Browsing by Author "Kara,A."

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Citation - Scopus: 1
Analysis of Measurement Instrumentation Delay in Modular Experimental Radar at C Band
(Institute of Electrical and Electronics Engineers Inc., 2018) Abdulrazigh,M.Y.A.; Uzundurukan,E.; Kara,A.; Department of Electrical & Electronics Engineering; Airframe and Powerplant Maintenance; 15. Graduate School of Natural and Applied Sciences; 13. School of Civil Aviation (4-Year); 01. Atılım University
Unlike pulsed radars, Frequency-Modulated Continuous Wave (FMCW) radar emits continuously very low power levels with the same signal to noise ratio (SNR) of an equivalent pulsed radar. FMCW can measure range and speed of the target. In modular design of such radar, time delay is experienced due to modular components such as low-noise amplifiers (LNA), antennas and, especially, cables. This time delay causes frequency shifts in the measured beat frequency resulting a range measurement error. Therefore, this time delay has to be studied for accuracy of measurements. In this study, experimental results of range measurement errors of a FMCW radar operating at C band are presented. Considering time delay of modular components, a range error of approximately 0.1m was obtained within a range of 10m. © 2018 IEEE.
Citation - Scopus: 1
An Approach for Identifying the Likelihood of an Irregular Terrain Profile Being a Multipath Scattering Center in Emitter Localization
(Association for Computing Machinery, 2017) Dalveren,Y.; Kara,A.; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
In a single-receiver source localization scenario, pulses radiated from an emitting source (emitter) are reradiated from distributed points over the irregular terrain due to the diffuse scattering. Obviously, diffuse scattering may be occurred at anywhere over irregular terrains in dense scattering environments. Hence, a particular region from which the multipath pulses are scattered over the irregular terrain can be taken as a scattering center. In fact, a multipath scattering center may be approximated as multiple reflection points visible to the receiver. For this reason, an uncertainty in location of multipath scattering centers is expected. However, as proposed in this study, the likelihood of a particular region from which the multipath pulses are scattered may be identified if digital data of the irregular terrain, positions of the receiver and the transmitter, and Angle of Arrival (AOA) of the multipath are provided. In this context, this study attempts to provide an approach for identifying the likelihood of a particular region being a scattering center over the irregular terrain. To this end, Geometric Optics (GO)-based wave propagation principles are exploited to estimate path loss that would a basis for estimating likelihoods. Simulations are performed to illustrate the effectiveness of the proposed approach. This study aims to make significant contribution to an ongoing research on passive localization of radar emitters by exploiting multipath in dense scattering environments. © 2017 Association for Computing Machinery.
Citation - Scopus: 25
Blockage/Shadowing and Polarization Measurements at 2.45ghz for Interference Evaluation Between Bluetooth and Ieee 802.11 Wlan
(2001) Kara,A.; Bertoni,H.L.; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
We present measurement results at 2.45 GHz to evaluate blockage shadowing and fading effects due to furniture and people next to terminals for short range indoor communication systems. The followings are the results: people crossing the link near to a terminal can cause fading up to 20dB which is more than furniture blockage measured of about 5-13dB depending on objects over the links, polarization coupling was also measured by using dual polarized antenna at receiving end, and coupling is higher for obstructed links, which suggests polarization diversity.
Citation - Scopus: 1
Characterization of satellite transponder impairments based on simulations with test data
(Institute of Electrical and Electronics Engineers Inc., 2015) Ulubey,O.; Gulgonul,S.; Kara,A.; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
A satellite transponder simulator based on actual test data of TURKSAT 3A satellite has been developed to analyze degradation in multicarrier scenarios. Communication impairment sources through a transponder are explained in conjunction with a methodology defined to characterize total degradation resulting from them. Several transponder utilization scenarios are studied with respect to total degradation and optimum operation conditions are demonstrated. © 2015 IEEE.
