Hasil untuk "Canals and inland navigation. Waterways"

Luciano Iess Mauro Di Benedetto Giovanni Boscagli Paolo Racioppa Andrea Sesta Fabrizio De Marchi Paolo Cappuccio Daniele Durante Serena Molli Michael K. Plumaris Pasquale Tartaglia Agnes Fienga Nicolas Rambeaux Fabrizio Santi Debora Pastina Nicola Linty Krzysztof Sosnica Grzegorz Bury Radoslaw Zajdel Jacopo Belfi Pietro Giordano Richard Swinden, Javier Ventura-Traveset

This paper presents a novel concept for orbit determination and time synchronization of a lunar radio navigation system. The proposed approach is based on small ground antennas that simultaneously track the entire constellation using K-band frequency links, implementing the concept of multiple spacecraft per aperture. This configuration ensures sufficient data rates and provides high accuracy in Doppler, range, and single-beam interferometry observables, enabling a precise orbit determination. We assess the achieved time transfer accuracies using both the standard asynchronous two-way satellite time and frequency transfer and a novel time transfer method that leverages onboard code epoch time-stamping and precise spacecraft range information. We propose a structure for the navigation message as well as a reference frame and associated time scale for user positioning. We complete the analysis by estimating the attainable accuracies of the signal-in-space error.

Saeid Mozafari, Hamed Mohammadkarimi, Mahsa Ghasemi et al.

This paper aims to provide navigation system designers with a detailed examination of the impact of inertial measurement unit (IMU) rotation on error reduction or induction in a rotary inertial navigation system (INS). The designer of a rotary INS can select the optimal rotation rate and direction by considering the dynamics of the carrier and the dominant errors based on the findings reported in three concise tables within this paper. This paper presents a comprehensive analytical derivation of error equations for the attitude, velocity, and position of a rotational INS, validated through numerical simulations. Experiments using a rotation platform and actual data from a micro-electromechanical system IMU sensor are also conducted to verify the effectiveness of mitigating errors through IMU rotation. Moreover, a tensor-based modeling technique is employed to facilitate exploring the impact of IMU rotation around an arbitrary axis on accumulated errors. This approach provides a modular platform for further research on rotational navigation systems.

Soung Sub Lee

This study proposes a dedicated closed-form solution and satellite phasing rules for designing a geosynchronous orbit (GSO) constellation. Trajectories of GSO satellites have a characteristic figure-eight shape because their rotation speed is the same as that of the Earth. The GSO has the advantage of providing good coverage performance for local areas. Recently, several countries have begun developing local navigation systems based on the GSO. Various GSO constellation designs are available for an effective regional navigation performance analysis; however, no dedicated GSO constellation solution exists. This study provides a solution for such constellations and proves its practicability through a comparative analysis and evaluation of the geometric dilution-of-precision performance for several cases.

Dr. Richard B. Langley

Welcome to the Fall 2025 issue of NAVIGATION. In this issue, we have articles on GNSS integrity and interference detection, issues related to low Earth orbit and geosynchronous navigation satellites, and studies of navigation in the cislunar and lunar environments. Plus, a number of other articles on state-of-the-art developments in positioning and navigation.

Thomas Pany, Dennis Akos, Javier Arribas et al.

Taking the work conducted by the global navigation satellite system (GNSS) software-defined radio (SDR) working group during the last decade as a seed, this contribution summarizes, for the first time, the history of GNSS SDR development. This report highlights selected SDR implementations and achievements that are available to the public or that influenced the general development of SDR. Aspects related to the standardization process of intermediate-frequency sample data and metadata are discussed, and an update of the Institute of Navigation SDR Standard is proposed. This work focuses on GNSS SDR implementations in general-purpose processors and leaves aside developments conducted on field programmable gate array and application-specific integrated circuit platforms. Data collection systems (i.e., front-ends) have always been of paramount importance for GNSS SDRs and are thus partly covered in this work. This report represents the knowledge of the authors but is not meant as a complete description of SDR history.

Wengxiang Zhao, Samer Khanafseh, Boris Pervan

Interference events, both intentional and unintentional, are significant threats to global navigation satellite system (GNSS) service continuity. In the presence of interference, it can be difficult for GNSS receivers to maintain continuous tracking of carrier phase and frequency. To address this issue, in place of a traditional phase-locked loop (PLL), we develop and validate a new estimation-based approach to allow GNSS receivers to correctly estimate carrier phase and frequency under conditions of low carrier-to-noise power. An adaptive Kalman filter forms the core of the estimator, with a multiple-model algorithm to account for discrete navigation data bit transitions. The performance of the estimator in the presence of wideband interference is validated through simulation and experiment, showing performance markedly superior to that of a PLL.

