Air Traffic Control Radar Research Articles

New algorithms for estimating the impact of wind turbines on telecommunication services

The estimation of the potential impact of a wind farm on the existing telecommunication services allows the modification of the wind farm layout or the planning of alternative solutions to guarantee the installation of a new wind farm without disturbing the surrounding services. This paper describes the development of new algorithms for the evaluation of the effect of a wind farm on telecommunication services (Air Traffic Control radars, Weather radars, radio links and radio navigation aids), and presents representative examples of impact studies. The novelty of these algorithms is that they estimate the safeguarding areas that should be avoided in the wind farm deployment, and therefore, they can be applied without a previous definition of the wind turbine locations. Therefore, results consist on the set of locations where a wind turbine might interfere in a specific service. These results are represented as visual masks on the terrain, easy to be used on GIS systems or Google Earth, and they are easy to combine with other constraints or datasets used in the wind farm design process (wind data, terrain slope, environmental protected areas, etc.). These algorithms will contribute to simplify and reduce the time required in the wind farm design process.

A Specific Emitter Identification System Design for Crossing Signal Modes in the Air Traffic Control Radar Beacon System and Wireless Devices.

To improve communication stability, more wireless devices transmit multi-modal signals while operating. The term 'modal' refers to signal waveforms or signal types. This poses challenges to traditional specific emitter identification (SEI) systems, e.g., unknown modal signals require extra open-set mode identification; different modes require different radio frequency fingerprint (RFF) extractors and SEI classifiers; and it is hard to collect and label all signals. To address these issues, we propose an enhanced SEI system consisting of a universal RFF extractor, denoted as multiple synchrosqueezed wavelet transformation of energy unified (MSWTEu), and a new generative adversarial network for feature transferring (FTGAN). MSWTEu extracts uniform RFF features for different modal signals, FTGAN transfers different modal features to a recognized distribution in an unsupervised manner, and a novel training strategy is proposed to achieve emitter identification across multi-modal signals using a single clustering method. To evaluate the system, we built a hybrid dataset, which consists of multi-modal signals transmitted by various emitters, and built a complete civil air traffic control radar beacon system (ATCRBS) dataset for airplanes. The experiments show that our enhanced SEI system can resolve the SEI problems associated with crossing signal modes. It directly achieves 86% accuracy in cross-modal emitter identification using an unsupervised classifier, and simultaneously obtains 99% accuracy in open-set recognition of signal mode.

Impact of Mode-S Enhanced Surveillance Weather Observations on Weather Forecasts over the MetCoOp Northern European Model Domain

Abstract Meteorological Cooperation on Operational Numeric Weather Prediction (MetCoOp) is a northern European collaboration on operational numerical weather prediction based on a common limited-area, kilometer-scale ensemble system. The initial states of this model are produced using a three-dimensional, variational, data assimilation scheme utilizing a large number of observations from conventional in situ measurements, weather radars, global navigation satellite systems, advanced scatterometer data, and satellite radiances. Since 2019, the MetCoOp system was enhanced by utilization of observations based on selective mode (Mode-S) enhanced surveillance (EHS) reports that are broadcast by aircraft in response to interrogation from air traffic control radar. These observations, obtained from the European Meteorological Aircraft Derived Data Center, are used to derive indirect information of atmospheric wind speed and temperature. The use of these observations compensated for the considerably reduced number of direct aircraft observations encountered as an effect of the COVID-19 pandemic. The MetCoOp observation handling system is described, with emphasis on Mode-S EHS data. The quality of these observations is evaluated, and we show that they are suitable to be used in MetCoOp data assimilation. The impact on average forecast verification scores of the additional Mode-S EHS data is slightly positive. The benefit of using Mode-S EHS was demonstrated for an individual case and also a demonstration of utilizing the Stockholm Arlanda receiver data in assimilation has been performed.

