In this paper, we introduce a new concept called “Compact Wide-Area RTK (WARTK)” which provides centimeter-level positioning service on national or continental scales. Using the network of multiple reference stations whose distance is 400-1000 km, the Compact WARTK system generates three types of high-precision corrections: satellite orbit correction, satellite code/phase clock (CPC) correction, tropospheric correction. This paper mainly focuses on generation method of tropospheric correction. We proposed a new real-time tropospheric delay modeling technique that combines the GPS-based tropospheric model, the Saastamoinen model with meteorological data, and the empirical UNB3 model all together. Even a small number of GPS reference stations, it is possible to model high-accuracy tropospheric delay using the meteorological data together. The zenith tropospheric delay is modeled as a spherical harmonics function. As a result, the modeling accuracy is about RMS 2 cm in rainy day. In conclusion, the Compact WARTK system can provide the centimeter-level position on the target service area within 1 minute using our precise tropospheric correction.

Keywords: compact RTK, network RTK, wide-area RTK, tropospheric correction