Citation - Scopus: 4
Comparative Analysis of Tdoa-Based Localization Methods in the Presence of Sensor Position Errors
(Institute of Electrical and Electronics Engineers Inc., 2017) Dalveren,Y.; Kara,A.; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
It is widely known that localization of emitters can be efficiently achieved by time difference of arrival (TDOA) techniques in a multiple sensor system. Several studies have been proposed in the literature to improve the localization accuracy of TDOA techniques. Among these, very few of them have considered the error in the sensor positions although the accuracy of localization is very sensitive to sensor position errors. In this study, existing TDOA-based localization methods in the presence of sensor position errors are briefly discussed, and then they are comparatively analyzed for specific scenarios. To this end, simulations are performed to compare the localization accuracy of the methods, specifically, with high level of sensor positional errors. It is intended to decide an efficient and robust estimator to be used for an ongoing research on passive localization of radar emitters in dense scattering environments. © 2017 IEEE.
Citation - WoS: 3
Citation - Scopus: 5
Convolutional Neural Network-Based Vehicle Classification in Low-Quality Imaging Conditions for Internet of Things Devices
(Multidisciplinary Digital Publishing Institute (MDPI), 2023) Maiga,B.; Dalveren,Y.; Kara,A.; Derawi,M.; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
Vehicle classification has an important role in the efficient implementation of Internet of Things (IoT)-based intelligent transportation system (ITS) applications. Nowadays, because of their higher performance, convolutional neural networks (CNNs) are mostly used for vehicle classification. However, the computational complexity of CNNs and high-resolution data provided by high-quality monitoring cameras can pose significant challenges due to limited IoT device resources. In order to address this issue, this study aims to propose a simple CNN-based model for vehicle classification in low-quality images collected by a standard security camera positioned far from a traffic scene under low lighting and different weather conditions. For this purpose, firstly, a new dataset that contains 4800 low-quality vehicle images with 100 × 100 pixels and a 96 dpi resolution was created. Then, the proposed model and several well-known CNN-based models were tested on the created dataset. The results demonstrate that the proposed model achieved 95.8% accuracy, outperforming Inception v3, Inception-ResNet v2, Xception, and VGG19. While DenseNet121 and ResNet50 achieved better accuracy, their complexity in terms of higher trainable parameters, layers, and training times might be a significant concern in practice. In this context, the results suggest that the proposed model could be a feasible option for IoT devices used in ITS applications due to its simple architecture. © 2023 by the authors.
Citation - Scopus: 20
Design and Development of a Remote and Virtual Environment for Experimental Training in Electrical and Electronics Engineering
(2010) Kara,A.; Aydin,E.; Ozbek,M.E.; Cagiltay,N.; Department of Electrical & Electronics Engineering; Software Engineering; 15. Graduate School of Natural and Applied Sciences; 06. School Of Engineering; 01. Atılım University
European Remote Radio Laboratory (ERRL) has been developed by the support of European Commission. It intends to provide remote access to high cost devices remotely, and perform experiments in radio frequency (RF), communications and microwave domains of Electrical ad Electronics Engineering. The system has been operational for two years, and been integrated into curriculum of some courses. In this work, the hardware and software structures of the system are presented. Then, experimental content and the motivations in the design of the system are discussed. ©2010 IEEE.
Citation - Scopus: 2
Design and Fabrication of Ka Band Circular Horn Antenna;
(2012) Danaci,S.; Gürtekin,E.; Özyurt,E.; Kara,A.; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
In this paper, design and fabrication of a circular horn antenna is presented. The antenna is designed for experimental use at Ka band. The design process includes feeding structure for coaxial line and geometrical parameters of the antenna. The bandwidth of the antenna is measured as 2.25GHz, (S 11 ≤-10dB) which satisfies the requirements of targeted experimental study. A reference monopole is also designed for the measurements of antenna parameters. Antenna radiation pattern is measured with the reference monopole antenna using a VNA (S12) instead of typical signal generator/spectrum analyzer pair. Accuracy of antenna parameters along with the errors made in fabrication process is also discussed in the paper. © 2012 IEEE.