A Single-Layer S/X- Band Shared Aperture Antenna with MIMO Characteristics at X-Band for Airborne Synthetic Aperture Radar Applications

New frequencies can be supported with very effective space use by using the shared aperture antenna This work presents on designing a dual-banddual-polarized (DBDP) S/X-band shared aperture antenna (SAA) for synthetic aperture radar (SAR) applications operating at S-band frequency (3.2 GHz) and X-band frequency (9.65 GHz). The single-layer SAA DBDP S-band antenna is designed in a square-shaped patch with coaxial feeding in both vertical and horizontal polarization. The X-band antenna design is in 1 × 3 vertical series with microstrip feeding and arranged at four corners of the proposed antenna. The S-band antenna is mainly used for airborne applications such as air traffic control and surface ship radar. In contrast, the X-band antenna application is maritime vessel traffic control, defense tracking, and vehicle speed detection for law enforcement. To verify the antenna, a prototype is fabricated and measured with s-parameters. The proposed design exhibits that the gain of the S-band is 7.2 dB and for the X-band is 12.4 dB, and the isolation is achieved more than −35 dB, and for this antenna, we achieved a bandwidth of 0.12 GHz for S-band and 0.27 GHz for X-band. However, the X-band antenna is a multi-input and multioutput antenna that is to be validated by using MIMO characteristic parameters such as envelope correlation coefficient (ECC), diversity gain (DG), channel capacity loss (CCL), mean effective gain, and mutual coupling. The MIMO characteristic parameter of X-band antenna values is found to be in a similar manner to both simulated and measured values. For this X-Band antenna, ECC, DG, CCL, and mutual coupling were achieved as below 0.05, 9.5 dB, 0.5 bps/Hz, and −30 dB to −55 dB, respectively. The total size of the antenna is 100 mm × 100 mm × 1.6 mm.

"Conical" Frustum Multi-Beam Phased Arrays for Air Traffic Control Radars.

The design of conical frustum phased array antennas for air traffic control (ATC) radar systems is addressed. The array architecture, which is controlled by a fully digital beam-forming (DBF) network, is composed by a set of equal vertical modules. Each module consists of a linear sparse array that generates on receive multiple instantaneous beams pointing along different directions in elevation. To reach the best trade-off between the antenna complexity (i.e., minimum number of array elements and/or radio frequency components) and radiation performance (i.e., matching a set of reference patterns), the synthesis problem is formulated in the Compressive Sampling (CS) framework. Then, the positions of the array elements and the complex excitations for generating each single beam are jointly determined through a customized version of the Bayesian CS (BCS) tool. Representative numerical results, concerned with ideal as well as real antenna models, are reported both to validate the proposed design strategy and to assess the effectiveness of the synthesized modular sparse array architecture also in comparison with conventional arrays with uniformly-spaced elements.

Research and Comparative Analysis of the Accuracy in Determining the Parameters of the Position of Aircraft by Air Traffic Control Radars Avia-W and GCA-2000

Abstract The aim of the article “Research and comparative analysis of the accuracy in determining the parameters of the position of aircraft by air traffic control radars Avia-W and GCA-2000” is to test the difference in determining the parameters of the position of aircraft objects by radars used at Dęblin airfield. In particular, the paper presents the results of positioning accuracy, azimuth and distance accuracy for two radars: GCA-2000 and Avia-W.

A Hybridized IT2FS-DEMATEL-AHP-TOPSIS Multi-Criteria Decision Making Approach: Case Study of Selection and Evaluation of Criteria for Determination of Air Traffic Control Radar Position

In this paper the criteria for selection of air traffic control (ATC) radar position that provide successfully fulfilled role of radar in air traffic management are determined and evaluated. Using the questionnaire, experts determined the initial criteria for selecting the radar position. Furthermore, the hybridized DEMATEL-AHP-TOPSIS model was modified by using the interval type-2 fuzzy sets (IT2FS). Less important criteria were eliminated by using the IT2FS-DEMATEL method, the prioritization of the final criteria was carried out by using the IT2FS-AHP method and a multi-criteria decision making model was proposed. Of the four ATC radar positions offered, the optimal position was selected by using the IT2FS-TOPSIS method. Validation of model was carried out by using Fuzzy and the IT2FS modified methods: TOPSIS, COPRAS and MABAC. A sensitivity analysis was carried out through 36 scenarios of changes in the criteria’s weights.

MAP SERVER FOR VISUALIZING AIR TRAFFIC BASED ON DATA FROM A REMOTE PSEUDO RADAR

In order to ensure the safety of aircraft operating in airspace, air traffic controllers apply a number of rules recommended by the ICAO, known as "separation rules". Previously using essentially the calculation of the estimates, they are based today on the visualization of the traffic through Air Traffic Management Systems. Traffic data comes from several sources. These include radar data from Air Traffic Control Radars. The objective of this work is to simulate, using a web map server, the evolution of air traffic: positions and flight levels of aircraft over time based on radar data. For this we use three parts. The first part, the pseudo radar, is a remote radar data server that, depending on the time, sends the data to the map server that is the second part. The latter receives this data and combines it with other geographical and cartographic data and sends them in turn to the client via the web server. The client, a simple interface finally displays the positions of aircraft on screen.

