On the earth rotation with GPS and VLBI observations

In this paper, first of all, VLBI observations (NGS format) are used to estimate the earth rotation parameters (ERP). Secondly, the NGS data related GPS observations by the GPS stations co-located with the above VLBI stations are used to estimate the ERP. Thirdly, their results are respectively compared with IERS 08 C04, which shows that the result of GPS cannot get the precision of VLBI stations of equal number. So, 22 GPS stations distributed evenly are chosen to estimate the ERP, the result of which shows that the precision of ERP estimated by GPS has not only been improved a lot, but also it can almost achieve precision of ERP estimated by the VLBI when the number of GPS stations is added to 80.