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  • 151.
    Sjögren, Thomas
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Vu, Viet
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Wang, Feng
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Murdin, Daniel
    Gustavsson, Anders
    Ulander, Lars
    Suppression of Clutter in Multichannel SAR GMTI2014Ingår i: IEEE Transactions on Geoscience and Remote Sensing, ISSN 0196-2892, E-ISSN 1558-0644, Vol. 52, nr 7, s. 4005-4013Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, results of moving target detection in multichannel UHF-band Synthetic Aperture Radar (SAR) data are shown. The clutter suppression is done using Finite Impulse Response (FIR) filtering of multichannel SAR in combination with a 2-stage Fast Backprojection (FBP) algorithm to focus the moving target using relative speed. The FIR filter coefficients are chosen with the use of STAP filtering. Two parameters are used for target focusing, target speed in range and in azimuth. When the target is focused, both speed parameters of the target are found. In the experimental results, two channels were used in order to suppress clutter. In the resulting SAR images it is obvious that very strong scatterers and the forest areas have been suppressed in comparison to the moving target in the image scene. The gain obtained can be measured using SCNR gain, which is about 19dB. Another way to measure signal processing gain is the ability to suppress the strongest reflecting object in the SAR scene. The gain of target in relation to this object is 25dB. This shows that using UHF-band SAR GMTI for suppressing forest and increasing the target signal can work.

  • 152. Sjögren, Thomas
    et al.
    Vu, Viet Thuy
    Pettersson, Mats
    2D apodization in UWB SAR using linear filtering2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, an investigation is made on how sidelobes can be suppressed in ultrawideband-ultrawidebeam (UWB) Synthetic Aperture Radar (SAR) using apodization. Due to the special properties of UWB SAR such as very wide integration angle and very large relative bandwidth, the support for the spectrum of a SAR image differs distinctively from a rectangle, which is the normal approximation in narrowband-narrowbeam (NB) SAR. The proposal in the paper is to apply non-separable windows to the spectrum, in order to suppress sidelobes. Non-separable windows are shown to give less broadening of mainlobe while maintaining the same suppression of sidelobes in comparison to separable windows. In the comparison, parameters for three different SAR systems are used.

  • 153. Sjögren, Thomas
    et al.
    Vu, Viet Thuy
    Pettersson, Mats
    Moving Target Refocusing Algorithm for Synthetic Aperture Radar Images2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the area of SAR imaging, it is of interest to be able to focus moving targets. In this paper, an algorithm for moving target focusing is presented. The algorithm is able to refocus a smeared moving target in a SAR image processed at one relative speed to the correct one.. The algorithm works in the frequency domain and is based on the Range Migration algorithm. The refocusing can be made on the whole SAR image or small sub images corresponding to physical areas of interest for the end user. By applying the algorithm to a small image, the computational cost is greatly reduced compared with using the full SAR image. The performance is illustrated by applying the algorithm to simulated SAR data according to the parameters for the LORA system.

  • 154. Smirnova, Tatiana
    Analysis, Modeling and Simulation of Machine Tool Parts Dynamics for Active Control of Tool Vibration2010Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Boring bar vibration in machine tools during internal turning operations is a pronounced problem in the manufacturing industry. Due to the often slender geometry of the boring bar, vibration may easily be induced by the material deformation process. One approach to overcome such vibration problems is to use active control of boring bar vibration. The design time of an active boring bar depends to a great extent on the knowledge of its dynamic properties when clamped in a lathe for different actuator positions and sizes, crucial for its performance. This thesis focuses on the development of accurate dynamic models of active boring bars with the purpose of providing qualitative information on suitable actuator position for a certain boring bar. The first part of the thesis considers the problem of building an accurate "3-D" finite element (FE) model of a standard boring bar used in industry. Results from experimental modal analysis of the actual boring bar are the reference. The second and the third parts discuss analytical and experimental methods for modeling the dynamic properties of a boring bar clamped in a machine tool. For this purpose, the Euler-Bernoulli and Timoshenko beam theories are used to produce both distributed-parameter system models and corresponding "1-D" FE models. A more complete "3-D" FE model of the system boring bar - clamping house is also developed. Spatial dynamic properties of these models are discussed and compared with adequate experimental modal analysis results from the actual boring bar clamped in a machine tool. The third part also investigates the sensitivity of the spatial dynamic properties of the derived boring bar models to variation in the structural parameters' values. The fourth part focuses on the development of a "3-D" FE model of the system boring bar - actuator - clamping house. Two models are discussed: a linear model and a model enabling variable contact between the clamping house and the boring bar with and without Coulomb friction in the contact surfaces. Based on these FE models fundamental bending modes and control path frequency response functions are discussed in conjunction with the corresponding quantities estimated for the actual active boring bar. In the fifth part, a method based on FE modeling and artificial neural networks for selecting a suitable actuator position inside an active boring bar is presented. Objective functions for selecting an actuator position are suggested. An active boring bar with an actuator position suggested by the method was manufactured and it displays fairly good correlation with the corresponding FE model. The final part focuses on modeling of an active boring bar vibration control system. A simple "1-D" FE model of a boring bar is utilized to simulate the dynamic response and an adaptive digital feedback controller realized by the feedback filtered-x LMS algorithm is used.

