On accurate time synchronization of multi-sensor mobile mapping systems

This paper introduces a GPS time synchronization method intended for airborne and ground-based mobile mapping systems, where multiple sensors simultaneously acquire geospatial data, and accurate co-registration of the data in space and time domains is necessary. Although more and more sensors are coming with built-in GPS capabilities, which provides for ideal GPS time-tagging, and thus for spatial registration of the data, the great majority of the sensors used in mobile mapping still lack this capability. The proposed method offers an effective and simple solution to precise GPS time-tagging of sensors that are connected to a PC-based data acquisition system. Using a timer board and a GPS receiver connection, a time base transformation is established between the high-performance processor time and the GPS time, which results in the system level availability of the GPS time for any data acquisition process.