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  • 251.
    Isaksson, Magnus
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Radio Frequency Power Amplifiers: Behavioral Modeling, Parameter-Reduction, and Digital Predistortion2007Doktoravhandling, med artikler (Annet vitenskapelig)
  • 252.
    Isaksson, Magnus
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Rönnow, Daniel
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    A Kautz-Volterra Behavioral Model for RF Power Amplifiers2006Inngår i: IEEE MTT-S International Microwave Symposium Digest, 2006, 2006, s. 485-488Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A new type of behavioral power amplifier (PA) model, a discrete-time Kautz-Volterra (KV) model, is presented. In the model a priori knowledge of the system properties in terms of different poles for different nonlinear orders is used, which is needed for modeling nonlinear and linear memory effects in PAs. An accurate model can thus be achieved with a small number of parameters. Simulated results of parallel Hammerstein and Wiener structures and from modeling the behavior of a PA are presented

  • 253.
    Isaksson, Magnus
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Rönnow, Daniel
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    A Parameter-Reduced Volterra Model for Dynamic RF Power Amplifier Modeling based on Orthonormal Basis Functions2007Inngår i: International Journal of RF and Microwave Computer-Aided Engineering, ISSN 1096-4290, E-ISSN 1099-047X, Vol. 17, nr 6, s. 542-551Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A nonlinear dynamic behavioral model for radio frequency power amplifiers is presented. It uses orthonormal basis functions, Kautz functions, with complex poles that are different for each nonlinear order. It has the same general properties as Volterra models, but the number of parameters is significantly smaller. Using frequency weighting the out-of-band model error can be reduced. Using experimental data it was found that the optimal poles were the same for different input powers and for the different nonlinear orders. The optimal poles were also the same for direct and inverse models, which could be explained theoretically to be a general property of nonlinear systems with negligible linear memory effects. The model can be used as either a direct or inverse model with the same model error for power amplifiers with negligible linear memory effects.

  • 254.
    Isaksson, Magnus
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Wisell, David
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Extension of the Hammerstein Model for Power Amplifier Applications2004Inngår i: 63rd ARFTG Conference Digest - Spring 2004, 2004, s. 131-137Konferansepaper (Fagfellevurdert)
  • 255.
    Isaksson, Magnus
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Royal Institute of Technology, Signal Processing Lab, Stockholm, Sweden.
    Wisell, David
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Royal Institute of Technology, Signal Processing Lab, Stockholm, Sweden; Ericsson AB, Gävle, Sweden.
    Eng, Anders
    Syntronic AB, Gävle, Sweden.
    Rönnow, Daniel
    WestemGeco AS, Asker, Norway.
    A Study of a Variable-Capacitance Drain Network's Influence on Dynamic Behavioral Modeling of an RF PA2007Inngår i: 69th ARFTG Microwave measurement conference, Honolulu, HI, USA, 2007, s. 112-116Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An investigation of the complex-valued parameters of two different dynamic behavioral models due to changes in the drain decoupling network of a PA has been performed. The study is based on complex-envelope measurements on a real PA. The complex coefficients of the parallel Hammerstein (PH) and the optimal pole placements of the Kautz-Volterra (KV) models are analyzed. It is concluded that the parameters follow smooth, predictable functions and that the KV poles give a robust description of the PA's memory effects compared with the PH model.

  • 256.
    Isaksson, Magnus
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Wisell, David
    Rönnow, Daniel
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    A Comparative Analysis of Behavioral Models for RF Power Amplifiers2006Inngår i: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 54, nr 1, s. 348-359Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A comparative study of nonlinear behavioral models with memory for radio-frequency power amplifier (PAs) is presented. The models are static polynomial, parallel Hammerstein (PH), Volterra, and radial basis-function neural network (RBFNN). Two PAs were investigated: one was designed for the third-generation (3G) mobile telecommunication systems and one was designed for the second-generation (2G). The RBFNN reduced the total model error slightly more than the PH, but the error out of band was significantly lower for the PH. The Volterra was found to give a lower model error than did a PH of the same nonlinear order and memory depth. The PH could give a lower model error than the best Volterra, since the former could be identified with a higher nonlinear order and memory depth. The qualitative conclusions are the same for the 2G and 3G PAs, but the model errors are smaller for the latter. For the 3G PA, a static polynomial gave a low model error as low as the best PH and lower than the RBFNN for the hardest cross validation. The models with memory, PH, and RBFNN, showed better cross-validation performance, in terms of lower model errors, than a static polynomial for the hardest cross validation of the 2G PA.

  • 257.
    Isaksson, Magnus
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Wisell, David
    Rönnow, Daniel
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Behavioural Amplifier Modelling Using Sampled Complex Envelope Measurement Data2005Inngår i: Proc. Gigahertz 2005, 2005, s. 213-216Konferansepaper (Fagfellevurdert)
  • 258.
    Isaksson, Magnus
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Wisell, David
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Ericsson AB, Gävle, Sweden.
    Rönnow, Daniel
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Nonlinear Behavioral Modeling of Power Amplifiers Using Radial-Basis Function Neural Networks2005Inngår i: 2005 IEEE MTT-S International Microwave Symposium Digest, 2005, s. 1967-1970Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A radial-basis function neural network (RBFNN) is proposed for modeling the dynamic nonlinear behavior of RF power amplifiers. In the model the signal's envelope is used. The model requires less training than a model using both IQ-data. Sampled input and output signals from a power amplifier for 3G were used in the identification and validation. The RBFNN is compared with a parallel Hammerstein model. For a memory depth of one sample the RBFNN gives a better model, in- and out-of-band; for three samples the RBFNN reduces the in-band error more while the Hammerstein model reduces the error out-of-band more.

  • 259.
    Isaksson, Magnus
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Wisell, David
    Rönnow, Daniel
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Wide-Band Dynamic Modeling of Power Amplifiers Using Radial-Basis Function Neural Networks2005Inngår i: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 53, nr 11, s. 3422-3428Artikkel i tidsskrift (Fagfellevurdert)
  • 260.
    Isaksson, Magnus
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Zenteno, Efrain
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    A synthetic vector network analyzing measurement system2011Inngår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 60, nr 6, s. 2154-2161Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper a synthetic vector network analyzing measurement system is presented. The system is based on a hardware set-up, including a signal generator and a vector signal analyzer, with the vector network analyzing functionality implemented in the software. The measurements of the proposed system demonstrated comparable performance in terms of accuracy and speed compared with a modern traditional vector network analyzer, but it is more flexible due to its inherent software implementation. The proposed system’s ability to measure nonlinear phenomena is addressed and discussed, and some preliminary results are given.