  • 155. Smirnova, Tatiana
    et al.
    Larsson, Martin
    Gertsovich, Irina
    Johansson, Sven
    Claesson, Ingvar
    Håkansson, Lars
    Initial investigations concerning modelling of sound propagation in ducts with ANC by means of two-port theory and FEM2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    Today mechanical ventilation systems are installed in many buildings to handle the ventilation. Such ventilation systems constitute a potential source of unwanted background noise in the buildings. In order to reduce the noise propagating through the ducts passive silencers are normally installed as a part of the ventilation system. However, the passive silencers are relatively ineffective in the low frequency range. A solution can be to use a combination of active noise control (ANC) and passive techniques where the ANC system extends the noise attenuation to include the low frequency noise. The construction of the ventilation systems can vary substantially between different buildings and may contain many different duct parts in different compositions etc. Hence, it may not be trivial to find a cost- and performance efficient installation of an ANC system in a ventilation system, e.g. to find a proper installation position of it and suitable passive silencers to combine it with, finding out if one or several ANC systems should be used, and so on. In order to make the design of a complete ventilation system (including one or several ANC systems) cost- and time efficient, an adequate mathematical model of the duct is required. The purpose of the model is to describe sound propagation in the duct. Such model can be built e.g. based on the two-port theory or by finite element method. In this paper initial investigations concerning modelling of standard duct parts were performed. Simulations were carried out to find parameters such as Noise Reduction etc., using both plane wave two-port theory and finite element modelling. The results of the simulations were compared with measurement results.

  • 156.
    Swartling, Mikael
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Direction of Arrival Estimation and Localization of Multiple Speech Sources in Enclosed Environments2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Speech communication is gaining in popularity in many different contexts as technology evolves. With the introduction of mobile electronic devices such as cell phones and laptops, and fixed electronic devices such as video and teleconferencing systems, more people are communicating which leads to an increasing demand for new services and better speech quality. Methods to enhance speech recorded by microphones often operate blindly without prior knowledge of the signals. With the addition of multiple microphones to allow for spatial filtering, many blind speech enhancement methods have to operate blindly also in the spatial domain. When attempting to improve the quality of spoken communication it is often necessary to be able to reliably determine the location of the speakers. A dedicated source localization method on top of the speech enhancement methods can assist the speech enhancement method by providing the spatial information about the sources. This thesis addresses the problem of speech-source localization, with a focus on the problem of localization in the presence of multiple concurrent speech sources. The primary work consists of methods to estimate the direction of arrival of multiple concurrent speech sources from an array of sensors and a method to correct the ambiguities when estimating the spatial locations of multiple speech sources from multiple arrays of sensors. The thesis also improves the well-known SRP-based methods with higher-order statistics, and presents an analysis of how the SRP-PHAT performs when the sensor array geometry is not fully calibrated. The thesis is concluded by two envelope-domain-based methods for tonal pattern detection and tonal disturbance detection and cancelation which can be useful to further increase the usability of the proposed localization methods. The main contribution of the thesis is a complete methodology to spatially locate multiple speech sources in enclosed environments. New methods and improvements to the combined solution are presented for the direction-of-arrival estimation, the location estimation and the location ambiguity correction, as well as a sensor array calibration sensitivity analysis.

  • 157. Swartling, Mikael
    et al.
    Grbic, Nedelko
    Calibration errors of uniform linear sensor arrays for DOA estimation: an analysis with SRP-PHAT2011Ingår i: Signal Processing, ISSN 0165-1684, E-ISSN 1872-7557, Vol. 91, nr 4, s. 1071-1075Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article presents an analysis of the sensitivity of geometrical sensor errors in acoustic source localization using the well-established SRP-PHAT method. The array in this analysis is a uniform linear array and the intended source is human speech in the far field. Two major results are presented: inner-sensor geometrical errors in the linear array produce smaller localization errors than corresponding geometrical errors do in the two end-point sensors, and the localization error rises sharply for a total geometrical error exceeding the equivalence of the acoustic propagation distance of 2/3 of the sample time instance (approximately 3 cm at 8 kHz). The article also provides a mathematical and graphical explanation of the results.

  • 158.
    Swartling, Mikael
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Ström Bartunek, Josef
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Nilsson, Kristian
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Gustavsson, Ingvar
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Simulations of the VISIR Open Lab Platform2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a queue simulation of the VISIR Open Lab Platform. A model of the platform and statistical distributions of how users interact with the system based on real log files are presented. The system is then simulated in order to determine how many concurrent students that can be allowed to use the platform while at the same time keeping a low response time to ensure the quality of the service. The results show, in a worst case setup with approximately 300 ms response time per experiment, that roughly 100 concurrent users is an upper limit to ensure an average response time below 2 s. The results also show that raising the limit of the desired experiment response time does not necessarily increase the number allowed concurrent users significantly once the system is saturated. However, improving the experiment response time can significantly increase the number of users that can simultaneously be connected.

  • 159. Swartling, Mikael
    et al.
    Sällberg, Benny
    Grbic, Nedelko
    Source localization for multiple speech sources using low complexity non-parametric source separation and clustering2011Ingår i: Signal Processing, ISSN 0165-1684, E-ISSN 1872-7557, Vol. 91, nr 8, s. 1781-1788Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article presents a new method for localization of multiple concurrent speech sources that relies on simultaneous blind signal separation and direction of arrival (DOA) estimation, as well as a method to solve the intersection point selection problem that arises when locating multiple speech sources using multiple sensor arrays. The proposed method is based on a low complexity non-parametric blind signal separation method, making is suitable for real-time applications on embedded platforms. On top of reduced complexity in comparison to a previously presented method, the DOA estimation accuracy is also improved. Evaluation of the performance is done with both real recording and simulations, and a real-time prototype of the proposed method has been implemented on a DSP platform to evaluate the computational and the memory complexities in a real application.

