Hasil untuk "Canals and inland navigation. Waterways"

V. V. Karetnikov, A. A. Prokhorenkov, K. I. Efimov

The study is focused on the development of methods for the practical application of electronic cartography aimed at reducing the limiting influence of navigational and hydrographic factors during the autumn–spring navigation period on inland waterways. Navigational and hydrographic factors are considered as a set of data describing waterway conditions that are used to ensure navigation support and vessel passage. It is noted that the main navigational hazards on inland waterways are isobaths, which restrict navigable areas and are represented on navigation charts and by floating aids to navigation. The practical use of navigational and hydrographic data is based on visual positioning through comparison of charted navigational aids with their actual positions observed from the navigation bridge. The complexity of navigation conditions during the autumn–spring period is caused by water level variations, channel processes, and ice phenomena, which significantly complicate navigation compared to the main navigation season. Although modern hydrographic technologies provide high-accuracy spatial data with sufficient discreteness, an equally important task is the presentation of navigational and hydrographic information in a form suitable for practical use. The article examines the use of existing and modified electronic chart functions, including ECDIS, to provide navigators with sufficient navigational information and to mitigate the limiting influence of navigational and hydrographic factors. It is emphasized that the application of electronic cartography enables effective solutions for ensuring navigation safety during the autumn–spring navigation period; however, this requires further investigation of functional capabilities and, where necessary, their targeted modification to improve the performance of navigation support tasks.

Samuele Larese, Giampiero Naletto, Paolo Zoccarato et al.

The concept of observing pulsars for space autonomous navigation has already caught the attention of space agencies. Driven by the extremely stable nature of pulsar radiation, many research works and in-orbit demonstrations have been performed, demonstrating the suitability of these sources for navigation. The core concepts of the in-orbit demonstrated X-ray pulsar-based navigation systems and the recently proposed space navigation by optical pulsars (SNOP) systems are based on the capability to accurately define the arrival times of a pulsar signal. Therefore, the performance of a pulsar-based navigation system depends on the timing accuracy of the measured signals, which is a function of the characteristics of the navigation payload onboard the satellite. The aim of this paper is to investigate the impact of the optical parameters of a photometer-based instrument on the timing accuracy of a SNOP system; moreover, a first optical design for the payload is proposed.

Clemens Sonnleitner, Thomas Hobiger

This paper proposes and evaluates a novel approach for wide area multilateration (WAM) airspace surveillance based on time difference of arrival (TDOA) navigation. Unlike commercial Automatic Dependent Surveillance-Broadcast (ADS-B)-based WAM solutions, which require high-grade clock synchronization, the framework proposed here achieves airspace surveillance without the need for highly stable clocks or time synchronization between ground stations. In the proposed approach, aircraft 3D positions and velocities and the relative clock offsets of the receivers are estimated consistently using an extended Kalman filter (EKF). The accuracy of the 3D aircraft position estimates was tested using simulated ADS-B messages across a variety of different ground station network configurations.

Rohith Boyinine, Jayanth Ammapalli, Anusna Chakraborty et al.

This paper presents CoNaV, a comprehensive framework for creating a multi-vehicle cooperative localization (CL) testbed designed to support the benchmarking, development, and deployment of cooperative navigation algorithms. Given the essential role of CL in improving localization accuracy for both defense and civilian applications, CoNaV provides a robust environment for rigorously validating algorithms under real-world conditions. By establishing a benchmark for CL algorithms, CoNaV lays a foundation for advancing research into more sophisticated and distributed CL solutions. This framework highlights the potential of cooperative navigation to enhance multi-vehicle operations and offers a scalable, practical approach for future developments in CL technology.

Richard B. Langley

ION promotes the research of journal authors in a variety of ways including video abstracts hosted on the ION website. The latest video abstracts are documented below. You can find the video abstract for any recently published article under the article’s supplemental menu item on the journal’s website. ION also engages with the PNT community, through its webinar series, to highlight current topics of interest to the community. The most recent webinars are also documented below.

Ariel Baron, Pini Gurfil, Hector Rotstein

Utilizing broadband low Earth orbit satellite signals in an opportunistic manner for navigation is becoming increasingly popular. This paper deals with a particularly useful approach for navigation based on satellite signals of opportunity, which uses carrier Doppler-shift observables. We provide analytically derived and simplified formulas for the Jacobian involved in the numerical computation of the navigation solution and derive a global navigation satellite system-like dilution-of-precision metric that can be used to assess accuracy. A numerical study provides preliminary computational results.

