TI aims audio DSP at 'hands-free' use

Electronic News, Oct 16, 1995 by Crista Hardie

Dallas--Texas Instruments this week will unveil the first in a planned series of wireless digital signal processor (DSP) solutions designed to offer audio quality features that TI said are needed for safety and convenience in the hands-free cellular telephone marketplace, but are not currently addressed by any cellular standard.

The initial offering in the series, the TMS320WP010 DSP, uses a combination of integrated circuit hardware and ROM-coded software that performs acoustic echo cancellation, noise suppression and line echo cancellation. According to Mike McMahan, TI fellow and applications manager for the Wireless Communications Systems division, these three features are intended to make it safer and more convenient for hands-free cellular telephone use while driving.

Acoustic echo cancel is the critical enabler for full duplex speaker mode, a coveted feature which allows both callers to speak at the same time and still hear each other. Line echo cancel was also added to eliminate noise that occurs in the wires in some analog cellular systems and creates "howling". Noise suppression senses changing backgrounds and eliminates noise from sources like the wind, engine and tires, while maintaining voice quality.

According to Mr. McMahan, no cradle product currently on the market addresses these features. "Almost everyone who owns a cellular phone can buy a phone cradle for the dashboard that allows hands-free operation," he said. "But then they find that the sound quality the outside caller hears is often so poor that the caller in the vehicle has to pick up the phone again."

Existing standards do not require the features, he said, although some standards bodies are beginning to look at them. Because it is compatible with all cellular standards, TI said its DSP solution is flexible enough for worldwide markets.

Now that the British Parliament has passed legislation requiring hands-free cellular phone operation, and other legislative bodies may follow suit, TI said the worldwide cradle market will increase significantly. Research from In-Stat Services, Shosteck Associates and TI's wireless group estimates the worldwide cradle market will grow to about 40 million units shipped by 1999, up from about 14 million in 1995.

Targeted for original equipment manufacturers (OEMs) who make cellular telephone cradles, the TMS320WP010 is said to be a complete DSP solution by itself, or it can be combined with two TI Voice Band Audio Processors (VBAPs) in a chipset designated TCS320WP010. TI will also license the software used in the TMS320WP010 to developers who want to integrate it with their own DSP code.

Down the road, TI plans other wireless peripheral devices with increasing functionality. Within the next year, the company plans to offer a DSP solution with voice recognition, enabling such functions as voice dialing. Further in the future are plans for a digital telephone answering device (DTAD), Mr. McMahan said.

The TI DSP solution addresses both analog and digital cellular markets, but the most benefit will be found in digital applications, Mr. McMahan said. "There is more of a need in a digital environment, because there is more delay in the communications paths, which makes the echo problem much worse. Vocoders for voice compression and decompression are more susceptible to noise."

Meanwhile, ROM-less samples of the TMS320WP010 DSP and the TCS320WP010 chip set are available for sampling directly from TI. Volume shipments are expected by the end of the year or 1Q96. The 'WP010 DSP, housed in a 100-pin TQFP, is priced at $14 each in 100,000-piece quantities. The 'WP010 chipset is priced at $19 per set in similar quantities. When purchased as part of the chipset, the VBAP devices come in 20-pin plastic wide-body small outline packages.