New DSP solution improves hands-free cellular capability

New DSP solution improves hands-free cellular capability

Look Ma! No hands!

"Traffic's heavy, but I'll be home soon."

"Wow. I don't hear the traffic. Your new speaker-phone is great!"

Texas Instruments has taken the next step in the evolution of wireless communications by eliminating the howls, echoes and jumps associated with hands-free cellular conversations.

A new digital signal processing solution will give cellular telephone users the safety of hands-free operation in the car along with the audio quality they are accustomed to in hand-held operation.

The recently disclosed TMS320WP010 is designed to be integrated into telephone cradles for hands-free cellular operation. It combines integrated circuit hardware and ROM-coded software that cancels acoustic and line echos and suppresses noise. In addition, it brings high-quality full-duplex transmission to hands-free cellular technology.

The device can be implemented with numerous analog and digital standards around the world, including:

Analog Mobile Phone Standard (AMPS)
Digital Interim Standards (IS-54B, IS-136)
Global System for Mobile Communications (GSM)
Personal Digital Communications (PDC)
Emerging code-division-multiple-access (CDMA) standards

No more echoes, howling or jumps

In hands-free cellular phone operation, a caller's voice comes out of the phone speaker, bounces off various surfaces inside the car and returns to the microphone, where it is heard by the caller as an echo. In addition, noises from the road, engine and wind also enter the microphone, and line echo or "howling" can also interfere with analog signals. The 'WP010 largely eliminates these sources of signal interference, clarifying the sound that cellular users hear.

The new device also supports simultaneous two-way, or full-duplex, transmission, allowing both callers to speak at the same time and still hear each other. In half-duplex systems, one caller's voice is cut off completely while the other caller speaks, causing annoying jumps in conversations.

Technology for the future

"Hands-free operation is still in its infancy," said Mike McMahan, applications manager for TI's Wireless Communications Systems. "With products such as the 'WP010, TI is putting the technology together that can make hands-free cellular phone operation commonplace in the future.

"We designed this product with convenience and safety in mind," he said. "And 'WP010 technology will allow us to add more features in the future for even greater convenience, such as voice recognition for hands-free dialing and digital telephone answering devices. Wireless designers are discovering that TI offers cost-effective, highly integrated digital processing solutions for their complex systems needs."

Pricing and availability

The device is available either by itself or with two TCM320AC36 Voice Band Audio Processors (VBAP) in the TCS320WP010 chipset. In addition, the software is available for licensing to developers who want to integrate it with their own DSP code. ROM-less samples of the device and the chipset are available now directly from Texas Instruments only. Neither version is available through distribution.

TMS320WP010: 100-pin TQFP - $14

TCS320WP010 chipset : w/ two VBAPs - $19

Suggested resale pricing in U.S. dollars in 100K units.

November 1995, vol. 12, no. 8

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