Global Navigation Satellite Systems

This paper presents geometrically and physically defined height systems, along with their evaluation by the means of Global Navigation Satellite Systems (GNSS) and Global Geopotential Models (GGM). The paper defines ellipsoid heights as an instance of geometrically defined heights; with physically defined heights being represented by definitions of orthometric and normal heights. Methods of normal heights calculation by the means of ellipsoid heights are presented in detail, as determined using the GNSS and height anomalies calculated from the GGM application. Apart from the above, numerical part of the paper evaluates normal height values and compares them to their conditionally accurate values at 1073 points with relatively uniform distribution over the entire territory of Serbia. Conditionally accurate values had been determined by the means of classical geodetic terrestrial methods. Under the procedure of evaluating normal height values, GGM - GGM05C was used, as created in 2016...

The development of technologies in the field of geodesy in recent decades has necessitated the optimization of work in the entire spectrum of geodetic work, including the main stages of creating cadastral maps. The preconditions are created for eliminating unnecessary stages that take time and financial resources from project contractors and also have a negative impact on the activities of the contracting authority. The pursuit of efficient and economically beneficial projects raises questions about which steps are practically significant and necessary, and which can be “neglected” as unnecessary.
One of these stages is the creation of the Geodetic Network of Local Significance (GNLS) - a stage that is necessarily provided for in the regulatory framework for the creation of cadastral maps and cadastral registers on the territory of the Republic of Bulgaria. Such a situation, which is in logical imbalance with the capabilities of modern positioning technologies, suggests and motivates the need for an analysis focused on the dilemma: “Are GNLSs a necessity or an inertial anachronism in the process of creating a cadastral map?”

In this paper, the performance of the wireless-signal map-matching method under a code division multiple access network is demonstrated. The wirelss-signal map-matching method is the key step to implement the recentely introduced wireless location technology named as the localization exploring network measurement occurances. With respect to the downlink pilot strength measurement messages collected under a typical urban environment, the wireless-signal map-matching method is applied. By experiment result, it is shown that the accuracy improvement is possible by revealing the spatial structure of non-line-of-sight errors without any GPS information.

Every commercial airliner begins its flight with a quiet, precisely defined moment: the ADIRU alignment ritual. The crew enters the local latitude and longitude, the aircraft remains stationary, and the Honeywell ring-laser gyros establish True North and lock a local reference frame that will remain rigid and planar for the entire journey.

The study of ionospheric behaviour is critical for maintaining the reliability of space-based technologies, including HF communication links and Global Navigation Satellite Systems (GNSS). Ionospheric delays can significantly degrade the performance and accuracy of trans-ionospheric signals; thus, robust forecasting of the parameter is essential. This study uses a long-term dataset (2009 to 2016 for training) of observations from the Jicamarca Observatory in Peru to implement and evaluate the Facebook Prophet (FB-Prophet) time-series forecasting technique. For the years 2017 to 2019, the FB-Prophet model was used to forecast. Its performance was verified using independent observational test data and accepted empirical standards, namely the IRI-2020 URSI and CCIR suboptions. The study results indicate that FB-Prophet effectively reproduces the diurnal and semi-annual variations in the ionosphere. During the initial forecast period (2017 to 2018), FB-Prophet demonstrated superior alignment with observational fluctuations compared to empirical models, achieving a Root Mean Square Error (RMSE) of 0.71 MHz and a Mean Absolute Error (MAE) of 0.57 MHz. However, as the forecast horizon extended into the deep solar minimum of 2019, the CCIR model exhibited higher precision with a minimum RMSE of 0.15 MHz, while FB-Prophet's uncertainty interval expanded as the lead time increased, and the solar environment transitioned into a significantly quieter regime. These findings demonstrate that FB-Prophet's time-series decomposition is a highly effective tool for multi-year ionospheric forecasting at equatorial latitudes. The study highlights that while empirical models remain reliable for long-term climatological averages, the FB-Prophet approach offers enhanced predictive accuracy for capturing non-linear variations during periods of moderate solar activity (107.68 ± 33.81 sfu).

Implementasi teknologi satelit mandiri Indonesia dicontohkan melalui satelit LAPAN-A3 yang dikembangkan oleh LAPAN dan IPB. Satelit ini berada di orbit LEO (ketinggian ±500 km) dan dilengkapi dengan sensor multispektral serta sistem Automatic Identification System (AIS) untuk pemantauan maritim dan pencegahan illegal fishing.

