GPS ground antenna and monitor station upgrades: system analysis and design

This paper discusses the system analysis and design aspects of the Global Positioning System Operational Control System (OCS) remote site modernization study. Requirements analysis for a mission-critical legacy system poses a unique set of challenges such as undocumented requirements, a continually evolving system, variances between documented requirements and the system as implemented, an unrecorded repository of knowledge in designers and operators of the system, and so on. The paper discusses how these challenges were recognized and overcome. The system architecture designed to meet these requirements also had to meet the broader goals of OCS modernization including an open system architecture, increased dependability, expandability and flexibility. The paper describes key features as well as the design rationale of the architecture selected to meet these requirements.