Using phase ambiguity resolution for millimeter-level rail positioning

The Applied Research Laboratories, The University of Texas at Austin (ARL:UT), has developed a prototype rail surveying system that utilizes a self-propelled railcart, along with a network of reference sites, and phase ambiguity resolution software to provide millimeter-level survey capability. This accuracy level is achieved using low-cost OEM receivers and custom postprocessing software. This paper reviews the operational concept and development constraints of the railcart system, and describes testing and operation of the railcart system. In addition, the custom ambiguity resolution software is discussed, along with preliminary performance results from early demonstration tests.