Aeronautical Navigation Research Articles

Circularly polarized multi-layered ellipsoidal coaxial fed dielectric resonator antenna for wireless applications

This paper presents a circularly polarized multi-layered Ellipsoidal Dielectric Resonator Antenna (CP-EDRA) having a footprint of 0.2λ0× 0.4λ0 operating in the frequency band 11.24-14.05 GHz. The structure is fed using a 50 Ω coaxial probe. Three layers of ceramic material have been stacked together in the increasing order of their dielectric constants in order to enhance the impedance bandwidth. There is an angular offset given to the topmost ellipsoidal cylinder which in turn leads to circular polarization radiation from the antenna with an optimum realized gain of 7.2 dBic and axial-ratio bandwidth (ARBW) of 1.7 GHz (12.3-14 GHz). The radiation and total efficiency are in good coincidence with each other and above 95% throughout the operating bandwidth. The prototype of CP-EDRA is fabricated and tested for experimental validation. The measured results of the fabricated antenna are in good agreement with simulated ones. The presented work finds its applications in broadcasting satellites, aeronautical navigation space research, etc. The antenna has a simple design and working principle with better performance compared to those reported so far.

Evaluation of DME network capability using combination of rule-based model and gradient boosting regression

The future development of aeronautical navigation foresees an infrastructure rationalization of radionavigation aids with the aim of maintaining only the Minimum Operational Network, which brings benefits in terms of operational cost savings, promotes sustainability and optimal use of the radio spectrum. To ensure that the necessary navigation performance is preserved, the Distance Measuring Equipment (DME) plays a significant role, as DME/DME navigation is a short-term contingency solution when Global Navigation Satellite System is unavailable. Therefore, new DME ground stations are put into operation even though other navigation aids are being decommissioned at the same time. This paper addresses a question of possible DME network rationalization by developing a software model using a combination of a rule-based model, approximating of airborne DME interrogators interacting with DME ground transponders, with the implementation of the Gradient Boosting Regression to predict load of DME ground stations. The model is validated by comparing the results with the real load data obtained from an Air Navigation Service Provider. Several test cases are performed to evaluate the capability of the European DME network, simulating a reduction in the number of en-route DME stations and increases in air traffic using clustering methods. The results show that the ground station load limit was rarely reached, demonstrating the robustness and the potential for rationalization of the DME infrastructure.

THE REDUCTION OF GEOMAGNETIC DATA FOR THE TERRITORY OF LATVIA TO THE EPOCH 2021.5

The article describes the sources of geomagnetic data, the reduction of geomagnetic data for the territory of Latvia to the epoch 2021.5, the history of previous magnetic observations in Latvia, the information available in the State Geodetic Network database and the information available in the World Geomagnetism Data Centre. The sequence of absolute measurements is described in detail. To visualise the changes in the magnetic declination value in the territory of Latvia, a 2021.5 year declination fluctuation has been created using ArcGIS Pro. The declination values in Latvia range from 6.68° to 10°, the inclination values range from 71.089° to 72.245° and the total magnetic field values from 51100 nT to 52594 nT. The values obtained for the magnetic field components refer to a magnetically clean environment, and there can be, and are, differences in the natural conditions in the Latvian territory, in natural anomalous locations and in locations with artificially high magnetic field noise (e.g. in cities, near railways, near high voltage lines, etc.). In the Latvian network, points have been selected in locations where the magnetic noise is minimal, as this is the technological process for building such stations. Magnetic observatories are even stricter, so the data coming from the observatories reflect the natural magnetic field without the influence of magnetic anomalies. The reduced magnetic field values and their representation on a map can be used for aeronautical navigation, military applications, identification of local magnetic anomaly sites or search for magnetically clean environments.