Bu-Gyeom Kim, Donguk Kim, Junesol Song et al.

Network real-time kinematic (NRTK) coverage is defined as the area inside a station network. In conventional NRTK, the distance between stations is limited to 100 km, thus restricting the coverage of NRTK. In this study, we propose the utilization of an ionospheric-free combination and the application of a Kriging weighting model to mitigate tropospheric delay to extend the coverage of NRTK through network expansion. A network with station distances exceeding 100 km was constructed, and the residual errors, along with the success-fix rate of integer ambiguities, were analyzed on both sunny and rainy days to confirm the potential for network expansion using the proposed method. The results confirm that the success-fix rate increased by up to 44.3% on rainy days, compared with that of the traditional interpolation method. Furthermore, a high level of performance in integer ambiguity resolution can be maintained within the expanded network, regardless of the weather conditions.

Chittimalla Srinu, Laxminarayana Parayitam

The GNSS software receiver has evolved as a promising tool for researchers and developers because of its flexibility and reconfigurability. As modernized GNSS signals have been emerging day by day, the need to adapt the software receiver to address the upcoming challenges of GNSS navigation has become inevitable. The main aim of this work is to assess the existing Global Navigation Satellite System Software Defined Receiver (GNSS-SDR) tool for Indian Regional Navigation Satellite System (IRNSS) signals using a low-cost RTL-SDR front-end. The IRNSS software receiver chain is developed using GNSS-SDR code and framework. GNSS-SDR is an open-source tool developed by the Centre Tecnològic de Telecomunicacions de Catalunya (CTTC) of Spain. This work is useful for carrying out various GNSS-related applications using IRNSS signals in the future and paves the way for further research and development of the IRNSS system by using it as a research/academic tool.

Marius Brachvogel, Michael Niestroj, Michael Meurer et al.

Antenna arrays and spatial processing techniques are among the most effective countermeasures against interference. Here, we demonstrate a new array concept consisting of spatially-distributed subarrays that are small enough to fit inside the non-metallic parts of an automobile. This will facilitate concealed installation of these devices in bumpers or side mirrors, which is a strict requirement of the industry and preferred by the customers. Using beamforming algorithms, this array was proven to be robust against jammers in the L1 band. The large distances between the individual antenna elements resulted in a non-negligible baseband delay that violated the narrowband assumption and increased with bandwidth. Hence, this paper demonstrates the influence of a jammer in the L5 band. Space-time adaptive processing that allows for compensation of the delays was introduced and analyzed. Improvements in interference mitigation capabilities were assessed and compared to those of pure spatial state-of-the-art implementation. Real-life measurement data was used to ensure realistic results.

Ciro Gioia, Daniele Borio

Several layers of defense can be implemented in a global navigation satellite system (GNSS) receiver to improve its performance in the presence of interference. These layers include the use of pre-correlation mitigation techniques, post-correlation quality indicators to screen measurements, and fault detection and exclusion (FDE) at the position solution level. This paper provides a characterization of the interactions between these layers of interference mitigation and a measurement quality check. Data collected in the presence of increasing levels of jamming were processed using different interference mitigation techniques, including robust interference mitigation (RIM) and the adaptive notch filter (ANF). A software defined radio (SDR) approach was adopted and measurements were generated by considering five interference-mitigation techniques. Position solutions were then computed using a forward-backward approach for receiver autonomous integrity monitoring (RAIM). Signals from GPS, Galileo, and Beidou were processed and both single and dual-constellation solutions were analyzed. The analysis revealed that interference mitigation allows the receiver to track a larger number of signals even in the presence of high levels of jamming power. This increased measurement availability was then effectively exploited by RAIM techniques to provide more reliable solutions. Measurements from several constellations further improved the reliable availability of the position solutions.

