Dr. John W. Betz

For significant contributions to GNSS Modernization.

Dr. John W. Betz is a fellow of The MITRE Corporation, supporting the GPS Joint Program Office in various ways including systems engineering, signal design, and international negotiations. In 1997, he began work in support of early studies to design a modernized GPS military signal and was selected to lead the Modulation and Acquisition Design Team of scientists and engineers. The resulting signal, now called the M-code signal, is being implemented on Block IIR-M and later satellites. As part of this work, he developed the binary offset carrier modulation used for M-code signal, assessed its benefits in terms of performance and compatibility, and subsequently proposed its use for modernized civil signals. Dr. Betz also developed the punctured acquisition aid used for M-code signal to speed signal acquisition without requiring a separate acquisition signal. He was the catalyst and systems engineer for developing the -DirAc integrated circuit for direct acquisition of the M-code signal.

With a co-author, he developed a generalized theory for predicting code tracking accuracy of arbitrary spreading modulations in non-white Gaussian noise and a lower bound on code tracking accuracy in non-white Gaussian noise. He popularized the use of root-mean square bandwidth to quantify potential code tracking performance and also generalized existing predictions of code tracking accuracy for conventional modulations in white noise.

Dr. Betz has contributed to recent work in developing a simple analytical approach for evaluating intrasystem and intersystem radio frequency interference and popularized the application of spectral separation coefficients for this purpose. He has helped apply this approach in bilateral discussions between the United States and the European Community for GPS-Galileo work, and between the United States and Japan for GPS-QZSS work.

He has been a member of the U.S. delegation in technical negotiations and working groups leading to the U.S.-E.U. Agreement on GPS and Galileo signed in June 2004 and continues to support these activities.

More recently he has contributed to the design of the modernized L1 civil signal called L1C and, since 2004, has been a member of the U.S. Air Force Scientific Advisory Board.

He was co-recipient of MITRE’s President’s Award for Outstanding Achievement for work on GPS modernization. He was co-recipient of The Institute of Navigation’s Samuel M. Burka Award. In 2004, he received the MITRE President’s Award for Outstanding Achievement and the U.S. State Department Superior Honor Award for work on the U.S./E.U. negotiations on GPS and Galileo.

Dr. Duncan B. Cox, Jr.

For his leadership and technical innovations in the development of inertial, GPS, and integrated navigation systems, and for his service to the Institute of Navigation.

Dr. Duncan B. Cox, Jr. has made vital contributions to inertial and radio navigation systems in his 40-year career that began as a staff member at the MIT Instrumentation Laboratory (later renamed C.S. Draper Laboratory).

At the Instrumentation Laboratory, he led the development of self-oscillating fluidic stabilization servos for the floated-sphere SABRE inertial navigation system and the electromagnetic attitude readout system for the follow-on AIRS inertial navigation system, later produced by Northrop for the USAF peacekeeper program.

After developing attitude measurement systems based on electromagnetic waves transmitted over fractions of an inch, Dr. Cox extended the tracking technology to radio navigation applications and led the development of techniques for tracking Loran-C and Omega navigation signals.

With the encouragement of the founding director of the GPS JPO, in the late 1970s, Dr. Cox shifted the emphasis of his group to the emerging GPS system. The ensuing GPS work became important enough for Draper Laboratory to create a Radio Navigation Division under his leadership. Significant technology contributions under his leadership include the invention and development of an important technique (extended range code tracking) for speeding the acquisition of NAVSTAR GPS signals in the presence of jamming, the development of a highly accurate GPS system for flight instrumentation, the first demonstration of a pre-correlation digital P-code GPS receiver, and the truly pioneering demonstration in collaboration with Dr. Richard Greenspan and Prof. Charles C. Counselman III of techniques for processing GPS carrier phase signals to provide measurements of short baselines with millimeter accuracies.

In 1986, Dr. Cox co-founded the Mayflower Communications Company, Inc., where he developed projects for advanced navigation and communication technology for the U.S. government. One example is the design of an experiment utilizing GPS and inertial sensors aboard the space shuttle to measure perturbations in the gravity field of the Earth.

In 1991, Dr. Cox founded DBC Communications, Inc., where he is currently president. His recent work there includes the co-invention of an optimum recursive estimator for systems including integer states, and the ongoing development of an ultra-tightly coupled GPS-INS receiver.

Dr. Todd Walter

For contributions to the development and deployment of the Wide Area Augmentation System.

Dr. Todd Walter received his doctorate from Stanford University in applied physics in 1993. At that time, he became the director of the Wide Area Augmentation System (WAAS) Laboratory at Stanford where he continues to serve in that capacity.

WAAS became operational on July 10, 2003—an event that would not have happened without Dr. Walter. The Federal Aviation Administration has repeatedly acknowledged that his participation is critical, and will be critical to the success of WAAS. Dr. Walter’s contributions include the following accomplishments.

Dr. Walter almost single-handedly implemented an experimental prototype of WAAS that was based on three West Coast reference stations and later became part of the National Satellite Testbed (NSTB). With these three stations, Dr. Walter led the Stanford team that prototyped a complete flight test system. This system included all of the hardware and software for the reference stations and a complete master station. It also included a VHF data link and later a geostationary satellite link to convey the corrections to the aircraft and the prototype WAAS avionics.

Using this prototype system, Dr. Walter led some of the earliest WAAS flight trials. The Stanford trials were the first to separate the GPS corrections into the vector components characteristic of any space based augmentation system. Accuracy was assessed using a laser altimeter and GPS carrier phase system. Typical accuracy in flight was approximately two meters in the vertical. These results were among the key early results that motivated the production of an operational WAAS.

Dr. Walter was also instrumental in the certification of WAAS. Specifically, he led the ionospheric team that was part of the larger WAAS Integrity Performance Panel effort and was the lead contributor to the re-design of the ionospheric algorithms. His algorithms developed the ionospheric corrections and more importantly the confidence intervals associated with those corrections. His ionospheric storm detector is also a key element in WAAS safety.