  • 261.
    Ivanchenko, I.
    et al.
    O. Ya. Usikov Institute for Radiophysics and Electronics of the NAS of Ukraine, Kharkiv, Ukraine.
    Khruslov, M.
    O. Ya. Usikov Institute for Radiophysics and Electronics of the NAS of Ukraine, Kharkiv, Ukraine.
    Popenko, N.
    O. Ya. Usikov Institute for Radiophysics and Electronics of the NAS of Ukraine, Kharkiv, Ukraine.
    Shestopalov, Yury
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Matematik.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Combined system of the microstrip antennas with different frequencies2016Inngår i: 2016 22nd International Conference on Applied Electromagnetics and Communications (ICECOM), 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The combined system with microstrip antennas (f1=1.85GHz; f2=3.7GHz, f3=1.75GHz, f4= 3.5GHz) is presented. The measurements of the prototype characteristics have shown that elevation angle of peak directivity of the antennas is oriented to zenith. Simulated S11 at stated frequencies with the following minimum values of S11 = -34dB, f=1.85GHz; S11=-21dB, f=3.7GHz; S11 = -22dB, f=1.75GHz; S11=-19dB, f=3.5GHz are observed.

  • 262.
    Ivanchenko, Igor
    et al.
    O. Ya. Usikov Institute for Radiophysics and Electronics of the NAS of Ukraine, Ukraine.
    Khruslov, Maksym
    O. Ya. Usikov Institute for Radiophysics and Electronics of the NAS of Ukraine, Ukraine.
    Plakhtiy, Vadim
    O. Ya. Usikov Institute for Radiophysics and Electronics of the NAS of Ukraine, Ukraine.
    Popenko, Nina
    O. Ya. Usikov Institute for Radiophysics and Electronics of the NAS of Ukraine, Ukraine.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    X-band aperture antenna with hybrid dielectric inserts2016Inngår i: Progress In Electromagnetics Research C, ISSN 1937-8718, E-ISSN 1937-8718, Vol. 61, s. 27-35Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An X-band radiator as an open-ended waveguide with a hybrid dielectric insert is proposed. The insert is in the form of a parallelepiped, which fills the entire cross section of the waveguide and constitutes a Teflon matrix with local inhomogeneities in the form of dielectric cylinders with a different permittivity. The design allows for forming various near-field distributions and, hence, the radiator performance by means of definite combinations of the local inhomogeneities can be modified. A number of configurations in the location of air and quartz cylinders are investigated. The calculated and experimental results are in good agreement. The proposed approach to the near-field formation of the aperture antenna is promising, because the variety of possible configurations in the location of local inhomogeneities with different permittivity provides new opportunities in terms of designing both single radiators and antenna arrays.

  • 263.
    Ivanchenko, Igor
    et al.
    O.Ya. Usikov Institute for Radiophysics and Electronics of the National Academy of Sciences of Ukraine, Ukraine.
    Khruslov, Maksym
    O.Ya. Usikov Institute for Radiophysics and Electronics of the National Academy of Sciences of Ukraine, Ukraine.
    Popenko, Nina
    O.Ya. Usikov Institute for Radiophysics and Electronics of the National Academy of Sciences of Ukraine, Ukraine.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Combined L–S-bands antenna module2019Inngår i: IET Microwaves, Antennas & Propagation, ISSN 1751-8725, E-ISSN 1751-8733, Vol. 13, nr 5, s. 541-545Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A combined L-S-band antenna module consists of four rectangular patch antennas, two of which operate at the frequencies of the first harmonics (L-band), and two others at the frequencies of the second harmonics (S-band). The module is intended for use in super heterodyne signal reception circuits, for example in studying the various non-linear phenomena. The results of this study are presented in terms of improving the performance of each antenna and minimising their mutual influence. The resonance frequencies of the L-band antenna differ by 50MHz. All the antennas radiate close to the zenith and their beamwidths in two principal planes are virtually the same. At the resonance frequencies, the reflection coefficient is S-11<-30dB for the transmitting antenna, and S-11<-20dB for the receiving antenna. The minimum allowable distance between the antennas is determined, at which their mutual influence can be neglected (S-12<-50dB).

  • 264.
    Ivanchenko, Igor
    et al.
    O.Ya. Usikov Institute for Radiophysics and Electronics, National Academy of Sciences of Ukraine, Kharkiv, Ukraine.
    Khruslov, Maksym
    O.Ya. Usikov Institute for Radiophysics and Electronics, National Academy of Sciences of Ukraine, Kharkiv, Ukraine.
    Popenko, Nina
    O.Ya. Usikov Institute for Radiophysics and Electronics, National Academy of Sciences of Ukraine, Kharkiv, Ukraine.
    Shestopalov, Yury
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Matematik.
    Tripathy, Malay Ranjan
    Amity University, Delhi, India.
    Derevyanchuk, Ekaterina
    Penza State University, Penza, Russian Federation.
    Determination of effective permittivity of metamaterial antenna cells2016Inngår i: 2016 10th European Conference on Antennas and Propagation: EuCAP 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, artikkel-id 7481369Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A numerical-analytical method of reconstructing complex frequency-dependent permittivities is proposed. Measurements of the transmission coefficient for three typical metamaterial antenna units are performed and the frequency-dependent effective complex permittivity of the units is reconstructed in a wide frequency range.

  • 265.
    Jabita, Abdul-Nafiu Abiodun
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap.
    Design of Singly Split Single Ring Resonator for Measurement of Dielectric Constant of Materials using Resonant Method2013Independent thesis Advanced level (degree of Master (Two Years)), 80 poäng / 120 hpOppgave
    Abstract [en]

    Scientists and engineers measure dielectric constant because it gives them better understanding of materials and helps them to know how to integrate these materials into their design processes;it also helps them to shorten design life cycle,and aside these two functions,it has numerous uses all of which cannot be enumerated in this section.Owing to its usefulness,various measurement methods of dielectric constant of materials have been developed over the years.Each method has its limitations which affect the accuracy of the measurement;these limitations range from frequency,temperature,and  mearsurement environment to material under test.

     

    In this thesis,four most common methods of measuring dielectric constant were discussed and the most accurate one,the resonant method,was chosen and worked on .The project was executed by making a mathematical analysis of the ring resonator which was later simulated in HFSS to get results which would be comparable to ones obtained in  laboratory measurements.

     

    The ring was fabricated and taken to the laboratory for measurement.Two monopole antennas were connected to the two ports of a VNA with one antenna serving as the transmitter and the other serving as the receiver.

