Although VLBI is unique among the geodetic space techniques, as it is the only one that delivers dUT1 values, other geodetic space techniques such as GNSS are able to measure the rate of change of dUT1, which is called Length Of Day (LOD). Thus, it is possible to estimate dUT1 over time by integrating LOD and adding the known dUT1 value at t0. The main drivers of variations in the Earth rotation rate are the variable mass distribution of the atmosphere and zonal winds as well as zonal tides of the solid Earth and oceans. The latter can be calculated from the IERS (International Earth Rotation and Reference Systems Service) model, while the atmosphere's variations are available as Atmospheric Angular Momentum (AAM) functions. The bachelor thesis' aim is to test how well dUT1 measurements from VLBI can be bridged by integration of LOD values obtained by both GNSS and AAM (+zonal tides). Preliminary combinations of both AAM and GNSS data by means of a Kalman filter deliver quite promising results with maximal dUT1 deviations compared to VLBI intensive sessions of 300's and an average deviation of 50's over a time span of 28 days. This is using one day solutions of a global network of GPS and Galileo satellites implementing the ECOM solar radiation model. Investigation of a longer period as well as comparisons between different GNSS LOD data, such as 1- and 3-day solutions of GPS or GPS + Galileo are planned.