Please use this identifier to cite or link to this item: https://hdl.handle.net/10321/5221
Title: Evaluating the model of multi : Global Navigation Satellite Systems (GNSS) constellation to mitigate the multipath signals
Authors: Madonsela, Bhekinkosi Pheneas 
Keywords: Global Navigation Satellite Systems (GNSS);Satellite constellation
Issue Date: May-2023
Abstract: 
The Global Navigation Satellite Systems (GNSS) are evolving continuously
and are being used in many applications across the world. The GNSS is used
in electrical industries, the banking sector, the agricultural sector, the
transportation and logistics sectors, etc. The architecture and operation of the
GNSS is made up of three subdivisions: the space section, control section,
and user section. The space segment consists of the satellite constellation to
generate and emit the GNSS code phase and carrier phase signals. The space
segment further stores and broadcasts the navigation data that is uploaded to
the system by the GNSS controllers. For accurate Position, Velocity and Time
(PVT), the satellite constellation must have at least three or four satellites
visible to the GNSS receiver. The control segment is also known as the ground
segment and is accountable for the complete operations of the GNSS. The
ground segment further controls and preserves the conformation files of the
satellite constellation, updates the navigation data to all satellites, controls the
atomic clock of the GNS, and predicts the satellite ephemeris. The user
segment is made up of GNSS receivers; their purpose is to receive the GNSS
signal that contains the code phase and carrier phase to determine the
pseudorange and other observables. There numerous issues that obstruct the
application of the GNSS across all sectors mentioned above; those are signal
attenuation in the satellite channels, signal diffraction, and signal multipath.
Hence, this thesis focused on mitigating the GNSS multipath signal by
investigating the concept of Combined Signal Detection (CSD). The purposes
was to reduce the impact of signal degradation and further enable the GNSS
receivers to withstand the signal degradation in deep rural areas. There are
numerous existing methodologies to mitigate multipath signal and improve the
positioning, velocity and timing in urban areas. However, the proposed CSD
approach provided the better performance by using the vector detection of all
visible satellites to improve (DP) Direct Positioning , High Sensitivity (HS) and
clock bias. Furthermore, the capabilities of the Global Positioning Systems (GPS) and
Galileo satellites are integrated to accommodate the adoption of CSD concept.
The CSD concept require the GNSS receiver that is capable of processing
multi-frequencies. The multi-constellation GNSS receiver use numerous
satellites that are in space, such as Global Positioning Systems (GPS)
satellites, BeiDou satellites, Galileo satellites, and Glonass satellites.
However, the similarities between the constellations is investigated before the
system is integrated for multi-constellation. The concept of CSD proved to be
capable of mitigating the signal multipath without introducing an external
device or circuit. This thesis further provided the comprehensive analysis of
sources that contribute towards the signal degradation
Description: 
Submitted in the fulfilment of the requirements of the degree of Doctor of Engineering in Electrical Power Engineering at the Durban University of Technology, Durban, South Africa, 2023.
URI: https://hdl.handle.net/10321/5221
Appears in Collections:Theses and dissertations (Engineering and Built Environment)

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