Mauro Leonardi

Wide area surveillance using SSR mode S multilateration: advantages and limitations

There is an increasing interest on the various applications of the SSR Mode S (secondary surveillance radar - mode selective) for air traffic and airport traffic management. This paper discusses the applications of ICAO standard Mode S signals, in particular in the down link channel around 1090 MHz, to locate and identify cooperating targets in the airport using multilateration (MLAT) and in the terminal area/en route using wide area multilateration (WAM). Performance analyses and some comparison with the more traditional SSR system (ATC radar beacon system : ATCBRS) are carried out

Two efficient localization algorithms for multilateration

Two localization algorithms for multilateration systems are derived and analyzed. Instead of the classical time difference of arrival (TDOA), a direct use of the time of arrival (TOA) is made. The algorithms work for arbitrary spatial dimensions and overdetermined systems. These derivations are tested in a real-case implementation with simulated data (in particular, the multilateration (MLAT) system installed on the Malpensa Airport in Milan was considered for the MLAT simulation and its possible extension to wide area multilateration (WAM) system was considered forWAMtrials). The results are also compared with the present-day algorithms performance, mostly based on TDOA.

An efficient multilateration algorithm

Two new closed form localization algorithms for multilateration systems are derived and analyzed. The derivation neglects the time difference of arrival in favor of the direct use of the time of arrival (TOA). The algorithms work for arbitrary spatial dimensions and overdetermined systems. A strategy for quick rejection of obviously false time measurements based on coding theory is also proposed.

ADS-B vulnerability to low cost jammers: Risk assessment and possible solutions

Automatic Dependent Surveillance-Broadcast (ADS-B) systems provide to the air traffic control centers flight and status information of the cooperating targets. Problems due to jamming and/or spoofing of the ADS-B channel are under study, as well as verification and validation techniques. In this paper, we show how a low cost jammer can affect an ADS-B receiver. Three types of threats were evaluated. A multichannel receiver permitted to evaluate the received signal stream with and without jammer. The measurements were carried out coupling the receiver antenna with the in-cable jammer radio frequency (1090 MHz) signal. The results show the detection loss as a function of jammer range and jammer type. Finally, possible solutions are proposed to mitigate the effects. Some trials to evaluate their effectiveness are described.

On the application of singular value decomposition and Tikhonov regularization to ill-posed problems in hyperbolic passive location

Abstract Hyperbolic passive location of targets (e.g. used in the Multilateration systems for civil aviation) calls for the solution of highly non-linear systems. In this paper, we show how the effect of typical ill-conditioning of passive location, arising in many operational conditions, may be significantly mitigated by regularization techniques. The pertaining advantages with respect to the conventional (non-regularized) approach are shown in a realistic situation.

The transponder data recorder: Implementation and first results

We have designed, implemented, and tested a flexible receiving and processing multichannel system for signals in the 1,090-MHz band with significant air traffic management applications in surveillance and communication. Thanks to a wide bandwidth and a large dynamic range, with four linear channels plus a logarithmic channel, this TDR allows us to record the signals of interest with minimal distortion, from sources whose distance from the antenna sys-tem ranges from a few tens of meters up to hundreds of kilometers. From the recorded signals, it is possible: 1) to characterize the traffic in the 1,090-MHz band, and 2) to test the effectiveness of different source separation algorithms, either based on space diversity or based on frequency diversity. The system permits a higher degree of automation and higher quantity of data acquisition than some previous experimental systems.

Airport Surveillance Processing Chain for High Resolution Radar

The paper focuses on the design of the digital processing chain of a surface movement radar (SMR) for airport traffic in the frame of A-SMGCS (advanced-surface movements guidance and control system); in order to reach, or exceed, the demanding requirements for the A-SMGCS surveillance function, special attention has to be paid to SMR processing, whose main functional blocks are the CFAR (constant false alarm rate) processor, the plot extractor, and the track-while-scan (TWS). A description of these processing functions, tailored to a noncoherent, high-resolution radar, and of their implementation is provided. The performance evaluation is accompanied by trials on recorded data, as obtained from a national research and development project called fast prototyping (FP) project (2001-2003) and its subsequent activities. The aim of the work presented here is to give a system view of the radar processing chain for high-resolution SMR, being rather different than standard surveillance radar.

Efficient location strategy for airport surveillance using mode-s multilateration systems

In this paper, the use of regularization methods to solve the location problem in multilateration systems, using Mode-S signals, is studied, evaluated, and developed. The Tikhonov method has been implemented as a first application to solve the classical system of hyperbolic equations in multilateration systems. Some simulations are obtained and the results are compared with those obtained by the well-established Taylor linearization and with the CramA©r-Rao lower bound analysis. Significant improvements, for the accuracy, convergence, and the probability of location, are found for the application of the Tikhonov method. © Cambridge University Press and the European Microwave Association, 2012.

Multiple faults integrity algorithm for mode S Multilateration Systems

Target position integrity is very important when this information is used for surveillance and safety purposes as in a multilateration system (MLAT). In this paper some of the classical satellite navigation algorithms are modified to be applied to the MLAT environmental and one of the big limitations of these algorithms i.e. the single fault hypothesis is removed. Simulated tests in a real scenario are also shown.

Evaluation of the Interferences of GNSS (Galileo/GPS) signals on Air Traffic Control Radar and Wind Profiler Radar

GNSS systems use frequency band close to that of L-band primary surveillance radar for Air Traffic Contro, i.e. 1250-1350 MHz, and of some Wind Profiler Radar (1290 MHz). According to the World Radio Communication Conference 2003 (WRC-03) resolution, in order to protect Aeronautic Radio Navigation System (ARNS) systems, Radio Navigation Satellite System (RNSS) administrations shall ensure that the equivalent power flux density (pfd) level produced by all RNSS space stations of all systems does not exceed - 121.5 dB(W/m2) in any 1 MHz band. However, in order to assess the performance of ATC L-Band radar, DME and Wind Profiler Radar with GNSS interfering signals, it is useful not only to reason in terms of pfd but, rather, to model (at least for some critical cases) the Radar receiver chains and evaluate the impact of the interfering signal (if present) on every stage of the receiver and on the overall output, i.e at the user level.