Local mitigation of higher-order ionospheric effects in DFMC SBAS and system performance evaluation

Dual-frequency multi-constellation (DFMC) satellite-based augmentation system (SBAS) is a new SBAS standard for aeronautical navigation systems. It supports aircraft navigation from the enroute to approach phases via the L1 and L5 frequencies (1575.42 and 1176.45 MHz). Although the ionosphere-free (IF) combination in the DFMC SBAS operation removes the first-order ionospheric delays in the pseudorange measurement, remaining terms including the satellite-clock offset errors and higher-order ionospheric (HOI) delays are still unaccounted for. The DFMC SBAS accuracy and integrity can be affected by the HOI effects, especially during severe ionospheric disturbances. In this work, we present the local DFMC SBAS corrections with and without the mitigation of HOI delays. We first estimate the HOI delay terms using the received pseudorange followed by separate satellite and receiver bias estimations based on the minimum sum-variance technique. The integrity terms can then be obtained. The performances of DFMC SBAS using the global navigation satellite system (GNSS) data including GPS, Galileo, and QZSS are evaluated using obtained GNSS data at stations in Thailand on the ionospheric quiet and disturbed days. The results show that with the HOI mitigation, the vertical positioning errors (VPE) on the quiet and disturbed days can be improved by 12% and 9%, whereas the vertical protection levels (VPL) are improved by 16% and 21%, respectively. In addition, we perform a preliminary assessment of DFMC SBAS based on the International Civil Aviation Organization (ICAO) requirements of two categories: Localizer Performance with Vertical guidance (LPV-200) and Category I precision approach (CAT-I) showing promising results.

Anomalous Long‐Distance Propagation of ILS LOC Signals by the Es Layer and Its Impact on Aviation Receivers

AbstractAnomalous long‐distance propagation of Very High Frequency radio waves of aeronautical navigation systems was investigated by an airborne Instrument Landing System (ILS) localizer (ILS LOC) receiver installed on the ground at Kure, Japan (34.245°N, 132.528°E). Intense ILS LOC type signals were observed and the received power was strong enough for the aviation receiver to output course deviation. The radio source was identified by receiving the Morse Code for identification as the localizer‐type directional aid (LDA) serving the Runway‐21 of the Hualien Airport, Taiwan (24.0396°N, 121.6221°E) of which beam pointed close to the receiver. This result supports that the source of the signals often observed at the same frequency at the same location is most probably the LDA at the Hualien Airport. The maximum received power was −99 dBm for an omni‐directional antenna. It was strong enough to cause co‐channel interference. Considering stronger power (−70 dBm) found in previous observations at the same frequency at the same location, anomalous propagation of ILS LOC signals by the Es layer could be a cause of interference when a receiver was near the center of the ILS LOC beam. The course deviation output was consistent with the geometry between the beam of Runway‐21 LDA at the Hualien Airport and the receiver. However, the observed course deviation fluctuated remarkably even when the received power was strong enough. The fluctuation of the course deviation may indicate the structure of the Es layer, and observation of the course deviation could be used to diagnose the Es layer structure.

The F/DR-D-10 Algorithm: A Novel Heuristic Strategy to Solve the Minimum Span Frequency Assignment Problem Embedded in Mobile Applications

Wireless communication supports various real-world applications, such as aeronautical navigation, satellite and TV broadcasting, wireless LANs, and mobile communications. The inherent characteristics of the electromagnetic spectrum impose constraints on telecommunication channels and their frequency bandwidths within mobile networks. A persistent challenge in these applications is providing high-demand services to mobile users, where frequency assignment problems, also known as channel assignment problems, assume significance. Researchers have developed several modeling approaches to address different facets of this problem, including the management of interfering radio signals, the assessment of available frequencies, and optimization criteria. In this paper, we present improved algorithms for solving the Minimum Span Frequency Assignment Problem in mobile communication systems using the greedy optimization approach known as F/DR. We solved and evaluated twenty well-known benchmark cases to assess the efficacy of our algorithms. Our findings consistently demonstrate that the modified algorithms outperform the F/DR approach with comparable computational complexity. The proposed algorithm notably achieves the following benchmarks: The modified algorithms consistently produce at least one local optimum better than the traditional algorithm in all benchmark tests. In 95% of the benchmarks evaluated, the probability of discovering a local optimum value (calculated by the modified algorithm) that is better than or equal to the one found by the conventional algorithm exceeds 50%.