Jianping Chen, Yang Gao

High-precision ionospheric corrections are essential for precise positioning using low-cost single-frequency GNSS receivers. Although Real-Time Global Ionosphere Maps (RT-GIMs) are available from the International GNSS Service (IGS), their ionospheric predictions continue to rely on networks of globally-distributed GNSS stations and real-time data links. In this paper, we develop a regional real-time ionospheric prediction model based on a long short-term memory (LSTM) deep learning method. Because the GIMs from the IGS are used as prediction bases, the requirement for real-time GNSS datalinks is eliminated. A comparison of the ionospheric predictions generated over 24 hours by the proposed method and the IGS GIM revealed a prediction accuracy root mean square error of 0.8 TECU. These results suggest that the proposed model may be suitable for use in real-time applications.

Derek Knowles, Grace Gao

Faulty signals from global navigation satellite systems (GNSSs) often lead to erroneous position estimates. A variety of fault detection and exclusion (FDE) methods have been proposed in prior research to both detect and exclude faulty measurements. This paper introduces a new technique for the FDE of GNSS measurements using Euclidean distance matrices. After a brief introduction to Euclidean distance matrices, both the detection and exclusion strategy is explained in detail. Euclidean distance matrix-based FDE is verified in two separate real-world data sets and proven to accurately detect and exclude GNSS faults on an average of 1.4-times faster than residual-based FDE and 70-times faster than solution separation FDE.

Richard B. Langley

Welcome to the Spring 2023 issue of NAVIGATION. In this issue, we feature articles on positioning and navigation in a wide range of situations and environments from open-pit mines to Earth-orbiting spacecraft. ION promotes the research of journal authors in a variety of ways including video abstracts hosted on the ION website. The latest video abstracts are documented below. You can find the video abstract for any recently published article under the article’s supplemental menu item on the journal’s website. ION also engages with the PNT community, through its webinar series, to highlight current topics of interest to the community. The most recent webinars are also documented below. And congratulations to Elisa Gallon, Mathieu Joerger, and Boris Pervan who were selected as the winners of the Institute of Navigation’s 2022 Samuel M. Burka Award, recognizing outstanding achievement in the preparation of a paper advancing the art and science of positioning, navigation, and timing. Presented at the ION International Technical Meeting in Long Beach, California, back in January, this award recognizes their paper as one of the most significant published in NAVIGATION in 2022 and I extend my personal congratulations to the authors.

Filipe Pereira, Patrick M. Reed, Daniel Selva

The success of future lunar missions depends on quality positioning, navigation, and timing (PNT) information. Earthbound GNSS signals can be received at lunar distances but suffer from poor geometric dilution of precision (GDOP) and provide no coverage of the lunar far side. This article explores the design space of a dedicated GNSS system in lunar orbit by using a multi-objective evolutionary algorithm framework to optimize GDOP, availability, space segment cost, station-keeping ?V, and robustness to single-satellite failure. Results show that Pareto approximate solutions that achieve a global GDOP availability (GDOP = 6.0) greater than 98% contain a minimum of 24 satellites in near-circular polar orbits at an altitude of ~2 lunar radii. The impact of single-satellite failure on GDOP outage is analyzed and a no-maneuver scenario is considered. Design rules characterizing optimal solutions are identified and trade-offs between station-keeping maneuver frequency, performance, and design lifetime are discussed.

Xiao Liu, Pau Closas, Adrià Gusi-Amigó et al.

Recently, the Snapshot Real-Time Kinematic (SRTK) technique was demonstrated, which aims at achieving high accuracy navigation solutions with a very short signal collection. The main challenge in implementing SRTK is the generation of valid carrier-phase measurements, which relies on a data bit ambiguity (DBA) resolution process. For pilot signals, this step is equivalent to the correct selection of secondary code indexes (SCIs) from the ambiguous sets obtained from a multi-hypotheses (MH) acquisition process. Currently, SCI ambiguities are solved independently for each satellite. However, this method is ineffective when the snapshot signal is relatively short. In order to tackle this problem, this article proposes a new method that makes use of assistance data and processes information from all satellites to jointly solve the DBA issue. This new method is shown to be more effective in determining the correct SCI and enabling valid snapshot carrier-phase measurements, largely expanding the scope of high-accuracy snapshot positioning.

Antoine Grenier, Pietro Giordano, Lorenzo Bucci et al.

