Sevigny P.,Defence RandD Canada Ottawa |
Difilippo D.J.,Defence RandD Canada Ottawa
IEEE National Radar Conference - Proceedings | Year: 2013
Through-wall radar imaging using ultrawideband signals is of interest for mapping interior room layouts of buildings, for detection of targets concealed within buildings and for determining in-wall structure. In this paper, we present some experimental results that demonstrate the benefits of a multi-look fusion approach for both interior room mapping and concealed target detection. In particular, we describe a concept of operation that requires only a single data collection pass in front of a building of interest, where the multiple looks are derived from images processed with different squint angles. © 2013 IEEE.
Wei Z.,Carleton University |
Tang H.,Defence RandD Canada Ottawa |
Yu F.R.,Carleton University |
Wang M.,Communications Research Center Canada |
Mason P.,Defence RandD Canada Ottawa
2014 IEEE International Conference on Communications, ICC 2014 | Year: 2014
Mobile Ad hoc NETworks (MANETs) are a promising communication technology for tactical environments and emergency response operations. However, the features of MANETs, including dynamic topology and open wireless medium, lead to many security vulnerabilities. Malicious nodes can drop or modify packets that are received from other nodes and diminish the reliability of networks. Therefore, secure routing in MANETs is an important area of research. In this paper, we propose a scheme that enhances routing security based on trust. In the proposed scheme, in order to improve the accuracy of trust values with indirect observations, we use Dempster-Shafer theory of evidence to fuse observers' opinions. Consequently, a more accurate trust value can be calculated from indirect observations. We then utilize the trust value to enhance the MANET routing protocol security. Simulation results are presented to demonstrate the effectiveness of the proposed scheme. © 2014 IEEE.
Flocchini P.,University of Ottawa |
Kellett M.,Defence RandD Canada Ottawa |
Mason P.C.,Defence RandD Canada Ottawa |
Santoro N.,Carleton University
Theory of Computing Systems | Year: 2012
Current mobile agent algorithms for mapping faults in computer networks assume that the network is static. However, for large classes of highly dynamic networks (e. g., wireless mobile ad hoc networks, sensor networks, vehicular networks), the topology changes as a function of time. These networks, called delay-tolerant, challenged, opportunistic, etc., have never been investigated with regard to locating faults. We consider a subclass of these networks modeled on an urban subway system. We examine the problem of creating a map of such a subway. More precisely, we study the problem of a team of asynchronous computational entities (the mapping agents) determining the location of black holes in a highly dynamic graph, whose edges are defined by the asynchronous movements of mobile entities (the subway carriers). We determine necessary conditions for the problem to be solvable. We then present and analyze a solution protocol; we show that our algorithm solves the fault mapping problem in subway networks with the minimum number of agents possible, k=γ+1, where γ is the number of carrier stops at black holes. The number of carrier moves between stations required by the algorithm in the worst case is O(k.nC 2.lR+nC.lR 2), where nC is the number of subway trains, and lR is the length of the subway route with the most stops. We establish lower bounds showing that this bound is tight. Thus, our protocol is both agent-optimal and move-optimal. © 2011 Her Majesty the Queen in Right of Canada, as represented by the Minister of National Defence.
Thayaparan T.,Defence RandD Canada Ottawa |
Stankovic L.J.,University of Montenegro |
Dakovic M.,University of Montenegro |
Popovic V.,University of Montenegro
IET Signal Processing | Year: 2010
Radar micro-Doppler (m-D) signatures are of great potential for identifying properties of unknown targets. All the techniques developed for extracting m-D features for the past decade rely primarily on the assumption that the time series of the signal contains at least one oscillation or more during the coherent integration time or imaging time. However, many applications in real-world scenarios involve short duration signals and often require the detection and the estimation of m-D characteristics. Short duration signals may contain only a fraction of an oscillation. In this study, the authors develop two techniques to estimate the m-D parameters from a fraction of the period. In these scenarios, the coherent integration will cover only 1/4 and 1/2 of the oscillation. The performance of the proposed methods are evaluated using both synthetic and experimental data. © 2010 The Institution of Engineering and Technology.
Hocking W.K.,MARDOC Inc. |
Thayaparan T.,Defence RandD Canada Ottawa |
Hocking A.,MARDOC Inc.
IET Signal Processing | Year: 2010
Joint spectral-temporal methods for target detection are not uncommon, but generally involve application of spectral processing on short sub-sections of the original time series. Usually a sliding window is applied, so that the region of truncation slides through the superset. Final analysis and interpretation are usually performed in the spectral domain. Here a new method of temporal-spectral analysis is presented. Truncation is used first in the spectral domain, and then multiple sets of resulting time series are employed for identification purposes. The method is called the ETISTI method ('enhanced truncated interleaved spectral-temporal interferometery'), and is adapted and extended from earlier meteor studies. It uses a combination of band-pass spectral filtering, auto-correlative algorithms and time-series analysis for target detection. It especially utilises long data sets of the order of hundreds to thousands of seconds, in order to improve spectral resolution, but at the same time achieves temporal resolution of the order of seconds. Signal-to-noise levels are determined locally rather than globally, using dynamic auotocovariance methods, thereby allowing adaptive time- and range-dependent noise-level determination, and hence better target discrimination. The method works especially well for accelerating targets, and for targets obscured by ionospheric interference, lightning and intermittent RF noise. © 2010 The Institution of Engineering and Technology.