  • 160. Tawfik, Mohamed
    et al.
    Sancristobal, Elio
    Sergio, Martin
    Gil, Rosario
    Diaz, Gabriel
    Colmenar, Antonio
    Nilsson, Kristian
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Zackrisson, Johan
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Håkansson, Lars
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Gustafsson, Ingvar
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Virtual Instrument Systems in Reality (VISIR) for Remote Wiring and Measurement of Electronic Circuits on Breadboard2013Ingår i: IEEE Transactions on Learning Technologies, ISSN 1939-1382, E-ISSN 1939-1382, Vol. 6, nr 1, s. 60-72Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reports on a state-of-the-art remote laboratory project called Virtual Instrument Systems in Reality (VISIR). VISIR allows wiring and measuring of electronic circuits remotely on a virtual workbench that replicates physical circuit breadboards. The wiring mechanism is developed by means of a relay switching matrix connected to a PCI eXtensions for Instrumentation (PXI) instrumentation platform. The entire equipment is controlled by LabVIEW server software, in addition to a measurement server software that protects the equipment from hazard connections by verifying input circuit designs, sent by students, before being executed. This paper addresses other approaches such as remote labs based on Data Acquisition Cards (DAQs), NetLab, and RemotElectLab, comparing them with VISIR in order to emphasize its singularity. Topics discussed are as follows: the technical description, software, operation cycle, features, and provided services. In addition, the feedback received by students at several universities and the encountered drawbacks along with the proposed solutions are highlighted. The paper finally addresses the ongoing and future challenges within the VISIR community including its integration with Learning Management Systems (LMSs) and iLab Shared Architecture (ISA), its new hardware version release that is based on LAN eXtensions for Instrumentation (LXI), and its new open platform version that supports federated access.

  • 161. Tegborg, Viktoria
    et al.
    Pettersson, Mats
    Claesson, Ingvar
    Experimental results of passive imaging of moving continuous broadband sound sources within a sensor field2011Ingår i: IEEE Journal of Oceanic Engineering, ISSN 0364-9059, E-ISSN 1558-1691, Vol. 36, nr 1, s. 26-37Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sparsely distributed sensors or sparse arrays can be associated with high positional accuracy and capability for large area surveillance. This paper shows, both through simulations and with real measurement data, that sparse sensor systems can be used to accomplish high-performance underwater surveillance. The paper focuses on measurement setups with several passive single hydrophones placed hundreds of meters apart in a water depth of dozen of meters. By such a setup, a sound source is more likely to move inside the array, and thus near-field processing can be considered. The sensor pairs will also be located in different directions in relation to the sound source. These two prerequisites give the possibilities to high spatial resolution. Images of the coherent sound activity for different sensor pairs are formed, and every sensor pair map is summarized into a resulting map. In this way, an arbitrary number of sound sources of a target can be resolved. Good correlation results are shown even when the sound sources are at the same distance as the baseline of the sensor pairs. This is achieved by Doppler compensating for target movement and also by whitening of the cross spectra. The analyses of the measurements also show that baseline-dependent bandwidth can improve the results. In this paper, it is indicated from experimental data that two propeller sound sources could be resolved, and in another measurement setup, the engine could be separated from the propellers.

  • 162. Thenmozhi, K
    et al.
    Konakalla, Vamsi
    Vabbilisetty, SPP
    Amirtharajan, R
    Space time frequency coded (STF) OFDM for broadband wireless communication systems2011Ingår i: Journal of Theoretical and Applied Information Technology, ISSN 1992-8645, E-ISSN 1817-3195, Vol. 31, nr 1, s. 53-59Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The current problems in wireless systems are multi-path propagation, frequency selective fading, Inter-Symbol Interference (ISI) and Inter-Carrier Interference (ICI), with the major challenge being transmission of information having high data rates over long distances. The Orthogonal Frequency Division Multiplexing (OFDM) systems solve a few of the above stated problems by the use of diversity schemes, which increase the reliability and security of the message. By adopting Multiple-Input Multiple-Output (MIMO) and OFDM technologies, wireless systems could reach data rates up to several hundreds of Mbps and achieve spectral efficiencies of several tens of bits/Hz/s, which are unattainable for conventional Single-Input Single-Output (SISO) systems. This paper deals with the simulation of Space Time Frequency (STF) coded OFDM system. The coding schemes like Space Time (ST), Space Frequency (SF) and Space Time Frequency (STF) coding are compared and from the results it is proved that STF scheme performs better than ST and SF schemes. The Space Time Frequency coded communication system when is used along with diversity schemes like MIMO and Multiple Input Single Output (MISO) is compared for their performance over a fading channel having inherent noise, and it is further proved that MIMO performs better than MISO schemes.

  • 163. Tran, Hung
    et al.
    Duong, Quang Trung
    Zepernick, Hans-Jürgen
    Average Waiting Time of Packets with Different Priorities in Cognitive Radio Networks2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we investigate the average waiting time of packets with different priorities in cognitive radio networks (CRN) using a preemptive priority queuing system. Specifically, we consider two scenarios for CRN, the first with the secondary user (SU) sensing at the beginning of each time slot and the other with the SU having continues sensing ability. Our analysis shows that the average waiting time of packets for the SU does not only depend on the size of packets and arrival rate of the SU traffic but also depends on the arrival rate and size of packets from primary users (PU). Moreover, the results show that an SU with continuous sensing ability can utilize spectrum better than sensing at the beginning of each time slot.

  • 164. Tran, Hung
    et al.
    Duong, Quang Trung
    Zepernick, Hans-Jürgen
    Performance of a Spectrum Sharing System over Nakagami-m Fading Channels2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we derive the probability density function and cumulative distribution function of packet transmission time in a spectrum sharing system. In combination with the time-out characteristics of packets, we further study the outage probability and average transmission time under peak power interference constraint over Nakagami-m fading channel. Especially, we employ the M/G/1 queuing model to calculate the average waiting time of packets and average number of packets waiting in the queue of a secondary user. The numerical results show the importance of the peak interference power constraint on the delay of packets at the secondary user.

  • 165. Tran, Hung
    et al.
    Duong, Quang Trung
    Zepernick, Hans-Jürgen
    Queuing Analysis For Cognitive Radio Networks Under Peak Interference Power Constraint2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we study the effect of peak interference power constraint on outage probability and transmission time of packets for secondary user (SU) in a spectrum sharing environment. In the considered cognitive radio network scenario, a secondary user transmitter sends its packets over a Rayleigh fading channel. In combination with the analysis of time out characteristics, queuing models are deployed to evaluate average transmission time of packets, average waiting time of packets, and average number of packets waiting in the queue of the cognitive user.

