zarlink's ZL38004 voice processing platform is now in production.
The chip is supported by an evaluation board, reference design, and full software package.
Future firmware will support 16kHz sampling and audio-quality DACs.
Complete information on the ZL38004 voice processing platform and Zarlink's voice processing technology is available to qualified customers.
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