Precise point positioning(PPP)time transfer technology is one of the important means of international time comparison and has made great contribution to the calculation of coordinated universal time(UTC).In order to investigate the performance of multi-system PPP time and fre-quency transfers,the station data from three international timing laboratories are selected to form two links,and eight experimental modes are used to compare and analyze the performance of single system,dual system,triple system and quadruple system PPP time and frequency transfers.The experimental results show that each multi-system combination has a greater improvement in the number of visible satellites than the single GPS system,and greatly improves the time dilution of precision(TDOP),which increases the robustness and reliability of the time comparison results.In terms of time transfer stability,for the PTBB-BRUX time link with a geodetic distance of 453.4 km,compared with the single GPS system,the GPS/BDS combination in the dual system has an excel-lent enhancement effect,with an enhancement rate of about 10.39％,the GPS/GLONASS/BDS combination in the triple system has an optimal enhancement rate of about 11.86％,and the quad-ruple system has an enhancement rate of 11.98％,which can be improved from 0.046 7 ns to 0.041 1 ns;for the PTBB-NIST time link with a geodetic distance of 8 031.8 km,the GPS/BDS combination enhancement rate is about 4.89％,the GPS/GLONASS/BDS combination enhance-ment rate is about 5.49％,and the quadruple system combination enhancement rate is 5.79％,which can be improved from 0.114 0 ns to 0.107 4 ns.In terms of frequency transfer stability,the average improvement within the first 10 000 s is 17.6％for dual system combinations,20.5％for triple system combinations,and 21.6％for quadruple system combinations.
Multi-systemPrecise point positioningTime transferFrequency transferTime sta-bility
维普
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