Wang Li, Yiping Jiang

A ground-based augmentation system (GBAS) is a critical component in civil aviation that augments the Global Positioning System (GPS) in providing precision approach and landing capabilities with guaranteed accuracy and integrity. The GBAS ground facility broadcasts a parameter known as svig to the aircraft, which is used to compute vertical protection levels for evaluating navigation integrity. svig represents the standard deviation of the vertical ionospheric gradients, which bounds the spatial gradients under nominal conditions. Although the time-step method has been widely utilized to estimate ionospheric spatial gradients, this strategy suffers from temporal effects. In this paper, an improved time-step method is developed for separating temporal gradients from spatial gradients using observation data collected from the Hong Kong Satellite Positioning Reference Station Network. We investigated two parameters: stg, which bounds the standard deviation of temporal gradients, and svig. The results show that a constant value of 5.5 mm/km can serve as an upper bound for all stg values. However, the results of svig vary seasonally, with maximum and minimum values occurring at the equinoxes and summer, respectively. To reflect this seasonality, quadratic polynomial expressions, given as functions of the day of the year, were derived to provide an upper bound for all svig values.

Adyasha Mohanty, Grace Gao

Smartphone positioning based on global navigation satellite systems is crucial for various applications, including navigation, emergency response, and augmented and virtual reality. Despite significant advancements, constraints on size, weight, power consumption, and cost still pose challenges, leading to degraded accuracy in challenging urban settings. To improve smartphone positioning accuracy, we introduce a novel framework that deeply couples a graph neural network (GNN) with a learnable backpropagation Kalman filter. This hybrid approach combines the strengths of both model-based and data-driven methods, enhancing adaptability in complex urban settings. We further augment the measurement modeling capabilities of the GNN with extended features, a novel edge creation technique, and an inductive graph learning framework. Additionally, we implement a unique backpropagation strategy that uses real-time positioning corrections to refine the performance of both the GNN and the learned Kalman filter. We validate our algorithm on real-world data sets collected via smartphone receivers in urban environments and demonstrate improved performance over existing model-based and learning-based approaches.

Javier Junquera-Sánchez, Carlos Hernando-Ramiro, Oscar Gamallo-Palomares et al.

As time goes on, quantum computing has become more of a reality, bringing several cybersecurity challenges. Modern cryptography is based on the computational complexity of specific mathematical problems; however, as new quantum-based computers are developed, classical methods might not be sufficient to secure communications. In this paper, we analyze the state of the Galileo open service navigation message authentication (OSNMA) to overcome these new threats. This analysis and its assessment have been performed using OSNMA documentation, where we have reviewed the available post-quantum cryptography (PQC) algorithms competing in the National Institute of Standards and Technology standardization process and assessed the possibility of OSNMA implementation in the Galileo service. The main barrier to adopting PQC approaches is the size of both the signature and the key. This analysis shows that OSNMA is not yet capable of facing quantum threats and that significant changes are required. This work concludes by assessing different transitory countermeasures that can be implemented to sustain the system’s integrity in the short term.

David Benz, Jan-Jöran Gehrt, René Zweigel et al.

The automation of mining haulage vehicles has great potential in terms of safety and economy. The performance of autonomous vehicles depends largely on highly accurate vehicle state information. Deep mines are especially challenging, as satellite-based localization methods are reaching their limits. Therefore, we introduce a new navigation filter concept for the precise and robust localization of the haulage fleet that can handle temporary GNSS interruptions in deep open-pit mines. The multi-sensor navigation filter utilizes an inertial measurement unit and is aided by GNSS. We introduce a new optical speed sensor update within the tightly coupled unscented Kalman filter. The speed sensor measures the slip-free two-dimensional speed above ground. The filter was validated with an articulated dumper in a gravel pit. The new filter achieved a mean position error of 0.24 m during a test drive of 190 s with a simulated GNSS outage of 90 s.

