SLR and VLBI technology trends

SLR and VLBI technology improvements are continuing, aimed at millimeter system performance. New SLR receiver components have achieved single shot RMS precision of 1 cm on LAGEOS. Recent VLBI phase delay observations have achieved sub-cm repeatability. New water vapor radiometers are achieving millimeter precisions in measurements of tropospheric path delay. These improvements, plus others to be discussed, will improve the accuracy of future polar motion measurements.