  • 166.
    Tran, Hung
    et al.
    Malardalen Univ, S-72123 Vasteras, Sweden..
    Zepernick, Hans-Juergen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem. Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem. Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling. Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation. Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Phan, Hoc
    Univ Reading, Reading RG6 6AY, Berks, England..
    On Throughput and Quality of Experience in Cognitive Radio Networks2016Ingår i: 2016 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE, IEEE , 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, a performance analysis for cognitive radio networks (CRNs) under the outage probability constraint of the primary user and peak transmit power constraint of the secondary user is conducted. Given an automatic repeat request protocol, analytical expressions for the packet delay and throughput of the CRN are derived. Most importantly, these expressions can be used to understand the quality of experience on web services which are assumed to be offered by the considered CRN.

  • 167. Tran, Nguyen Nam
    et al.
    Duong, Quang Trung
    Training Design upon Mutual Information for Spatially Correlated MIMO-OFDM2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    Our goal in this paper is to address channel estimations for spatially correlated multiple-input multiple-output with orthogonal frequency-division multiplexing (MIMO-OFDM) system upon the conditional mutual information (CMI). The design of superimposed training signal by maximizing the channel CMI is fully investigated. First, the interior-point-method is employed to obtain the optimal superimposed training signals for the general case of channel correlations. In addition, two efficient approximate designs are also proposed by invoking Karush-Kuhn-Tucker condition for optimality of convex programming. The first approximate design is obtained by proposing a iterativebisection-procedure (IBP), while the second one is in “waterfilling” closed-form. Numerical results demonstrate the excellent performance of the proposed designs and give the connection between channel estimation error and mutual information.

  • 168.
    Uddin, Jia
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Faisal, Mohammed
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Azam, Facihul
    Muzahidur Rahman, A. F. M.
    Performance analysis of multicarrier code division multiple access over Rayleigh fading channel2012Ingår i: Advanced Materials Research, Shenyang, Liaoning: Trans Tech Publications , 2012, Vol. 457-458, s. 985-988Konferensbidrag (Refereegranskat)
    Abstract [en]

    Recently, multi-carrier transmission schemes have been introduced into Code Division Multiple Access (CDMA) systems to gain advantages for high data rate transmission as well as security. Due to pseudorandom code there is no chance to Inter Symbol Interference (ISI). There are different techniques to mitigate multipath fading. One of the method is to transmit identical narrowband direct-sequence (DS) waveforms in parallel over a number of sub-channels using frequency diversity. Implementation this multi-carrier modulation technique in CDMA system is known as multi-carrier CDMA (MC-CDMA). In Rayleigh fading channel, due to multi-carrier modulation, when one subcarrier goes deep fade another subcarrier may remain safe. Therefore it combats multi-path fading and signal can be received in low bit error rate.

  • 169.
    Valirad, sina
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Parsasirat, Mahyar
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Iran's electric power system2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Abstract Iran is a very vast country with about 80 million population that they are really fragmented. Providing electricitypower for all the society which is duty of power ministry of Iran according to the resources and facilities. The thesis gives an overview of production of electrical energy in Iran and how the production is divided ondifferent energy sources. At the present time there are 197 power plants are producing electricity to supportthe country that they are combination of 8 kind of different power plants which are thermal power plants, gaspower stations, combined cycles, hydro power plants, biogas plants, wind power stations, solar plants andnuclear power stations. During the last decade Iran took care of renewable energy sources to produce electricitythat cause wind power plants and solar power plants can take a small share from the total production. Althoughthey are not play a serious role yet but the policy of the country is improving these kind of power plants. Foreach source the production principle is described briefly by help of a diagram and also there is a table of allpower plants which are included details of each power plant like: name of power plant, state (location) , year ofinstallation, nominal power, gross power, efficiency, consumption (fuel, water,…) and so on. For each kind ofpower plants there is a bar chart which compares the nominal power of all power plants at a glance and alsothere is a map that the location of each station has been marked on. Total data for production in a year has been presented. Also there is a list of power plants which they are underconstruction and will be ready in future. For transmitting electricity power in the country there are four kind of transmission lines which are: 400 KV, 230KV, 132 KV and 66 KV. The development of each kind of transmission lines since 1963 is presented in a table anda chart. Also Iran has export and import electricity with 8 neighbor countries like: Iraq, Afghanistan, Azerbaijan,Turkmenistan, Turkey, Pakistan, Armenia and Nakhjavan. The range of exchange since 1993 is shown in a tableand a chart.

  • 170.
    Vu, Viet
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Nehru, Dheeraj
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    An Experimental Ground-based SAR System for Studying SAR Fundamentals2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper introduces a simple experimental groundbased SAR system for studying SAR fundamentals. The SAR system is developed on a vector network analyzer (VNA), for example Agilent E5071C, with some useful built-in functions such as transform and gating. The procedure of acquiring the data by using the SAR system is presented in details. The acquired empirical data is also used to reconstruct the illuminated scene. The possibilities to use the SAR system to support SAR research topics are also discussed in this paper.

  • 171.
    Vu, Viet
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Another possibility to focus moving targets by normalized relative speed in UWB SAR2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper presents another possibility to focus moving targets using normalized relative speed (NRS). Similar to the currently used focusing approach, the focusing approach proposed in this paper aims at the ultrawideband and ultrawidebeam synthetic aperture radar systems (UWB SAR) like CARABAS-II. The proposal is shown to overcome the shortcomings of the original focusing approach and can be extended to more complicated cases, for example bistatic SAR.

  • 172.
    Vu, Viet
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    The Capability of Time- And Frequency-domain Algorithms for Bistatic SAR Processing2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper presents a study of the capability of time- And frequency-domain algorithms for bistatic SAR processing. Two typical algorithms, Bistatic Fast Backprojection (BiFBP) and Bistatic Range Doppler (BiRDA), which are both available for general bistatic geometry, are selected as the examples of time- And frequency-domain algorithms in this study. Their capability is evaluated based on some criteria such as processing time required by the algorithms to reconstruct SAR images from bistatic SAR data and the quality assessments of those SAR images.

