scholarly journals GNSS Interference Environment in Malaysia: A Case Study

2021 ◽  
Vol 3 (1) ◽  
pp. 13-16
Author(s):  
Ooi Wei Han ◽  
Shahrizal Ide Moslin ◽  
Wan Aminullah
Keyword(s):  
Public Awareness ◽  
Essential Element ◽  
Global Navigation Satellite Systems ◽  
Space Technology ◽  
Local Study ◽  
Satellite Systems ◽  
Wide Range ◽  
Global Navigation Satellite ◽  
Significant Interference

Global Navigation Satellite Systems or GNSS is a space technology that has become an essential element nowadays for positioning, navigation & timing (PNT) with wide range of applications in many civilian sectors as well as across military. The reliability, accuracy and availability of GNSS are highly important especially for critical and precise positioning applications. However, the signals from space are weak and it can be easily blocked, disrupted or compromised by several other threats including intentional and unintentional interferences or jamming. GPS jammer is widely available off the shelf with an affordable price and capable of interfering the GPS signal, and many authorities worldwide have raised concerns and a lot of efforts and research have been put in place to reduce and mitigate the threats. In Malaysia, understanding and countering threats to GNSS/GPS based applications will be a new and unfamiliar discipline for public and organizations. This study intended to provide an overview of the GNSS interferences environment in a local study area, in terms of interference type and the number of activity pattern that were detected. A system called Detector V1 has been used in this study. The result showed that significant interference cases happened in the study area and some of the high power interferences may impact GNSS tracking and precision of the positioning output. The role objective of having this done is to create a public awareness regarding the threat of GNSS interferences to the local users. The content also includes the proposed initiative to overcome the issue.

scholarly journals The Optimal Location of Ground-Based GNSS Augmentation Transceivers

Geosciences ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 107 ◽  
Author(s):  
Jacek Rapinski ◽  
Artur Janowski
Keyword(s):  
Wide Band ◽  
Optimal Location ◽  
Point Of View ◽  
Global Navigation Satellite Systems ◽  
Design Stage ◽  
Shift Measurement ◽  
Satellite Systems ◽  
Global Navigation Satellite ◽  
Selection Of

Modern Global Navigation Satellite Systems (GNSS) allow for positioning with accuracies ranging from tens of meters to single millimeters depending on user requirements and available equipment. A major disadvantage of these systems is their unavailability or limited availability when the sky is obstructed. One solution is to use additional range measurements from ground-based nodes located in the vicinity of the receiver. The highest accuracy of distance measurement can be achieved using ultra wide band (UWB) or ZigBee phase shift measurement. The position of the additional transmitter must be carefully selected in order to obtain the optimal improvement in the dilution of precision (DOP), which reflects the improvement in the geometry of solution. The presented case study depicts a method for selecting the optimal location of a ground-based ranging source. It is based on a search of a minimum DOP value as a transmitter location function. The parameters of objective function are the elevation and azimuth of the transceiver. The solution was based on a limited-memory Broyden–Fletcher–Goldfarb–Shanno with Box constraints (L-BFGS-B) method and a numerical optimization algorithm for parameter value estimation. The presented approach allows for the selection of the optimal location of a ground-based source of ranging signals in GNSS processing from a geometry of solution point of view. This can be useful at the design stage of an augmentation network of ground-based transceivers. This article presents a theoretical basis and a case study presenting the selection of the optimal location of a ground-based ranging source.

scholarly journals Experimental Assessment of UWB and Vision-Based Car Cooperative Positioning System

2021 ◽  
Vol 13 (23) ◽  
pp. 4858
Author(s):  
Andrea Masiero ◽  
Charles Toth ◽  
Jelena Gabela ◽  
Guenther Retscher ◽  
Allison Kealy ◽  
...  
Keyword(s):  
Essential Element ◽  
Wide Band ◽  
Global Navigation Satellite Systems ◽  
Learning Tools ◽  
Satellite Systems ◽  
Cooperative Positioning ◽  
Performance Improvements ◽  
Gnss Measurements ◽  
Global Navigation Satellite ◽  
Gnss Data