Richard B. Langley

Welcome to the Fall 2023 issue of NAVIGATION. In this bumper issue, we feature 16 articles reporting on significant advances in PNT research covering topics such as improved modeling the ionosphere and further reducing its impact on positioning and navigation, the authentication of augmentation systems and GNSS navigation messages, improving and supplementing GNSS use in difficult reception environments, and the navigation of a spacecraft in the vicinity of the moon. 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.

Dominik Dötterböck, Thomas Pany, Roman Lesjak et al.

This work explores the use of a low-cost global navigation satellite system (GNSS) antenna array including front-ends and a global navigation satellite system (GNSS) software receiver to receive signals of opportunity (SoO) whose pseudorandom noise (PRN) code is unknown. The front-ends are only loosely synchronized in time and frequency via hardware elements, and precise synchronization or calibration is achieved by using open service global navigation satellite system (GNSS) signals. After calibration, the raw received signals from all antenna elements are added coherently, which allows the pseudorandom noise (PRN) codes of the unknown signals of opportunity (SoO) to be estimated. The pseudorandom noise (PRN) sequences are then fed into a test receiver with a single antenna element that uses the sequences to acquire and track the signals of opportunity (SoO) in a conventional way. The process of chip estimation combined with the use of these sequences in a test receiver is called blind processing. The paper discusses the used algorithms, limitations, the expected performance in the chip error rate (CER), and effective loss of signal power when tracking the signals of opportunity (SoO) in a test receiver. An experimental setup with an array of 40 antenna elements is described, and results from simulated data and from one real global positioning system (GPS) M-code signal used as the signals of opportunity (SoO) show the feasibility of this concept. Among the types of global navigation satellite system (GNSS) signals of opportunity (SoO), the GPS M-code is more difficult to estimate than its Galileo or BeiDou counterparts due to its high chipping rate. A chip error rate (CER) of 15.1 % is achieved for the M-code signal. Applications of blind processing include receiver prototyping, signal quality monitoring of the signals of opportunity (SoO), and server-side processing for the purpose of signal authentication.

Daniele Borio

Generalized binary offset carrier (BOC) modulations and global navigation satellite system (GNSS) meta-signals require advanced processing algorithms to overcome problems associated with their multi-peaked correlation functions. In this paper, bicomplex numbers are introduced for GNSS signal representation and for algorithm development. Bicomplex numbers generalize complex numbers and are characterized by four real components. These numbers have the potential to represent multicomponent signals, such as GNSS meta-signals, leading to a compact notation that allows effective derivations and algorithm development. Moreover, bicomplex numbers allow one to express a meta-signal as the product of a code, a carrier, and a subcarrier component: this representation leads to acquisition and tracking algorithms that are capable of effectively processing GNSS meta-signals, thus solving the code ambiguity problem. Theoretical developments are demonstrated using real data collected using software-defined radio front-ends for the Galileo alternative BOC modulation and the BeiDou B1I/B1C meta-signal.

Rick H. Yuan, Clark N. Taylor, Scott L. Nykl

One of the fundamental problems of robotics and navigation is the estimation of the relative pose of an external object with respect to the observer. A common method for computing the relative pose is the iterative closest point (ICP) algorithm, where a reference point cloud of a known object is registered against a sensed point cloud to determine relative pose. To use this computed pose information in downstream processing algorithms, it is necessary to estimate the uncertainty of the ICP output, typically represented as a covariance matrix. In this paper, a novel method for estimating uncertainty from sensed data is introduced.

Weisong Wen, Xiwei Bai, Li-Ta Hsu

In this paper, a three-dimensional vision-aided method is proposed to improve global navigation satellite system (GNSS) real-time kinematic (RTK) positioning. To mitigate the impact of reflected non-line-of-sight (NLOS) reception, a sky-pointing camera with a deep neural network was employed to exclude these measurements. However, NLOS exclusion results in distorted satellite geometry. To fill this gap, complementarity between the low-lying visual landmarks and the healthy but high-elevation satellite measurements was explored to improve the geometric constraints. Specifically, inertial measurement units, visual landmarks captured by a forward-looking camera, and healthy GNSS measurements were tightly integrated via sliding window optimization to estimate the GNSS-RTK float solution. The integer ambiguities and the fixed GNSS-RTK solution were then resolved. The effectiveness of the proposed method was verified using several challenging data sets collected in urban canyons in Hong Kong.

