Sensors

2022

Jump to: 2021, 2020

17 pages, 5747 KiB

Open AccessArticle

DAB Signal Preprocessing for Passive Coherent Location

by Gustaw Mazurek

Sensors 2022, 22(1), 378; https://doi.org/10.3390/s22010378 - 5 Jan 2022

Cited by 2 | Viewed by 2772

Abstract

Digital Audio Broadcast (DAB) transmitters can be successfully used as illumination sources in Passive Coherent Location (PCL). However, extending the integration time in such a configuration leads to the occurrence of periodical artifacts in the bistatic range/Doppler plots, resulting from the time structure [...] Read more.

Digital Audio Broadcast (DAB) transmitters can be successfully used as illumination sources in Passive Coherent Location (PCL). However, extending the integration time in such a configuration leads to the occurrence of periodical artifacts in the bistatic range/Doppler plots, resulting from the time structure of the DAB signal. In this paper, we propose some methods of signal preprocessing (based on symbol removal, substitution by noise, and duplication) that operate on the DAB transmission frame level and improve the received signal’s correlation properties. We also demonstrate that two of these methods allow us to avoid the mentioned artifacts and thus to improve the quality of the range/Doppler plots with detection results. We evaluate the performance of the proposed methods using real DAB signals acquired in an experimental PCL platform. We also provide the analysis of the Signal to Noise Ratio (SNR) during the detection of a moving target which shows that the proposed solution, based on symbol duplication, can offer around 3 dB of gain in SNR. Finally, we carry out the computational complexity analysis showing that the proposed method can be implemented with a minimal cost after some optimizations. Full article

► Show Figures

Figure 1

2021

Jump to: 2022, 2020

16 pages, 3275 KiB

Open AccessArticle

Bistatic Forward ISAR with DVB-T Transmitter of Opportunity

by Andon Dimitrov Lazarov and Todor Pavlov Kostadinov

Sensors 2021, 21(19), 6662; https://doi.org/10.3390/s21196662 - 7 Oct 2021

Viewed by 1922

Abstract

The radar geometry defined by a spatially separated transmitter and receiver with a moving object crossing the baseline is considered as a Bistatic Forward Inverse Synthetic Aperture Radar (BFISAR). As a transmitter of opportunity, a Digital Video Broadcast-Terrestrial (DVB-T) television station emitting DVB-T [...] Read more.

The radar geometry defined by a spatially separated transmitter and receiver with a moving object crossing the baseline is considered as a Bistatic Forward Inverse Synthetic Aperture Radar (BFISAR). As a transmitter of opportunity, a Digital Video Broadcast-Terrestrial (DVB-T) television station emitting DVB-T waveforms was used. A system of vector equations describing the kinematics of the object was derived. A mathematical model of a BFISAR signal received after the reflection of DVB-T waveforms from the moving object was described. An algorithm for extraction of the object’s image including phase correction and two Fourier transformations applied over the received BFISAR signal—in the range and azimuth directions—was created. To prove the correctness of mathematical models of the object geometry, waveforms and signals, and the image extraction procedure, graphical results of simulation numerical experiments were provided. Full article

► Show Figures

Figure 1

18 pages, 4725 KiB

Open AccessArticle

An Experimental Multi-Target Tracking of AM Radio-Based Passive Bistatic Radar System via Multi-Static Doppler Shifts

by Xueqin Zhou, Hong Ma and Hang Xu

Sensors 2021, 21(18), 6196; https://doi.org/10.3390/s21186196 - 15 Sep 2021

Cited by 2 | Viewed by 2239

Abstract

This paper presents a description of recent research and the multi-target tracking in experimental passive bistatic radar (PBR) system taking advantage of numerous non-cooperative AM radio signals via multi-static doppler shifts. However, it raises challenges for use by multiple spatially distributed AM radio [...] Read more.