  • 173.
    Vu, Viet
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Two-Dimensional Spectrum for BiSAR Derivation Based on Lagrange Inversion Theorem2014Ingår i: IEEE Geoscience and Remote Sensing Letters, ISSN 1545-598X, E-ISSN 1558-0571, Vol. 11, nr 7, s. 1210-1214Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A 2-D spectrum for bistatic synthetic aperture radar is derived in this letter. The derivation is based on the commonly used mathematic principles such as themethod of stationary phase and the Fourier transform and the Lagrange inversion theorem in order to find the point of stationary phase in the method of stationary phase. Using the Lagrange inversion theorem allows minimizing the initial assumptions or the initial approximations. The derived 2-D spectrum is compared with the commonly used 2-D spectrum to verify it and illustrate its accuracy.

  • 174. Vu, Viet Thuy
    Practical Considerations on Ultrawideband Synthetic Aperture Radar2009Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The practical considerations in ultrawideband (UWB) synthetic aperture radar (SAR) data processing in general and UWB SAR imaging in particular are clarified and presented in detail in this thesis. They are imaging algorithm, impulse response function in SAR imaging (IRF-SAR), apodization, RF interference (RFI) and SAR image quality measurement. Different algorithms in both time- and frequency domain and their suitability to process UWB SAR data are investigated and evaluated. The necessary modifications for these algorithms are proposed to fulfill the requirements of UWB SAR data processing. The time-domain imaging algorithms are highly recommended for UWB SAR data processing due to their characteristics such as integrated motion error compensation, unlimited scene size and local processing. A new IRF-SAR, which is a function of fractional bandwidth and antenna beamwidth, is derived. The function allows us to investigate different UWB SAR systems. Such investigations are not facilitated by currently used IRF-SAR, Sinc functions. The derived IRF-SAR is totally valid to investigate narrowband (NB) SAR systems. A discussion about the apodization techniques and possibilities to apply to UWB SAR data processing is given in this thesis. Handling orthogonal and non-orthogonal sidelobe in UWB SAR imaging is shown to be challenging with the currently used apodization approaches. The linear apodization approaches always result in the loss in resolutions while the phase information can be destroyed by the nonlinear apodization approaches. A new approach to suppress RFI in UWB SAR signal, which is easy to be disturbed by RFI sources, is suggested. The advantages of the approach compared to the others can be found in adaptive and real time processing characteristics. A new definition of SAR image quality measurement is also presented in this thesis. The complicated behavior of IRF-SAR over fractional bandwidth and antenna beamwidth results in the unsuitability of the currently used definition for UWB SAR image quality measurements. The unsuitability is mainly caused by the inappropriate delimitation of mainlobe and sidelobe areas, the fixed broadening factors and the fixed spreading factor of the orthogonal and non-orthogonal sidelobes. Based on these practical considerations, the thesis also presents some possibilities to propose a definition of UWB SAR which is still not available. The beginning investigated results show that these possibilities comply with the UWB definition proposed by Federal Communications Commission (FCC) in 2002.

  • 175. Vu, Viet Thuy
    Ultrawideband-Ultrawidebeam Synthetic Aperture Radar – Signal Processing and Applications2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This dissertation presents practical issues in Ultrawideband – Ultrawidebeam (UWB) Synthetic Aperture Radar (SAR) signal processing and crucial applications developed on UWB SAR. In the context of this dissertation, UWB SAR refers to the SAR systems utilizing large fractional bandwidth signals and synthesizing long apertures associated with wide antenna beamwidths. On one hand, such specific systems give us opportunities to develop unique applications. One the other hand, signal processing for data collected by these systems is very challenging and therefore requires much effort due to their characteristics. In the signal processing part, the tools supporting the UWB SAR system design and evaluation are introduced. They include an Impulse Response Function in UWB SAR imaging (IRF-SAR), azimuth and range resolution equations for UWB SAR, and a definition of UWB SAR quality measurements. Pre-processing, processing and post-processing for UWB SAR are also topics that will be examined in the signal processing part. The processing is here defined by SAR algorithms. With this definition, the pre-processing refers to RFI suppression approaches whereas the post-processing implies apodization or sidelobe control methods. In the application part, Ground Moving Target Indication (GMTI) is selected for study due to its interest to both military and civilian end-users. GMTI developed on UWB SAR relates to the moving target detection by focusing technique which can be combined with the space-time processing such as Displaced Phase Center Antenna (DPCA) and Space-Time Adaptive Processing (STAP).

  • 176.
    Vu, Viet Thuy
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap. Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling. Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för matematik och naturvetenskap. Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap.
    thomas, Sjögren
    Swedish Defence Research Agency, SWE.
    Moving Target Focusing in SAR Image with Known Normalized Relative Speed2017Ingår i: IEEE Transactions on Aerospace and Electronic Systems, ISSN 0018-9251, E-ISSN 1557-9603, Vol. 53, nr 2, s. 854-861Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the moving target focusing method, whichallows focusing moving targets in complex synthetic aperture radar(SAR) images without raw data. The method is developed on the rangemigration algorithm, where focusing moving target is an interpolationstep in the wave domain. The simulated results are provided in thepaper to illustrate the proposed method whereas the experimentalresults show its practicality. The method can be flexibly applied fromsmall area to the whole SAR scene.

  • 177.
    Vu, Viet Thuy
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Sjogren, Thomas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Minardi, Michael
    Studying Csar Systems Using Irf-Csar2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, Impulse Response Function in Circular Synthetic Aperture Radar Imaging (IRF-CSAR), which is a special version of Impulse Response Function in Ultrawideband-Ultrawidebeam Synthetic Aperture Radar Imaging (IRF-USAR), is presented and shown to be valid for representing the CSAR image of a point-like scatterer. IRF-CSAR can therefore be used in studying different CSAR systems such as predicting the pattern of a point-like scatterer illuminated by a CSAR system, estimating resolution achieved by that system. Applying IRF-CSAR to define the image quality assessments for CSAR is also presented in the paper.