El Hubble nació con un error que lo volvió miope, pero su diseño permitió repararlo y transformarlo en un triunfo del ingenio. Cinco misiones lo convirtieron en un Barco de Teseo cuya continuidad depende del conocimiento transmitido. Tras el fin de los transbordadores, veteranos y software extendieron su vida más allá de lo previsto. Su legado es la persistencia y la capacidad humana de rehacer lo que parecía perdido.

Foundation models for navigation and Global Navigation Satellite Systems (GNSS) exhibit a striking empirical dichotomy: transformer-based architectures achieve remarkable performance on trajectory prediction and state estimation, yet consistently struggle with fault detection, cycle slip identification, and integrity monitoring. Despite the proliferation of navigation transformers, no theoretical framework explains which navigation tasks admit efficient in-context learning (ICL) and which are fundamentally intractable. This gap has critical implications for safetycritical applications including aviation, autonomous vehicles, and maritime navigation, where theoretical guarantees are essential for certification. We address this gap by extending the ICL characterization framework to navigation and GNSS domains. Our main result is the Navigation Dichotomy Theorem: every natural navigation function class falls into exactly one of two categories. Type A (ICL-Easy) tasks-including position estimation, velocity estimation, atmospheric delay modeling, and trajectory prediction-possess additive sufficient statistics computable by attention mechanisms, achieving sample complexity matching the statistical optimum. Type C (ICL-Hard) tasks-including satellite fault detection, cycle slip detection, spoofing detection, and integrity monitoringrequire combinatorial sufficient statistics over C(M,J) fault hypotheses, rendering them intractable for standard ICL when the number of faults J exceeds the threshold J* ≈ 2-3 (for navigation; J* ≈ 2-4 across GeoAI domains). Building on recent advances in chain-of-thought (CoT) reasoning, we prove that CoT prompting provides a mechanism to overcome ICL-Hard barriers in navigation. We establish that T = Ω(J) tokens are necessary and sufficient for J-fault detection, with a navigation-specific token multiplier κnav ≈ 3.5. The effective hardness threshold shifts to J*CoT(T) ≈ J* + T/κnav, enabling detection of up to 7 simultaneous faults with 20 reasoning tokens. We provide complete classification of 32 navigation tasks across six categories (Table 6), derive seven testable predictions for navigation transformer behavior, and analyze implications for safety certification under aviation (DO-229D/DO-253D), automotive (ISO 26262), and maritime (IMO) standards. Our results establish that hybrid architectures-combining ICL for state estimation with explicit algorithms for integrity monitoring-are not merely practical conveniences but fundamental computational necessities. This work completes a seven-paper theoretical program characterizing ICL across all major geospatial AI domains, establishing a Hawarey, M., ICL Characterization of Navigation and GNSS FMs. 10.65737/AIRMCS2026525 2 unified science of when and why foundation models succeed or fail on Earth observation and navigation tasks.

Choć nawigacja poprawnie działała na moim biurku, to przeprowadzenie kolejnych testów poza domem wymagało wprowadzenia pewnych zmian, aby instalacja stała się mobilna: należało zadbać o niezależne zasilanie, łącze internetowe oraz interfejs użytkownika. Poniżej pokrótce opiszę rozwiązania, na jakie się zdecydowałem. Ponieważ Raspberry Pi zasilane jest poprzez gniazdo USB, oczywistym rozwiązaniem jest użycie powerbanku. Zmierzony pobór prądu mojego Raspberry Pi 3 wraz z podłączonym odbiornikiem GNSS i wyświetlaczem LCD wynosi około 0,8 A. Pozwala to oczekiwać, że powerbank o pojemności 20 000 mAh zapewni urządzeniu wiele godzin nieprzerwanej pracy. W domu Raspberry Pi mogło korzystać z routera Wi-Fi, jednak w terenie należało zapewnić inne łącze internetowe. Zdecydowałem się na "hotspot osobisty", który można dziś aktywować w niemal każdym smartfonie. W zasięgu sieci 5G szybkość transmisji okazała się w pełni wystarczająca do przesyłania poprawek RTK do modułu GNSS.