3-D tracking of air targets using a single 2-D radar

Three-dimensional (3-D) aircraft tracking using two-dimensional (2-D) radar measurements is a common task in air traffic control (ATC) systems. In this paper, a new algorithm using a 2-D ATC radar, called HPEKF with probabilistic data association (HP-PDA-EKF), is proposed for aircraft tracking with false alarms and missed detections. An improved filter initialization technique is also proposed to yield better estimates. To mitigate the degradation in altitude estimation accuracy with increasing aircraft distance, ATC waypoints are used as extra measurement information, and a new height-parametrized cascaded PDA filter (HP-CPDAF) algorithm is proposed to make use of waypoints. The posterior Cramér–Rao lower bounds (PCRLBs) quantifying the achievable accuracies of these two filters are derived. Simulations are carried out to analyze the relationship between aircraft distance, waypoint accuracy and state estimation accuracy. The viability of using a single 2-D radar for 3-D ATC and the usefulness of the proposed algorithms under different operating conditions are analyzed. Simulation results demonstrate the validity of the proposed algorithms.

Radar Signal Parameters Estimation Using Phase Accelerogram in the Time-Frequency Domain

Radar signal parameter estimation, in the context of the reconstruction of the received signal in a passive radar utilizing other radars as a source of illumination, is one of the fundamental steps in the signal processing chain in such a device. The task is also a crucial one in electronic reconnaissance systems, e.g., electronic intelligence systems. In order to obtain accurate results it is important to measure, estimate and precisely reconstruct the considered signal. Then it is necessary to identify it. The following paper presents a new approach to the estimation of the phase parameters of radar pulses. The novel method of chirp-rate estimation is described and used to analyze such signals. First, the method was examined by simulated pulses, and then true measured signals collected from the air traffic control radar were utilized. Using the phase accelerogram, an instantaneous chirp-rate was computed thanks to three novel estimators and the results were compared to results acquired using a different, already known, and estimation method of the phase coefficients based on matching filtration– extended generalized chirp transform.

Air traffic control radar interference event in the Galileo E6 band: Detection and localization

The Galileo E6 band operates at a nonprimary frequency band within the L‐band. This presents challenging situations in the vicinity of other, legitimate, radiolocation services. This is the case for Air Traffic Control (ATC) radar, which is seen as an in‐band–pulsed interference by a GNSS receiver. This paper provides a detailed study of the impact of such interference, as well as localization approaches. Particularly, the paper describes the ATC jamming event captured on a GNSS permanent station, its effects on a real receiver, and how it was tracked to localize the source of interference. An ultra low‐cost array‐based solution is prototyped, based on commercial off‐the‐shelf devices, that implements a two‐element array. Experimental results are shown and discussed using real data, validating the localization performance of the prototype.

Random forest‐based track initiation method

In this study, a novel method based on the random forest is presented to solve the problem of track initiation in the air-traffic-control (ATC) radar system. ATC radar is the most common civilian surveillance radar. There are dense targets with different moving models in its observation area. When implementing track initiation, previous heuristic methods often fail to meet its high requirements for target detection rate and false track suppression. In the method proposed in this study, the general track initiation problem is modelled as a two-category classification problem of measurement sequences. From the historical data, the sample set is constructed. The classification function is derived by Breiman's random forest. Simulation experiments and measurement experiments show that the proposed method outperforms conventional heuristic methods in the scene of the ATC system.

Deep Learning Classification of 3.5 GHz Band Spectrograms with Applications to Spectrum Sensing.