Novel attitude determination method by integration of electronic level meter, INS, and low-cost turntable for level attitude evaluation and calibration of INS

Attitude references are greatly needed for the evaluation and calibration of Inertial Navigation Systems (INSs), which are widely used in gravimeter, marine, and aeronautical navigation. High-accuracy turntable, INS, and Global Navigation Satellite System have been utilized to verify the performance of relatively low-accuracy INS. The accuracy requirement of the attitude reference continuously increases with the rapid improvement of inertial sensors and navigation algorithms. However, the cost of attitude determination system increases rapidly with the increase of attitude accuracy requirement. To solve this limitation, the integration of level meter, INS, and low-cost turntable is proposed to provide level attitude, such as roll and pitch. The turntable is utilized to rotate the INS. An integration model of the level meter and INS is built to estimate the level attitude and reduce the cost of the turntable. The proposed method successfully avoids the dependence on high-accuracy turntables. An observability degree analysis is conducted to improve the level attitude accuracy further. The simulation and turntable test results indicate that the proposed method can provide high-accuracy level attitude without high-accuracy INS or turntable and is applicable to error calibration and attitude evaluation of INS.

Automation of aeronautical information processing based on multi-agent technologies

Progress in the development of computer engineering provides an opportunity to address a wider variety of challenges using computer software systems. The task of automatic aeronautical navigation information processing is referred to the number of such issues. This stipulates the necessity to adopt new approaches to design and develop similar systems. One of these approaches is based on the application of the collective activity idea of a set of agents – multi-agent technologies. In this regard, the purpose of the article is to consider the features of the automated aeronautical navigation information processing implementation on the basis of multi-agent technologies. To achieve this goal, the problem-structural methodology of hybrid systems synthesis, which allows us to create self-organizing models, was selected. Each element of which develops, obtaining data and knowledge from other elements. In the research process, a formal definition of the multi-agent system of automatic aeronautical information processing is presented, which involves a set of agents, environment of agent functioning, a set of permissible relations between agents, description of rules for forming a network of agents, a set of individual and joint actions, communication interactions, behavior and actions strategies, a possibility of system evolution. Furthermore, an emphasis is placed on the description of each agent. For this purpose, the authors propose to use four elements: a set of variables, inputs and outputs, an autonomous technique that performs appropriate changes over a set of variables. As agents, the paper comes up with the idea to use the following: Pilots Notification Agent, Preflight Information Bulletin Agent, Data Generation Agent, Aviation Processes Agent, Aviation Database Generation Agent, Aeronautical Maps Creation Agent, Aeronautical Data Set Export/Import Agent, Publications and References Agent. In addition, the article presents the multi-agent system diagram of automated aeronautical information processing and describes in detail processing an application in the agent using the mathematical expression. The results, obtained in the course of investigations, can be used to improve the effectiveness of the analytical component in the structure of the system to form the direct and reverse coordination relationship while solving aerial navigation problems.

Considerations Regarding the Climate Change Induced Hazards on Airports in Romania – A Case Study of Timişoara International Airport

