scholarly journals QUALITY OF SATELLITE COMMUNICATION IN SELECTED MOBILE ANDROID SMARTPHONES

2021 ◽  
Vol 11 (4) ◽  
pp. 32-37
Author(s):  
Przemysław Falkowski-Gilski
Keyword(s):  
Mobile Devices ◽  
Satellite Communication ◽  
Urban Environments ◽  
Global Navigation Satellite Systems ◽  
Mobile Terminals ◽  
Everyday Activity ◽  
Satellite Systems ◽  
Global Navigation Satellite ◽  
Application Developers

Today, thanks to mobile devices, satellite communication is available to anyone and everywhere. Gaining information on one’s position using GNSS (Global Navigation Satellite Systems), particularly in unknown urban environments, had become an everyday activity. With the widespread of mobile devices, particularly smartphones, each person can obtain information considering his or her location anytime and everywhere. This paper is focused on a study, considering the quality of satellite communication in case of selected mobile terminals. It describes a measurement campaign carried out in varying urban environments, including a set of Android-powered smartphones coming from different manufacturers. Based on this, respective conclusions and remarks are given, which can aid consumers as well as device manufacturers and application developers.

scholarly journals A Survey for Recent Techniques and Algorithms of Geolocation and Target Tracking in Wireless and Satellite Systems

2021 ◽  
Vol 11 (13) ◽  
pp. 6079
Author(s):  
Abulasad Elgamoudi ◽  
Hamza Benzerrouk ◽  
G. Arul Elango ◽  
René Landry
Keyword(s):  
Target Tracking ◽  
Satellite Communication ◽  
Interference Mitigation ◽  
Global Navigation Satellite Systems ◽  
Military Operations ◽  
Satellite Systems ◽  
Disturbance Source ◽  
Single Radio ◽  
Novel Algorithms ◽  
Global Navigation Satellite

A single Radio-Frequency Interference (RFI) is a disturbance source of modern wireless systems depending on Global Navigation Satellite Systems (GNSS) and Satellite Communication (SatCom). In particular, significant applications such as aeronautics and satellite communication can be severely affected by intentional and unintentional interference, which are unmitigated. The matter requires finding a radical and effective solution to overcome this problem. The methods used for overcoming the RFI include interference detection, interference classification, interference geolocation, tracking and interference mitigation. RFI source geolocation and tracking methodology gained universal attention from numerous researchers, specialists, and scientists. In the last decade, various conventional techniques and algorithms have been adopted in geolocation and target tracking in civil and military operations. Previous conventional techniques did not address the challenges and demand for novel algorithms. Hence there is a necessity for focussing on the issues associated with this. This survey introduces a review of various conventional geolocation techniques, current orientations, and state-of-the-art techniques and highlights some approaches and algorithms employed in wireless and satellite systems for geolocation and target tracking that may be extremely beneficial. In addition, a comparison between different conventional geolocation techniques has been revealed, and the comparisons between various approaches and algorithms of geolocation and target tracking have been addressed, including H∞ and Kalman Filtering versions that have been implemented and investigated by authors.

scholarly journals Practical Modeling of GNSS for Autonomous Vehicles in Urban Environments

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4236
Author(s):  
Woosik Lee ◽  
Hyojoo Cho ◽  
Seungho Hyeong ◽  
Woojin Chung
Keyword(s):  
Motion Estimation ◽  
Autonomous Vehicles ◽  
Autonomous Navigation ◽  
Urban Environments ◽  
Global Navigation Satellite Systems ◽  
Navigation Satellite ◽  
Key Technology ◽  
Satellite Systems ◽  
Agricultural Robots ◽  
Global Navigation Satellite

Autonomous navigation technology is used in various applications, such as agricultural robots and autonomous vehicles. The key technology for autonomous navigation is ego-motion estimation, which uses various sensors. Wheel encoders and global navigation satellite systems (GNSSs) are widely used in localization for autonomous vehicles, and there are a few quantitative strategies for handling the information obtained through their sensors. In many cases, the modeling of uncertainty and sensor fusion depends on the experience of the researchers. In this study, we address the problem of quantitatively modeling uncertainty in the accumulated GNSS and in wheel encoder data accumulated in anonymous urban environments, collected using vehicles. We also address the problem of utilizing that data in ego-motion estimation. There are seven factors that determine the magnitude of the uncertainty of a GNSS sensor. Because it is impossible to measure each of these factors, in this study, the uncertainty of the GNSS sensor is expressed through three variables, and the exact uncertainty is calculated. Using the proposed method, the uncertainty of the sensor is quantitatively modeled and robust localization is performed in a real environment. The approach is validated through experiments in urban environments.

