Centimeter Level Precise Positioning with a Low-Cost GNSS Antenna

The demand for lower priced precise positioning is growing rapidly, as evident in the areas of intelligent transportation systems, precise agriculture, and unmanned aerial vehicle (UAV) guidance. High precise positioning can be achieved with Real-Time Kinematics (RTK) technology, which is a differential method that is generally applied to geodetic receivers and can typically provide centimeter level solutions within only a few seconds if corrections from a physical or virtual reference station are available. In recent years, low-cost GNSS receivers, such as U-blox, have been proven to be able to perform stable RTK comparable to geodetic-grade receivers. Instead of using a consumer-grade antenna, a geodetic one is usually chosen to perform reliable integer-ambiguity resolution in low-cost RTK. There are two disadvantages of using geodetic antenna. First, the size of a geodetic antenna is not small enough to be placed on platform such as agricultural UAVs. Second, the price of a geodetic-grade antenna is much more expensive than a consumer-grade one. In this paper, we proposed a combined BDS/GPS RTK algorithm to obtain centimeter level positioning using a low-cost single-frequency helix antenna. The results show that a positioning accuracy of 2-3 cm (>95%) is achievable in static mode, with an ambiguity fixing rate greater than 98%. For kinematic test, the ambiguity fixing rate is about 95% with a false fixing rate less than 0.015%, and a dynamic positioning accuracy of 5 cm in horizontal and 10 cm in vertical can also be obtained for more than 95% of the time.