  • 178. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Fast backprojection algorithm for UWB bistatic SAR2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper introduces an algorithm for Ultrawideband Ultrawidebeam (UWB) bistatic Synthetic Aperture Radar (SAR). The algorithm works in time-domain and therefore inherits time-domain characteristics such as unlimited scene size, local processing and manageable motion compensation. The proposed algorithm is not limited by any configuration of bistatic SAR. The algorithm processes the UWB bistatic SAR data on a subaperture and subimage basis. This means, instead of backprojecting directly the SAR data to a ground image plane, the algorithm handles the data in two stages: beam forming and local backprojection. The algorithm is named Bistatic Fast Backprojection (BiFBP) and has been tested successfully with the simulated UWB bistatic SAR data.

  • 179. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Fast Detection of Moving Targets by Focusing in Multi-Channel Ultra-Wideband SAR2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Long processing time and, in certain cases, restricted ability to detect moving targets are seen as the shortcomings of the moving target detection by focusing technique. The detection ability reduces significantly when Normalized Relative Speeds (NRS) with respect to the speed of the platform are approximated or equal to one. This paper propose solutions for such problems. Local Backprojection (LBP) replaces Global Backprojection (GBP) in the focusing approach of the detection method to save the processing time and a space-time processing technique, namely Displaced Phase Center Antenna (DPCA) is used to pre-process multi-channel SAR data to strengthen detection ability. Simulation results demonstrates a fast- and reliable detection achieved with these proposals.

  • 180. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Fast factorized backprojection algorithm for UWB SAR image reconstruction2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    The fast factorized backprojection for bistatic SAR algorithm (BiFFBP), which processes the bistatic SAR data in more than one beam forming stage, is presented in this paper. The algorithm is developed on the bistatic fast backprojection algorithm SAR (BiFBP) and inherits time-domain characteristics such as unlimited scene size, real time processing, local processing, manageable motion compensation, and large range migration handling. Also, the algorithm works well with different kinds of bistatic configuration. For these reason, it is very suitable for UWB bistatic SAR processing. The proposed algorithm is tested successfully with simulated UWB bistatic SAR data.

  • 181.
    Vu, Viet Thuy
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Fast Time-Domain Algorithms for UWB Bistatic SAR Processing2013Ingår i: IEEE Transactions on Aerospace and Electronic Systems, ISSN 0018-9251, E-ISSN 1557-9603, Vol. 49, nr 3, s. 1982-1994Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two fast time-domain algorithms are introduced for ultrawideband-ultrawidebeam (UWB) bistatic synthetic aperture radar (SAR) processing; they are bistatic fast backprojection (BiFBP) and bistatic fast factorized backprojection (BiFFBP). Both algorithms process radar echoes on a subaperture and subimage basis in order to minimize processing time. They are shown to work with any configuration of bistatic SAR. They also own time-domain characteristics, which are essential for UWB radar signal processing. BiFBP and BiFFBP are experimented successfully on the CARABAS-II simulated data.

  • 182.
    Vu, Viet Thuy
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Ground Moving Target Detection and Estimation with Different Sar Linear Flight Tracks2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper proposes a groundmoving target detection and estimation method aiming at UltraWide Band and -Beam (UWB) Synthetic Aperture Radar (SAR) systems. The method is developed on the moving target detection by focusing technique and requires a SAR system flying with two different linear flight tracks. The method allows us to detect ground moving target, even hidden by clutter, and to estimate the target parameters such as speed and direction of motion. The accuracy of the estimations depends strongly on the computational cost and can therefore be controlled.

  • 183. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Integrating Space-time Processing Into Time-Domain Backprojection Process to Detect and Imaging Moving Objects2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper discusses a possibility to integrate space-time processing into the time-domain backprojection process. This combination allows detection as well as imaging moving objects. Two space-time techniques, Displaced Phase Center Antenna (DPCA) and Space-Time Adaptive Processing (STAP), are considered for this integration. Simulated results based on the LORA parameters demonstrate the efficiency of detection and imaging moving objects.

  • 184.
    Vu, Viet Thuy
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Moving Target Focusing with Normalized Relative Speed in Azimuth-Invarian Bistatic Sar2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Focusing moving targets with Normalized Relative Speed (NRS) for bistatic synthetic aperture radar (SAR) is discussed in this paper. The discussion concentrates on azimuth invariant bistatic geometry. The focusing approach for azimuth-invariant bistatic geometry is derived analytically. The validity of the proposed approach for other bistatic geometry like azimuth-variant is also investigated.

  • 185.
    Vu, Viet Thuy
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    On Apodization Techniques for Ultra-wideband SAR Imaging2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ultra-wideband (UWB) SAR imaging suffers from a number of inherent problems in which the apodization has not been investigated appropriately. This paper presents a discussion on apodization techniques and possibilities to apply these techniques in UWB SAR imaging.

  • 186.
    Vu, Viet Thuy
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för matematik och naturvetenskap.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för matematik och naturvetenskap.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för matematik och naturvetenskap.
    On Synthetic Aperture Radar Spatial Azimuth and Range Resolution Equations2012Ingår i: IEEE Transactions on Aerospace and Electronic Systems, ISSN 0018-9251, E-ISSN 1557-9603, Vol. 48, nr 2, s. 1764-1769Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper discusses spatial resolutions for narrowband narrowbeam (NB) synthetic aperture radar (SAR) as well as for ultrawideband ultrawidebeam (UWB) SAR. The similarity and difference between the impulse response function in NB SAR imaging (IRF-NSAR) - sinc function - and the impulse response function in UWB SAR imaging (IRF-USAR) is investigated and the result of this investigation shows that in the intensity interval from −6 dB to 0 dB, the behavior of IRF-NSAR and IRF-USAR in azimuth and range are similar. This is the basis for a derivation of new spatial resolution equations for UWB SAR based on −3 dB width or half power beamwidth (HPBW). The investigated result also shows that there exists the so-called HPBW narrowing/broadening factor in an IRF-USAR.

