The first GPS satellite radio optimized for automatic vehicle location

摘要

A GPS (Global Positioning System) radio designed to serve the needs of the automatic vehicle location (AVL) market is discussed. Market research revealed several key demands for an AVL GPS radio: (i) minimization of urban building blockage; (ii) easy programmability to minimize mobile data transmission costs; (iii) high accuracy for streetmap level coordination; (iv) interface capability with nondigital specialized mobile radios; and (v) selling price close to that of alternatives such as Signposts and Loran-C. The developed system operates at high accuracy in an urban environment and is plug-compatible with nearly all vehicle radios. Among the engineering and production breakthroughs described are a unique approach to satellite tracking, enabling up to 8 GPS satellites to be used for position determination with a two-channel receiver, and a receiver-in-a-microdome design. A powerful application-specific integrated circuit has enabled MARCO to bring GPS within the easy reach of millions of AVL users such as buses, taxis, and delivery vehicle fleets.