Philippe Rigo

AbstractThis keynote paper presents the PIANC Inland Navigation Commission (INCOM; http://incomnews.org/). INCOM is one of the 4 technical commissions of PIANC, which is targeting to Inland Navigation, and particularly to the waterway infrastructure and management.

Colton Lindstrom, Randall Christensen, Jacob Gunther et al.

The need to successfully navigate in the absence of GNSS has grown in recent years. In particular, light aircraft such as UAVs are growing in popularity for a variety of applications vulnerable to GPS denial. The research presented here develops a GPS-denied navigation scheme for light aircraft employing images formed from a synthetic aperture radar system. Past research has explored the utility of radar telemetry in GPS-denied systems. This research advances previous work by exploiting radar images to obtain range and cross-range position measurements. Images are formed using the Range-Doppler Algorithm, an efficient image formation algorithm ideal for the sometimes limited processing packages available to light aircraft. An inertial navigation and radar processing system is implemented using both real and simulated radar images to aid in estimating an aircraft’s state in a GPS-denied environment. The results show that navigation in the absence of GPS using synthetic aperture radar is feasible with converging and bounded estimation errors.

Gerardo Allende-Alba, Steffen Thoelert, Stefano Caizzone

For GNSS signal power monitoring systems, the characterization of satellite antennas plays an important role. Recently, gain pattern reconstructions of Galileo satellite antennas have been obtained using single-station observations. However, due to the characteristics of GPS orbits, such an approach is less suitable for GPS satellite antennas. This study introduces a methodology for multi-station satellite antenna gain pattern reconstruction. To overcome the unavailability of receiver antenna gain patterns at the employed stations, a dedicated algorithm is introduced that uses an antenna at a base station to remotely characterize the antennas in network stations. Obtained reconstructions of L1 antenna gain patterns of selected GPS satellites show a consistency at the 0.3–0.4 dB level (95%) with data provided by the manufacturer and better than 0.3 dB (95%) with ground-based observations using a high-gain antenna. The introduced methodology may be employed in the establishment of permanent multi-constellation GNSS signal power monitoring systems.

Jonathon S. Gipson, Robert C. Leishman

The Autonomous and Resilient Management of All-source Sensors (ARMAS) framework monitors residual-space test statistics across unique sensor-exclusion banks of filters (known as subfilters) to provide a resilient, fault-resistant all-source navigation architecture with assurance. A critical assumption of this architecture, demonstrated in this paper, is fully overlapping state observability across all subfilters. All-source sensors, particularly those that only provide partial state information (altimeters, TDoA, AOB, etc.), do not intrinsically meet this requirement. This paper presents a novel method to monitor real-time overlapping position state observability and introduces an observability bank within the ARMAS framework, known as stable observability monitoring (SOM). SOM uses a monitoring-epoch stability analysis to provide an intrinsic awareness to ARMAS of the capabilities of the fault detection and exclusion (FDE) functionality. We define the ability to maintain consistent all-source FDE to recover failed sensors as navigation resilience. A resilient FDE capability is one that is aware of when it requires more sensor information to protect the consistency of the FDE and integrity functions from corruption. SOM is the first demonstration of such a system for all-source sensors that the authors are aware of. A multi-agent 3D environment simulating both GNSS and position and velocity alternative navigation sensors was created and individual GNSS pseudorange sensor anomalies are utilized to demonstrate the capabilities of the novel algorithm. This paper demonstrates that SOM seamlessly integrates within the ARMAS framework, provides timely prompts to augment new sensor information from other agents, and indicates when framework stability and preservation of all-source navigation integrity are achieved.

Zhao-Yang Gao, Xi-Yun Hou

A comprehensive study on the autonomous orbit determination (AOD) performance of satellite pairs in halo orbits and distant retrograde orbits (DROs) is carried out. A factor called dynamic and geometric dilution of precision (DAGDOP) is proposed to simultaneously incorporate influences from the dynamics and geometry of satellite pairs. Based on the DAGDOP, the effect of different observation arcs on the AOD accuracy is investigated. Next, the AOD accuracy of three different types of satellite pairs—halo+halo, DRO+DRO, and halo+DRO—is systematically analyzed. The hybrid halo+DRO type shows the best overall accuracy. Finally, the AOD performance of the hybrid type is verified in a realistic model. Our studies find that the average AOD accuracy of the halo orbit is about 170 meters, and that of the DRO is about 190 meters. The relative time synchronization error of two satellites is less than 30 nanoseconds.