The interest in Moon exploration has grown substantially in the last few years, appointing the Moon as the first step toward deep space exploration. However, the current state-of-the-art approach for lunar landing does not always reach the required performance levels. This contribution presents a potential implementation of a dedicated lunar communication and navigation service (LCNS) and the performance levels achievable by a representative lunar lander mission that uses the LCNS. The expected positioning precision during the final descent and at the landing site is demonstrated here with a variance-covariance analysis starting from reasonable assumptions about the capabilities of a potential dedicated LCNS system. The performance in positioning and navigation achievable during a generic moon-landing phase significantly outperforms existing ground-based baseline solutions, enabling the stringent requirements from the International Space Exploration Coordination Group (ISECG) to be met.

Niklas Stenberg, Erik Axell, Jouni Rantakokko et al.

GNSS receivers are vulnerable to spoofing attacks in which false satellite signals deceive receivers to compute false position and/or time estimates. This work derives and evaluates algorithms that perform spoofing mitigation by utilizing double differences of pseudorange or carrier phase measurements from multiple receivers. The algorithms identify pseudorange and carrier-phase measurements originating from spoofing signals, and omit these from the position and time computation. The algorithms are evaluated with simulated and live-sky meaconing attacks. The simulated spoofing attacks show that mitigation using pseudoranges is possible in these tests when the receivers are separated by five meters or more. At 20 meters, the pseudorange algorithm correctly authenticates six out of seven pseudoranges within 30 seconds in the same simulator tests. Using carrier phase allows mitigation with shorter distances between receivers, but requires better time synchronization between the receivers. Evaluations with live-sky meaconing attacks show the validity of the proposed mitigation algorithms.

Kamil Staniec, Michal Kowal, Slawomir Kubal et al.

Precise localization is considered one of the most salient features of Industry 4.0 manufacturing facilities. For this reason, multiple solutions have already been proposed. The method presented in this paper entails the use of double-band radio and optical technologies for near-real-time location tracking and remote reporting, with a final tracking accuracy of 0.5 meters. To preserve low-energy operations, the system infrastructure part is deployed on passive radio-frequency identification (RFID) tags, whereas the part installed on tracked assets implements energy-saving mechanisms. The system was deployed in an automotive production plant which allowed us to draw practical remarks on such aspects as the separation of onboard Ultra High Frequency (UHF) antennas; proper electromagnetic isolation of radio modules to prevent signal blocking; the placement and mechanical securing of RFID tags on the floor; as well as how to implement procedures to decrease the duty cycle, allowing for a trade-off between system sensitivity and energetic efficiency.

John D. Quartararo, Steven E. Langel

Extended Kalman filters (EKFs) that monitor innovations over time have been demonstrated to be effective at detecting slowly accumulating measurement faults (Quartararo & Langel, 2020; Tanil et al., 2018). This paper first demonstrates that a single cumulative monitor becomes increasingly sensitive to measurement error model uncertainty as the accumulation interval increases, leading to false alarm and detection rates that can differ significantly from predefined design parameters. In response, a bank of finite-length cumulative innovations monitors is explored for fault detection in multisensor navigation systems. A novel extension to traditional covariance analysis (Covariance Analysis Including Expected Values or CAIEV) is developed to accommodate measurement faults and is used in addition to Monte Carlo simulations to present detection results for a variety of GPS fault profiles and inertial measurement unit (IMU) grades. Data for time-to-detect is presented alongside the position-domain bias induced by the fault at the time of detection. We show that the monitor bank can reliably detect the presence of faulty measurements after the position-domain bias has reached only tens of meters using tactical and aviation-grade IMUs for the cases considered, an improvement over other innovations-based techniques.

A. Althaf, H.B. Hablani

The estimation of static baselines using NavIC L5 double-differenced (DD) pseudoranges and carrier phases is investigated. We estimate the baseline with increasing accuracy by using the DD pseudoranges, smoothing the DD pseudoranges with the DD carrier phases, fixing the ambiguities in DD carrier phases, and imposing height-constraints on ambiguity and baseline estimates. Using the DD pseudoranges in estimating a 6-m baseline, the 3D root-mean-square error (RMSE) is 1.71 m. By incorporating the DD carrier-phase measurements and fixing its ambiguities, we achieved a 3D steady-state accuracy of 3 cm and convergence time of 23 minutes for a 350-m baseline in the secondary service area of NavIC. Further performance gains were achieved using a height-constrained solution in which 3D steady-state accuracy and convergence time was improved to 1 cm and 8 minutes, respectively.