The activity of the Stazione Astronomica di Cagliari (SAC, Sardinia-Italy) mainly concerns observations and data reduction/analysis based on astronomical and space geodesy techniques, such as GPS and SLR. Within 2004 a new 64 meters radio-telescope near the SAC will be operative for VLBI campaigns also. In the recent past the local geoid, vertical deflections and trigonometric zero order benchmarks were evaluated in loco by means of classical topographic and GPS surveys. In order to determine the transform parameters from such local frames to the SLR geodynamic network, we have started collocation experiments between fixed and mobile Laser Ranging stations and GPS observation data. We present here the method and preliminary results of our investigations. The project concerning the future VLBI antenna with regard to the space geodesy collocation is shown in advance.