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An improved adaptive algorithm for clutter and direct path interference removal in DVB-T based passive radar
, Article Proceedings International Radar Symposium, Dresden ; Volume 2 , June , 2013 , Pages 1049-1055 ; 21555753 (ISSN) ; 9783954042234 (ISBN) ; Moniri, M. R ; Shekhi, A ; Radmard, M ; Sharif University of Technology
2013
Abstract
The present study aims to evaluate the important issue of elimination of direct path interference and clutter in ambiguity function and detection of passive radars with adaptive filters. The efficiency and performance of each of them were investigated. Finally, by simulation and their learning curve, the best algorithm was proposed for these radars
A Survey With Simulation on DVB-Based Passive Radar
, M.Sc. Thesis Sharif University of Technology ; Bastani, Mohammad Hassan (Supervisor) ; Behnia, Ferydon (Supervisor)
Abstract
One of non-cooperative illuminators recently considered for passive radar application is the DVB-T signal. Its thumbtack ambiguity function beside the constancy over time makes it very desirable. But there are some ambiguities in its ambiguity function that can not be neglected. In this paper, after studying the reasons of the ambiguities we propose some processings to remove them. It is shown that for removing the ambiguities, it’s sufficient to filter out continual pilots and equalize scattered pilots. The results show that an ambiguity function relatively without ambiguities will be obtained. A method for compensating the target’s range migration-that results in processing gain decrease...
Advantages of the DVB-T signal for passive radar applications
, Article 4th Microwave and Radar Week MRW-2010 - 11th International Radar Symposium, IRS 2010 - Conference Proceedings, 16 June 2010 through 18 June 2010 ; 2010 , Pages 274-278 ; 9789955690184 (ISBN) ; Bastani, M ; Behnia, F ; Nayebi, M. M ; Sharif University of Technology
2010
Abstract
One of the attractive opportunistic signals for passive radar applications is the DVB-T (Digital Video Broadcasting- Terrestrial) signal. The thumbtack ambiguity function of the DVB-T signal in addition to being stationary makes such signal a good candidate for such applications. In this paper we want to consider its feasibility for this application in more details. So we first examin this signal for the main parts of the the passive radar: Resolving ambiguities before evaluating CAF and direct path intereference rejection, and then consider its processing gain in detecting targets
Passive radar processing blocks gain estimation
, Article International MultiConference of Engineers and Computer Scientists 2007, IMECS 2007, Kowloon, 21 March 2007 through 23 March 2007 ; Volume 2 , 2007 , Pages 1748-1752 ; 20780958 (ISSN) ; 9789889867171 (ISBN) ; Behnia, F ; Sharif University of Technology
2007
Abstract
Passive radars use illuminators of opportunity to detect target and measure its parameters. The usual processing routine consists of direct path interference and clutter removal and computation of cross ambiguity function (CAF) to estimate ampIitude-range-Doppler surface. Main parameters affecting this procedure are direct path interference and clutter, receiver thermal noise and near large targets. This paper presents an investigation on effect of each parameter and tries to estimate processing gain of each Block. A comparison between different adaptive interference removal methods also presented
Hypoenergetic and nonhypoenergetic digraphs
, Article Linear Algebra and Its Applications ; Volume 618 , 2021 , Pages 129-143 ; 00243795 (ISSN) ; Das, K. C ; Khalashi Ghezelahmad, S ; Koorepazan Moftakhar, F ; Sharif University of Technology
Elsevier Inc
2021
Abstract
The energy of a graph G, E(G), is the sum of absolute values of the eigenvalues of its adjacency matrix. This concept was extended by Nikiforov to arbitrary complex matrices. Recall that the trace norm of a digraph D is defined as, N(D)=∑i=1nσi, where σ1≥⋯≥σn are the singular values of the adjacency matrix of D. In this paper we would like to present some lower and upper bounds for N(D). For any digraph D it is proved that N(D)≥rank(D) and the equality holds if and only if D is a disjoint union of directed cycles and directed paths. Finally, we present a lower bound on σ1 and N(D) in terms of the size of digraph D. © 2021 Elsevier Inc
Hypoenergetic and nonhypoenergetic digraphs
, Article Linear Algebra and Its Applications ; Volume 618 , 2021 , Pages 129-143 ; 00243795 (ISSN) ; Das, K. C ; Khalashi Ghezelahmad, S ; Koorepazan Moftakhar, F ; Sharif University of Technology
Elsevier Inc
2021
Abstract
The energy of a graph G, E(G), is the sum of absolute values of the eigenvalues of its adjacency matrix. This concept was extended by Nikiforov to arbitrary complex matrices. Recall that the trace norm of a digraph D is defined as, N(D)=∑i=1nσi, where σ1≥⋯≥σn are the singular values of the adjacency matrix of D. In this paper we would like to present some lower and upper bounds for N(D). For any digraph D it is proved that N(D)≥rank(D) and the equality holds if and only if D is a disjoint union of directed cycles and directed paths. Finally, we present a lower bound on σ1 and N(D) in terms of the size of digraph D. © 2021 Elsevier Inc
Target Detection and Tracking in Passive Forward Scattering Radar based on Satellite Signals
, M.Sc. Thesis Sharif University of Technology ; Behroozi, Hamid (Supervisor)
Abstract
In this thesis, we investigate a passive forward scattering radar system based on satellite signal. In this thesis we have used the GPS satellite signal as a non-cooperative transmitter.In order to analyze the passive forward scattering radar system as a subset of the bistatic radars, first the features and equations of the bistatic radar will be presented, and then we will discuss the important advantages and disadvantages of the passive forward scattering radar.In order to investigate the features of passive forward scattering radar based on satellite signal, an appropriate geometry will be presented with the characteristics of this radar and parameters such as time delay between direct...