Design Considerations for Near To the Ground Communication System and Associated Sub-Ghz Low Profile Antenna
(Institute of Electrical and Electronics Engineers Inc., 2017) Yilmaz,V.S.; Bilgin,G.; Aydin,E.; Kara,A.; Department of Electrical & Electronics Engineering; Electrical-Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 06. School Of Engineering; 01. Atılım University
This paper presents propagation aspects of a peer-to peer communication link where antennas are placed near to the ground (low height). First, some of the propagation models are evaluated for understanding of propagation mechanisms. In this regard, as the height of the antennas are very low and the distance is large enough, reflecting angle becomes very small that makes use of two ray model. On the other hand, in the horizontal plane, the positions of the scattering objects, as a source of lateral waves, might vary largely due to the terrain undulations along with variety of objects around the link. This makes propagation mechanisms a little bit complicated. In order to design low profile, high gain sub-GHz antenna for such propagation environment, microstrip antenna with vertical ground was designed and fabricated. The antenna is required to be protected from natural and man-made effects. Therefore, the antenna with associated sensors are embedded into a metal box with a dielectric cover. All these are discussed and some of the findings are presented. © 2017 IEEE.
Citation - Scopus: 4
Design of a Scenario-Based Synthetic Mixed Pulse Generator;
(2013) Gençol,K.; Kara,A.; At,N.; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
Electronic Support Measures (ESM) plays an important role in modern Electronic Warfare (EW) systems. The main purpose of an ESM system is to intercept as many emissions as it can, and then to deinterleave mixed streams of pulses that are interleaved in natural time of arrival order, and thus to identify surrounding emissions. In real life, such systems may encounter with a continuous stream of pulses accompanied by many imperfections, and it should work on real-time basis. In order to handle such circumstances and to develop better deinterleaving algorithms, a simulation tool is needed. In this study, design of a scenario-based mixed pulse generator (simulator) is presented. © 2013 IEEE.
Citation - Scopus: 11
Design of Low-Cost Modular Rf Front End for Rf Fingerprinting of Bluetooth Signals
(Institute of Electrical and Electronics Engineers Inc., 2017) Uzundurukan,E.; Ali,A.M.; Kara,A.; Department of Electrical & Electronics Engineering; Airframe and Powerplant Maintenance; 15. Graduate School of Natural and Applied Sciences; 13. School of Civil Aviation (4-Year); 01. Atılım University
For RF fingerprinting of wireless devices, data acquisition has a critical role. Because of this, highly sophisticated devices are used for data capturing or acquisition. In this paper, design of a RF receiver front end with modular components is presented. This design contains filtering and down conversion processing of Bluetooth signals for cellular phones. Moreover, AWR VSS and MATLAB have been used for simulating the down converter circuit. With this simulation, effects of components that used in the design on recorded signal have been observed. In this work in progress paper, only high SNR conditions are considered. © 2017 IEEE.
Citation - Scopus: 1
Development of a Digital Communications Course Enriched by Virtual and Remote Laboratory Tools
(2011) Kara,A.; Kara, Ali; Cagiltay,N.; Çağıltay, Nergiz; Dalveren,Y.; Dalveren, Yaser; Kara, Ali; Çağıltay, Nergiz; Dalveren, Yaser; Department of Electrical & Electronics Engineering; Software Engineering; Software Engineering; Department of Electrical & Electronics Engineering; Software Engineering; 15. Graduate School of Natural and Applied Sciences; 06. School Of Engineering; 01. Atılım University
Digital communications is a basic concept for rapidly growing fields of Electrical, Computer and Electronics Engineering like wireless and mobile communication systems, radar and electronic warfare, telemetry and many signal processing techniques. A re-designed digital communications course with ICT (Information and Communication Technologies) based diverse tools including matlab assignments, remote experiments and interactive simulators is described in this study. First, the objectives of the course, learning outcomes and evaluation methods are described. The re-designed course is offered in the last semester at Atilim University, and performance increase in students is compared with the previous year's offering, and by evaluating the course on a topic-based approach. © 2011 IEEE.
