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Martin Kriegel

Operationelle Prozessierung satellitengestützer GNSS-Messungen zur Ableitung des Gesamtelektronengehalts (TEC)

Hochschule Neubrandenburg, 2013

Abstract: As part of the reconstruction of three-dimensional electron density distributions of the upper ionosphere and plasmasphere from GPS measurements of the satellite missions CHAMP and GRACE, this work treats two main topics. The first part decribes the quality assurance of GPS measurements in terms of cycle slip detection and correction. In this context different methods for cycle slip detection are examined for their use with satellite-based GPS measurements. These methods using the Melborne-Wübbena wide lane linear combination, the TEC rate and the signal strength are implemented in a fully automated processing system for detecting cycle slips, and applied to previously prepared data of the CHAMP satellite mission from 2001. The assessment of the quality of these detection methods is implemented by the detection of simulated cycle slips. As a result, in terms of optimization of the current used cycle slip detection, a hybrid method using Melborne-Wübbena wide lane linear combination and TEC rate according to Heise (2002) and Liu (2010) is recommended. The second part of this thesis deals with the model-based determination of the differential code bias from a GPS receiver on a LEO satellite, with focus on porting the processor CHBIAS according to Heise (2002) from Fortan77 to C++. After analyzing the method and its implementation the description of the design and implementation in C++ follows. The resulting ported processor CHBIAS_RELOADED is easily extensible and maintainable using object-oriented paradigms while being (downward) compatible with the whole processing environment. In addition to the ability of using PIM there is the possibilty to use the NEDM-v1 ionosphere model developed by the DLR at Neustrelitz, Germany. To validate the porting procedure, the daily differential code biases of the CHAMP satellite for the whole of 2004 - both with the use of PIM, as well as taking advantage of NEDM-v1 - are processed and compared with the results based on the original Fortran 77 implementation.

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