Climate change is regarded as a global scale process in which an increase of magnitude and intensity of severe weather events is observed, thus affecting both air travel as well as airport infrastructure. Although the COVID-19 crisis has a significant negative impact on air travel and thus on the further development of airport infrastructure, the demand for air travel will continue to rise as the crisis nears the end. The aim of this paper is to analyse and highlight the climate change associated hazards for the airport infrastructure as well as for the safety of passengers and goods in the Western part of Romania, mainly Traian Vuia International Airport from Timişoara. Throughout this analysis, aviation related severe weather events, such as thunderstorms, hail events, fog, icing, squalls, low level wind shear, snow falls and heavy precipitation, which affect airport infrastructure and thus air travel, are highlighted. By analysing meteorological parameters from the time scale 1980-2010 together with climate change scenarios, and thus developing weather hazard maps, a better perspective of area-related hazards and therefore customized mitigation measures and adaptation strategies are to be developed. The implementation of modern forecasting equipment such as dual polarization Terminal Doppler Weather Radar (TDWR) is thus necessary in order to prevent loss of human lives, to reduce financial losses and to protect the airport infrastructure and the aeronautical navigation and communication facilities. Long term changes in meteorological parameters include an increase in air temperature, an increase in speed for both horizontal and vertical windshear during severe weather events, an increasing number of air mass thunderstorms and an increase of situations with limited visibility especially during the late autumn and early spring time.

Variations of the Time to Failure (TTF) for Specific Components in Aeronautical Navigation Systems

Aeronautical navigation systems installed at specific locations within Saudi Arabia report the actual observed data of the times to failure (TTFs) for many types of engineering elements made by some typical international highly-acclaimed manufacturers. There is a need to compare these observed data to the estimated data provided by the manufacturers themselves. The paper gathers a lot of data on the actual failure instances of many components produced by a variety of manufacturers and installed at different locations within the extensive area of Saudi Arabia. These data are used to calculate the mean times between failures for these components. The paper points to an inadvertent discrepancy between these data and the corresponding mean times between failures (MTBFs) suggested by some prominent manufacturers. Such suggested MTBFs are typically optimistic and unrealistically high irrespective of the elements, the location, and the manufactures. The work reported herein is a preliminary assessment of this phenomenon that might lead to its theoretical modeling and subsequent understanding.

Visualizing sporadic E using aeronautical navigation signals at VHF frequencies

To understand the dynamical properties of sporadic E layer (Es), we have developed a method to visualize the two-dimensional spatial structure of Es by monitoring the occurrence of anomalous propagation of VHF waves used for aeronautical navigation systems in combination with the electron density disturbance index ROTI, that is the Rate of total electron content (TEC) Index obtained from ground-based GPS receivers. We introduce a case of strong Es layer which occurred for ~4 h during daytime of July 4, 2019. In this interval, we succeeded in imaging the structure of Es elongating more in the east–west direction and moving northward gradually. This result indicates that the combination of network observations of aeronautical navigation signals and ROTI is capable of imaging the 2D structure of Es in a wide area including the sea surface, which enables us to discuss the dynamical characteristics and generation mechanism of Es.

Implementation of innovative aeronautical communication, navigation and surveillance (CNS) systems

This paper introduces implementation of innovative Satellite Communication, Navigation and Surveillance (CNS) systems in function of Global Satellite Augmentation System (GSAS) integrated by the current and new projected Regional Satellite Augmentation System (RSAS) worldwide. The satellite communication and navigation systems are presently in use, however the main aspect of any hypothetical RSAS network is implementation of satellite surveillance system employing previous and new CNS solutions for improved Air Traffic Control (ATC) and Air Traffic Management (ATM) in all phases of flight, approaching to airports and during landing. The CNS network also enhances safety and emergency systems, transport security and control of transportation freight, logistics and the security of the crew and passengers onboard aircraft. The proposals for modern multifunctional space segment, DVB-RCS network, RSAS infrastructure, Satellite Automatic Dependent Surveillance-Broadcast SADS-B system for surveillance and movement guidance and control are also discussed as special solutions in airports environments.

Miniaturized microstrip diplexer with high performance using a novel structure for wireless L-band applications

This paper presents a high-performance microstrip diplexer based on the coupled triangular microstrip cells. The proposed diplexer has a compact size of 0.018 λg2. It is designed to work at 1 GHz for aeronautical military systems and aeronautical navigation and 1.3 GHz for active sensors, GNSS repeaters, radiolocation, and satellite systems. The low insertion and return losses better than 0.21 dB and 25 dB respectively, are obtained at both channels. Another advantage of this diplexer is high isolation of 40 dB between its channels. Moreover, the 1st, 2nd and 3rd harmonics are suppressed with a maximum level of − 30 dB. The designing process is based on proposing an LC model of a novel microstrip cell. Then, the effective parameter on the resonance frequency is found. To verify the designing method, the introduced diplexer is simulated, fabricated and measured. The simulation results are in a good agreement with the measurements.