In the United States, the Federal Communications Commission has adopted rules permitting commercial wireless networks to share spectrum with federal incumbents in the 3.5 GHz Citizens Broadband Radio Service band. These rules require commercial systems to vacate the band when sensors detect radars operated by the U.S. military; a key example being the SPN-43 air traffic control radar. Such sensors require highly-accurate detection algorithms to meet their operating requirements. In this paper, using a library of over 14,000 3.5 GHz band spectrograms collected by a recent measurement campaign, we investigate the performance of thirteen methods for SPN-43 radar detection. Namely, we compare classical methods from signal detection theory and machine learning to several deep learning architectures. We demonstrate that machine learning algorithms appreciably outperform classical signal detection methods. Specifically, we find that a three-layer convolutional neural network offers a superior tradeoff between accuracy and computational complexity. Last, we apply this three-layer network to generate descriptive statistics for the full 3.5 GHz spectrogram library. Our findings highlight potential weaknesses of classical methods and strengths of modern machine learning algorithms for radar detection in the 3.5 GHz band.

A Method for the Analysis of Interference from DME to ATCRBS in the Time Domain

Analysis of the coexistence of two or more types of equipment is increasingly important. However, at present studies on the analysis method in the time domain are scant. Therefore, the aim of this paper is to explore the characteristics of signals and relations between interfering and desired signals in the time domain. Based on the periodicity of a signal, this paper presents a Periodic Pulse Overlap Method (PPOM). Using PPOM to analyze the interference from Distance Measuring Equipment (DME) to Air Traffic Control Radar Beacon System (ATCRBS) in the time domain, we obtain almost the same result as that based on the Monte Carlo Method (MCM). Furthermore, we discover the measures to reduce or even avoid interference, such as changing the Pulse Recurrence Frequency (PRF), adjusting the difference of initial time, and switching the operating modes of the equipment.

Solar radio emission as a disturbance of aeronautical radionavigation

On November 4th, 2015 secondary air traffic control radar was strongly disturbed in Sweden and some other European countries. The disturbances occurred when the radar antennas were pointing at the Sun. In this paper, we show that the disturbances coincided with the time of peaks of an exceptionally strong (∼105 Solar Flux Units) solar radio burst in a relatively narrow frequency range around 1 GHz. This indicates that this radio burst is the most probable space weather candidate for explaining the radar disturbances. The dynamic radio spectrum shows that the high flux densities are not due to synchrotron emission of energetic electrons, but to coherent emission processes, which produce a large variety of rapidly varying short bursts (such as pulsations, fiber bursts, and zebra patterns). The radio burst occurs outside the impulsive phase of the associated flare, about 30 min after the soft X-ray peak, and it is temporarily associated with fast evolving activity occurring in strong solar magnetic fields. While the relationship with strong magnetic fields and the coherent spectral nature of the radio burst provide hints towards the physical processes which generate such disturbances, we have so far no means to forecast them. Well-calibrated monitoring instruments of whole Sun radio fluxes covering the UHF band could at least provide a real-time identification of the origin of such disturbances, which reports in the literature show to also affect GPS signal reception.

A Compact Hybrid Multiband Antenna for Wireless Applications

This paper presents design of Compact Hybrid Multiband Antenna (CHMA) for various wireless applications. The projected antenna geometry is designed by integrating moore and gosper curves and their characteristics are investigated. The antenna reveals multiband behavior along with satisfactory values of all performance parameters in spite of less complexity and compact size. The small cost simulated antenna is designed on FR4 substrate, which shows gain of 16.65 dB along with return loss of −18.39 dB and VSWR of 1.27 at 2.4 GHz frequency. Simulated results exhibits six operational bands that cover various significant frequency bands like Air traffic control RADAR (0.96–1.215 GHz), GSM (1.85–1.99 GHz), Wi-Fi (2.4 GHz for 802.11b, 802.11n and 802.11g), WLAN 802.11a/b (5.15–5.35 GHz), WLAN 802.11ac (5.5 GHz) and military satellite applications (7.9–8.4 GHz). The simulation results of antenna in terms of antenna parameters like Return Loss (RL), radiation pattern, Voltage Standing Wave Ratio (VSWR) and Gain (G) are evaluated using HFSS (High Frequency Structural Simulator); v13 software. The hybrid antenna is designed with line feed having compact size of 55 mm (L) × 60 mm (W) × 1.6 mm (H) on FR4_epoxy substrate with er 4.4. Both simulated and measured results are analyzed, compared and presented in the paper. Proposed antenna operates from 0.98 to 8.1 GHz and covers L, S, C and X band applications.

