Air Traffic Control Radar Research Articles

Quantitative Risk Evaluation of Obstacle Limitation Surfaces for Final Approaches at Airports

Obstacle limitation surfaces (OLS) are the main safeguard against objects that can pose a hazard to aircraft operations at and around airports. The standard dimensions of the most of those surfaces were estimated using the pilot’s experience at the time when they were included in the standard documents. As a result, some of these standards may have been overestimated, while others may not provide an adequate level of safety. With airports moving to the Safety Management System (SMS) approach to design and operations safety, proper evaluation of the level of safety provided by OLS at specific sites becomes important to airport operators. Therefore, this study attempts to collect actual flight path data using information provided by air traffic control radars and to construct a methodology to assess the probability of aircraft deviating from their approach path. This will be helpful to estimate safe and efficient standard dimensions of the OLS and assess the risk level of objects to the aircraft operations around airports. The methodology is presented using the aircraft trajectories of approaches at Ottawa International Airport (CYOW). Estimated dimensions of Code 3 approach surfaces also are presented.

Impact analysis of wind farms on telecommunication services

Abstract Wind power is one of the fastest-growing technologies for renewable energy generation. Unfortunately, in the recent years some cases of degradation on certain telecommunication systems have arisen due to the presence of wind farms, and expensive and technically complex corrective measurements have been needed. This paper presents a comprehensive review on the impact of wind turbines on the telecommunication services. The paper describes the potential affections to several telecommunication services, the methodology to evaluate this impact, and mitigation measures to be taken in case of potential degradation, both preventive and corrective. The telecommunication services included in this review are those that have demonstrated to be more sensitive to nearby wind turbines: weather, air traffic control and marine radars, radio navigation systems, terrestrial television and fixed radio links. The methods described in the paper allow a thorough case-by-case analysis before the wind farm is installed, taking into account the particular features of each installation and the involved services. The prediction of the potential impact makes it possible to propose alternative solutions in order to assure the coexistence between the wind turbines and the telecommunication services.

Design and Application of Real-Time Flight Information Acquisition System

In the radar target validation systems, the flight information as an important external information source occupies the irreplaceable position. However, in the resent researches, how to obtain the flight information stays focused and unsolved. The Real-time Multi-task Flight Information Acquisition System we designed and realized in this paper could obtain the flight information in real time and provide the real-time, reliable, detailed and complete flight information for the detective area. This system has already successfully used in Airway-nonairway Classification in an ATCRS (Air Traffic Control Radar System).

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.

Quality assessment of Automatic Dependent Surveillance Contract (ADS-C) wind and temperature observation from commercial aircraft

Abstract. Aircraft observations of wind and temperature are very important for upper air meteorology. In this article, the quality of the meteorological information of an Automatic Dependent Surveillance-Contract (ADS-C) message is assessed. The ADS-C messages broadcast by the aircraft are received at air traffic control centres for surveillance and airline control centres for general aircraft and dispatch management. A comparison is performed against a global numerical prediction (NWP) model and wind and temperature observations derived from Enhanced Surveillance (EHS) air-traffic control radar which interrogates all aircraft in selective mode (Mode-S EHS). Almost 16 000 ADS-C reports with meteorological information were compiled from the Royal Dutch Airlines (KLM) database. The length of the data set is 76 consecutive days and started on 1 January 2011. The wind and temperature observations are of good quality when compared to the global NWP forecast fields from the European Centre for Medium-Range Weather Forecasts (ECMWF). Comparison of ADS-C wind and temperature observations against Mode-S EHS derived observations in the vicinity of Amsterdam Airport Schiphol shows that the wind observations are of similar quality and the temperature observations of ADS-C are of better quality than those from Mode-S EHS. However, the current ADS-C data set has a lower vertical resolution than Mode-S EHS. High vertical resolution can be achieved by requesting more ADS-C when aircraft are ascending or descending, but could result in increased data communication costs.

MQ-9 Unmanned Aircraft Responsiveness to Air Traffic Controller Commanded Maneuvers: Implications for Integration into the National Airspace System

Unmanned Aircraft Systems (UAS) integration into the National Airspace System (NAS) will require overcoming numerous challenges, including evaluating the responsiveness of Unmanned Aircraft (UA) to Air Traffic Control (ATC) commands. Since developing a complete understanding requires a series of investigations, the purpose herein is to provide a foundation for future studies.An MQ-9 UAS simulator was connected to a UFA ATC radar simulator and scripts were flown by Certified Flight Instructor (Instrument) (CFI(I)) rated pilots to measure response and maneuver completion times. The MQ-9 was flown in stick-and-rudder mode to emulate manned aircraft (MA) and provides a baseline for future studies.Response and heading-change-maneuver-completion times for the simulated MQ-9 UAS were comparable to those estimated for MA. Use of strict maneuver-completion requirements, however, resulted in a high bias in heading-change-maneuver-completion times. Suggestions for future work are provided.