scholarly journals EVALUATION AND TAILORING OF GLOBAL GEOPOTENTIAL MODELS IN THE DETERMINATION OF GRAVITY FIELD IN SERBIA

2020 ◽  
Vol 14 (1) ◽  
Author(s):  
Oleg Odalović ◽  
Danilo Joksimović ◽  
Dušan Petković ◽  
Marko Stanković ◽  
Sanja Grekulović
Keyword(s):  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Average Value ◽  
Free Air ◽  
Geopotential Models ◽  
Normal Heights ◽  
Discrete Values ◽  
Global Navigation Satellite

Within this paper, we evaluated the quality of three Global Geopotential Models entitled: EGM96,EGM2008, and GOCO05c. The models were evaluated by using 1001 terrestrial discrete values ofheight anomalies determined by Global Navigation Satellite Systems and normal heights, which weconsidered to be true values within this research. In addition to the quality evaluation, we tailoredthe models by using more than 80000 free air anomalies. The results obtained from the evaluationand tailoring indicate that by using the GOCO05c it is possible to determine a set of anomaly heightsacross Serbia, which are in agreement with terrestrial values with an average value of -7 cm, thestandard deviation of ±9 cm and with the range of 44 cm.

scholarly journals Seamless Vehicle Positioning by Lidar-GNSS Integration: Standalone and Multi-Epoch Scenarios

2021 ◽  
Vol 13 (22) ◽  
pp. 4525
Author(s):  
Junjie Zhang ◽  
Kourosh Khoshelham ◽  
Amir Khodabandeh
Keyword(s):  
Autonomous Driving ◽  
Measurement Model ◽  
Urban Environments ◽  
Global Navigation Satellite Systems ◽  
High Definition ◽  
Satellite Systems ◽  
The Road ◽  
Gnss Receivers ◽  
Vehicle Positioning ◽  
Global Navigation Satellite

Accurate and seamless vehicle positioning is fundamental for autonomous driving tasks in urban environments, requiring the provision of high-end measuring devices. Light Detection and Ranging (lidar) sensors, together with Global Navigation Satellite Systems (GNSS) receivers, are therefore commonly found onboard modern vehicles. In this paper, we propose an integration of lidar and GNSS code measurements at the observation level via a mixed measurement model. An Extended Kalman-Filter (EKF) is implemented to capture the dynamic of the vehicle movement, and thus, to incorporate the vehicle velocity parameters into the measurement model. The lidar positioning component is realized using point cloud registration through a deep neural network, which is aided by a high definition (HD) map comprising accurately georeferenced scans of the road environments. Experiments conducted in a densely built-up environment show that, by exploiting the abundant measurements of GNSS and high accuracy of lidar, the proposed vehicle positioning approach can maintain centimeter-to meter-level accuracy for the entirety of the driving duration in urban canyons.

scholarly journals GNSS Performance Modelling and Augmentation for Urban Air Mobility

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4209 ◽  
Author(s):  
Suraj Bijjahalli ◽  
Roberto Sabatini ◽  
Alessandro Gardi
Keyword(s):  
Failure Modes ◽  
Primary Source ◽  
Urban Environments ◽  
Unmanned Aircraft ◽  
Global Navigation Satellite Systems ◽  
Urban Air ◽  
Performance Modelling ◽  
Satellite Systems ◽  
Urban Structures ◽  
Global Navigation Satellite

One of the primary challenges facing Urban Air Mobility (UAM) and the safe integration of Unmanned Aircraft Systems (UAS) in the urban airspace is the availability of robust, reliable navigation and Sense-and-Avoid (SAA) systems. Global Navigation Satellite Systems (GNSS) are typically the primary source of positioning for most air and ground vehicles and for a growing number of UAS applications; however, their performance is frequently inadequate in such challenging environments. This paper performs a comprehensive analysis of GNSS performance for UAS operations with a focus on failure modes in urban environments. Based on the analysis, a guidance strategy is developed which accounts for the influence of urban structures on GNSS performance. A simulation case study representative of UAS operations in urban environments is conducted to assess the validity of the proposed approach. Results show improved accuracy (approximately 25%) and availability when compared against a conventional minimum-distance guidance strategy.