This paper presents a description of recent research and the multi-target tracking in experimental passive bistatic radar (PBR) system taking advantage of numerous non-cooperative AM radio signals via multi-static doppler shifts. However, it raises challenges for use by multiple spatially distributed AM radio illuminators for multi-target tracking in PBR system due to complex data association hypotheses and no directly used tracking algorithm in the practical scenario. To solve these problems, after a series of key array signal processing techniques in the self-developed system, by constructing a nonlinear measurement model, the novel method is proposed to accommodate nonlinear model by using the unscented transformation (UT) in Gaussian mixture (GM) implementation of iterated-corrector cardinality-balanced multi-target multi-Bernoulli (CBMeMBer). Simulation and experimental results analysis verify the feasibility of this approach used in a practical PBR system for moving multi-target tracking. Full article

► Show Figures

Figure 1

21 pages, 855 KiB

Open AccessArticle

Detection of LFM Radar Signals and Chirp Rate Estimation Based on Time-Frequency Rate Distribution

by Ewa Swiercz, Dariusz Janczak and Krzysztof Konopko

Sensors 2021, 21(16), 5415; https://doi.org/10.3390/s21165415 - 10 Aug 2021

Cited by 13 | Viewed by 4582

Abstract

Linear frequency-modulated (LFM) signals are the most significant example of waveform used in low probability of intercept (LPI) radars, synthetic aperture radars and modern communication systems. Thus, interception and parameter estimation of the signals is one of the challenges in Electronic Support (ES) [...] Read more.

Linear frequency-modulated (LFM) signals are the most significant example of waveform used in low probability of intercept (LPI) radars, synthetic aperture radars and modern communication systems. Thus, interception and parameter estimation of the signals is one of the challenges in Electronic Support (ES) systems. The methods, which are widely used to accomplish this task are mainly based on transformations from time to time-frequency domain, which concentrate the energy of signals along an instantaneous frequency (IF) line. The most popular examples of such transforms are the short time Fourier transform (STFT) and Wigner-Ville distribution (WVD). However, for LFM waveforms, methods that concentrate signal energy along a line in the time-frequency rate domain may allow to obtain better detection and estimation performance. This type of transformation can be obtained using the cubic phase (CP) function (CPF). In the paper, the detection of LFM waveform and its chirp rate (CR) parameter estimation based on the extended forms of the standard CPF is proposed. The CPF was originally introduced for instantaneous frequency rate (IFR) estimation for quadratic frequency modulated (QFM) signals i.e., cubic phase signals. Summation or multiplication operations on time cross-sections of the CPF allow to formulate the extended forms of the CPF. Based on these forms, detection test statistics and the estimation procedure of LFM signal parameters have been proposed. The widely known estimation methods assure satisfying accuracy for high SNR levels, but for low SNRs the reliable estimation is a challenge. The proposed approach based on joint analysis of detection and estimation characteristics allows to increase the reliability of chirp rate estimates for low SNRs. The results of Monte-Carlo simulation investigations on LFM signal detection and chirp rate estimation evaluated by the mean squared error (MSE) obtained by the proposed methods with comparisons to the Cramer-Rao lower bound (CRLB) are presented. Full article

► Show Figures

Figure 1

15 pages, 14960 KiB

Open AccessArticle

Design and Validation of a Reflectarray Antenna with Optimized Beam for Ground Target Monitoring with a DVB-S-Based Passive Radar

by Javier Rosado-Sanz, María-Pilar Jarabo-Amores, Jean-Yves Dauvignac, David Mata-Moya, Jérôme Lanteri and Claire Migliaccio

Sensors 2021, 21(16), 5263; https://doi.org/10.3390/s21165263 - 4 Aug 2021

Cited by 4 | Viewed by 3594

Abstract

A reflectarray antenna with an optimized sectorial beam is designed for the surveillance channel of a DVB-S-based passive radar (PR). The employment of satellite illuminators requires a high gain antenna to counteract the losses due to the great distance from the transmitter, but [...] Read more.