Dragosevic M.V.,MDTerraBytes Inc. |
Burwash W.,MDA Systems Ltd. |
Chiu S.,Defence RandD Canada Ottawa
IEEE Transactions on Geoscience and Remote Sensing | Year: 2012
This paper describes in detail several multichannel variants of the famous displaced phase center antenna (DPCA) method suitable for spaceborne multichannel synthetic aperture radar ground moving target indication (GMTI), which has become available through the RADARSAT-2 moving-object detection experiment (MODEX). A flexible signal processing architecture was developed at Defense Research and Development Canada to support R&D work in GMTI and to provide a tool for MODEX system validation. The presented multichannel DPCA method is one of the first algorithms that have been implemented and successfully tested using this architecture. The main objective is to provides a simple, yet effective and robust way to detect ground moving vehicles and to estimate their position and velocity. This work forms a baseline for further advancement in the GMTI area. © 2012 IEEE.
Liu C.,Defence RandD Canada Ottawa |
Shang J.,Agriculture and Agri Food Canada |
Vachon P.W.,Defence RandD Canada Ottawa |
McNairn H.,Agriculture and Agri Food Canada
IEEE Transactions on Geoscience and Remote Sensing | Year: 2013
This paper studies the feasibility of monitoring crop growth based on a trend analysis of three elementary radar scattering mechanisms using three consecutive years (2008-2010) of RADARSAT-2 (R-2) Fine Quad Mode data. The polarimetric synthetic aperture radar analysis is based on the Pauli decomposition. Multitemporal analysis is applied to RGB images constructed using surface scattering, double-bounce, and volume scattering, along with intensity analysis of these scattering mechanisms. The test site is located in Eastern Ontario, Canada where the cropping system is dominated by corn, spring wheat, and soybeans. Each crop has unique physical structural characteristics which provide different responses for these scattering mechanisms. Significant changes occur in these scattering mechanisms as the crops move from one phenological stage to the next. By monitoring these changes over the season, the crop growth cycle from emergence to harvest can be observed. When harvest occurs, the backscatter intensities change significantly, and these changes aid in identifying crops. The temporal evaluation of the intensity of the scattering mechanisms generally track the measured leaf area index and observed phenological plant development. Changes in growth stage are crop type specific. Thus, to monitor changes in crop phenology and the occurrence of harvest activities, knowledge of the crop grown in any particular field is required. To accommodate this requirement, a maximum likelihood classification was performed on the R-2 data to produce a crop map. An overall classification accuracy of 85% was achieved. © 1980-2012 IEEE.
Wang S.,Defence RandD Canada Ottawa |
Wang S.,Communications Research Center Canada |
Jackson B.R.,Defence RandD Canada Ottawa |
Inkol R.,Defence RandD Canada Ottawa
2012 26th Biennial Symposium on Communications, QBSC 2012 | Year: 2012
Linear least squares (LS) and maximum likelihood (ML) estimators are derived for emitter geolocation using both received signal strength (RSS) and angle of arrival (AOA) information obtained from an heterogeneous sensor array. The results of simulation experiments provide useful insights into the behavior of these hybrid approaches and demonstrate that the use of simple RSS sensors to augment traditional AOA sensors can significantly improve the attainable geolocation accuracy. © 2012 IEEE.
Wu C.,Defence RandD Canada Ottawa |
Rajan S.,Defence RandD Canada Ottawa
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013
The fast Fourier sampling (FFS) method is related to the new sampling paradigm, compressive sampling (CS). This paper explores the application of the FFS method in an ultra-wide band digital receiver. The aim of the study is to quickly detect sparsely distributed carrier frequencies in an ultra-wide frequency band using fewer digital sampled data when compared to ubiquitous methods, such as the fast Fourier transform (FFT). Study shows that the FFS method can be applied to ultra-wide band sparse radar signal detection using randomly selected data from conventional analog-todigital converter and has the added advantage that it can be implemented on DSP hardware using a short-length of FFT. © 2013 SPIE.
Riddolls R.J.,Defence RandD Canada Ottawa
IEEE National Radar Conference - Proceedings | Year: 2014
An Over-The-Horizon Radar (OTHR) has been deployed near Ottawa, Canada. The radar is aimed northward and collects auroral echoes through line-of-sight propagation and ground echoes from beyond the horizon through ionospheric reflection. These echoes have been resolved in the three spatial dimensions of range, azimuth, and elevation, as well as in the temporal dimension of Doppler. It is shown that the three-dimensional spatial resolving capability is useful for separating the auroral and ground echo components. © 2014 IEEE.