     

    The resonant frequencies obtained were combined with the geometric parameters of the ring resonator and that of the MUT in equations written into MATLAB scripts;this equations were used to extract the dielectric constant of the MUT.

  • 266. Jacobs, Theo
    et al.
    Virk, Gurvinder S.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    ISO 13482 - The new safety standard for personal care robots2014Inngår i: Proceedings for the joint conference of ISR 2014, 45th International Symposium on Robotics and Robotik 2014, 8th German Conference on Robotics, 2 - 3 June 2014, Munich, Germany, parallel to AUTOMATICA, VDE Verlag GmbH, 2014, s. 698-703Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In the future, personal care robots will work in close interaction with humans. This poses a great challenge to the manufacturers of such robots who have to ensure the safety of their systems. Up to now, only general safety standards for machines were available and the lack of a specialized safety standard with detailed requirements has resulted in uncertainty and a relatively high residual risk for manufacturers. This situation is changed with the publication of ISO 13482, a safety standard for personal care robots. This paper gives an overview about the contents of the new safety standard and the expected effects for service robot manufacturers and the way, personal care robots will be developed in the future. The scope of the standard and its application in the risk assessment process is described. Special focus lies on the aspect of intended close-interaction and contact between human and robot, and the possibility to validate that all safety requirements have been met.

  • 267.
    Jakobsson, Jonathan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Färdigställande av datainsamlingssystem för elektronisk näsa2020Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Ett datainsamlingssystem för en elektronisk näsa utvecklat av tre studenter vid högskolan i Gävle har undersökts för att sedan vidareutvecklas.

    Det tidigare systemet utvecklades för att samla in data från en elektronisk näsa med fyra sensorkort. Detta system hade brister i strömförsörjning vilket gav felaktiga mätresultat samt endast möjlighet att mäta data från ett av de fyra sensorkorten på den elektroniska näsan.

    I denna rapport föreslås en vidareutveckling av detta system. Det nya systemet möjliggör mätningar med näsan från alla dess sensorer. Den äldre spänningsdelen har ersatts med en ny vilken klarar av de strömmar som systemet kräver.

    Efter konstruktion och testmätningar så har data som samlats in klassificerats. Datainsamlingen har skett i ett interface skapat i LabView. Data har sedan förbehandlats genom att filtreras samt har karakteristiker plockats ur data med hjälp av Matlab. Efter att data behandlats klassificerades den med hjälp av Principalkomponentanalys och K-Nearest Neighbours. Båda metoderna bedöms ha lyckats med klassificering av data.

    Vidare föreslås förbättringar och andra konstruktionsmöjligheter för att föra arbetet vidare.

  • 268.
    Jamaly, Nima
    Högskolan i Gävle, Institutionen för teknik och byggd miljö.
    Comparative Study of Different Excitation Techniques for Microstrip-like Structures over an Infinite Perfect Electric Conductor Plane2006Independent thesis Advanced level (degree of Magister), 20 poäng / 30 hpOppgave
    Abstract [en]

    The overall goal of the thesis is to establish detailed comparisons among different well-known models of excitations in their application on Microstrip-like Monopoles. Comparisons are made over the input impedances predicted by these excitations. In this way, the Galerkin’s version of the Method of Moment is applied and rooftops functions are chosen as our basis/weighting functions. Different excitation models have their influence over the excitation vector and a unique MoM matrix is used to give input impedances. We shall elicit the effects of several parameters over relative input self/mutual impedances derived from these excitation models and finally make conclusions about their differences in anticipating the input Resistance, input Reactance and also resonance frequencies.

  • 269.
    Jasim, Rubayat
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap.
    An Overview of PAPR Methods2017Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
  • 270.
    Javashvili, Otar
    Högskolan i Gävle, Radio Center Gävle. Högskolan i Gävle, Institutionen för teknik och byggd miljö.
    UWB Antennas for Wall Penetrating Radar Systems2009Independent thesis Advanced level (degree of Master (Two Years)), 30 poäng / 45 hpOppgave
    Abstract [en]

    Basic properties and new design principles of ultra wideband Vivaldi antennas are presentedand discussed in this paper. The focus will be on the modeling of Vivaldi antenna design curves, by which it is constructed; its simulation results, realization and the measurements.

    According to the aim of this research the discussion starts with the review of the previous researches done for Vivaldi antennas. Introductory part of the report also contains the problem description for the current project and the classification of the goals to be achieved. As a theoretical review, the discussion initiates with the definitions anddescription of basic parameters of the antennas and covers a short presentation of UWBpulse-based radar system. The attention will be focused on UWB signals behavior and characterization, their propagation principles and basic troubles stands nowadays. As anapplication the wall penetrating Radar systems will be considered. The major part of thereport holds on the investigation of the design principles of Vivaldi Antenna andoptimization of the key parameters for achieving the best performance for radar. Theending part of the report shows the simulations and measurement results and theircomparisons following with conclusions/discussions.

    The report will be supportive for the antenna designers, who work for UWB systems andparticularly for Vivaldi antennas, as long as there are showing up detailed descriptions ofVivaldi antenna characteristics depending on its shape and substrate properties. The modelfor designing Vivaldi antennas, given in this project, can successfully be applied for almostall the cases used in practice nowadays.

  • 271.
    Javashvili, Otar
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Andersson, Daniel
    Radarbolaget.
    New method for design implementation of Vivaldi antennas to improve its UWB behaviour (EuCAP 2010)2010Inngår i: Proceedings of the Fourth European Conference on Antennas and Propagation: EuCAP 2010 - The 4th European Conference on Antennas and Propagation, 2010, artikkel-id 5505298Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The aim of this paper is to investigate the parameters of one of the UWB Sensors, called Vivaldi Antenna, and to propose the new ways how they can be improved. As a practical implementation of the sensor, the UWB radar for wall penetrating applications with impulse excitation was utilized. For wall penetration low frequency (0.3 – 8 GHz) supporting UWB signals are required. Within the scope of this project, the Vivaldi antenna parameters are improved in order to optimize the radiation bandwidth with an usable gain response along the whole operating band, including lower frequencies. It also automatically leads to the optimization of the size of the antenna. In addition, an investigation of the phase linearity and UWB behavior of the antenna was carried out.