A reflectarray antenna with an optimized sectorial beam is designed for the surveillance channel of a DVB-S-based passive radar (PR). The employment of satellite illuminators requires a high gain antenna to counteract the losses due to the great distance from the transmitter, but without forgetting a beamwidth wide enough to provide angular coverage. A method based on optimizing the position of several contiguous beams is proposed to achieve the required sectorial pattern. Different reflectarray elements are designed to achieve S-curves with smooth slopes and covering all the required phases (the S-curve represents the reflection phase of a single element, as a function of size, rotation and incidence angle). The real phase and modulus of the reflection coefficient of each element are considered in the optimization process to achieve the best real prototype. Geometry has been studied and adapted to employ commercial elements for the feed, feed-arm and the structure that holds the aperture. The designed prototype has been characterized in an anechoic chamber achieving a stable gain greater than 19 dBi in almost the complete DVB-S band, from

10.5

GHz to 12 GHz with a sectorial beam of

{8.7}^{\circ} \times {5.2}^{\circ}

. The prototype has also been validated in PR trials in terrestrial scenarios allowing the detection of cars at distances up to 600 m away from the PR, improving the performance achieved with commercial parabolic dish antennas. Full article

► Show Figures

Figure 1

17 pages, 6819 KiB

Open AccessArticle

Dual Cancelled Channel STAP for Target Detection and DOA Estimation in Passive Radar

by Giovanni Paolo Blasone, Fabiola Colone, Pierfrancesco Lombardo, Philipp Wojaczek and Diego Cristallini

Sensors 2021, 21(13), 4569; https://doi.org/10.3390/s21134569 - 3 Jul 2021

Cited by 10 | Viewed by 2658

Abstract

This paper deals with the problem of detection and direction of arrival (DOA) estimation of slowly moving targets against clutter in multichannel mobile passive radar. A dual cancelled channel space-time adaptive processing (STAP) scheme is proposed, aiming at reducing the system computational complexity, [...] Read more.

This paper deals with the problem of detection and direction of arrival (DOA) estimation of slowly moving targets against clutter in multichannel mobile passive radar. A dual cancelled channel space-time adaptive processing (STAP) scheme is proposed, aiming at reducing the system computational complexity, as well as the amount of required training data, compared to a conventional full array solution. The proposed scheme is shown to yield comparable target detection capability and DOA estimation accuracy with respect to the corresponding full array solution, despite the lower computational cost required. Moreover, it offers increased robustness against adaptivity losses, operating effectively even in the presence of a limited set of training data, as often available in the highly non-homogeneous clutter scenarios experienced in bistatic passive radar. The effectiveness of the proposed scheme and its suitability for passive GMTI are demonstrated against both simulated and experimental data collected by a DVB-T-based multichannel mobile passive radar. Full article

► Show Figures

Graphical abstract

20 pages, 9672 KiB

Open AccessArticle

A Joint Low-Rank and Sparse Method for Reference Signal Purification in DTMB-Based Passive Bistatic Radar

by Luo Zuo, Jun Wang, Te Zhao and Zuhan Cheng

Sensors 2021, 21(11), 3607; https://doi.org/10.3390/s21113607 - 22 May 2021

Cited by 10 | Viewed by 2453

Abstract

In a digital terrestrial multimedia broadcasting (DTMB)-based passive bistatic radar (PBR) system, the received reference signal often suffers from serious multipath effect, which decreases the detection ability of low-observable targets in urban environments. In order to improve the target detection performance, a novel [...] Read more.

In a digital terrestrial multimedia broadcasting (DTMB)-based passive bistatic radar (PBR) system, the received reference signal often suffers from serious multipath effect, which decreases the detection ability of low-observable targets in urban environments. In order to improve the target detection performance, a novel reference signal purification method based on the low-rank and sparse feature is proposed in this paper. Specifically, this method firstly performs synchronization operations to the received reference signal and thus obtains the corresponding pseudo-noise (PN) sequences. Then, by innovatively exploiting the inherent low-rank structure of DTMB signals, the noise component in PN sequences is reduced. After that, a temporal correlation (TC)-based adaptive orthogonal matching pursuit (OMP) method, i.e., TC-AOMP, is performed to acquire the reliable channel estimation, whereby the previous noise-reduced PN sequences and a new halting criterion are utilized to improve channel estimation accuracy. Finally, the purification reference signal is obtained via equalization operation. The advantage of the proposed method is that it can obtain superior channel estimation performance and is more efficient compared to existing methods. Numerical and experimental results collected from the DTMB-based PBR system are presented to demonstrate the effectiveness of the proposed method. Full article

