Communication Tower Based Experiment and Analysis of Differential Augmentation for Auto-Steering Guidance of Agricultural Machinery

Abstract

UHF based single station RTK is widely used for auto-steering guidance of agricultural machinery in China currently. Too many reference stations in a region will cause serious interference of radio frequency. Moreover, the reliability is very low, since most of the stations were built on the residential buildings. Considering the above problems, we propose to construct the reference station on the communication tower because of the advantages including distribution density, infrastructure guarantee, high quality communication, and relative height compared with ordinary building. We select three communication towers for experiment in Beijing. The average baseline is 43.3 km. We place the GNSS antennas on the roof of communication equipment room, and put the reference receivers (PD318) in the room. An agri-CORS is constructed by using PowerNetwork software. We use 4G of China Mobile to transfer observation data and ephemeris data in real time. We put the antennas of UHF radio on the tower, which is nearly 50 m high. Results show that the data integrity of three reference stations are better than 99%. The signal-to-noise ratio of L1, L2, B1, B2, and B3 are greater than 46, 35, 44, 46, and 40% respectively. The multipath of all the bands are less than 0.50. The average accuracy of baseline after adjustment is better than 0.001 m. Both average internal accord accuracy of CORS and single station RTK are better than 0.01 m, and both average external accord accuracy of CORS and single station RTK are better than 0.025 m. Therefore, we get the basic conclusion that the selected communication towers are suitable for construction of GNSS reference station and the CORS and single station RTK meet the application requirement of auto-steering guidance of agricultural machinery.