A low-cost RTK-GNSS base station using a Raspberry Pi 4 with a cellular sim card as a server was developed for precise positioning. A u-blox ZED-F9 P GNSS module connected to an antenna was connected to the Raspberry Pi 4 for correcting RTK signals. An open source NTRIP 1.0 caster was utilised after which a tractor, fixed-wing UAV and multi-rotor UAVs could be connected at the same time with a fast time-to-first fix (TTFF). For accuracy comparison, it was found that positions calculated with RTK data from Memuro Base Station had a lower horizontal error of 7.2±4.5 mm compared to that of conventional subscription Nippon GPS Data Service which had a horizontal error of 9.2±5.75 mm.