► Show Figures

Figure 1

27 pages, 681 KiB

Open AccessArticle

Effects of Movement for High Time-Bandwidths in Batched Pulse Compression Range-Doppler Radar

by Dominik Bok, Daniel O’Hagan and Peter Knott

Sensors 2021, 21(7), 2492; https://doi.org/10.3390/s21072492 - 3 Apr 2021

Cited by 9 | Viewed by 3176

Abstract

Radar detection and track building performance is an essential part of a radar system. A high realized coherent integration gain often contributes to an improved performance. This is essential to the successful detection and tracking of weak moving targets. However, the actual movement [...] Read more.

Radar detection and track building performance is an essential part of a radar system. A high realized coherent integration gain often contributes to an improved performance. This is essential to the successful detection and tracking of weak moving targets. However, the actual movement within the coherent processing interval can introduce range walk effects. The processing will then result in range and Doppler frequency resolutions that become finer than a single moving point scatterer’s spread over range and—often not considered—over Doppler frequency. In particular for a wide instantaneous bandwidth, the impact on the achievable integration gain can become severe already for a constant effective velocity. Therefore, high desired integration gains as required in passive radar are not easily achieved against relatively fast moving targets. The main intent of this article is to present the movement effects on a classical range-Doppler analysis to give an insight on the achievable performance and to quantify otherwise appearing degradations. Interestingly, a classical analysis of experimental datasets evaluated from a DVB-T based passive radar measurement campaign even resolved the fluctuation of a target response within the instantaneously processed bandwidth. The findings strengthen the need for advanced processing methods that can at least partly address individual implications of fast moving targets in real-time applications properly. Full article

► Show Figures

Figure 1

20 pages, 2265 KiB

Open AccessArticle

Advancing Ground-Based Radar Processing for Bridge Infrastructure Monitoring

by Chris Michel and Sina Keller

Sensors 2021, 21(6), 2172; https://doi.org/10.3390/s21062172 - 20 Mar 2021

Cited by 36 | Viewed by 3285

Abstract

In this study, we further develop the processing of ground-based interferometric radar measurements for the application of bridge monitoring. Applying ground-based radar in such complex setups or long measurement durations requires advanced processing steps to receive accurate measurements. These steps involve removing external [...] Read more.

In this study, we further develop the processing of ground-based interferometric radar measurements for the application of bridge monitoring. Applying ground-based radar in such complex setups or long measurement durations requires advanced processing steps to receive accurate measurements. These steps involve removing external influences from the measurement and evaluating the measurement uncertainty during processing. External influences include disturbances caused by objects moving through the signal, static clutter from additional scatterers, and changes in atmospheric properties. After removing these influences, the line-of-sight displacement vectors, measured by multiple ground-based radars, are decomposed into three-dimensional displacement components. The advanced processing steps are applied exemplarily on measurements with two sensors at a prestressed concrete bridge near Coburg (Germany). The external influences are successfully removed, and two components of the three-dimensional displacement vector are determined. A measurement uncertainty of less than 0.1 mm is achieved for the discussed application. Full article

► Show Figures

Figure 1

22 pages, 4372 KiB

Open AccessArticle

Experimental Verification of the Concept of Using LOFAR Radio-Telescopes as Receivers in Passive Radiolocation Systems

by Julia Kłos, Konrad Jędrzejewski, Aleksander Droszcz, Krzysztof Kulpa, Mariusz Pożoga and Jacek Misiurewicz

Sensors 2021, 21(6), 2043; https://doi.org/10.3390/s21062043 - 14 Mar 2021

Cited by 7 | Viewed by 2498

Abstract

The paper presents a new idea of using a low-frequency radio-telescope belonging to the LOFAR network as a receiver in a passive radar system. The structure of a LOFAR radio-telescope station is described in the context of applying this radio-telescope for detection of [...] Read more.