Trial Results on Bistatic Passive Radar Using Non-Cooperative Pulse Radar as Illuminator of Opportunity

Trial Results on Bistatic Passive Radar Using Non-Cooperative Pulse Radar as Illuminator of Opportunity The paper presents the concept of passive radar exploiting the active Air Traffic Control (ATC) radar as the source of illumination, and the primary results of the measurement campaign carried out at the DSP Laboratory of the Warsaw University of Technology. The system, built using commercial off the shelf components, was able to detect and track airliners landing at Warsaw airport. To verify the system accuracy the IFF mode S messages were recorded, providing ground truth of the observed planes.

An FPGA Based Architecture for Moving Target Indication (MTI) Processing Using IIR Filters

Design and implementation of an IIR filter based Moving Target Indication (MTI) processor is presented. IIR filters offer an advantage compared to FIR filters in terms of hardware resources but are prone to problems in implementation. These are variable overflows and accumulating error. This results in a need for calculation of range and error bounds for the filter variables. This paper presents a method for dealing with these issues and proposes a time shared architecture for the processor. The design is implemented on a Virtex-4SX35 device on the Xilinx Xtreme DSP kit. The processor is tested using unprocessed baseband data from a working TA-10K air traffic control radar.

Simulation of radar signal on wind turbine

This describes the radar signal features of a typical wind turbine and the simulation of the wind turbine signal based on a high resolution Doppler radar. The simulated signal is under-sampled with lower PRF to match an air traffic control (ATC) radar. The simulated signal is compared to the ATC radar data collected at two different sites. Remarkable similarities of the signal features are identified. These features may help to improve the primary radar detection and tracking performance in the future.

On Scientific Realism and Instrumentalism in Manoeuvring Target Modelling and Tracking

On Scientific Realism and Instrumentalism in Manoeuvring Target Modelling and Tracking The basic problem of tracking manoeuvring moving objects (e.g. aircrafts, ships) lies in unpredictability of object manoeuvres, with respect to the time of occurrence, duration and the type of trajectory. In this paper most representative methods of modelling and state estimation techniques applied to Manoeuvring Target Tracking (MTT) are briefly reviewed. Classification of existing approaches is made in the context of realistic and instrumentalistic paradigms of the philosophy of science. A practical example is also given that shows the impact of selecting models and estimation methods on the performance of the tracking filter for Air Traffic Control (ATC) radar.

High-resolution wind and temperature observations from aircraft tracked by Mode-S air traffic control radar

[1] Wind, temperature, and humidity observations from radiosonde and aircraft are the main sources of upper air information for meteorology. For mesoscale meteorology, the horizontal coverage of radiosondes is too sparse. Aircraft observations through Aircraft Meteorological Data Relay (AMDAR) sample an atmospheric profile in the vicinity of airports. However, not all aircraft are equipped with AMDAR or have the system activated. Observations inferred from an enhanced tracking and ranging (TAR) air traffic control radar can fill this gap. These radars follows all aircraft in the airspace visible to the radar for air traffic management. The TAR radar at Schiphol airport in Netherlands has a range of 270 km. This Mode-S radar contacts each aircraft every 4 s on which the transponder in the aircraft responds with a message that contains information on flight level, direction, and speed. Combined with the ground track of an aircraft, meteorological information on temperature and wind can be inferred from this information. Because all aircraft are required to respond to the TAR radar, the data volume is extremely large, being around 1.5 million observations per day. Note that there are no extra costs for this data link. The quality of these observations is assessed by comparison to numerical weather prediction (NWP) model information, AMDAR observations, and radiosonde observations. A preprocessing step is applied to enhance the quality of wind and temperature observations, albeit with a reduced time frequency of one observation of horizontal wind vector and temperature per aircraft per minute. Nevertheless, the number of observations per day is still very large. In this paper it is shown that temperature observations from Mode-S, even after corrections, are not very good; an RMS which is twice as large as AMDAR is observed when compared to NWP. In contrast to the temperature observations, the quality found for wind after correction and calibration is good; it is comparable to AMDAR, slightly worse than radiosonde but certainly very valuable for mesoscale NWP.