scholarly journals IMPLEMENTATION OF THE GLOBAL AERONAUTICAL DISTRESS AND SAFETY SYSTEM (GADSS)

Aviation ◽  
2018 ◽  
Vol 22 (1) ◽  
pp. 24-30
Author(s):  
Dimov Stojce Ilcev
Keyword(s):  
Communication Systems ◽  
Satellite Communication ◽  
Safety System ◽  
International Standards ◽  
Global Navigation Satellite Systems ◽  
Civil Aviation ◽  
Satellite Systems ◽  
Land Vehicles ◽  
Global Navigation Satellite ◽  
Global Communications

In this paper is introduced the first proposal for development of Global Aeronautical Distress and Safety System (GADSS) in 1999 by the author of this article. The GADSS is de facto the integration of space (radio and satellite) Communication, Navigation and Surveillance (CNS) with Tracking, Detecting and Search and Rescue (SAR) systems, which have to provide airmen with global communications and locating networks. The GPS, GLONASS and other Global Navigation Satellite Systems (GNSS) provide precise positioning data for vessels, land vehicles and aircraft, but modern CNS demands need for enhanced services and augmentation of GNSS networks. Both networks have to be integrated under an GADSS umbrella with elements capable of being operated by any individual onboard aircraft to ensure prompt distress alert for SAR procedure. The enhanced concept of GADSS is that SAR authorities ashore and ships in the immediate vicinity of the aircraft in distress have to be rapidly alerted via radio and satellite communication systems and to assist in a coordinated SAR operations with the minimum of delay. In 2016, 16 years in delay, the International Civil Aviation Organization (ICAO) has begun its process to amend international standards and recommended practices to align with GADSS concept. This paper will also introduce the necessary networks and equipment, which has to ensure harmonized and enhanced maritime and aeronautical global SAR systems.

scholarly journals Evaluation of normal heights by the means of global navigation satellite systems and global geopotential model

2015 ◽  
Vol 95 (4) ◽  
pp. 103-124 ◽  
Author(s):  
Oleg Odalovic ◽  
Danilo Joksimovic ◽  
Sanja Grekulovic ◽  
Miljana Todorovic-Drakul ◽  
Jovan Popovic
Keyword(s):  
Global Navigation Satellite Systems ◽  
Geopotential Model ◽  
Navigation Satellite ◽  
Normal Height ◽  
Satellite Systems ◽  
Normal Heights ◽  
Global Navigation ◽  
Global Navigation Satellite ◽  
Ellipsoid Heights

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 by the Center for Space Research, University of Texas at Austin. In order to evaluate the quality of applying the model above, data on normal heights evaluation were also presented, using the GGM EGM96, created in 1996 by the National Imagery and Mapping Agency (NIMA), Goddard Space Flight Center (GSFC - NASA) and Ohio State University, presently being the most commonly used model. The comparison above indicates that application of the GGM05C model provides 50 % greater quality of normal heights evaluations against the ones obtained using the EGM96 model.

scholarly journals FULLY AUTOMATIC FEATURE-BASED REGISTRATION OF MOBILE MAPPING AND AERIAL NADIR IMAGES FOR ENABLING THE ADJUSTMENT OF MOBILE PLATFORM LOCATIONS IN GNSS-DENIED URBAN ENVIRONMENTS

2017 ◽  
Vol XLII-1/W1 ◽  
pp. 317-323 ◽  
Author(s):  
P. Jende ◽  
F. Nex ◽  
M. Gerke ◽  
G. Vosselman
Keyword(s):  
Urban Areas ◽  
Urban Environments ◽  
Global Navigation Satellite Systems ◽  
Aerial Images ◽  
Mobile Mapping ◽  
High Resolution Data ◽  
Satellite Systems ◽  
Correct Orientation ◽  
Fully Automatic ◽  
Global Navigation Satellite

