Development of a GPS codeless receiver for ionospheric calibration and time transfer

A Global Positioning System (GPS) dual-frequency codeless receiver, which has a design similar to that proposed by M. Imae et al. (1988), is developed for measurement of the total electron content in the ionosphere. The authors built a simulator to calibrate the codeless receiver and made calibrations with an accuracy of about 2-3 ns. Ionospheric measurements are made along the line of sight of the scheduled GPS satellites and time comparisons between KRISS (Korea Research Institute of Standards and Science) and CRL (Communications Research Laboratory) are carried out using the measured ionospheric delays at both sites under the common-view schedule of BIPM. The precision of time comparison is improved by using the measured ionospheric data.<
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