Measurement of electromagnetic fields generated by air traffic control radar systems with spectrum analysers

Air traffic control (ATC) primary radars are 'classical' radars that use echoes of radiofrequency (RF) pulses from aircraft to determine their position. High-power RF pulses radiated from radar antennas may produce high electromagnetic field levels in the surrounding area. Measurement of electromagnetic fields produced by RF-pulsed radar by means of a swept-tuned spectrum analyser are investigated here. Measurements have been carried out both in the laboratory and in situ on signals generated by an ATC primary radar.

The aversive effect of electromagnetic radiation on foraging bats: a possible means of discouraging bats from approaching wind turbines.

Large numbers of bats are killed by collisions with wind turbines and there is at present no accepted method of reducing or preventing this mortality. Following our demonstration that bat activity is reduced in the vicinity of large air traffic control and weather radars, we tested the hypothesis that an electromagnetic signal from a small portable radar can act as a deterrent to foraging bats. From June to September 2007 bat activity was compared at 20 foraging sites in northeast Scotland during experimental trials (radar switched on) and control trials (no radar signal). Starting 45 minutes after sunset, bat activity was recorded for a period of 30 minutes during each trial and the order of trials were alternated between nights. From July to September 2008 aerial insects at 16 of these sites were sampled using two miniature light-suction traps. At each site one of the traps was exposed to a radar signal and the other functioned as a control. Bat activity and foraging effort per unit time were significantly reduced during experimental trials when the radar antenna was fixed to produce a unidirectional signal therefore maximising exposure of foraging bats to the radar beam. However, although bat activity was significantly reduced during such trials, the radar had no significant effect on the abundance of insects captured by the traps.

Improving weather radar observations using pulse‐compression techniques

AbstractPulse‐compression techniques have been used for many years to increase sensitivity and range resolution in military and air traffic control radar systems. However, their application to ground‐based weather radar has, so far, been very limited and restricted to research applications. This article describes the practical implementation of pulse compression using non‐linear frequency modulation (NLFM) in a commercial digital processor/receiver and demonstrates its application to operational weather radars.Three case studies are presented, including the first application of pulse compression to ground‐based travelling wave tube (TWT) weather radars. TWT radars use coherent transmitters with relatively low peak power compared to traditional magnetron or klystron systems, so in this case the sensitivity gain is crucial. The cases are from two different operational radars and illustrate the improved range resolution and sensitivity gain obtained using NLFM pulses compared to traditional simple pulses. Observations obtained using NLFM 40 µs pulses were nearly 15 dB more sensitive than those recorded with lower resolution using 1 µs simple pulses. A comparison of concurrent precipitation observations obtained with a TWT radar using pulse compression and low peak power (NLFM 40 µs and 8 kW) and a nearby traditional magnetron weather radar (2 µs and 250 kW) is also presented. The higher power system was more sensitive by less than 4 dB, but the improved resolution in the pulse compression allowed for enhanced Doppler filtering of ground clutter. Copyright © 2007 Royal Meteorological Society

Bats avoid radar installations: could electromagnetic fields deter bats from colliding with wind turbines?

Large numbers of bats are killed by collisions with wind turbines, and there is at present no direct method of reducing or preventing this mortality. We therefore determine whether the electromagnetic radiation associated with radar installations can elicit an aversive behavioural response in foraging bats. Four civil air traffic control (ATC) radar stations, three military ATC radars and three weather radars were selected, each surrounded by heterogeneous habitat. Three sampling points matched for habitat type and structure, dominant vegetation species, altitude and surrounding land class were located at increasing distances from each station. A portable electromagnetic field meter measured the field strength of the radar at three distances from the source: in close proximity (<200 m) with a high electromagnetic field (EMF) strength >2 volts/metre, an intermediate point within line of sight of the radar (200–400 m) and with an EMF strength <2 v/m, and a control site out of sight of the radar (>400 m) and registering an EMF of zero v/m. At each radar station bat activity was recorded three times with three independent sampling points monitored on each occasion, resulting in a total of 90 samples, 30 of which were obtained within each field strength category. At these sampling points, bat activity was recorded using an automatic bat recording station, operated from sunset to sunrise. Bat activity was significantly reduced in habitats exposed to an EMF strength of greater than 2 v/m when compared to matched sites registering EMF levels of zero. The reduction in bat activity was not significantly different at lower levels of EMF strength within 400 m of the radar. We predict that the reduction in bat activity within habitats exposed to electromagnetic radiation may be a result of thermal induction and an increased risk of hyperthermia.