  • 272.
    Jawdat, Suzan
    Högskolan i Gävle, Institutionen för teknik och byggd miljö.
    Dynamic nonlinear pre-distortion of signal generators for improved dynamic range2009Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In this thesis, a parsimoniously parameterized digital predistorter is derived for linearization of the IQ modulation mismatch and the amplifier imperfection in the signal generator [1]. It is shown that the resulting predistorter is linear in its parameters, and thus they may be estimated by the method of least-squares. Spectrally pure signals are an indispensable requirement when the signal generator is to be used as part of a test bed. Due to the non-linear characteristic of the IQ modulator and power amplifier, distortion will be present at the output of the signal generator. The device under test was the IQ modulation mismatch and power amplifier deficiencies in the signal generator.

    In [2], the dynamic range of low-cost signal generators are improved by employing model based digital pre-distortion and the designed predistorter seems to give some improvement of the dynamic range of the signal generator.

    The goal of this project is to implement and verify the theory parts [1] using data program (Matlab) to improve the dynamic range of the signal generator. The design digital pre-distortion that is implemented in software so that the dynamic range of the signal generator output after predistortion is superior to that of the output prior to it. In this project, we have observed numerical problems in the proposed theory and we have found other methods to solve the problem.

    The polynomial model is commonly used in power amplifier modeling and predistorter design. However, the conventional polynomial model exhibits numerical instabilities when higher order terms are included, we have used the conventional and orthogonal polynomial models. The result shows that the orthogonal polynomial model generally yield better power amplifier modeling accuracy as well as predistortion linearization performance then the conventional polynomial model.

  • 273.
    Jens, Sjögren
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Studie av positionerings- och kommunikationsteknologier i ett IoT-samhälle under utveckling: LPWAN och Wi-Fi som komplement till GSM och GPS2018Independent thesis Basic level (university diploma), 180 hpOppgave
    Abstract [sv]

    I dagens informationssamhälle är begrepp som smarta städer och IoT (Internet of Things) heta ämnen. Alla möjliga apparater ska vara uppkopplade på nätet och dessa ska prata och kommunicera med varandra. För att visioner för smarta städer ska förverkligas ställs nya krav på flera befintliga teknologier och även nya tekniker utvecklas för att ersätta eller komplettera de gamla.

    Denna rapport fokuserar på att jämföra äldre tekniker med nya inom områden för positionering och trådlös kommunikation. För positionering jämförs traditionell GPS (Global Positioning System) med Wi-Fi-baserade tjänster och inom kommunikation jämförs GSM (Global System for Mobile communications) med Sigfox, som är speciellt utvecklat för IoT-applikationer.

    En mätutrustning konstrueras av elektronikmoduler och en smarttelefon för att samla in data från olika geografiska områden och miljöer. Från insamlade data kan resultat visa hur positioneringstjänster förhåller sig till varandra och hur täckning kan förväntas av kommunikationsteknikerna. En indikation ges också på hur energiförbrukning kan förväntas vid användandet av de olika teknikerna.

    Till sist ges slutsatser på hur kombinationer av teknologier kan användas och vilka för- och nackdelar som kommer med varje kombination. Detta för att underlätta vid komponentvalet i en produktutvecklingsfas.

  • 274.
    Ji, Jie
    Högskolan i Gävle, Institutionen för teknik och byggd miljö.
    Investigation of Skew on Differential High Speed Links2008Independent thesis Advanced level (degree of Magister), 20 poäng / 30 hpOppgave
    Abstract [en]

    Skew in telecommunication normally means the difference in arrival time of bits transmitted at the same time in differential transmission. As an increasing of transmission data bit rate and more importantly, a data and clock signal rise time of become faster, digital system interconnects became behaving as transmission line. The high speed signals become microwave in nature. The problem is that modern digital designs and verifications require knowledge that has formerly not been needed for a data bit rate of below than 100Mbit but also at the higher frequency range as 5 to 15GHz, however, most references on the necessary subjects are too abstract to be immediately applicable to the skew. For this reason a new method to investigate the skew were introduced, and with which, test board were measured. Since the test boards are made in devise material, and lines on the boards are configured out in distinct structures. In this paper, several methods were applied to find out the skew, and by comparing the results, it could be found that how factors affect the skew, not only the material factor, but some manufactory reason.

  • 275.
    Joel, Öhrling
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Internet of Micropumps: A secure IoT implementation of micropumps2017Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    The Internet of Things is a hot topic for development and research right now.More and more devices get connected to Internet by the day, but sometimesthe security of Internet of Things is neglected. Xavitech is a manufacturer ofmicropump that is interested in entering the world of the Internet of Things.This thesis work was done in collaboration with Xavitech and aimed to look athow an Internet of Things implementation for micropump could be designedin a secure manner. The goal was to design a concept application that could beused to calibrate micropumps remotely over the Internet, with primary focuson the security of the in-flight data of the application. When designing thisconcept application, an existing reference model was used as a basis. Acomparison of different protocols suitability for this application was alsoconducted and the most suitable protocol was implemented. The conceptapplication proposed in this thesis is an example of how a secure Internet ofThings implementation for micropumps can be designed.

  • 276.
    Johansson, Anders
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Matematik.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    An analysis of Kautz-Volterra models for modeling block structure nonlinear systems2010Rapport (Annet vitenskapelig)
    Abstract [en]

    Kautz-Volterra (KV) models of some nonlinear systems were analyzed. The relationsbetween the true pole of the analyzed systems and the optimal pole of the KV modelswere analyzed. The properties of nonlinear systems depend on the order of thesubsystems, since nonlinear operators do not commute. Wiener (H-N) andHammerstein (N-H) systems were analyzed.

  • 277.
    Johansson, Gustav
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Grunden till en simulering av batterier och batterisystem2019Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
  • 278.
    Johansson, Simon
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap.
    Integrering av styrsystem till SIMATIC PCS 7: En fördjupning i SIMATIC PCS 7/Open OS2017Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Denna studie ämnar undersöka hur styrsystem från Siemens som inte ingår i ordinarie produktbibliotek till deras processkontrollsystem PCS 7 kan integreras. Integreringen kommer utföras med hjälp av ett tilläggspaket till PCS 7, SIMATIC PCS7/Open OS. Styrsystemen som ska integreras i detta arbete är vanligt förekommande på industrier idag, SIMATIC S7-300/1500. Dessa styrs normalt inte via processkontrollsystem, mer vanligt är att de styrs lokalt via en operatörspanel intill maskinen. Genom att integrera dessa till processkontrollsystem kommer de att kunna styras från större kontrollrum, samtidigt som fördelarna med att integrera moderna styrsystem med ny teknik erhålls i produktionen.

