Characterizing the Impact of Precision Time and Range Measurements from Two-Way Time Transfer Systems on Network Differential GPS Position Solutions
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
Pagination or Media Count:
Many GPS applications require precise relative positioning of a network of vehicles such as aircraft, tanks, troops, etc. Although GPS has become commonplace in todays society, there are still limitations affecting the system. Recent advances in dynamic Two-Way Time Transfer TWTT have potentially provided a means to improve precise relative positioning accuracy over differential GPS DGPS-only approaches. TWTT is a technique in which signals are simultaneously exchanged between users. This research investigates the impact of using Two-Way Time Transfer TWTT time measurements to augment differential GPS systems to improve the relative positioning solutions of vehicle networks. Incorporating the TWTT time meas. into the DGPS solution improves the 3-D relative positioning accuracy by up to 44 with pseudorange measurements and 35 with phase measurements. Normally, the TWTT measurements are used in a manner that cancels out the impact of the vehicle position in order to obtain a precise relative time measurement. The research also implements an innovative approach to using TWTT measurement to obtain a precise measurement of the vehicle position in addition to the time measurement. The results show that 3-D relative positioning solutions can be improved by up to 48 when using pseudorange measurements augmented with TWTT time and range measurement and up to 40 when using phase meas. augmented with TWTT time and range meas.
- Navigation and Guidance