Ionospheric Gradient Threat Mitigation in Future Dual Frequency GBAS

The Ground Based Augmentation System (GBAS) is a landing system for aircraft based on differential corrections for the signals of Global Navigation Satellite Systems (GNSS), such as GPS or Galileo. The main impact on the availability of current single frequency systems results from the necessary protection against ionospheric gradients. With the introduction of Galileo and the latest generation of GPS satellites, a second frequency is available for aeronautical navigation. Dual frequency methods allow forming of ionospheric free combinations of the signals, eliminating a large part of the ionospheric threats to GBAS. However, the combination of several signals increases the noise in the position solution and in the calculation of error bounds. We, therefore, developed a method to base positioning algorithms on single frequency measurements and use the second frequency only for monitoring purposes. In this paper, we describe a detailed derivation of the monitoring scheme and discuss its implications for the use in an aviation context.

Dual Resonant Microstrip Patch Antenna Design employing triangular slotted substrate for Active Satellite Sensors and Aeronautical Navigation applications

Dual Resonant Microstrip Patch Antenna Design employing triangular slotted substrate for Active Satellite Sensors and Aeronautical Navigation applications

Compact asymmetric coplanar strip fed Sinc shaped monopole antenna for multiband applications

A compact asymmetric coplanar strip fed Sinc shaped monopole antenna suitable for multifrequency operations is proposed for portable wireless devices. The proposed Sinc shaped monopole antenna with truncated half ground plane operates at three frequency bands, 2110–2380, 4180–4600, and 5200–5678 MHz, showing fractional impedance bandwidths of 12, 9, and 8.8%, respectively, suitable for Universal Mobile Telecommunications System, Long Term Evolution handheld devices, Worldwide Interoperability for Microwave Access, Wireless Local Area Network, Hyperlan-2, and aeronautical navigation applications. Proposed antenna shows a dual mode of polarization. Finally a prototype model is developed for a typical configuration and the simulated results are validated experimentally.

A Compact Multiband Hybrid Fractal Antenna for Multistandard Mobile Wireless Applications

This paper presents a compact Multiband hybrid fractal antenna designed for mobile wireless applications it has planar structure and suitable for mobile applications at low cost. The proposed antenna structure is obtained by integrating a Koch curve and Minkowski curve. It exhibits multiband behavior, acceptable values of return loss, VSWR and gain in-spite of its compact size and less complexity. The proposed antenna design has been examined up to 2nd iteration of the new fractal geometry. The simulated results exhibited seven bands of operation covering some important frequency bands like GPS (L1 = 1227.60 MHz), bluetooth (2.41---2.49 GHz) of ISM band, WLAN 802.11 a/b (5.15---5.35 GHz) and other bands covers applications like mobile/fixed satellite and aeronautical navigation (3.876---4.375, 6.6188---7.0045, 7.9698---8.3373 and 9.1648---9.6214 GHz). Proposed antenna is designed by using scripting method of HFSS using MATLAB.

Comparison of the Radio Frequency Interference (RFI) in the Region of Solar Burst Type III Data at Selected CALLISTO Network