    En annan del av studien har för avsikt att jämföra tidigare fall av liknande integreringar där andra typer av tekniker har använts. Dessa fall har visat att det finns idag standardiserade tekniker för att integrera enstaka fältenheter så att dessa kan hanteras av övergripande kontrollsystem. I en av studierna som undersöks, där det har gjorts försök att integrera funktionen av ett styrsystem som kontrollerar flertalet fältenheter, finns det enligt studien begränsningar i tekniken som används. Enligt Siemens AG ska dock tillägget SIMATIC PCS 7/Open OS klara att integrera ett styrsystem med dess fulla funktionalitet till processkontrollsystemet PCS 7.

    Resultatet av arbetet visar att integrering av styrsystemen till PCS 7 genom att använda tillägget är möjlig och styrsystemets fulla funktion kunde erhållas från ett PCS7-HMI. För att integreringen med tilläggspaketet ska ske smidigare rekommenderas att förberedelser, såsom att skapa bibliotek både i PCS 7 och i styrsystemet utförs innan integreringsarbetet påbörjas. Biblioteken bör innehålla funktionsblock förexempelvis motordrifter i styrsystemet och grafikelement som motsvarar dessa i PCS7.

  • 279.
    Kaltenböck, Viktor
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Measurement system for low frequency and low amplitude AC voltage of given frequency2019Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    This work is about digital signal processing methods to be used to determine information of low frequency low amplitude signals of known frequency. Different adaptive filter concepts such as Wiener filter, NLMS filter and lock-in are implemented and compared to each other. The comparison carried out for different input signal amplitude and noise variance with the objective to find the best algorithm for noise cancelling. The comparison is done using a signal of interest combined with white noise as input to the filter element. The aim of the comparison is to find the most appropriate filter for further signal analyzis. The key topics for the evaluation are the efficiency of noise cancelling and ease of implementation in a data processing unit.

  • 280.
    Kamagaluh, Braisa
    et al.
    South Westphalia Univ Appl Sci, Dept Elect Engn, D-59494 Soest, Germany.
    Kumar, John Sujith
    South Westphalia Univ Appl Sci, Dept Elect Engn, D-59494 Soest, Germany.
    Virk, Gurvinder S.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    DESIGN OF MULTI-TERRAIN CLIMBING ROBOT FOR PETROCHEMICAL APPLICATIONS2012Inngår i: Adaptive Mobile Robotics: Proceedings of the 15th International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines, CLAWAR 2012, 2012, s. 639-646Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A multi-terrain climbing robot provides more flexibility while doing inspection in scenarios where the environments comprise several types of landscape such as walls, steps, ceiling, and sloped ferromagnetic surfaces. This paper presents the development of a walking and climbing robot named Winspecbot which uses legs with magnetic padded feet to climb on steel pipes and is planned to have a hand gripper to perform inspection tasks. The robot is designed to carry about 1 kg inspection tools while it is climbing. With the use of Wi-Fi communications, the user is able to monitor the operational conditions of the robot when it is working in complex environments.

  • 281.
    Karlsson, Carl
    Högskolan i Gävle, Institutionen för teknik och byggd miljö.
    IMPULSIVE NOISE MODELING AND COEXISTENCE STUDY OF IEEE 802.11 AND BLUETOOTH2008Independent thesis Advanced level (degree of Magister), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis describes the interference problem between IEEE 802.11 and Bluetooth. These well established communication standards are often used together simultaneously. Since both standards operate in the ISM-band at 2.45 GHz, they interfere with each other. In addition to this, interference from e.g. microwave ovens, heating processes, electric motors and cordless phones also occurs on the ISM-band. Due to this interference problem, a model has been developed in MATLAB to further investigate these interferences and the effects for the user.

    The interference is modelled using the well known Class-A model for impulsive noise. The interference model is parameterized in the model and therefore the noise source(s) is described by a set of parameters derived from real measurements. Models for IEEE 802.11 legacy/b and Bluetooth are based on work published on the user community of MATHWORKS. To get a measure of performance, results from the model are presented as BER (Bit Error Rates) and PER (Packet Error Rates). When Bluetooth is used as a voice link, sound quality can also be performance evaluated directly by simply listening to a voice output file. To be able to track down a specific problem cause, measuring tools have also been included in the model to gain insight into what is causing bit/packet error.

    A model describing the interference problem has been developed describing the real world usage of the standards by the use of state machines. Due to the complexity of the problem, and also for the model to be user friendly, this thesis is not composed of a thorough mathematical derivation describing BER probability for different modulation forms. The derivations for these has already been done and is therefore summarized and compared to when the model is validated. The model has been developed as a proof of concept for further work to fully support the current and coming IEEE standards for IEEE 802.11 and Bluetooth.

  • 282.
    Karlsson, Carl
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Ängskog, Per
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Ferrer Coll, Javier
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Chilo, José
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Stenumgaard, Peter
    FOI.
    Outdoor electromagnetic interference measurements in industrial environments2009Konferansepaper (Fagfellevurdert)
  • 283.
    Khan, Jahanzeb
    Högskolan i Gävle, Institutionen för teknik och byggd miljö.
    Design of Microstrip Patch Antenna on Liquid Crystal Polymer (LCP) for Applications at 70GHz2008Independent thesis Advanced level (degree of Magister), 20 poäng / 30 hpOppgave
    Abstract [en]

    The demand of small size electronic systems has been increasing for several decades. The physical size of systems is reduced due to advancements in integrated circuits. With reduction in size of electronic systems, there is also an increasing demand of small and low cost antennas. Patch antennas are one of the most attractive antennas for integrated RF front end systems due to their compatibility with microwave integrated circuits. To fulfil the demand of integrated RF front end systems, a design of microstrip patch antenna with optimum performance at 70GHz is investigated. The procedure could be extended to design other planar antennas that act in a similar way.

    In this work, three different design methods to design patch antennas for applications at 70GHz are investigated that include use of analytical models, numerical optimization, and numerical variation of dimensions. Analytical models provide a basic understanding of the operation of a patch antenna and they also provide approximate dimensions of a patch antenna for a targeted frequency without using numerical simulations. However, as the operating frequencies of RF systems reach mm-wave frequencies, we expect that the accuracy of analytical models become less accurate. For example, the excitation of substrate modes and effect of ground size are not predicted in simple analytical models.