  • 187.
    Vu, Viet Thuy
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Phase Error Calculation for Fast Time-Domain Bistatic SAR Algorithms2013Ingår i: IEEE Transactions on Aerospace and Electronic Systems, ISSN 0018-9251, E-ISSN 1557-9603, Vol. 49, nr 1, s. 631-639Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In synthetic aperture radar (SAR) processing, there is a trade-off between accuracy and speed. The approximations in an algorithm help to increase the algorithm’s speed but cause deterministic phase errors which directly affect the SAR image quality. This paper discusses the phase error calculations for bistatic fast backprojection (BiFBP) and bistatic fast factorized backprojection (BiFFBP) which are essential for setting their parameters. The phase error calculation principle for bistatic SAR in comparison to monostatic SAR is presented. This principle is used to derive the maximum phase error equation.

  • 188.
    Vu, Viet Thuy
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för matematik och naturvetenskap.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för matematik och naturvetenskap.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för matematik och naturvetenskap.
    SAR Imaging in Ground Plane Using Fast Backprojection for Mono- and Bistatic Cases2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper discusses the possibilities to reconstruct an illuminated Synthetic Aperture Radar (SAR) scene in a ground plane instead of a slant-range plane using Fast Backprojection (FBP) algorithm. Hence, two methods to reconstruct a SAR scene in a ground plane are introduced in this paper. The methods are then considered to be extended for bistatic cases where the formation of a SAR scene in a ground plane is highly recommended. The proposals are examined with simulated SAR data and the simulation results indicate that rebuilding a SAR scene in a ground plane using FBP is possible.

  • 189. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Space time adaptive processing for moving target detection and imaging in bistatic SAR2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    A combination of space time adaptive processing (STAP) and bistatic SAR seems to bring a promising technique of moving target detection and imaging. Moving target detection based on STAP is the most advanced and reliable detection method and mainly used in multichannel monostatic SAR whereas bistatic SAR has shown unique advantages such as the flexibility in design and the ability to observe a target with different angles. The paper investigates the possibility to employ STAP for detection and imaging of moving targets in bistatic SAR.

  • 190. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Ultrawideband Chirp Scaling Algorithm2010Ingår i: IEEE Geoscience and Remote Sensing Letters, ISSN 1545-598X, E-ISSN 1558-0571, Vol. 7, nr 2, s. 281-185Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new version of chirp scaling (CS), the so-called ultrawideband (UWB) CS (UCS), is proposed in this letter. UCS aims at UWB synthetic aperture radar (SAR) systems utilizing large fractional bandwidth and wide antenna beamwidth associated with a wide integration angle. Furthermore, it is also valid for SAR systems with special characteristics such as ground moving target indication SAR systems with a very high pulse repetition frequency.

  • 191. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Gustavsson, Anders
    Ulander, Lars
    Detection of Moving Targets by Focusing in UWB SAR—Theory and Experimental Results2010Ingår i: IEEE Transactions on Geoscience and Remote Sensing, ISSN 0196-2892, E-ISSN 1558-0644, Vol. 48, nr 10, s. 3799-3815Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Moving-target detection in ultrawideband (UWB) synthetic aperture radar (SAR) is associated with long integration time and must accommodate azimuth focusing for reliable detection. This paper presents the theory on detection of moving targets by focusing and experimental results on single-channel SAR data aimed at evaluating the detection performance. The results with respect to both simulated and real data show that the ability to detect moving targets increases significantly when applying the proposed detection technique. The improvement in signal-to-clutter noise ratio, which is a basic requisite for evaluating the performance, reaches approximately 20 dB, using only single-channel SAR data. This gain will be preserved for the case of multichannel SAR data. The reference system for this study is the airborne UWB low-frequency SAR Coherent All RAdio BAnd Sensing II.

  • 192. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Hellsten, Hans
    An Impulse Response Function for Evaluation of UWB SAR Imaging2010Ingår i: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 58, nr 7, s. 3927-3932Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Based on analysis of a point target imaged by different synthetic aperture radar (SAR) systems, the commonly used impulse response function in SAR Imaging (IRF-SAR)—a two-dimensional (2-D) sinc function—is shown to be inappropriate for ultrawideband-ultrawidebeam (UWB) SAR systems utilizing a large fractional signal bandwidth and a wide antenna beamwidth. As a consequence, the applications of the 2-D sinc function such as image quality measurements and spatial resolution estimations are limited to narrowband-narrowbeam (NB) SAR systems exploiting a small fractional signal bandwidth and a narrow antenna beamwidth. In this paper, a more general IRF-SAR, which aims at UWB SAR systems, is derived with an assumption of flat two-dimensional (2-D) Fourier transform (FT) of a SAR image and called IRF-USAR. However, the derived IRF-USAR is also valid for NB SAR systems.

  • 193. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Håkansson, Lars
    An Approach to Suppress RFI in Ultrawideband Low Frequency SAR2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper proposes an approach for the Radio Frequency Interference (RFI) suppression in ultrawideband (UWB) low frequency Synthetic Aperture Radar (SAR). The basis of the approach is an Adaptive Line Enhancer (ALE) controlled by the Normalized Least Mean Square (NLMS) algorithm. The proposal is tested successfully on the simulated CARABAS-II data.

  • 194. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Håkansson, Lars
    Gustavsson, Anders
    Ulander, Lars
    RFI Suppression in Ultrawideband SAR Using an Adaptive Line Enhancer2010Ingår i: IEEE Geoscience and Remote Sensing Letters, ISSN 1545-598X, E-ISSN 1558-0571, Vol. 7, nr 4, s. 694-698Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this letter, we propose an approach to suppress radio-frequency interference (RFI) in ultrawideband (UWB) low-frequency synthetic aperture radar (SAR). According to the proposal, RFI is suppressed by using an adaptive line enhancer controlled by the normalized least mean square algorithm. The approach is tested successfully on real UWB low-frequency SAR data. In order to keep the computational burden down, possible ways to integrate the RFI suppression approach into SAR imaging algorithms are also suggested.