Citation - Scopus: 1
Development of a low cost radio controller for Tele operation systems: Crane controller design as an industry sponsored undergraduate research
(2013) Kaynaköz,G.; Daǧdeviren,B.; Kapusuz,K.Y.; Kara,A.; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
This study presents some of the design and development stages of a radio control system for dense interference environments. All design and development stages were conducted by undergraduate students, with an undergraduate research project sponsored by a local company. The study starts with an overview of the system including choice of main components and modules. Then, it discusses the design stages of the system from analog to digital conversion to driving circuit of the targeted mechanical system (crane), and provides some preliminary results and conclusions. One of the design criteria in the project was minimization of the cost and size, and the preliminary results have shown that the prototype could compete with many commercial equivalents.
Citation - Scopus: 4
Distance Laboratory Applications Errl: a Study on Radio Communication in Electronic Field
(2008) Aydin,C.Ç.; Türkmen,G.; Özyurt,E.; Aydm,E.U.; Çaǧiltay,N.E.; Özbek,M.E.; Kara,A.; Department of Electrical & Electronics Engineering; Computer Engineering; 15. Graduate School of Natural and Applied Sciences; 06. School Of Engineering; 01. Atılım University
In the last decade, the effect of internet usage in education is gradually increased. When we look from academic perspective, the new technologies provided alternatives for students learning. As distance education becomes important everyday, the indispensable elements of teaching and education, laboratories must be reachable via remote connection. Consequently, the education that is going to be given to the students will be more flexible with respect to place and time constraints and students can reach laboratory facilities at any time and anywhere not only in lectures and practical hours. In this study, European Remote Radio Laboratory (ERRL) which is a distance remote Radio Frequency (RF) laboratory designed for electrical-electronics students, is described generally. The software architecture, infrastructure and experiment that can be done with a remote connection have been described.
Citation - Scopus: 2
An Experimental Study Towards Examining Human Body Movements in Indoor Wave Propagation at 18-22 Ghz
(Institute of Electrical and Electronics Engineers Inc., 2018) Alabish,A.; Kara,A.; Dalveren,Y.; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
As 5G communication may use Millimeter waves (mmWave) bands, it is necessary to evaluate short-range indoor links from the link blockage point of view. This paper presents some initial studies for characterizing effects of human body movements on short range indoor links at 18-22 GHz. Firstly, measurement system is described, and then, calibration measurements along with initial results of the impact of human body movement on the channel are presented for some scenarios. To the best of our knowledge, this study is the first to experimentally examine the effects of human body movements at this band. Yet, as this study constitutes a part of an ongoing research, further results will be anticipated to present the effects of objects over and around the link on the directional propagation at mmWave bands (28-30 GHz). © 2018 IEEE.
An Experimental Study Towards Examining Human Body Movements in Indoor Wave Propagation at 18-22 Ghz
(Institute of Electrical and Electronics Engineers Inc., 2018) Alabish,A.; Kara,A.; Dalveren,Y.; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
As 5G communication may use Millimeter waves (mmWave) bands, it is necessary to evaluate short-range indoor links from the link blockage point of view. This paper presents some initial studies for characterizing effects of human body movements on short range indoor links at 18-22 GHz. Firstly, measurement system is described, and then, calibration measurements along with initial results of the impact of human body movement on the channel are presented for some scenarios. To the best of our knowledge, this study is the first to experimentally examine the effects of human body movements at this band. Yet, as this study constitutes a part of an ongoing research, further results will be anticipated to present the effects of objects over and around the link on the directional propagation at mmWave bands (28-30 GHz). © 2018 IEEE.