    Due to these expected limitations of the analytical design methods, the accuracy of these models is investigated by numerical electromagnetic field simulations. In this work, CST Microwave Studio Transient Solver is used for that purpose. In order to make sure that the appropriate settings of the solver are applied, the simulation settings such as mesh density, boundary conditions and the port dimensions are investigated. The simulation settings may affect computation time and convergence of the results. Here, in this work, the accuracy of the simulator for a specific design of inset feed rectangular patch antenna is verified. The patch dimensions obtained from analytical calculations are optimized at 70GHz by using the optimizer of the transient solver. The patch dimensions obtained from optimizer are verified by varying the patch dimensions in equidistant steps around the found result of the optimizer.

    In a rectangular microstrip patch antenna design, the use of a width of 1.5 times the length is an approximate rule of thumb [1] for low dielectric constant substrates. It is also investigated how the performance properties of a microstrip patch antenna are affected by varying the width to length ratio of the patch. There are occasions where a different ratio is required because of space limitations, or to change the input impedance. The patch designs having various width to length ratios were optimized with the feed location.

    The analytically calculated dimensions provided good initial values of the rectangular patch antenna for further optimization using more accurate techniques. The design have been optimized at 70GHz for the investigated mesh density, boundary conditions and the port dimensions. The numerical variation of dimensions is found to be most reliable among the investigated design methods but it is more complicated with many parameters.

  • 284.
    Khan, Zain Ahmed
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. KTH Royal Institute of Technology, Stockholm, Sweden.
    Characterization and Compensation of Hardware Impairments in Transmitters for Wireless Communications2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Increasing demands for data rate, energy efficiency and reliability in wireless communications have resulted in the introduction of radio frequency (RF) multiple input multiple output (MIMO) transmitters. However, MIMO transmitters suffer from additional crosstalk impairments along with the power amplifier (PA) and I/Q imbalance distortions observed in single input single output (SISO) transmitters. Therefore, this thesis focuses on the characterization and compensation of these hardware impairments in RF SISO and MIMO transmitters.

    PA distortions are often compensated using the Volterra series, but it suffers from high computational complexity. Therefore, a non-parametric method based on density estimation has been proposed in this thesis to estimate the PA transfer function, from which pruned Volterra models can be developed. The method is validated for a Doherty PA and achieves competitive error performance at a lower complexity than its competitors.

    For MIMO transmitters, a characterization technique that uses multitone excitation signals has been proposed. Multitone signals yield non-overlapping tones at the outputs of the MIMO Volterra kernels. These kernel outputs are used to identify the dominant crosstalk impairments, from which block structure and base-band behavioral models are developed. The method is validated for 2x2 and 3x3 MIMO transmitters and it is shown that the derived models achieve a better complexity accuracy trade-off than the other pruned MIMO Volterra models considered in this thesis.

    Finally, the thesis presents compensation models for joint static I/Q imbalance and MIMO PA distortions based on conjugate pair and real-valued basis functions. The models are augmented with sub-sample resolution to compensate for dynamic I/Q imbalance distortions. The proposed models are validated for a 2x2 RF MIMO transmitter and achieve a better complexity accuracy trade-off than the other state-of-the-art models considered in this thesis.

  • 285.
    Khan, Zain Ahmed
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. KTH, Royal Institute of Technology.
    Händel, Peter
    KTH, Royal Institute of Technology, Stockholm, Sweden.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    A Comparative Analysis of the Complexity/Accuracy Tradeoff in the Mitigation of RF MIMO Transmitter Impairments2017Inngår i: 2017 89th ARFTG Microwave Measurement Conference (ARFTG), IEEE, 2017, artikkel-id 8000827Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents a comparative analysis of the complexity accuracy tradeoff in state-of-the-art RF MIMO transmitter mitigation models. The complexity and accuracy of the candidate models depends on the basis functions considered in these models. Therefore, a brief description of the mitigation models is presented accompanied by derivations of the model complexities in terms of the number of FLOPs. Consequently, the complexity accuracy tradeoff in the candidate models is evaluated for a 2 × 2 RF MIMO transmitter. Furthermore, the model complexities are analyzed for increasing nonlinear orders and number of antennas.

  • 286.
    Khan, Zain Ahmed
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Royal Institute of Technology, KTH.
    Zenteno, Efrain
    Universidad Católica San Pablo.
    Händel, Peter
    Royal Institute of Technology (KTH).
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Digital Predistortion for Joint Mitigation of I/Q Imbalance and MIMO Power Amplifier Distortion2017Inngår i: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 65, nr 1, s. 322-333, artikkel-id 7600411Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper analyzes the joint effects of in-phase and quadrature (I/Q) imbalance and power amplifier (PA) distortion for RF multiple input multiple output (MIMO) transmitters in the presence of crosstalk. This paper proposes candidate models for the digital predistortion of static I/Q imbalanced sources exciting a dynamic MIMO Volterra system. The proposed models are enhanced using a novel technique based on subsample resolution to account for dynamic I/Q imbalance distortions. Finally, the computational complexity of the proposed models is analyzed for implementation suitability in digital platforms. It is shown that the error spectrum for the proposed models in subsample resolution reaches the noise floor of the measurements. The proposed models achieve a normalized mean squared error of -50 dB and an adjacent channel power ratio of -57 dB for signal bandwidths upto 65 MHz and crosstalk levels ranging to -10 dB. These results demonstrate the effectiveness of the proposed techniques in the joint mitigation of I/Q imbalance and PA distortion with crosstalk for a typical 2x2 MIMO telecommunication setup.

  • 287.
    Khan, Zain Ahmed
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Department of Information Science and Engineering, KTH Royal Institute of Technology, Stockholm, Sweden.
    Zenteno, Efrain
    Universidad Católica San Pablo, Arequipa, Peru.
    Händel, Peter
    Department of Information Science and Engineering, KTH Royal Institute of Technology, Stockholm, Sweden.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Extraction of the Third-Order 3x3 MIMO Volterra Kernel Outputs Using Multitone Signals2018Inngår i: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 66, nr 11, s. 4985-4999Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper uses multitone signals to simplify the analysis of 3×3 multiple-input multiple-output (MIMO) Volterra systems by isolating the third-order kernel outputs from each other. Multitone signals fed to an MIMO Volterra system yield a spectrum that is a permutation of the sums of the input signal tones. This a priori knowledge is used to design multitone signals such that the third-order kernel outputs are isolated in the frequency domain. The signals are designed by deriving the conditions for the offset and spacing of the input frequency grids. The proposed technique is then validated for the six possible configurations of a 3x3 RF MIMO transmitter impaired by crosstalk effects. The proposed multitone signal design is used to extract the third-order kernel outputs, and their relative contributions are analyzed to determine the dominant crosstalk effects for each configuration.

