New software feature offers breakthrough in TDMA digital cellular audio quality

June 7, 1995

DALLAS - Northern Telecom (Nortel) today introduced a breakthrough in audio quality for Time Division Multiple Access (TDMA) digital cellular telephone calls - a new switch-based software feature that eliminates the "waterfall effect" occasionally experienced when a caller is not speaking.

Digital cellular service, now widely available in North America and other parts of the world, has demonstrated superior audio quality to analog service. But the digital speech codecs currently deployed in many cellular networks have difficulty encoding background noise. When a caller is not speaking, this sometimes results in a sound described as water swirling or falling, instead of the actual background noise.

Nortel's Background Noise Conditioning feature, available in the third quarter of this year, more accurately reproduces the background noise present during a TDMA digital cellular call, regardless of the brand of handset being used.

"Our field trials of Background Noise Conditioning have demonstrated a reduction in 'waterfall' noise," said Tony Schultz, vice president of engineering, Bell Mobility Cellular of Toronto. "We expect this new feature to provide improved voice quality for our digital subscribers."

"Nortel was first to put TDMA digital cellular in commercial service in North America, and this improvement in voice quality demonstrates our on-going commitment to enhancing the technology," said Matt Desch, vice president and general manager, Wireless Networks, Nortel.

Background Noise Conditioning is a software enhancement to the Digital Signal Processing Module (DSPM) of Nortel's DMS-MTX digital cellular switching systems. It allows service providers to improve call quality for all digital subscribers with a software upgrade at the switch, rather than requiring upgrades at multiple cell sites.

Nortel is one of the world's most broadly diversified developers of communications products, systems, and networks in three key market segments - Enterprise Networks, Wireless Networks, and Carrier Networks (switching, broadband, and network applications solutions). Nortel provides equipment, services, and network solutions for information, entertainment, and communications networks operated by telephone companies, personal and mobile telecommunications companies, cable TV companies, corporations, governments, universities, and other institutions worldwide.

Nortel had 1994 revenues of $US 8.9 billion and has approximately 57,000 employees worldwide.