Recipient: Dr. Charles R. Cahn Citation: For sustained and profound technical contributions, leadership, and analysis, from the early 1970's through current modernization activities, which have shaped the most basic GPS signal structures, pioneered receiver signal processing techniques, and thereby substantially improved system performance for both military and civilian GPS users. These ongoing contributions span more than 30 years, beginning with the GPS-predecessor 621-B Program and continuing. For over thirty years, Dr. Charles R. Cahn has been a pioneer and a major contributor in the area of analysis and design of GPS signal structures and receivers. His work on the 621-B program, and during Phase-I of GPS was vital in defining the GPS signal structures we enjoy today. More recently, he made critical contributions to the GPS modernization program including analysis and design of key elements of the military GPS signal. Subsequently, Dr. Cahn was instrumental in the development and analysis of a similar Time Division Data Multiplexing (TDDM) approach for the M-code signal, enabling benefits of a dataless signal component. While Dr. Cahn has made several notable contributions to the GPS modernization efforts in recent years, his accomplishments span a lifetime of contributions to GPS signal and receiver developments. Together, these achievements define irreplaceable contributions to present and future navigation capabilities of the Global Positioning System and Satellite-based navigation technology in general. His most recent achievements were made as a consultant to the Aerospace Corporation, where he continues to be an extraordinarily productive contributor to both the civil and military GPS modernization programs.