Time-frequency method for detecting an accelerating target in sea clutter

The authors design a time-frequency (TF) method for use in high-frequency surface-wave radar (HFSWR) for detecting a small accelerating target in sea clutter. The clutter is modelled by pseudo targets moving with Bragg velocity towards and away from the radar. The design is based on the Wigner distribution (WD) defined by Chan (type-III WD, in our terminology) rather than the WD defined by Claasen and Mecklenbrauker (1980) (2times type-I WD, in our terminology). Like the type-I WD, the type-III WD also concentrates a chirp signal onto a straight line in the TF plane. The type-III WD has the following advantages: 1) Its range of unambiguously measurable frequencies (RUMF) is [-pi,pi] rad/s, whereas for the type-I WD the RUMF is [-pi/2,pi/2] rad/s. 2) It allows a target separated from the clutter by pi rad/s to be detected, whereas the type-I WD coalesces such a target with the clutter and thereby mask it. An ambiguity function (AF) was defined corresponding to the type-III WD and use it to derive a smoothed type-III WD that mitigates the clutter. The smoothed type-III WD method is applied to real radar data and shown to be superior to the conventional Fourier transform method. The advantages of the type-III WD over the type-I WD are also demonstrated. The design principles laid out in the paper can also be used to develop a TF method for use in air traffic control radar (ATCR) for detecting an accelerating target in land clutter

RFI detection and mitigation for microwave radiometry with an agile digital detector

A new type of microwave radiometer detector has been developed that is capable of identifying high and low levels of radio-frequency interference (RFI) and of reducing or eliminating its effect on the measured brightness temperatures. High-level, localized RFI can be easily identified by its unnatural appearance in brightness temperature imagery. Low-level or persistent RFI can be much more difficult to identify and filter out. The agile digital detector (ADD) can discriminate between RFI and natural thermal emission signals by directly measuring higher order moments of the signal than the variance that is traditionally measured. After detection, the ADD then uses spectral filtering methods to selectively remove the RFI. ADD performance is experimentally verified in controlled laboratory tests and in the field near a commercial air traffic control radar. High-level RFI is easily identified and removed. Very low level RFI contamination, with power levels as low as the radiometric measurement uncertainty of the radiometer, is also shown to be reliably detected and removed.

A study on high‐resolution target height estimation in multipath environment—subarray configuration

AbstractIt is well known that a large spike error and a bias error occur in the monopulse angle measurement process (of height estimation due to sea surface reflection or road surface reflection) when height estimation of a low‐altitude target is carried out with an air traffic control radar or a tracking radar with a monopulse antenna. In this paper, a target height estimation method is proposed that can seek the estimation object with only one parameter of the target height, even if fading prevention by frequency hopping and a subarray configuration of the array antenna based on the maximum likelihood estimation method is used. By means of computer simulation, the S/N dependence and equivalent earth radius error dependence of the target height estimation error are evaluated when the conventional ΣΔ monopulse method, the maximum likelihood estimation method without frequency hopping for four subarrays, and the proposed maximum likelihood estimation method with frequency hopping are used. Even though the evaluation is within the limited conditions, it is confirmed that the proposed method can estimate the target height while fading prevention is attempted in a multipath environment. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(11): 39–48, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10208

PEGASUS—Performance Experiments in Germany on ADS-B Using Mode S Extended Squitter

Future surveillance systems have to be capable of operating worldwide and to co-exist with other systems in the same frequency band. Extended Squitter is an ADS-B system which uses the same frequencies as current SSR (Secondary Surveillance Radar) systems (also called ATCRBS = Air Traffic Control Radar Beacon System). The German CAA, Deutsche Flugsicherung GmbH (DFS), and the U.S. Department of Transportation/Federal Aviation Administration (FAA) agreed to collaborate on a measurement activity in 2000 using Extended Squitter as the ADS-B medium. The Extended Squitter frequency 1090 MHz is actively being used for replies to secondary surveillance radars and for TCAS air-to-air surveillance. Frankfurt was chosen to perform the measurements under high interference conditions.The primary objective of the tests was the Extended Squitter performance measurement in the dense interference environment of Frankfurt. Both air-to-air and air-to-ground receptions were to be tested. For a good understanding of the results and to allow estimates for future environments, measuring the interference environment, the aircraft density and distribution was another objective. Results of these background measurements as well as of Extended Squitter performance in this specific environment are presented below.

Civil Marine Radar – A Fresh Look at Transmitter Spectral Control and Diversity Operation

This year marks a watershed in the design, production and operational use of Civil Marine Radar (CMR) as we know it. Tighter regulations for in-band spectral purity and out-of-band transmission, when coupled to a possible loss of S-band frequencies for both CMR and Air Traffic Control (ATC) radars, will seriously restrict the synergistic advantage of dual-band systems, as well as the form of new RF heads. There is a conflict of IMO requirements to still retain simple pulse radars to activate Racons and SARTS while also meeting these new stringent spectral regulations. Options are given for serious discussion amongst all concerned before it is too late.