ExaminaUons on the accuracy of DGPS made by tbe of Agn cultural Engineering FreisingWeihenstephan using an lnfrared-Tracking System (lTS) as reference system for DGPS in five epplicetion, Ulling and harvest..ing measures respectively show deviaUons of the systems to each other in the range of few meters and swaying in dependence of the position of tbe tracking prism in reletioti to the tachymeter site; tbere is no correletion to be recognized to important GPS parameters suggesUng errors in posiiioninq of the reference systetn, too. Tests of tbe tachymeter on a linear guidance in cooperetioti with the Institute of Geodesie show an influence of a time delay of distance measuring to angle measuring; but tbis delay cannot be the only explanaUon of the observed facts in tbe reference measurings. Tiieretore. an exact detection of all troubling influences on the tachymeter positioninq and a respective celibretioti of tbe recorded data will be necessary before it can be used as reference Ior DGPS.