Mobile Mapping (MM) has gained significant importance in the realm of high-resolution data acquisition techniques. MM is able to record georeferenced street-level data in a continuous (laser scanners) and/or discrete (cameras) fashion. MM’s georeferencing relies on a conjunction of Global Navigation Satellite Systems (GNSS), Inertial Measurement Units (IMU) and optionally on odometry sensors. While this technique does not pose a problem for absolute positioning in open areas, its reliability and accuracy may be diminished in urban areas where high-rise buildings and other tall objects can obstruct the direct line-of-sight between the satellite and the receiver unit. Consequently, multipath measurements or complete signal outages impede the MM platform’s localisation and may affect the accurate georeferencing of collected data. This paper presents a technique to recover correct orientation parameters for MM imaging platforms by utilising aerial images as an external georeferencing source. This is achieved by a fully automatic registration strategy which takes into account the overall differences between aerial and MM data, such as scale, illumination, perspective and content. Based on these correspondences, MM data can be verified and/or corrected by using an adjustment solution. The registration strategy is discussed and results in a success rate of about 95 %.

Assessment of geodetic products from MGEX analyses for the Onsala site

2020 ◽  
Author(s):  
Periklis-Konstantinos Diamantidis ◽  
Grzegorz Klopotek ◽  
Rüdiger Haas
Keyword(s):  
Global Navigation Satellite Systems ◽  
Observation Data ◽  
International Gnss Service ◽  
Satellite Systems ◽  
Troposphere Gradients ◽  
Combined Solution ◽  
Gnss Receivers ◽  
Global Navigation Satellite ◽  
Gnss Data

<div>The emergence of BeiDou and Galileo as operational Global Navigation Satellite Systems (GNSS), in addition to Global Positioning System (GPS) and GLONASS which are already in use, opens up possibilities in delivering geodetic products with higher precision. Apart from ensuring the homogeneity of the derived products, multi-GNSS analysis takes the advantage of new frequencies and an improved sky coverage. This should lead to better phase ambiguity resolution and an improved estimation of target parameters such as zenith wet delays (ZWD), troposphere gradients (GRD) and station positions. The International GNSS Service (IGS) has realised this potential by initiating the Multi-GNSS Experiment (MGEX) which provides orbit, clock and observation data for all operational GNSS. Correspondingly, the multi-technique space geodetic analysis software c5++ has been augmented with a MGEX-compliant GNSS module. Based on this new module and the Precise Point Positioning (PPP) approach using six-month of data, an assessment of the derived geodetic products is carried out for several GNSS receivers located at the Onsala core site. More specifically, we perform both single- and multi-GNSS data analysis using Kalman filter and least-squares methods and assess the quality of the derived station positions, ZWD and GRD. A combined solution using all GNSS together is carried out and the improvement with respect to station position repeatabilities is assessed for each station. Inter-system biases, which homogenise the different time scale that each GNSS operates in and are necessary for the multi-GNSS combination, are estimated and presented. Finally, the applied inter-system weighting is discussed as well as its impact on the derived geodetic products.</div>

Dynamic GNSS Mission Planning Using DTM for Precise Navigation of Autonomous Vehicles

2016 ◽  
Vol 70 (3) ◽  
pp. 483-504 ◽  
Author(s):  
Aleksander Nowak
Keyword(s):  
Autonomous Vehicles ◽  
Autonomous Vehicle ◽  
Digital Terrain Model ◽  
Dead Reckoning ◽  
Urban Environments ◽  
Mission Planning ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Terrain Model ◽  
Global Navigation Satellite

Nowadays, the most widely used method for estimating location of autonomous vehicles in real time is the use of Global Navigation Satellite Systems (GNSS). However, positioning in urban environments using GNSS is hampered by poor satellite geometry due to signal obstruction created by both man-made and natural features of the urban environment. The presence of obstacles is the reason for the decreased number of observed satellites as well as uncertainty of GNSS positioning. It is possible that in some sections of the vehicle route there might not be enough satellites necessary to fix position. It is common to use software for static GNSS measurement campaign planning, but it is often only able to predict satellite visibility at one point. This article presents a proposal for dynamic GNSS mission planning using a Digital Terrain Model (DTM) and dead reckoning. The methodology and sample results of numerical experiments are also described. They clearly show that proper dynamic GNSS mission planning is necessary in order to complete a task by an autonomous vehicle in an obstructed environment.

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