Mass-market L1 GPS receivers for mobile mapping applications: a novel approach

Over last twenty years, positioning with low cost sensors has developed rapidly in the U.S.A. and in Europe at both a commercial and academic research level. In this respect, the Geomatics Research Group of LEGEND at the Politecnico di Torino has also designed and developed a universal system for Mobile Mapping, called LCMMS (Low Cost Mobile Mapping System), which uses only low-cost sensors and instrumentation. It is possible to find results of the various experiments conducted by this group in the bibliography (De Agostino, 2009 and Piras et al., 2008), where the integration and use of inertial equipment (3 IMU - Inertial Measurements Units) and GPS instruments (GPS 3 u-Blox + 1 Leica 1230+) were considered. This work is a continuation of the above described research but without the use of inertial equipment and with only L1 low cost GPS instruments, except a Leica 1230+, used only to obtain the control of the trajectory with a high precision tool. The use of this type of instrumentation introduces a number of problems, such as the accuracy that determines the position of the rover: the true goal of this work is to improve the quality of positioning and the control of the same quality. In order to solve this type of problem and to test the possibility of using L1 low cost GPS receivers for mobile mapping, the Research Group has developed a software written in MATLAB language, which allows the single epoch network kinematic positioning of a certain number of rovers in reference to a mobile master, experiments that, to the Authors knowledge, have not been carried out before. To improve but also to control the quality of positioning the idea is to insert, in addition to the measurement equations, for every age, the constraint equations of the distances between the antennas. A mobile mapping test was conducted to validate this algorithm in order to understand the accuracy that can be achieved with this low cost instrument under various satellite visibility conditions, in terms of urban obstructions.