NRL Researchers win Bowen Patent Invention Award for Voice Communication Processing System

6/5/2002 - 33-02r
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George S. Kang and Larry J. Fransen (now retired) of the Naval Research Laboratory's (NRL's) Information Technology Division are the recipients of the 2001 Vice Admiral Harold G. Bowen Award for Patented Inventions from the Office of Naval Research (ONR). Rear Admiral Jay Cohen, Chief of Naval Research, presented the award in a ceremony at ONR on May 9.

The Bowen Award, named in honor of Vice Admiral Harold Gardiner Bowen, the first Chief of Naval Research, recognizes inventions of great benefit to the Navy patented by current or former, civilian or military Navy personnel. The invention must have a significant impact upon the operation of the Navy as measured by the extent of its use, cost savings, increased military capability or increased quality of life.

The winning NRL invention, the Voice Communication Processing System, improves speech communication at low data rates benefiting Naval tactical voice communications. This new technology has enhanced speech intelligibility on secure telephones and provided direct interoperability between old and new speech parameters, allowing new secure phones and legacy secure phones to work together. Ensuring that the legacy secure phones need not be retired prematurely and unnecessarily has resulted in a cost savings to date of nearly $600 million.

Speech encoded at lower data rates in radio systems can reach over longer distances. Another advantage of low-data-rate-speech is that it sounds better over narrow bandwidth circuits, such as public telephone networks. However, the speech signal cannot be transmitted in the same way as with a conventional telephone. Speech is transmitted in terms of parameters, such as pitch frequency, loudness parameter, and resonant frequencies. At the receiver, speech is regenerated using these same parameters. The resultant speech quality depends significantly on the parameters transmitted.

To improve speech quality at lower data rates, the invention discloses new speech parameters called line spectrum pairs (LSPs), which are frequency-domain parameters that can be optimized for human auditory perception characteristics, such as the diminished ability to resolve higher frequencies. High LSP frequencies need not be represented as finely as low LSP frequencies. As a result, speech quality is high at appreciably lower rates.

LSPs were first implemented on the enhanced Secure Telephone Unit-Third Generation (STU-III) operating at 4800 bits per second, an improved version of the earlier STU-III operating at 2400 bits per second, and have been used in all recent DoD low-data-rate secure telephones.

Mr. Kang came to NRL in 1971, and is currently head of the Voice Systems Section of ITD's Transmission Technology Branch. Previously, he has received the IEEE Senior Publication Award, the Navy Superior Civilian Service Award, 12 NRL Research Publication Awards, two NRL Technology Transfer Awards and an NRL 75th Anniversary Award for Innovation. Mr. Kang is also the recipient of four patent awards, one of which led to the Bowen Award.

During his career, Mr. Kang has specified voice-encoding algorithms for four different Navy and DoD secure telephones, which have been deployed by the thousands.

Mr. Larry Fransen retired from NRL in 1999. He joined NRL in 1974 and performed research in speech processing techniques that produced five NRL Research Publications Awards and three patent awards. Prior to working at NRL, Mr. Fransen was a naval officer teaching mathematics at the U.S. Naval Academy.

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