  • 288.
    Khan, Zain Ahmed
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. KTH Royal Institute of Technology.
    Zenteno, Efrain
    Universidad Católica San Pablo.
    Händel, Peter
    KTH Royal Institute of Technology.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. University of Gävle.
    Identification of Third Order 3x3 MIMO Volterra Kernels using Multitone Excitation SignalsManuskript (preprint) (Annet vitenskapelig)
  • 289.
    Khan, Zain Ahmed
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. KTH Royal Institute of Technology, Stockholm, Sweden.
    Zenteno, Efrain
    Department of Electronics and Telecommunications, Universidad Catolica San Pablo, Arequipa, Peru.
    Händel, Peter
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Multitone design for third order MIMO volterra kernels2017Inngår i: 2017 IEEE MTT-S International Microwave Symposium (IMS), IEEE conference proceedings, 2017, s. 1553-1556Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper proposes a technique for designing multitone signals that can separate the third order multiple input multiple output (MIMO) Volterra kernels. Multitone signals fed to a MIMO Volterra system yield a spectrum that is a permutation of the sums of the input signal tones. This a priori knowledge is used to design multitone signals such that the output from the MIMO Volterra kernels does not overlap in the frequency domain, hence making it possible to separate these kernels from the output of the MIMO Volterra system. The proposed technique is applied to a 2×2 RF MIMO transmitter to determine its dominant hardware impairments. For input crosstalk, the proposed method reveals the dominant self and cross kernels whereas for output crosstalk, the proposed method reveals that only the self kernels are dominant.

  • 290.
    Khan, Zain Ahmed
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Department of Signal Processing, KTH Royal Institute of Technology, Stockholm, Sweden .
    Zenteno, Efrain
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Department of Signal Processing, KTH Royal Institute of Technology, Stockholm, Sweden .
    Händel, Peter
    Department of Signal Processing, KTH Royal Institute of Technology, Stockholm.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Study of the Power Amplifier transfer function symmetry and its relation to dynamic effects2015Inngår i: 2015 IEEE 16th Annual Wireless and Microwave Technology Conference (WAMICON), IEEE conference proceedings, 2015, s. 1-6Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Future wireless networks will employ unprecedentedly high number of transmitters along-with larger bandwidth signals. Therefore, complexity efficient Power Amplifier (PA) modelling methods with the ability to quantify memory effects are required. This paper presents a low complexity method to quantify memory effects by studying the symmetry in the PA transfer functions estimated with the density estimation method. It is shown that the symmetry helps in reducing the method complexity by more than two orders of magnitude. Further, it is verified that the symmetry can be used as a non-model based metric for quantifying memory effects in PAs. 

  • 291.
    Khan, Zain Ahmed
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. KTH.
    Zenteno, Efrain
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. KTH.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Händel, Peter
    KTH.
    Density estimation models for strong nonlinearities in RF power amplifiers2014Inngår i: Proceedings of the Asia-Pacific Microwave Conference 2014, 2014, s. 116-118Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The paper presents a method for modeling strongnonlinear effects in power amplifiers based on the principlesof density estimation. The static nonlinear transfer function isobtained by averaging measured data. The performance obtainedwith density estimation is similar to the one using high ordernonlinear static polynomial models. The benefit of consideredmethod over the ones using polynomial models is that the formerestimates blindly the structure of the transfer function and doesnot suffer from numerical instabilities.

  • 292.
    Khudur, Tatiana
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap.
    Mätsystem för elektrolys2014Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 293.
    Khulbe, Manisha
    et al.
    Ambedkar Institute of Advanced Communication Technologies and Research (AIACTR), Delhi, India.
    Tripathy, Malay Ranjan
    Amity School of Engineerng and Technology, Amity University, Noida, India.
    Parthasarathy, Harish
    Netaji Subhash Institute of Technology (NSIT), N. Delhi, India.
    Shestopalov, Yury
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Matematik.
    Lagovsky, Boris
    Russian Technological University, MIREA, Moscow, Russia.
    Inverse Scattering and Imaging Using Second Order Optical Nonlinearities2019Inngår i: 2019 6th International Conference on Signal Processing and Integrated Networks, SPIN 2019, IEEE, 2019, s. 1086-1089Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper a mathematical technique is developed to find the parameters of a medium in terms of its scattered electromagnetic fields. Optical nonlinearity plays an important role in finding the scattering parameters of a medium. Using perturbation theory and nonlinear inverse scattering techniques with first order, second order and third order optical nonlinearity we find scattered electromagnetic fields. Using error minimization techniques parameters are estimated in term of permittivity and permeability up to second order. © 2019 IEEE.

  • 294.
    Kolluri, Sowjanya
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap.
    Automation of depowdering step in binder-jet additive manufacturing: Commissioning of KUKA robot2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The aim of this thesis is to automate the depowdering step in binder-jet additive manufacturing using KUKA kr6 robot.

    The major tasks involved in this thesis work are commissioning of the KUKA kr6 robot, plan the actions required for automation process of binder jet considering the scaling factor of green bodies. For this purpose KUKA robot with a standard KUKA compact controller (KRC4) and KUKA system software 8.3 (KSS) has been used. In Peter Corke Matlab toolbox (Matlab toolbox), KUKA kr6 robot model has been simulated to understand forward kinematics problem which shows the study the motion of end effector of robot in space for picking process. These transformations between the Joint coordinate systems and Cartesian coordinate systems give the forward and inverse kinematics.

    Firstly, a KUKA kr6 robot has been programmed in a KUKA Robot Language (KRL) using an algebraic approach with geometric operator to automate the picking process of green bodies. These are fragile bodies thereby many number of tests have been conducted to improve the program. Also additional effort has been placed to test the customized gripper used for the layered pick and place of the components, customized vacuum cleaner for the vacuum cleaning in between the layers and to consider the scaling factor during the sintering step of the binder jet.

    Finally, KUKA kr6 robot model has been simulated in Matlab toolbox. The picking point in the space has been simulated to study the forward kinematics and to understand how the robot reaches a position and orientation in space. Cartesian trajectory has been simulated. Also, the Jacobian matrix, its rank and determinant are studied to understand the singularities in KUKA kr6 robot, basing on which the thesis work can be continued and enhanced further.

  • 295.
    Kota, Madhava Reddy
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö.
    Shrestha, Binod
    Högskolan i Gävle, Akademin för teknik och miljö.
    Global Backprojection for Imaging of Targets Using M-sequence UWB radar system2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Synthetic Aperture Radar (SAR) is an emerging technique in remote sensing. The technology is capable of producing high-resolution images of the earth surface in all-weather conditions. Thesis work describes the present available methods for positioning and imaging targets using M-sequence UWB (Ultra-Wideband) radar signals with moving antennas and SAR algorithm to retrieve position and image of the target.