Citation - Scopus: 5
Heterogeneity in Classes: Cooperative Problem-Solving Activities Through Cooperative Learning;
(FACTEACHEREDUCATION, 2014) Cigdemoglu,C.; Kapusuz,K.Y.; Kara,A.; Department of Electrical & Electronics Engineering; Public Relations and Advertising; 15. Graduate School of Natural and Applied Sciences; 05. School of Business; 01. Atılım University
Teachers, from primary schools to college, experience challenges regarding both increased class sizes and a greater diversity of students having a broad spectrum of abilities, interests, needs, and goals. The aim of this paper is to investigate the effect of cooperative learning through Cooperative Problem-Solving (CPS) activities on homogenous and heterogeneous grouping in an engineering course. As a mixed method design, the study utilized both quantitative and qualitative data. The participants, 47 engineering students selected conveniently, were enrolled in a communication systems course. The analysis of the quantitative data indicated that no significant difference (p=.791) exists between the ways in which the students in homogenous and the students in heterogeneous group understand communication systems. In order to reveal the perceptions of students regarding the implementation, they were interviewed at the end of the semester. The qualitative data obtained from these interviews suggests that students prefer heterogeneous to homogenous grouping. The findings also imply that further research should concentrate on heterogeneous grouping strategies and more detailed qualitative data in order to reveal what kind of patterns emerge from students’ interactions in different groupings. © 2014, FAC TEACHER EDUCATION. All right reserved.
Citation - Scopus: 27
Improvements on Transient Signal Detection for Rf Fingerprinting
(Institute of Electrical and Electronics Engineers Inc., 2017) Ali,A.M.; Uzundurukan,E.; Kara,A.; Department of Electrical & Electronics Engineering; Airframe and Powerplant Maintenance; 15. Graduate School of Natural and Applied Sciences; 13. School of Civil Aviation (4-Year); 01. Atılım University
The detection of the transient signal plays a significant role in RF fingerprinting for transmitter devices. This paper proposes modifications on two transient signal detection methods, namely, Bayesian change point detection and phase based detection. For initial tests, Bluetooth signals captured in the laboratory are used for performance analysis of the proposed methods. Preliminary results show that the proposed methods can be used in RF fingerprinting of wireless devices. © 2017 IEEE.
Citation - Scopus: 3
An Industry Sponsored Undergraduate Research (ur) Experience: Preliminary Study on Fulfillment of Program Outcomes and Industry Requirements
(IEEE Computer Society, 2014) Kapusuz,K.Y.; Kara, Ali; Kara,A.; Kara, Ali; Department of Electrical & Electronics Engineering; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
This study presents educational results of an industry sponsored undergraduate research (UR) project. The aim of the study is to show how such project works contribute to students in acquiring qualifications or skills necessary by the industry, and abilities regarding with program outcomes of accreditation organisations. The study is based on quantitative (surveys) and qualitative (self descriptions) data collected from senior students who worked in 9 months UR project sponsored by a company in Radio frequency (RF) and Communications domain. The preliminary results showed that an industry sponsored undergraduate research project may serve to both short term (industry requirements) and longer term (program outcomes) expectations in undergraduate curriculum of engineering departments. © 2014 IEEE.
Citation - Scopus: 15
Linear Wireless Sensor Networks for Cathodic Protection Monitoring of Pipelines
(Institute of Electrical and Electronics Engineers Inc., 2019) Kara,A.; Al Imran,M.A.; Karadag,K.; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
This paper presents design considerations and implementation of linear wireless sensor networks (LWSNs) to be used in cathodic protection (CP) monitoring of oil and natural gas pipelines. Firstly, the paper overviews the CP monitoring system of pipelines. Then, it presents the proposed design of LWSN along with some implementation details by providing high-level design illustrations and system parameters. Moreover, some hardware and software design issues and challenges are addressed briefly. LWSN based CP monitoring system is designed for the use in high rise mountains along with deep valleys, and some other extreme or unattended locations where communication infrastructure is unavailable, or there exists limited or interrupted access to the infrastructure. © 2019 IEEE.