J. Rosado-Sanz

Passive Radar Array Processing with Non-Uniform Linear Arrays for Ground Target’s Detection and Localization

The problem of ground target detection with passive radars is considered. The design of an antenna array based on commercial elements is presented, based on a non-uniform linear array optimized according to sidelobe level requirements. Array processing techniques are applied in the cross-ambiguity function domain to exploit integration gain, system resolution and the sparsity of targets in this domain. A modified two-stage detection scheme is described, which is based on a previously-published one by other authors. All of these contributions are validated in a real semiurban scenario, proving the capabilities of detection, the direction of arrival estimation and the tracking of ground targets in the presence of big buildings that generate strong clutter returns. Detection performance is validated through the probability of false alarm and the probability of detection estimation with specified estimation errors.

2C-SVM Based Radar Detectors in Gaussian and K-Distributed Real Interference

This paper tackles the design and evaluation of cost sensitive Support Vector Machine (2C-SVM) based radar detectors in presence of Gaussian and K-Distributed clutter. 2C-SVM based solutions are able to approximate the Neyman-Pearson detector for a specific false alarm rate (\(P_{FA}\)). Real data acquired in different wind conditions by a coherent, pulsed and X-Band radar were considered. A statistical analysis is carried out to design the 2C-SVM for detecting targets with unknown parameters in Gaussian and non-Gaussian interference. A grid search of the best training parameters to approximate the pair detection probability (\(P_D\)) and \(P_{FA}\) of the NP detector is required. Results prove the capability of the 2C-SVM based detectors to maximize the \(P_D\) for a desired \(P_{FA}\) independently of the detection problem likelihood functions.

Coherent VI-MLP-CFAR detector for IDEPAR demonstrator (DVB-T passive radar) in ground traffic monitoring

Coherent CFAR (Constant False Alarm Rate) detectors were designed and evaluated in non-homogeneous DVB-T (Digital Video Broadcasting-Terrestrial) passive radar scenarios. Conventional CFAR techniques are usually applied to noncoherent detector that can not be optimal attending to Neyman-Pearson criterion. The capability to approximate function of neural networks (NN) was used to maintain the false alarm rate without a priori knowledge of the optimum detector outputs. In addition, variability index (VI) was used to provide robustness against non-homogeneous interference. The considered detection scheme was evaluated with real passive radar data acquired by IDEPAR demonstrator, a DVB-T passive radar system, in a terrestrial scenario. Results confirm the potentiality of the coherent VI-MLP-CFAR detector as a low-cost solution for traffic monitoring.

Nondesired effects in DVB-T based passive radar due to sporadic interference

This paper tackles the study of the nondesired effects in the detection capabilities and system resolution of Passive Radar (PR) solutions due to sporadic interference. Real radar data acquired by IDEPAR demonstrator (DVB-T based PR system developed by the University of Alcala) with the presence of an interference were considered. The ambiguity function is calculated to estimate the pedestal mean level and the equivalent information bandwidth. A degradation of the range resolution and a reduction of the Signal-to-Noise Ratio are observed. A simulated radar scenario was designed using the acquired data and adding terrestrial targets to obtain a good approximation of a real environment. Although the resulted detection capabilities are reduced, the target trajectories can be identified. This trend can be explained based on the power migration along range dimension associated with the interference bandwidth, generating blind Doppler shifts in the detection stage. Then, these nondesired effects should be taking into account to improve the PR availability against sporadic interferences.

Study of the ghost target phenomenon on a real DVB-T passive radar scenario

Passive radars are emerging technologies that use non-cooperative transmitters instead of dedicated ones. They present a set of advantages with respect to active ones, such as lower cost and low probability of intercept, but require complex signal processing stages due to the use of non-controlled transmitters. IDEPAR demonstrator is a DVB-T based passive radar developed by the University of Alcalá. DVB-T signals were selected due to their proved good features. Among them, the high availability of transmitters is of great value, but it is associated with the ghost target phenomenon in single frequency networks. In urban and semi-urban scenarios, strong multipaths generated by buildings can also generate phantom targets. In this paper, a study about ghost targets sources on a real scenario is carried out, using real and simulated data. Results prove the big impact of multipaths generated by buildings, concluding that a preliminary study of the presence of these elements in a radar scenario is as important as the analysis of the potential illuminators, specially in urban and semi-urban scenarios, which are of high interest in passive radar applications.