Separation of multiple secondary surveillance radar sources in a real environment for the near-far case

Multilateration systems based on Secondary Surveillance Radar (SSR) systems and omni-directional antennae are operational today [1,2]. Assuming the replacement of the single-element antenna by an array, we proposed new algorithms to discriminate overlapped signals in previous works [3,4,5]; other solutions were also proposed in the literature [6,7,8]. Unfortunately, all have either some shortcomings, or an expensive computational cost, or no simple practical implementation. Therefore, we proposed in [9] a reliable, simple, and effective projection algorithm. Nevertheless, some issues were overlooked: in particular the relative power ratio between the signals to be separated may be important, which we study in this paper with real-life signals

Coherent source separation based on sparsity: an application to SSR signals

Systems based on secondary surveillance radar (SSR) downlink signals, both with directional and with omni-directional antennae (such as in multilateration), are operational today and more and more installations are being planned. In this frame, high-density traffic leads to the reception of a mixture of several overlapping SSR replies. By nature, SSR sources are sparse, i.e. with amplitude equal to zero with significantly high probability. While in the literature several algorithms performing sources separation with an m-element antenna have been proposed, none has satisfactorily employed the full potential of sparsity for SSR signals. Most sparsity algorithms can separate only real-valued sources, although we present in this study two algorithms to separate the complex-valued SSR sources. Recorded signals in a live environment are used to demonstrate the effectiveness of the proposed techniques. Copyright © Cambridge University Press and the European Microwave Association 2009

Clustering methods for Mode S stations: Evaluation and perspectives

Grouping of a set of Secondary Surveillance Radar (SSR) Mode S stations into functional entities called clusters has significant operational facets; it calls for a constrained optimization, an important significant constraint being the scarcity of Interrogation Identifier (II) codes. This clustering problem can be approached by two ways, i.e., integer programming methods and heuristic approaches. The definition of a general, usable decision support tool to build up and evaluate clustering strategies in any operational airspace, e.g. the one of a nation or, even more complicated, of a system such as the European one, is a very challenging task. This paper describes some steps toward this envisaged result proposing a mathematical formulation and a heuristic approach for the problem

Degarbling Mode S replies received in single channel stations with a digital incremental improvement

Multilateration and automatic dependent surveillance – broadcast systems are used in air traffic control to detect, locate and identify cooperating aircraft using signals emitted by airborne transponders and received by dedicated ground stations. In areas with a high traffic density, these stations may receive simultaneously several superimposed signals. Present operational systems use only one receiving channel connected to a non-directional antenna. When the received replies are superimposed, that is, ‘garbled’, their detection and/or decoding are severely affected in nowadays equipment. The aim of this study is to transform the single channel problem into a multiple channels problem in order to solve it using specific knowledge about the Mode S signals. In fact, the multiple channels problem is a typical signals separation problem applied to Mode S mixture for which several algorithms already exist. The authors’ algorithm, named projection algorithm (PA) single antenna, is based on the existing PA and can be easily implemented on existing receiving stations. The effectiveness of their method is demonstrated using real data collected from their experimental receiver

W-band multi-radar processing for airport foreign object debris and humans detection

The need to improve efficiency, safety and security of airports becomes every day much more demanding. Today, different Radar-based systems are available for these purposes: for Advanced Surface Movement Guidance Control System, for Foreign Object Debris detection, for Bird Strike prevention and for intrusion detection. Millimeter-wave radars have, mainly, the capability to provide all these functions thanks to their high resolution, high renewal rate and high sensitivity to small objects. In this paper the performances of an airport W-band Radar Network are evaluated (with real and simulated data) in presence of small objects and/or humans. In particular, a radar raw level data-fusion is proposed and evaluated to improve the system detection capability in case of Foreign Object and Human

1090 ES receiving capacity improvement using ADS-B ground receivers with signals discrimination capability

A typical ADS-B (Automatic Dependent Surveillance – Broadcast) ground receiver is equipped with an omnidirectional antenna to receives the messages transmitted by the ADS-B equipped aircraft. The aircraft transmit unsolicited ADS-B messages periodically, on the 1090 MHz downlink channel. There are other ATC systems using the same frequency (Secondary Surveillance Radar SSR, Traffic Information System – Broadcast TIS-B), then, considering that the ADS-B receiving stations use omnidirectional antenna or in some cases a six sector antenna, the probability of interference grows with the air traffic increase. Therefore there is a risk of data loss due to “garbled” ADS-B OUT 1090 ES messages in the receiving station, with a reduction of the valid data rate. In this paper an ADS-B ground receiver with signals discrimination capability is proposed. Such device is able to detect and solve signals overlapping events. This feature is useful to improve the 1090 extended squitters receiving capacity for a ground receiver station. The proposed receiver is composed by the antenna system, an analog-digital front-end and a pre-processing unit followed by a RTCA-DO 260 compliant 1090 MHz decoder. The pre-processing unit implements the signal discrimination and separation procedures. These procedures are based on processing algorithms studied and developed by Tor Vergata University RadarLab. This unit differs depending if the antenna is single element or an array, for which case the underlying algorithm has better performances. The algorithms are introduced, and their analyses allow to evaluate the resulting channel capacity as a function of the environmental messages density

The transponder data recorder: First implementation and applications

International audienc

The transponder data recorder: first implementation and applications

The Transponder Data Recorder is an experimental 1090 MHz signal acquisition system designed by the Radar and Navigation group at Tor Vergata University to record the signals in the Secondary Surveillance Radar band, centered at 1090 MHz. The peculiarity of the receiver is that it is based on five receiving chains (4 linear chains with large dynamic range and one with a logarithmic receiver) connected to a wideband linear array antenna. The TDR was developed in order to analyze the channel traffic and to test the new signal processing algorithms, in the research frame on multilateration (MLAT) and Automatic Dependent Surveillance (ADS-B), with real signals

Time for a change in phased array radar architectures- part II: The d-radar

A novel multifunction phased array radar is introduced, characterized by conformal arrays, extensive usage of digital beam forming and separation between Tx and Rx arrays. Some significant design trade-off and radar operating aspects are described, including the radar management and scheduling, showing the main differences with respect to the classical, four faces phased array multifunction radar architecture