Direct Path Cancellation in Satellite Signal Based Forward Scattering Radar
, M.Sc. Thesis Sharif University of Technology ; Behroozi, Hamid (Supervisor)
Abstract
Passive bistatic radars (PBR) using transmitters of opportunity have attracted a lot of attention recently. Advantages of these radars include the covert operation as well as the low cost of their building and maintenance. Such radars are intended to use signals in the environment as transmitters. These transmitters can be terrestrial transmitters such as TV broadcasts or even satellite transmitters such as global positioning system (GPS) satellites.Satellite transmitters have global coverage and their signal is available at all times, but the design of these transmitters for non-radar applications causes the reduction of the reception power at receivers. So BR systems have attempted to use...
Outage-dependent and traditional power optimisations for amplify and forward incremental relaying with channel estimation errors
, Article IET Communications ; Volume 6, Issue 10 , 2012 , Pages 1234-1244 ; 17518628 (ISSN) ; Sadeghi, P ; Pakravan, M. R ; Sharif University of Technology
2012
Abstract
In this study, the authors optimise the outage probability of amplify and forward incremental relaying (IR) scheme using two different power allocation methods in the presence of channel estimation errors. The authors find the outage probability of IR scheme and minimise it subject to traditional power (TP) constraint in which the sum of nodes' powers is fixed and outage-dependent power (ODP) constraint which is compatible with the physical concept of IR and takes into account the quality of the direct path in the optimisation problem. The authors provide closed-form expressions to allocate power to pilot and data symbols of both the source and the relay. Although, their analysis uses high...
Outage-dependent and traditional power optimisations for amplify and forward incremental relaying with channel estimation errors
, Article IET Communications ; Volume 6, Issue 10 , 3 July , 2012 , Pages 1234-1244 ; Sadeghi, P ; Pakravan, M. R. (Mohammad Reza) ; Sharif University of Technology
Abstract
In this study, the authors optimise the outage probability of amplify and forward incremental relaying (IR) scheme using two different power allocation methods in the presence of channel estimation errors. The authors find the outage probability of IR scheme and minimise it subject to traditional power (TP) constraint in which the sum of nodes' powers is fixed and outage-dependent power (ODP) constraint which is compatible with the physical concept of IR and takes into account the quality of the direct path in the optimisation problem. The authors provide closed-form expressions to allocate power to pilot and data symbols of both the source and the relay. Although, their analysis uses high...
Target detection by passive coherent FM based bistatic radar
, Article 2008 International Conference on Radar, Radar 2008, Adelaide, SA, 2 September 2008 through 5 September 2008 ; October , 2008 , Pages 412-415 ; 9781424423224 (ISBN) ; Nayebi, M. M ; Norouzi, Y ; CEA Technologies Pty Ltd; Cranfield University; Diversified Technologies, Inc; Information, Telecommunications and Electronic Engineering (ITEE); Board of Engineers Australia ; Sharif University of Technology
2008
Abstract
Bistatic passive radars have many advantages over the monostatic ones because they are undetectable and silent. In passive coherent location, the original source of energy is derived from a waveform of opportunity in the environment and the re-radiated energy from the target is processed to decide about the existence of the target. More over bistatic radars receive forward scatters from target in place of the backscatters in monostatics systems. As a result of the larger forward scattered RCS, the stealth targets can be detected easier. Passive radar does not need any frequency allocation so are very attractive for surveillance. Multipath effects and direct path interference are two problems...