The availability of global navigation satellite systems (GNSS) on consumer devices has caused a dramatic change in every-day life and human behaviour globally. Although GNSS generally performs well outdoors, unavailability, intentional and unintentional threats, and reliability issues still remain. This has motivated the deployment of other complementary sensors in such a way that enables reliable positioning, even in GNSS-challenged environments. Besides sensor integration on a single platform to remedy the lack of GNSS, data sharing between platforms, such as in collaborative positioning, offers further performance improvements for positioning. An essential element of this approach is the availability of internode measurements, which brings in the strength of a geometric network. There are many sensors that can support ranging between platforms, such as LiDAR, camera, radar, and many RF technologies, including UWB, LoRA, 5G, etc. In this paper, to demonstrate the potential of the collaborative positioning technique, we use ultra-wide band (UWB) transceivers and vision data to compensate for the unavailability of GNSS in a terrestrial vehicle urban scenario. In particular, a cooperative positioning approach exploiting both vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) UWB measurements have been developed and tested in an experiment involving four cars. The results show that UWB ranging can be effectively used to determine distances between vehicles (at sub-meter level), and their relative positions, especially when vision data or a sufficient number of V2V ranges are available. The presence of NLOS observations is one of the principal factors causing a decrease in the UWB ranging performance, but modern machine learning tools have shown to be effective in partially eliminating NLOS observations. According to the obtained results, UWB V2I can achieve sub-meter level of accuracy in 2D positioning when GNSS is not available. Combining UWB V2I and GNSS as well V2V ranging may lead to similar results in cooperative positioning. Absolute cooperative positioning of a group of vehicles requires stable V2V ranging and that a certain number of vehicles in the group are provided with V2I ranging data. Results show that meter-level accuracy is achieved when at least two vehicles in the network have V2I data or reliable GNSS measurements, and usually when vehicles lack V2I data but receive V2V ranging to 2–3 vehicles. These working conditions typically ensure the robustness of the solution against undefined rotations. The integration of UWB with vision led to relative positioning results at sub-meter level of accuracy, an improvement of the absolute positioning cooperative results, and a reduction in the number of vehicles required to be provided with V2I or GNSS data to one.

scholarly journals The Snow-Friction of Freestyle Skis and Snowboards Predicted From Snow Physical Quantities

2021 ◽  
Vol 7 ◽  
Author(s):  
Fabian Wolfsperger ◽  
Frédéric Meyer ◽  
Matthias Gilgien
Keyword(s):  
Coefficient Of Friction ◽  
Global Navigation Satellite Systems ◽  
Multivariate Statistical ◽  
Severe Injuries ◽  
Satellite Systems ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
Snow Conditions ◽  
Global Navigation Satellite ◽  
Physical Quantities

Previous research has shown that friction between ski and snow can vary substantially due to changes in snow conditions. The variation of friction affects the speed a freestyle skier or snowboarder (athlete) reaches during the in-run of a jump. Athletes risk severe injuries if their take-off speed is not within the right margin to land in the “sweet spot” zone. To reduce the risk of injury, snow park designers and competition managers need to calculate the speed athletes reach during the in-run. However, despite multiple attempts over the last decades, to date no model can predict ski-snow friction from snow physical quantities. Hence, simulations of in-run speeds suffer from insufficient validity. For the first time, this work combines kinematic athlete data and comprehensive snow surface measurements to infer the coefficient of friction of freestyle skis and snowboards across a wide range of snow conditions. Athletes’ point mass kinematics were recorded at more than 200 straight gliding runs with differential global navigation satellite systems. The subjects’ air drag and lift were deployed from wind tunnel measurements. Along with the kinematic data and data from wind measurements, a mechanical model of the athlete was established to solve the equation of motion for the coefficient of friction between ski/snowboard and snow. The friction coefficients for ski (snowboard) ranged from 0.023 ± 0.006 (0.026 ± 0.008) to 0.139 ± 0.018 (0.143 ± 0.017) and could be explained well (Radj2 = 0.77) from the measured snow parameters using a multivariate statistical model. Our results provide a new quantitative tool for practitioners to predict the friction of skis and snowboard on snow of various conditions, which aims to increase athletes’ safety in slopestyle and big air.

scholarly journals Timing and Navigation in UAVs

2018 ◽  
Vol 5 (1) ◽  
pp. 17-25
Author(s):  
Karen Von Hünerbein ◽  
Werner R Lange
Keyword(s):  
Time Synchronization ◽  
Health And Safety ◽  
Test Methods ◽  
Global Navigation Satellite Systems ◽  
External Control ◽  
Satellite Systems ◽  
Environment And Health ◽  
Wide Range ◽  
Correct Function ◽  
Global Navigation Satellite

