NAVSTAR Global Positioning System Collins User Equipment: An Evolutionary Assessment

Abstract

This paper describes the evolution of Collins GPS receiver architecture as it has matured from Phase I. The growth in functional capabilities required of the receiver over the course of the GPS program has necessitated the development of various processes and techniques to ensure that User Equipment (UE) could be produced at low cost while meeting the imposed performance requirements. The results of Life Cycle Cost (LCC) trade studies became the driving force in determining receiver architecture as the receiver design progressed from Phase I. Phase I, Concept Validation was structured to prove three major tasks. These were: (1) GPS validity as a navigational system, (2) verification of the engineering concept chosen for implementation, and (3) demonstration of military utility. These tasks necessitated the development of various types of User Equipment (eg, GDM, High and Medium Dynamic sets, Manpacks) tailored to provide certain test data without, necessarily, optimizing for costs or producibility. Phase 2, Full Scale Development, demonstrated the integration of GPS Receivers into a select group of eight Host Vehicles (HVs) representing a wide range of HV types across low, medium and high dynamic applications. The emphasis in this phase was to utilize available technology to produce receivers (in a factory environment) that provided the required performance and survived the Host Vehicle environment. LCC results played the key role in determining the Phase IIB architecture—the production baseline for Phase III. Phase III is concentrating on optimizing the integration concepts to take full advantage of the increased functional capabilities of the GPS receiver. Improvements in Hardware (HW), as well as an inventive interface processing approach in Software (SW) have allowed the receiver to offer the basic navigational data in a wide range of functional “flavors” while minimizing the HW and SW changes from Phase IIB. Finally, a glimpse of improvements planned for future receivers will be shown.