An application of GPS dual frequency codeless receiver for ionospheric delay to single frequency VLBI observation

A dual-frequency codeless Global Positioning System (GPS) receiver for measuring ionospheric delay, called GTR-2, has been developed. Results of a feasibility study of using GTR-2 for single-frequency very-long-baseline interferometry (VLBI) experiments are presented. GTR-2 uses a cross-correlation property of the P-code signals transmitted from GPS satellites to measure ionospheric total electron content (TEC) with a measurement uncertainty of about 2*10/sup 16/ electrons/m/sup 2/ along the line of site to the satellite. Ionospheric compensation of the signal from radio stars is studied using the TEC data obtained from GTR-2.<
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