The paper presents a new idea of using a low-frequency radio-telescope belonging to the LOFAR network as a receiver in a passive radar system. The structure of a LOFAR radio-telescope station is described in the context of applying this radio-telescope for detection of aerial (airplanes) and space (satellite) targets. The theoretical considerations and description of the proposed signal processing schema for the passive radar based on a LOFAR radio-telescope are outlined in the paper. The results of initial experiments verifying the concept of a LOFAR station use as a receiver and a commercial digital radio broadcasting (DAB) transmitters as illuminators of opportunity for aerial object detection are presented. Full article

► Show Figures

Figure 1

13 pages, 2738 KiB

Open AccessArticle

Experimental Comparison of Radon Domain Approaches for Resident Space Object’s Parameter Estimation

by Selenia Ghio, Marco Martorella, Daniele Staglianò, Dario Petri, Stefano Lischi and Riccardo Massini

Sensors 2021, 21(4), 1298; https://doi.org/10.3390/s21041298 - 11 Feb 2021

Cited by 3 | Viewed by 1912

Abstract

The fast and uncontrolled rise of the space objects population is threatening the safety of space assets. At the moment, space awareness solutions are among the most calling research topic. In fact, it is vital to persistently observe and characterize resident space objects. [...] Read more.

The fast and uncontrolled rise of the space objects population is threatening the safety of space assets. At the moment, space awareness solutions are among the most calling research topic. In fact, it is vital to persistently observe and characterize resident space objects. Instrumental highlights for their characterization are doubtlessly their size and rotational period. The Inverse Radon Transform (IRT) has been demonstrated to be an effective method for this task. The analysis presented in this paper has the aim to compare various approaches relying on IRT for the estimation of the object’s rotation period. Specifically, the comparison is made on the basis of simulated and experimental data. Full article

► Show Figures

Figure 1

11 pages, 1332 KiB

Open AccessArticle

Clutter-Masked Waveform Design for LPI/LPD Radarcom Signal Encoding

by Richard Washington, Brenton Bischof, Dmitriy Garmatyuk and Saba Mudaliar

Sensors 2021, 21(2), 631; https://doi.org/10.3390/s21020631 - 18 Jan 2021

Cited by 4 | Viewed by 2320

Abstract

In this work we propose a method of in situ clutter deconvolution and modeling using experimentally obtained UWB radar data. The obtained clutter models are then used for random sequence encoding of radar-communication (radarcom) signals to achieve clutter-masked transmissions and improve communication security. [...] Read more.

In this work we propose a method of in situ clutter deconvolution and modeling using experimentally obtained UWB radar data. The obtained clutter models are then used for random sequence encoding of radar-communication (radarcom) signals to achieve clutter-masked transmissions and improve communication security. We present the results of clutter modeling from the laboratory data obtained with the software-defined radar system. We then show that such clutter-masked radarcom signals generated using the local clutter model are highly likely to be interpreted as just clutter returns by an unauthorized interceptor. We also present the results of communication and radar performance of these radarcom signals and contrast them with those obtained using a linear frequency modulated waveform. It is shown that the proposed radarcom design method has high potential to achieve secure communications in adversarial conditions, while simultaneously addressing radar sensing needs. Full article

► Show Figures

Figure 1

18 pages, 4963 KiB

Open AccessArticle

FSR Systems for Detection of Air Objects Using Cosmic Radio Emissions

by Hristo Kabakchiev, Vera Behar, Ivan Garvanov, Dorina Kabakchieva, Avgust Kabakchiev and Hermann Rohling

Sensors 2021, 21(2), 465; https://doi.org/10.3390/s21020465 - 11 Jan 2021

Cited by 5 | Viewed by 2207

Abstract

The paper analyses the possibility of Forward Scatter Radar (FSR) systems to detect airplanes using cosmic emission from pulsars and planets (pulsar, Sun, Moon). A suboptimal multichannel algorithm for joint detection and evaluation of the parameters of the forward scattering signal created by [...] Read more.