Precise timing and precise location information are provided by Global Navigation Satellite Systems (GNSS) and play a crucial role in the positioning, navigation and data acquisition of most Unmanned Aerial Vehicles (UAV). GNSS functions include the following applications in UAVs: time-stamping and geo-referencing of collected data and images, synchronization of swarm flying and follow-me flights, determination of position and attitude in-flight, flight trajectory by following a pre-defined number of waypoints, mission planning, return home automatically without external control, avoidance of obstacles and geo-fencing.  Some of these critical operations have implications for the safety of the UAV, the surrounding environment and health and safety of people, for example UAVs threatening to bring down aircrafts  at airports, which are no-fly zones for UAVs. The appropriate GNSS based function to avoid this is geo-fencing. Another example is obstacle avoidance to prevent collisions and damages both for the UAV and the obstacle, e.g. anything from a window pane, tree, human being, to a power line. In order to ensure health and safety it is thus important to ensure correct function of the navigation and the timing, under a wide variety of circumstances, and in different signal environments. There can be signal disturbances, such as obscurations by buildings or reflected GNSS signals, called multipath. The performance of timing and navigation based on GPS/GNSS can be tested and verified in a controlled and repeatable way in the laboratory with different types of test equipment. We will give an introduction to a wide range of potential threats to GNSS Positioning, navigation and timing and an overview of different test methods. In addition, we are presenting a method for time synchronization of drones to enable safe swarm and follow flights in UAVs.

scholarly journals GEODESIC METHODS FOR CREATION OF UNIQUE GEOINFORMATION SPACE

2019 ◽  
Vol 1 (1) ◽  
pp. 173-183
Author(s):  
Sergey Gorobtsov ◽  
Vladimir Obidenko
Keyword(s):  
Laser Scanning ◽  
Spatial Information ◽  
Survey Methods ◽  
Essential Element ◽  
Global Navigation Satellite Systems ◽  
3D Laser Scanning ◽  
Foreign Markets ◽  
Satellite Systems ◽  
Ground Survey ◽  
Global Navigation Satellite

Modern geodesic support is an integral and essential element of the process of collecting spatial information. The article considers geodesic methods for creating a unique geoinformation space: digitization of cartographic materials, ground survey methods (electronic total stations, 3D laser scanning), remote sensing and methods of the global navigation satellite systems GLONASS and GPS. The article also contains recommended conversion options between the coordinate systems SK-95 and GSK-2011. A comparative analysis of the surveyed geodesic methods for geodata col-lection was carried out. Russian and foreign markets of specialized software for processing geodata are considered, appropriate conclusions are made.

scholarly journals Applications of Space Technologies to Global Health: Scoping Review (Preprint)

2017 ◽  
Author(s):  
Damien Dietrich ◽  
Ralitza Dekova ◽  
Stephan Davy ◽  
Guillaume Fahrni ◽  
Antoine Geissbühler
Keyword(s):  
Global Health ◽  
Scoping Review ◽  
Satellite Communication ◽  
Global Navigation Satellite Systems ◽  
Navigation Satellite ◽  
Space Technology ◽  
Satellite Systems ◽  
Key Stakeholders ◽  
Global Navigation ◽  
Global Navigation Satellite

BACKGROUND Space technology has an impact on many domains of activity on earth, including in the field of global health. With the recent adoption of the United Nations’ Sustainable Development Goals that highlight the need for strengthening partnerships in different domains, it is useful to better characterize the relationship between space technology and global health. OBJECTIVE The aim of this study was to identify the applications of space technologies to global health, the key stakeholders in the field, as well as gaps and challenges. METHODS We used a scoping review methodology, including a literature review and the involvement of stakeholders, via a brief self-administered, open-response questionnaire. A distinct search on several search engines was conducted for each of the four key technological domains that were previously identified by the UN Office for Outer Space Affairs’ Expert Group on Space and Global Health (Domain A: remote sensing; Domain B: global navigation satellite systems; Domain C: satellite communication; and Domain D: human space flight). Themes in which space technologies are of benefit to global health were extracted. Key stakeholders, as well as gaps, challenges, and perspectives were identified. RESULTS A total of 222 sources were included for Domain A, 82 sources for Domain B, 144 sources for Domain C, and 31 sources for Domain D. A total of 3 questionnaires out of 16 sent were answered. Global navigation satellite systems and geographic information systems are used for the study and forecasting of communicable and noncommunicable diseases; satellite communication and global navigation satellite systems for disaster response; satellite communication for telemedicine and tele-education; and global navigation satellite systems for autonomy improvement, access to health care, as well as for safe and efficient transportation. Various health research and technologies developed for inhabited space flights have been adapted for terrestrial use. CONCLUSIONS Although numerous examples of space technology applications to global health exist, improved awareness, training, and collaboration of the research community is needed.

