2011 Weems Award

Presented to: Clyde E. Edgar, Jr.

Citation: For sustained contributions to GPS satellite payload and signal design and engineering, professional collaboration, and promotion of scholarship in navigation science and engineering.

In nearly twenty years of supporting the GPS Directorate at The Aerospace Corporation, Clyde Edgar has made numerous contributions to the GPS program, its users, and researchers in the field of navigation. Clyde has played a central role in the design of all modernized GPS satellite payloads; and key contributions to multiple investigations of multipaction, power fluctuations, and other RF component anomalies experienced in ground testing and on orbit. As an expert in the design of the isoflux phased array antennas, Clyde has also made significant contributions to understanding the performance of GPS satellite L-band arrays, including working with NASA on characterizing side-lobes for use by high-altitude spacecraft. Clyde's work with Boeing and the USGS on a study of 12 Block II L-band antenna arrays led directly to signal-in-space accuracy improvements through more accurate knowledge of the phased array phase center.

In order to ensure that service to high accuracy civil users was preserved, Clyde developed new flex power modes for GPS IIR-M and IIF spacecraft, helped incorporate these new modes into the spacecraft specifications, supported multiple successful on-orbit test campaigns of this new modernized spacecraft capability, and coordinated these new modes with the National PNT Engineering Forum (NPEF) and other stakeholders. Clyde worked with engineers at SRI to develop a frequency tunable L-Band test measurement scheme using the 150 foot large aperture radio telescope for high resolution signal measurements. As a result, SRI has become the primary signal quality measurement facility for GPS, and has enabled precise measurements of a number of key GPS signal quality metrics such as axial ratios, phase center offsets, and digital distortion.

Clyde has served as the GPS Directorate's technical liaison to the radio astronomy community for over a decade, investigating and resolving claims of interference, assisting with testing and data collection efforts, and proposing a number of operational and signal processing techniques to mitigate interference with radio astronomy facilities around the world. Clyde is the lead GPS Directorate's expert on space weather and the impacts of solar radio bursts and scintillation on both GPS spacecraft and users. Clyde was first within the GPS Directorate to correctly identify the December 2006 solar radio burst anomaly as an L-band interference event emanating from the Sun and affecting GPS users worldwide.

Additionally, Clyde has been extremely active in the ION's Southern California Section and on the ION Council. He is currently a member of the ION's Executive Committee.