  • 195. Vu, Viet Thuy
    et al.
    Sjögren, Thomas
    Pettersson, Mats
    Marques, Paulo
    Application of Moving Target Detection by Focusing Technique in Civil Traffic Monitoring2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents an application of the detection of moving target by focusing technique (DMTF) in civil traffic monitoring. With an assumption of known moving directions of vehicles, DMTF allows first detecting these vehicles, then estimating their speed and finally imaging the vehicles of interest. With DMTF, the civil traffic monitoring requires only a singlechannel airborne SAR system.

  • 196.
    Vu, Viet Thuy
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Sjögren, Thomas
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Minardi, Michael
    The Availability ff Fast Time-Domain Algorithms for Circular Sar Data Processing2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper shows an investigation of the availability of the fast time-domain algorithms to process data collected by synthetic aperture radar systems with circular apertures (CSAR). In the investigation, the reconstruction of CSAR images from data is suggested to be in a ground plane instead of a slant-range plane. The Fast Backprojection (FBP) algorithms are considered to examine the availability of time-domain algorithms for CSAR data processing. However, the availability is also applied to the Fast Factorized Backprojection (FFBP) algorithms. The simulated CSAR data with respect to the CARABAS-II parameters is used.

  • 197. Yang, Jing
    et al.
    Fan, Pingzhi
    Duong, Quang Trung
    Lei, Xianfu
    Exact Performance of Two-Way AF Relaying in Nakagami-m Fading Environment2011Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 10, nr 3, s. 980-987Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The performance of two-way amplify-and-forward (AF) relaying networks over independently but not necessarily identically distributed (i.n.i.d.) Nakagami-m fading channels, with integer and integer plus one-half values of fading parameter m, is studied. Closed-form expressions for the cumulative distribution function (CDF), probability density function (PDF), and moment generating function (MGF) of the end-to-end signal-to-noise ratio (SNR) are presented. Utilizing these results, we analyze the performance of two-way AF relaying system in terms of outage probability, average symbol error rate (SER), and average sum-rate. Simulations are performed to verify the correctness of our theoretical analysis.

  • 198.
    Yang, Zhe
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Coexistence, Deployment and Business Models of Heterogeneous Wireless Systems Incorporating High Altitude Platforms2013Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The increased demand for broadband communications has led to the rapid development of the conventional terrestrial and satellite wireless communications systems. One of the main challenges to next generation wireless systems is to deliver high-capacity and cost-efficient solutions to cope with an increasing usage of broadband services and applications. In the recent years, an emerging competitive system has attracted the attention for providing wireless broadband communications and other services based on quasi-stationary aerial platforms operating in the stratosphere known by high altitude platforms (HAPs), and located 17-22 km above the earth surface. This solution has been described by the International Telecommunication Union (ITU) as "a new and long anticipated technology that can revolutionize the telecommunication industry''. The HAP systems provide important advantages such as low cost, high elevation angles, low propagation delay, easy and incremental deployment, flexibility in operation, broad coverage, broadcast and broadband capability, ability to move around in emergency situations, etc. Therefore, they have been proposed by ITU for the provision of fixed, mobile services and applications, e.g. the third generation (3G) services licensed by ITU and backbone link for terrestrial networks in remote areas. This thesis explores and investigates the wireless communication and techno-economic performance of terrestrial systems and HAPs. An overview of research and development on aerial platforms worldwide is given. Coexistence performance and techniques of heterogeneous systems to provide broadband wireless communications based on Worldwide Interoperability Microwave Access (WiMAX) are investigated. A heterogeneous scenario is developed to examine the coexistence performance of heterogeneous systems. The capacity and deployment aspects of HAPs are analyzed, and further compared with terrestrial Universal Mobile Telecommunications Systems (UMTS) through techno-economic studies including a proposed partnership based business model for HAPs. Performance of wireless sensor network applications via HAPs is also investigated, and shows the high potential of HAPs for large-area and long-endurance surveillance and emergency applications. The thesis shows that communications from the aerial platforms provide the best features of both terrestrial and satellite systems. HAPs can effectively coexist in a heterogeneous radio environment, and are competitive solutions in urban and suburban scenarios in terms of capacity, coverage and business perspective. This makes HAP a viable competitor and complement to conventional terrestrial infrastructures and satellite systems.

  • 199. Yang, Zhe
    et al.
    Mohammed, Abbas
    Deployment and Capacity of Mobile WiMAX from High Altitude Platform2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we investigate the deployment and capacity of delivering mobile WiMAX based on IEEE 802.16e-2005 from aerial platform such as High Altitude Platforms (HAPs). A urban scenario and an suburban scenario with mobile broadband usages as complement or substitute to the fixed Internet connection are developed to compare the delivery of broadband services from terrestrial and aerial platforms. A deployment strategy is based on maximizing and meeting the networking traffic demand and coverage area. In the end, a comparison based on cell radii and capacities between services from aerial platforms and existing terrestrial based solutions, such as universal mobile telecommunications system (UMTS) and high speed packet access (HSPA) is proposed. Currently, most research has been done to develop advanced technologies to enhance standards to support a higher data rate in a cost-effective way for wireless communication systems. From analysis and investigation, aerial platform can provide a cost-effective solution for a large area with a medium to high traffic demand.

  • 200. Yang, Zhe
    et al.
    Mohammed, Abbas
    Wireless communications from high altitude platforms: Applications, deployment and development2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, an overview of the HAP concept development and HAP trails is introduced to show the worldwide interest and development in the emerging novel technology. A comparison of the HAP, terrestrial and satellite system characteristics is given. Main advantages of HAPs for wireless communication applications are large coverage area, high capacity and cost-effective deployment. Three applicable scenarios of HAP communication are shown.

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