A Dual-Mode GPS Real-Time Kinematic System for Seamless Ultrahigh-Precision Positioning and Navigation

A variety of broadband wireless access technologies were investigated for improving the performance of GPS RTK systems. Compared with UHF radio modems, broadband wireless access technologies provide great advantages for RTK applications. For example, the line-of-sight condition for a radio link is not required any more except for “last mile” wireless connection (i.e., wireless connection of end-user devices to wired networks). This potentially improves the available performance of an RTK system, especially in medium and long-baseline applications. Also, network-based global RTK applications and diversified location-based services integrated with RTK and multimedia are feasible. These advantages are mainly thanks to broadband access connectivity from the core infrastructure network to enduser devices. As end-user devices and GPS resources such as permanent (or localized) reference stations become available more and more on the network, we can expect more practical and fully operational RTK systems. In this paper, we introduce the UNB RTK system which was initially developed for a rubber-tired gantry crane (RTGC) auto-steering system and discuss recent upgrades to improve the availability of the RTK system by using broadband wireless communication.