Region-enhanced passive radar imaging

The authors adapt and apply a recently-developed region-enhanced synthetic aperture radar (SAR) image reconstruction technique to the problem of passive radar imaging. One goal in passive radar imaging is to form images of aircraft using signals transmitted by commercial radio and television stations that are reflected from the objects of interest. This involves reconstructing an image from sparse samples of its Fourier transform. Owing to the sparse nature of the aperture, a conventional image formation approach based on direct Fourier transformation results in quite dramatic artefacts in the image, as compared with the case of active SAR imaging. The regionenhanced image formation method considered is based on an explicit mathematical model of the observation process; hence, information about the nature of the aperture is explicitly taken into account in image formation. Furthermore, this framework allows the incorporation of prior information or constraints about the scene being imaged, which makes it possible to compensate for the limitations of the sparse apertures involved in passive radar imaging. As a result, conventional imaging artefacts, such as sidelobes, can be alleviated. Experimental results using data based on electromagnetic simulations demonstrate that this is a promising strategy for passive radar imaging, exhibiting significant suppression of artefacts, preservation of imaged object features, and robustness to measurement noise

Target DoA estimation in passive radar using non-uniform linear arrays and multiple frequency channels

In this paper we present a robust approach for target direction of arrival (DoA) estimation in passive radar that jointly exploits spatial and frequency diversity. Specifically we refer to a DVB-T based passive radar receiver equipped with a linear array of few antenna elements non-uniformly spaced in the horizontal dimension, able to collect multiple DVB-T channels simultaneously. We resort to a maximum likelihood (ML) approach to jointly exploit the target echoes collected across the antenna elements at multiple carrier frequencies. Along with an expected improvement in terms of DoA estimation accuracy, we show that the available spatial and frequency diversity can be fruitfully exploited to extend the unambiguous angular sector useful for DoA estimation, which represent an invaluable tool in many applications. To this purpose, a performance analysis is reported against experimental data collected by a multi-channel DVB-T based passive radar developed by Leonardo S.p.A

Impact of beacon interval on the performance of WiFi-based passive radar against human targets

The capability of WiFi-based passive radar to detect, track and profile human targets in both indoor and outdoor environment has been widely demonstrated. This paper investigates the impact of the Beacon Interval (BI) on the passive radar performance. The results of a dedicated acquisition campaign show that both the detection capability and the localization accuracy progressively degrade as the BI increases due to both the reduction of the received beacons and to the intrinsic undersampling of the target motion. Limit values are suggested for practical applications

2D localization with WiFi passive radar and device-based techniques: an analysis of target measurements accuracy

The aim of the work is to investigate the performance of two localization techniques based on WiFi signals: the WiFi-based passive radar and a device-based technique that exploits the measurement of angle of arrival (AoA) and time difference of arrival. This paper focuses specifically on the accuracy of the AoA measurements. As expected, the results show that for both techniques the AoA accuracy depends on the signal-to-noise ratio also in terms of the number of exploited received signal samples. For the passive radar, very accurate estimates are obtained; however, loss of detections can appear only when the rate of the Access Point packets is strongly reduced. In contrast, device-based estimates accuracy is lower, since it suffers of the limited number of emitted packets when the device is not uploading data. However, it allows localization also of stationary targets, which is impossible for the passive radar. This suggests that the two techniques are complementary and their fusion could provide a sensibly increase performance with respect to the individual techniques

Passive Radar Using Software-Defined Radio for Detection of Aircraft

Passive radar offers several advantages over ubiquitous active systems. These advantages include low system costs and low power requirements. These attributes make it feasible for passive radar systems to be widely deployed in remote areas for applications such as national border security. Software-defined radio allows flexible passive radar systems to be quickly implemented in software with a minimum of hardware. The purpose of this research is to implement a passive radar system using software-defined radio and assess its performance. This thesis details the implementation of such a system and presents analysis of data collected with the system

Vehicle recognition analysis in LTE based forward scattering radar

By integrating the forward scattering radar (FSR) mode in passive radar can provide many advantages to the conventional passive radar system. The system can benefit from the enhancement in radar cross section (RCS), the low cost and the simple receiver system. In addition, the receiver circuit is less complicated as it does not require a synchronization signal from the transmitter. This paper presents the experimental results for ground target detection and classification in a passive radar system exploiting the effect of forward scatter. The latest 4G Long-Term Evolution (LTE) technology signal is used as the source of the signal transmission. The receiver, the detection and the classification system is explained. Results have shown the system's capability for detecting and classifying ground targets using the FSR technique in passive radar. Hence, it opens up a new frontier in passive radar that can be used for many applications, including border protection, microwave fences, building monitoring and etc

Passive radar parallel processing using General-Purpose computing on Graphics Processing Units

In the paper an implementation of signal processing chain for a passive radar is presented. The passive radar which was developed at the Warsaw University of Technology, uses FM radio and DVB-T television transmitters as "illuminators of opportunity". As the computational load associated with passive radar processing is very high, NVIDIA CUDA technology has been employed for effective implementation using parallel processing. The paper contains the description of the algorithms implementation and the performance results analysis

Ground moving target detection using LTE-based passive radar

This paper examines the feasibility of 4G (LTE)-based passive radar for detecting ground moving targets. Specifically, the focus of this paper is to describe the proposed LTE-based passive radar system and to conduct an experiment using a real LTE eNB transmitter as an illumination source. Seven scenarios were carried out to investigate the detection performance of the proposed system on moving targets. Each scenario had different types of ground targets moving with a variety of speeds and directions. The experimental results showed that the LTE-based passive radar system has the capability to detect typical ground targets/objects like cars, motorbikes and humans moving with different speeds, trajectories and ranges. The positive results opened up a new frontier for passive radar systems to be used in many potential applications, including border protection, microwave fences, monitor of buildings and others

Moving target detection by using new LTE-based passive radar

This paper examines the feasibility of LTE-based passive radar for detecting ground moving targets. Specifically, the focus of this paper is to describe the proposed LTE-based passive radar system and to conduct an experiment using a real LTE eNB transmitter as an illumination source. Seven scenarios were carried out to investigate the detection performance of the proposed system on ground moving targets with different speeds, trajectories and range. In addition, multi-target detection was also tested. The experimental results showed that the LTE-based passive radar system has the capability to detect typical ground targets/objects like cars, motorbikes and humans moving at different trajectories. The positive results opened up a new frontier for passive radar systems to be used in many potential applications, including security, border protection, microwave fences, monitor of buildings and others

CFAR Detectors for DVB-T Passive Radar in non-homogeneous scenarios

CFAR (Constant False Alarm Rate) detectors were designed and evaluated in non-homogeneous DVB-T (Digital Video Broadcasting-Terrestrial) passive radar scenarios. The CA-CFAR (Cell-Averaged CFAR) is the most widespread incoherent CFAR technique. CA-CFAR detector is optimal under the assumption of homogeneous interference, but CA-CFAR performance is degraded when this assumption is not fulfilled. As an attempt to design CFAR algorithms in non-homogeneous environment, VI-CFAR (Variability Index-CFAR) was proposed. CA-CFAR and VI-CFAR detectors were designed and evaluated in a simulated and real passive radar scenarios. The real data were acquired by IDEPAR demonstrator, a DVB-T passive radar system. Results confirm the suitability of VICFAR based solutions in passive radar scenarios providing detection probabilities much higher than the detection capabilities associated with CA-CFAR.Ministerio de Economía y CompetitividadUniversidad de Alcal