Since 2012, researchers at the Institute of Geodesy, Working Group Navigation, have been continuously working on robust and generally valid RTK software named eRTK. In doing so, low-cost single-frequency hardware components are used. The on-going development, closely linked to the low-cost GNSS market, contributes to the use of GPS and GLONASS systems for RTK processing. For raw data transfer, which is essential in RTK, a special system architecture is developed consisting of an UMTS data transmission and an interface to synchronize the data in real time. Using a high-sensitivity GNSS receiver, a proprietary data format for GNSS raw data was designed to exploit the full signal bandwidth and, as a consequence, to support the RTK filter. The resulting increase of robustness could be confirmed within numerous test runs. Thus, it is possible to use the developed RTK demonstrator even under difficult GNSS conditions (edge of the forest, urban area, etc.).
Basically, within PPP, code and phase measurements of single static or kinematic receivers are used to estimate an independent solution of three-dimensional position coordinates, receiver clock estimates and tropospheric parameters with the aid of externally provided precise orbit and clock information instead of using the imprecise navigation data broadcast by the satellites themselves.
Since 2010, researchers at the Institute of Geodesy, Working Group Navigation, have been working on a PPP software, called PPPsoft, with ambiguity resolution and fixing. This software package has been used in various funded projects.
After achieving outstanding results (see the dissertation of Katrin Huber), the work was continued for single-frequency PPP and low-cost GNSS receivers for special applications like RPAS (remotely piloted aircraft systems) where a continuous data link cannot be guaranteed but high precision and/or accuracy is required.