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.
The U.S. Naval Research Laboratory is the Navy's full-spectrum corporate laboratory, conducting a broadly based multidisciplinary program of scientific research and advanced technological development. The Laboratory, with a total complement of nearly 2,500 personnel, is located in southwest Washington, D.C., with other major sites at the Stennis Space Center, Miss., and Monterey, Calif. NRL has served the Navy and the nation for over 85 years and continues to meet the complex technological challenges of today's world. For more information, visit the NRL homepage or join the conversation on Twitter, Facebook, and YouTube.
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