Weather radar: Operation and phenomenology

Radar is an indispensable technology in areas of defense, air traffic control (ATC), and weather surveillance. The usual goal of defense and air traffic control radars is to detect and track individual targets; in contrast, the target of weather radars may stretch hundreds of kilometers. The meteorology, defense, and ATC communities typically publish research in different venues, and each community has a vernacular and characteristic ways of approaching problems. The goals of this article are twofold. Its primary goal is to summarize typical weather radar systems and define associated jargon in terms more familiar to other radar communities. The second goal is to provide a detailed discussion of the physical scattering phenomenology exploited specifically in radar meteorology. Furthermore, while there are a number of operational weather radars, we focus throughout much of this article on the most common weather radar, Weather Surveillance Radar 1988 Doppler (WSR-88D), as a canonical example, because much of the current research and phenomenological analysis are based on its operational parameters.

Sharing Spectrum UE LTE and Air-Traffic Control Radars in 800 MHz Band

The need to ensure LTE network coverage in sparsely populated and rural areas of Europe (ITU Region 1) has led to a massive use of 800 MHz band (band 20) with its good characteristics of radio wave propagation in LTE networks. However, the frequency band of 800 MHz called “digital dividend” in Region 1 is used on a primary basis not only by the terrestrial mobile service but also by air-traffic control radars (ATCR) that can lead to the creation of harmful interferences at the receivers’ input of ATCR. Such scenarios of mutual interferences became possible after granting licenses for LTE-800 frequencies to operators in such countries as Azerbaijan, Kazakhstan, Russia and other CIS countries, so this problem should be solved by operators at the deployment of LTE-800 networks in airports and areas close to them. So far, for such scenarios the ITU and CEPT have not formulated criteria for interference protection. The proposed protection criteria for receivers of ATCR from user devices’ interferences of LTE-800 networks were tested by experimental studies and can provide a solution to the electromagnetic compatibility (EMC) problem in a complex electromagnetic environment of modern airports and cross-order coordination of 800 MHz frequency bands in Region 1.

Spectrum sharing between communications and ATC radar systems

Increasing demand for wireless communications services within the spectrum bands that are most conducive to operating cellular and mobile broadband systems is aggravating frequency congestion within the electromagnetic spectrum. Primary–secondary spectrum sharing can be exploited to alleviate spectrum congestion by allowing secondary systems to access opportunistically the allotted frequency band of a primary system. In this study, the feasibility of spectrum sharing between air traffic control (ATC) radar and long-term evolution (LTE) wireless communications systems is investigated through waveform-level simulations and link budget analyses. Numerical results show that with moderate frequency and range separation, spectrum sharing between a scanning ATC radar and a single LTE cell in L-band is possible, though both systems are ultimately subject to quantified performance degradations due to the impact each has on the other.

Chirp Signals and Noisy Waveforms for Solid-State Surveillance Radars

Since the advent of “pulse compression” radar, the “chirp” signal (Linear Frequency Modulation, LFM) has been one of the most widely used radar waveforms. It is well known that, by changing its modulation into a Non-Linear Frequency Modulation (NLFM), better performance in terms of Peak-to-Sidelobes Ratio (PSLR) can be achieved to mitigate the masking effect of nearby targets and to increase the useful dynamic range. Adding an appropriate amplitude modulation, as occurs in Hybrid-NLFM (HNLFM), the PSLR can reach very low values (e.g., PSLR < −60 dB), comparable to the two-way antenna sidelobes in azimuth. On the other hand, modern solid-state power amplifier technology, using low-power modules, requires them to be combined at the Radio Frequency (RF) stage in order to achieve the desired transmitted power. Noise Radar Technology (NRT) represents a valid alternative to deterministic waveforms. It makes use of pseudo-random waveforms—realizations of a noise process. The higher its time-bandwidth (or BT) product, the higher the (statistical) PSLR. With practical BT values, the achievable PSLR using pure random noise is generally not sufficient. Therefore, the generated pseudorandom waveforms can be “tailored” (TPW: Tailored Pseudorandom Waveforms) at will through suitable algorithms in order to achieve the desired sidelobe level, even only in a limited range interval, as shown in this work. Moreover, the needed high BT, i.e., the higher time duration T having fixed the bandwidth B, matches well with the low power solid-state amplifiers of Noise Radar. Focusing the interest on (civil) surveillance radar applications, such as ATC (Air Traffic Control) and marine radar, this paper proposes a general review of the two classes of waveforms, i.e., HNLFM and TPW.