Receiver Interface Requirements for Deep INS/GNSS Integration and Vector Tracking

2010 ◽  
Vol 63 (3) ◽  
pp. 471-489 ◽  
Author(s):  
Paul D Groves ◽  
Christopher J Mather
Keyword(s):  
Inertial Navigation System ◽  
Global Navigation Satellite Systems ◽  
Signal To Noise ◽  
Satellite Systems ◽  
Gnss Receiver ◽  
Wide Range ◽  
Vector Tracking ◽  
Update Rate ◽  
Global Navigation Satellite ◽  
Data Latency

Vector tracking of global navigation satellite systems (GNSS) signals and deeply integrating GNSS with an inertial navigation system (INS) improve robustness and accuracy in poor GNSS signal-to-noise environments. Both require a dedicated interface between the GNSS receiver and the navigation processor to enable the GNSS receiver to output the correlator measurements and input numerically-controlled oscillator (NCO) commands. This paper investigates the requirements for such an interface. Data latency is analysed for a range of different stand-alone GNSS vector tracking and deep INS/GNSS integration architectures. Suitable latency compensation techniques are identified. It is shown that, for the majority of applications, an NCO command update rate of 50 Hz with latency compensation and 100 Hz without is sufficient. An approach to interface standardisation which can handle a wide range of different GNSS signals and receiver designs is proposed.

Interference and Spoofing

2014 ◽  
pp. 54-83
Author(s):  
Fabio Dovis ◽  
Luciano Musumeci ◽  
Nicola Linty ◽  
Marco Pini
Keyword(s):  
Global Navigation Satellite Systems ◽  
Added Value ◽  
Positioning System ◽  
Navigation Satellite ◽  
Satellite Systems ◽  
Wide Range ◽  
Global Positioning ◽  
Military Applications ◽  
Processing Algorithms ◽  
Global Navigation Satellite

This chapter deals with one of the major concerns for reliable use of Global Navigation Satellite Systems (GNSS), providing a description of intentional and unintentional threats, such as interference, jamming, and spoofing. Despite the fact that these phenomena have been studied since the early stages of Global Positioning System (GPS), they were mainly addressed for military applications of GNSS. However, a wide range of recent civil applications related to user safety or featuring financial implications would be deeply affected by interfering or spoofing signals intentionally created. For such a reason, added value processing algorithms are being studied and designed in order to embed in the receiver an interference reporting capability so that they can monitor and possibly mitigate interference events.

scholarly journals Analytical Computation of the Spatial Resolution in GNSS-R and Experimental Validation at L1 and L5

2020 ◽  
Vol 12 (23) ◽  
pp. 3910
Author(s):  
Adriano Camps ◽  
Joan Francesc Munoz-Martin
Keyword(s):  
Spatial Resolution ◽  
Water Reservoir ◽  
Coherent Scattering ◽  
Step Function ◽  
Global Navigation Satellite Systems ◽  
Step Response ◽  
Satellite Systems ◽  
Remote Sensing Technique ◽  
Wide Range ◽  
Global Navigation Satellite

Global navigation satellite systems reflectometry (GNSS-R) is a relatively novel remote sensing technique, but it can be understood as a multi-static radar using satellite navigation signals as signals of opportunity. The scattered signals over sea ice, flooded areas, and even under dense vegetation show a detectable coherent component that can be separated from the incoherent component and processed accordingly. This work derives an analytical formulation of the response of a GNSS-R instrument to a step function in the reflectivity using well-known principles of electromagnetic theory. The evaluation of the spatial resolution then requires a numerical evaluation of the proposed equations, as the width of the transition depends on the reflectivity values of two regions. However, it is found that results are fairly constant over a wide range of reflectivities, and they only vary faster for very high or very low reflectivity gradients. The predicted step response is then satisfactorily compared to airborne experimental results at L1 (1575.42 MHz) and L5 (1176.45 MHz) bands, acquired over a water reservoir south of Melbourne, in terms of width and ringing, and several examples are provided when the transition occurs from land to a rough ocean surface, where the coherent scattering component is no longer dominant.

scholarly journals Slow deformation event between large intraslab earthquakes at the Tonga Trench

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yuta Mitsui ◽  
Hinako Muramatsu ◽  
Yusaku Tanaka
Keyword(s):  
Subduction Zone ◽  
Global Navigation Satellite Systems ◽  
Benioff Zone ◽  
Plate Interface ◽  
Satellite Systems ◽  
Deep Earthquakes ◽  
Wide Range ◽  
Slip Event ◽  
Deformation Event ◽  
Global Navigation Satellite

AbstractSlow deformations associated with a subducting slab can affect quasi-static displacements and seismicity over a wide range of depths. Here, we analyse the seismotectonic activities in the Tonga subduction zone, which is the world’s most active area with regard to deep earthquakes. In our study, we combine data from global navigation satellite systems with an earthquake catalogue. We focus on the deep earthquakes that are below 400 km at the lower part of the Wadati–Benioff zone. We find that trenchward transient displacements and quiescence of deep earthquakes, in terms of background seismicity, were bounded in time by large intraslab earthquakes in 2009 and 2013. This “slow deformation event” between 2009 and 2013 may have been triggered by a distant and shallow M8.1 earthquake, which implies a slow slip event at the plate interface or a temporal acceleration of the subduction of the Pacific Plate. These findings provide new insights into the relationship between shallow and deep earthquakes in the subduction zone.

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