    M-sequence UWB radar technology used as signal source for transmission and receiving echoes of target. Pseudo random binary sequence is used as a transmitted signal. These radars have an ability to penetrate signal through natural and unnatural objects. It offers low cost and quality security system. Among a number of techniques of image retrieval in Synthetic Aperture Radar, study of Global back projection (GBP) algorithm is presented. As a time domain algorithm, GBP possesses inherent advantages over frequency domain algorithm like ability to handle long integration angle, wider bandwidth and unlimited aperture size. GBP breaks the full synthesis aperture into numbers of sub-apertures. These sub-apertures are treated pixel by pixel. Each sub-aperture is converted to a Cartesian image grid to form an image.  During this conversion the signal is treated with linear interpolation methods in order to achieve the best quality of the images.

    The objective of this thesis is the imaging of target using M-sequence UWB radar and processing SAR raw data using Global back projection algorithm. 

  • 296.
    Kozłowski, K.
    et al.
    Poznan University of Technology, Poland.
    Tokhi, M. O.
    University of Sheffield, United Kingdom.
    Virk, Gurvinder Singh
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Mobile service robotics2014 (oppl. 1)Bok (Annet vitenskapelig)
    Abstract [en]

    Interest in control of climbing and walking robots has remarkably increased over the years. Novel solutions of complex mechanical systems such as climbing, walking, flying and running robots with different kinds of locomotion and the technologies that support them and their applications are the evidence of significant progress in the area of robotics. Supporting technologies include the means by which robots use to sense, model, and navigate through their environments and, of course, actuation and control technologies. Human interaction including exoskeletons, prostheses and orthoses, as well as service robots, are increasingly active important pertinent areas of research. In addition, legged machines and tracked platforms with software architecture seem to be currently the research idea of most interest to the robotics community.

  • 297.
    Krantz, Emil
    Högskolan i Gävle, Akademin för teknik och miljö.
    Design of a Digital Down Converter for LTE in an FPGA2010Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    In thesis a Digital Down Converter (DDC) for Long Term Evolution (LTE) signals is designed. The DDC shall be implemented in hardware in a Field Programmable Gate Array (FPGA). For an FPGA the desired operating speed is high. The purpose of this thesis is therefore to determine if it is possible to design such a system.

     The proposed DDC design consists of an efficient quadrature demodulator and a data rate decimation system. The decimation system consists of a Cascaded Integrator Comb (CIC) filter and a compensating Finite Impulse Response (FIR) filer. It is shown how the CIC and FIR filter can be made parallel in order to increase the data rate while still maintaining the clock speed.

    This thesis shows that it is possible to design an FPGA based DDC for LTE signals with a decimation factor of 13, running at 399.36 MHz. The estimated performance increase of FPGA based design compared to the software based design is 319 times. Since floating-point numbers is inefficient to implement in hardware, thesis uses integer filter coefficients. This introduced gain in the system. This shows that fixed-point filter coefficients is to prefer.

  • 298.
    Krishna, Pothula Hari
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Cánovas, Victor
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Ramachandran, Prasadh
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Beckman, Claes
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Multi-band PIFA for combined 3G and DVB-H Terminals: a preliminary study2007Inngår i: 2007 IEEE International Workshop on Antenna Technology: Small & Smart Antennas, Metamaterials and Applications : iWAT 2007, S²AMA : conference proceedings : Cambridge, UK, March 21-23, 2007, Piscataway, NJ: IEEE , 2007, s. 439-442Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Based on the work by Ciais et. al, a small, efficient and low profile Planar Inverted-F antenna with multi-band operations for the use in mobile telephones has been studied. The antenna was designed using a High Frequency Structure Simulator, HFSS, built and verified. In order to increase the bandwidth of the antenna from the original design it is further optimized by frequency tuning using the shorts of different parasitic element. The resulting antenna operates over two wide bands from (710-1200) MHz and from (1750-2170) MHz, covering five cellular bands and the upper part of the UHF-band allowing it to be used in terminals combining cellular and DVB-H operations.

  • 299.
    Krishnan, Rakesh
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Robotics, Perception and Learning, School of Computer Science and Communication, KTH - Royal Institute of Technology, Stockholm, Sweden.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    SHAPE Algorithm for Approximate Computation of Angular Velocities in Humeral Motion2017Inngår i: 2017 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), IEEE, 2017, s. 714-718Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Estimating human motion is an area of emerging interest in instrumentation and measurement. Importantly, in such applications the physicality of the solution is paramount. Therefore, our paper proposes the SHAPE algorithm to estimate angular velocities of a moving segment from a cluster of passive markers used in a standard motion capture system known as stereophotogrammetry. We demonstrate the efficacy of our formulation with reference to the well known shape-matching algorithm in computer graphics. It is shown that our method is superior over the shape-matching algorithm.

  • 300.
    Krishnan, Rakesh
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik. Robotics, Perception and Learning, School of Computer Science and Communication, KTH - Royal Institute of Technology, Stockholm, Sweden; BioMEx Center, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Gutierrez-Farewik, Elena
    KTH Engineering Sciences, Mechanics, Royal Institute of Technology (KTH), Stockholm, Sweden; BioMEx Center, Royal Institute of Technology (KTH), Stockholm, Sweden .
    Smith, Christian
    Robotics, Perception and Learning, School of Computer Science and Communication, KTH - Royal Institute of Technology, Stockholm, Sweden; BioMEx Center, Royal Institute of Technology (KTH), Stockholm, Sweden.
    A survey of human shoulder functional kinematic representations2019Inngår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 57, nr 2, s. 339-367Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    In this survey, we review the field of human shoulder functional kinematic representations. The central question of this review is to evaluate whether the current approaches in shoulder kinematics can meet the high-reliability computational challenge. This challenge is posed by applications such as robot-assisted rehabilitation. Currently, the role of kinematic representations in such applications has been mostly overlooked. Therefore, we have systematically searched and summarised the existing literature on shoulder kinematics. The shoulder is an important functional joint, and its large range of motion (ROM) poses several mathematical and practical challenges. Frequently, in kinematic analysis, the role of the shoulder articulation is approximated to a ball-and-socket joint. Following the high-reliability computational challenge, our review challenges this inappropriate use of reductionism. Therefore, we propose that this challenge could be met by kinematic representations, that are redundant, that use an active interpretation and that emphasise on functional understanding.

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