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標題: Factors affecting the estimation of GPSreceiver instrumental biases
關鍵字: Total electron content;differential code biases;inter-frequency biases;GPS, Ionosphere
Project: Survey Review, Volume 45, Issue 328.
Global positioning system (GPS) has been widely used to investigate the ionosphere through theestimation of the total electron content (TEC) and its distributions in space. One of the importantfactors affecting the ionosphere TEC estimation accuracy is the hardware differential code biases(DCBs) inherited in both GPS satellites and receivers. This paper investigates various factorsaffecting GPS receiver instrumental bias estimation accuracy. Through a number of designedtests, we concluded that the most important factor is the ionosphere model accuracy. Some oflarge daily bias variations of receiver DCB detected by other studies, such as receivers in lowlatitude regions, are not due to the DCB changes, but the estimation errors. The DCB estimationvalues can vary significantly for different ionospheric models and different sizes of networks. Forexample, the receiver DCB values obtained from the global and the station- specific modelsexhibit difference from 22?5 to 14?3 TEC unit (TECU) for different stations. Different dataprocessing methods also contribute to DCB estimation errors. The results from smoothing andnon-smoothing GPS observation show that the difference of DCB reaches up to 6?8 TECU forsome stations, with the mean difference of 3 TECU. On the other hand, the elevation cut-off angledoes not play an import role in ionospheric delay estimation. For elevation cut-off angles from 10to 30u, our tests show that the DCB estimation differences are ,0?4 TECU.
Appears in Collections:土木工程學系所

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