Compact Astronomical Low-frequency, Low-cost Instrument for Spectroscopy in Transportable Observatories (CALLISTO) is a global network of spectrometer system with the purpose to observe the Sun’s activities. There are 25 stations that are used for this purpose. Radio Frequency Interference (RFI) is a major obstacle when performing observation with CALLISTO. We have confirmed at least 2 stations out of 10 stations with a complete overview spectral (OVS) made available to us showed clear detection of these consistent types of RFI for each specific region. In Malaysia, these RFI are also clearly detected. The major RFI affecting CALLISTO within radio astronomical windows below 1 GHz are local electronic system specifically radio navigation (at 73.1 MHz and 75.2 MHz), broadcasting (at (i) 151 MHz, (ii) 151.8 MHz and 152 MHz), aeronautical navigation (at (i) 245.5 MHz, (ii) 248.7 MHz and (iii) 249 MHz and fixed mobile at (i) 605 MHz, (ii) 608.3 MHz, (iii) 612.2 MHz, (iv) 613.3 MHz). It is obviously showed that all sites within this region are free from interference at 320-330 MHz and is the best specific region to be considered for solar burst monitoring. We also investigate the effect of RFI on detection of solar burst. We have considered type III solar bursts on 9th March 2012 in order to measure the percentage of RFI level during the solar burst. The RFI level is as low as 6.512% to 80.769% above solar burst detection.

Comparison of the Radio Frequency Interference (RFI) in the Region of Solar Burst Type III Data at Selected CALLISTO Network

Compact Astronomical Low-frequency, Low-cost Instrument for Spectroscopy in Transportable Observatories (CALLISTO) is a global network of spectrometer system with the purpose to observe the Sun’s activities. There are 25 stations that are used for this purpose. Radio Frequency Interference (RFI) is a major obstacle when performing observation with CALLISTO. We have confirmed at least 2 stations out of 10 stations with a complete overview spectral (OVS) made available to us showed clear detection of these consistent types of RFI for each specific region. In Malaysia, these RFI are also clearly detected. The major RFI affecting CALLISTO within radio astronomical windows below 1 GHz are local electronic system specifically radio navigation (at 73.1 MHz and 75.2 MHz), broadcasting (at (i) 151 MHz, (ii) 151.8 MHz and 152 MHz), aeronautical navigation (at (i) 245.5 MHz, (ii) 248.7 MHz and (iii) 249 MHz and fixed mobile at (i) 605 MHz, (ii) 608.3 MHz, (iii) 612.2 MHz, (iv) 613.3 MHz). It is obviously showed that all sites within this region are free from interference at 320-330 MHz and is the best specific region to be considered for solar burst monitoring. We also investigate the effect of RFI on detection of solar burst. We have considered type III solar bursts on 9th March 2012 in order to measure the percentage of RFI level during the solar burst. The RFI level is as low as 6.512% to 80.769% above solar burst detection.

A Terrain Referenced UAV Localization Algorithm Using Binary Search Method

This study focuses on localization of Unmanned Aerial Vehicles (UAV) since permanent navigation has vital significance to support position information and to avoid getting lost. Actually, there exist effective aeronautical navigation systems in use. Inertial Navigation System (INS) and Global Positioning System (GPS) are two representatives of the most common systems utilized in traditional aerial vehicles. However, an alternative supporter system for UAVs should be mentioned since INS and GPS have serious deficiencies for UAVs such as accumulated errors and satellite signal loss, respectively. Such handicaps are coped with integrating these systems or exploiting other localization systems. Terrain Referenced Navigation (TRN) could be a good alternative as a supporter mechanism for these main systems. This study aims to localize a UAV accurately by using only the elevation data of the territory in order to simulate a TRN system. Application of the methodology on a real UAV is also considered for the future. Thus assumptions and limitations are designed regarding the constraints of real systems. In order to represent terrain data, Digital Elevation Model (DEM) with original 30 meter-resolution (Eroglu and Yilmaz 2013) and also synthetically generated 10 meter-resolution maps are utilized. The proposed method is based on searching the measured elevation values of the flight within the DEM and makes use of simulation techniques to test the accuracy and the performance. The whole system uses sequences of elevation values with a predefined length (i.e. profile). Mainly, all possible profiles are generated and stored before the flight. We identify, classify and sort profiles to perform search operations in a small subset of the terrain. During the flight, a measured flight profile is searched by the Binary search method (Eroglu 2013) within a small neighborhood of corresponding profile set.