Browsing by Author "Pinell, Christina"

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    Design considerations of navigation satellite constellation for low Earth orbit
    (2023) Praks, Jaan; Saleem, Zainab; Mayank; Celikbilek, Kaan; Prol, Fabricio; Sharma, Shikha; Kuusniemi, Heidi; Ferranti, Luca; Lohan, Elena Simona; Pinell, Christina; Kaasalainen, Sanna; Bhuiyan, M. Zahidul H.; Department of Electronics and Nanoengineering; Department of Electrical Engineering and Automation; Tampere University; National Land Survey of Finland; University of Vaasa
    In this study we provide an overview of feasibility assessment of Low Earth Orbit Position, Timing and Navigation (LEO-PNT) satellite system. We discuss several aspects of such a design, such as signal design, accuracy assessment, satellite constellation design, satellite payload design and satellite platform design. We conclude, that such a system is feasible and provide general parameters for implementation.
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    Receiver Architectures for Positioning with Low Earth Orbit Satellite Signals
    (2021-12-13) Pinell, Christina; Bhuiyan, Zahidul; Sähkötekniikan korkeakoulu; Praks, Jaan
    The field of positioning, navigation, and timing, PNT, with Low Earth Orbit satellites is a rapidly growing sector. It is responding to gaps present in current Global Navigation Satellite Systems, that reside in Medium Earth Orbit, higher above LEO. The GNSS signal strength is decreased in congested, indoor or remote environments. This lends itself to both unintentional and intentional signal interference. Two distinct types of approaches are addressing the challenges with LEO satellites, dedicated, opportunistic and also a combined version. The proximity of a LEO satellite to the user improves signal power at reception. This makes LEO satellites an appealing candidate to improve PNT in weak signal environments. The aim of this thesis is to study how to exploit LEO to maximize PNT benefits for the user. To this extent, the receivers in the user segment are of significance, as they compute the PNT solution. A PNT receiver is composed out of a Radio Frontend, baseband processing, and a navigation processor. The RF receives a satellite's radio signal, the baseband and navigation processing track the signal and compute the PNT solution. The receiver needs to be specified to a given signal in order to perform these functions. Thus, LEO satellite constellations and their signals are studied with respect to their implications on receiver architecture design. Finally, an analysis is presented on receiver architectures for opportunistic and dedicated signals. Both receiver architectures require RFs with large bandwidth, a Software Defined Radio with adjusted tracking and acquisition loops, and a navigation filter. The latter is almost exclusively implemented as a Kalman filter variant.
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    Receiver architectures for positioning with low earth orbit satellite signals: a survey
    (Springer, 2023-12) Pinell, Christina; Prol, Fabricio S.; Bhuiyan, M. Zahidul H.; Praks, Jaan; Department of Electronics and Nanoengineering; Jaan Praks Group; National Land Survey of Finland
    Positioning, Navigation and Timing (PNT) are services generally provided by Global Navigation Satellite Systems (GNSS). GNSS reside in medium to high orbital altitudes from the Earth’s surface, resulting in weak signal reception. However, user applications are increasingly in need of higher power signal strength or alternative PNT solutions. An influx of satellites in Low Earth Orbit (LEO) are driving such innovation in PNT technology. Improved signal strength compared to GNSS can be obtained from LEO satellites merely due to their proximity to Earth. Therefore, even communication satellite transmissions are becoming appealing to navigation, as so-called Signals of OPportunity (SOP). In order to benefit user applications, the receiver architectures for LEO-SOP, as well as potential LEO-PNT signals are explored.