The paper analyses the possibility of Forward Scatter Radar (FSR) systems to detect airplanes using cosmic emission from pulsars and planets (pulsar, Sun, Moon). A suboptimal multichannel algorithm for joint detection and evaluation of the parameters of the forward scattering signal created by an airplane (duration and velocity) is proposed, with preliminary compensation of the powerful direct signal emitted by cosmic sources (pulsar, Sun and Moon). The expressions for calculation of the Signal-to-Noise Ratio (SNR) at the input of the detector and the compensator are obtained. The detection characteristics are also obtained, and the requirements for the suppression coefficient of the compensator are evaluated. A methodology for calculating the maximum distance for detecting an aircraft using a described algorithm is proposed. The obtained results show that due to the Forward Scatter (FS) effect, there is the theoretical possibility to detect airplanes at close ranges by FSRs, which use very weak signals from cosmic sources. Full article

► Show Figures

Figure 1

2020

Jump to: 2022, 2021

12 pages, 2977 KiB

Open AccessLetter

Method of Calculating Desynchronization of DVB-T Transmitters Working in SFN for PCL Applications

by Karol Klincewicz and Piotr Samczyński

Sensors 2020, 20(20), 5776; https://doi.org/10.3390/s20205776 - 12 Oct 2020

Cited by 4 | Viewed by 2898

Abstract

This paper presents a novel method of calculating desynchronization between transmitters working in a single frequency digital video broadcasting-terrestrial (DVB-T) network. The described method can be a useful tool for enhancing passive radar operations and improving passive coherent location (PCL) sensors to correct [...] Read more.

This paper presents a novel method of calculating desynchronization between transmitters working in a single frequency digital video broadcasting-terrestrial (DVB-T) network. The described method can be a useful tool for enhancing passive radar operations and improving passive coherent location (PCL) sensors to correct their measurements of target localization. The paper presents the problem of localizing DVB-T transmitters utilized by passive radars, and proposes a novel method based on Time Difference of Arrival (TDoA) techniques to solve the problem. The proposed technique has been validated using real signals collected by a PCL sensor receiver. The details of the experiment and extensive result analysis are also contained in this article. Full article

► Show Figures

Figure 1

11 pages, 6660 KiB

Open AccessArticle

Detection of Low RCS Supersonic Flying Targets with a High-Resolution MMW Radar

by Nezah Balal, Yael Balal, Yair Richter and Yosef Pinhasi

Sensors 2020, 20(11), 3284; https://doi.org/10.3390/s20113284 - 9 Jun 2020

Cited by 9 | Viewed by 3698

Abstract

In this study, the detection of a low radar cross-section (RCS) target moving at a very high speed using a high-resolution millimeter-wave radar is presented. This real-time detection is based on the transmission of a continuous wave and heterodyning of the received signal [...] Read more.

In this study, the detection of a low radar cross-section (RCS) target moving at a very high speed using a high-resolution millimeter-wave radar is presented. This real-time detection is based on the transmission of a continuous wave and heterodyning of the received signal reflected from the moving target. This type of detection enables one to extract the object’s movement characteristics, such as velocity and position, while in motion and also to extract its physical characteristics. In this paper, we describe the detection of a fired bullet using a radar operating at an extremely high-frequency band. This allowed us to employ a low sampling rate which enabled the use of inexpensive and straightforward equipment, including the use of small antennas that allow velocity detection at high resolution and with low atmospheric absorption. Full article

► Show Figures

Figure 1

Journal Menu

Journal Browser

Modern Radar Systems (Closed)

Share This Topical Collection

Editors

Topical Collection Information

Published Papers (15 papers)

2022

Jump to: 2021, 2020

2021

Jump to: 2022, 2020

2020

Jump to: 2022, 2021

Further Information

Guidelines

MDPI Initiatives

Follow MDPI