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  • 301.
    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.
    Smith, Christian
    Robotics, Perception and Learning, School of Computer Science and Communication, KTH - Royal Institute of Technology, Stockholm, Sweden.
    Segmenting humeral submovements using invariant geometric signatures2017Inngår i: 2017 IEEE/RSJ International Conference on Intelligent Robots and Systems (Iros) / [ed] Bicchi, A., Okamura, A., IEEE, 2017, s. 6951-6958, artikkel-id 8206619Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Discrete submovements are the building blocks of any complex movement. When robots collaborate with humans, extraction of such submovements can bevery helpful in applications such as robot-assisted rehabilitation. Our work aims to segment these submovements based on the invariant geometric information embedded in segment kinematics. Moreover, this segmentation is achieved without any explicit kinematic representation.Our work demonstrates the usefulness of this invariant framework in segmenting a variety of humeral movements, which are performed at different speeds across different subjects. Our results indicate that this invariant framework has high computational reliability despite the inherent variability in human motion.

  • 302.
    Krishnan, Rakesh
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Cruciani, Silvia
    KTH, Stockholm, Sweden.
    Gutierrez-Farewik, Elena M
    KTH, Stockholm, Sweden.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektroteknik, matematik och naturvetenskap, Elektronik.
    Smith, Christian
    KTH, Stockholm, Sweden.
    Reliably Segmenting Motion Reversals of a Rigid-IMU Cluster Using Screw-Based Invariants2019Inngår i: 2018 IEEE-RAS 18TH INTERNATIONAL CONFERENCE ON HUMANOID ROBOTS (HUMANOIDS), 2019, s. 88-95, artikkel-id 8624969Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Human-robot interaction (HRI) is moving towards the human-robot synchronization challenge. In robots like exoskeletons, this challenge translates to the reliable motion segmentation problem using wearable devices. Therefore, our paper explores the possibility of segmenting the motion reversals of a rigid-IMU cluster using screw-based invariants. Moreover, we evaluate the reliability of this framework with regard to the sensor placement, speed and type of motion. Overall, our results show that the screw-based invariants can reliably segment the motion reversals of a rigid-IMU cluster.

  • 303.
    Kullman, L.
    et al.
    Department of Technology, Uppsala University, Uppsala, Sweden.
    Rönnow, Daniel
    Department of Technology, Uppsala University, Uppsala, Sweden.
    Granqvist, C. G.
    Department of Technology, Uppsala University, Uppsala, Sweden.
    Elastic Light Scattering and Electrochemical Durability of Electrochromic Tungsten-oxide-based Films1996Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 288, nr 1-2, s. 330-333Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electrochromic W-oxide-based films were produced by reactive d.c. magnetron sputtering. Fluorination and substrate bias were used to modify the film properties. Spectral measurements of the total and diffuse light scattering showed that the diffuse component remained at much less than 1% in the visible, irrespective of electrochemical degradation, which is low enough for smart windows applications.

  • 304.
    Kumar, Devesh
    et al.
    Department of ECE, ASET, Amity University Uttar Pradesh, Noida, India.
    Tripathy, M. R.
    Department of ECE, ASET, Amity University Uttar Pradesh, Noida, India.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Geethu, P. S.
    Department of ECE, ASET, Amity University Uttar Pradesh, Noida, India.
    Saurabh, Lucky
    Department of ECE, ASET, Amity University Uttar Pradesh, Noida, India.
    Performance analysis of meta-material based bow-tie shaped fractal antenna for THz application2017Inngår i: Proceedings of the 7th International Conference Confluence 2017 on Cloud Computing, Data Science and Engineering, IEEE, 2017, s. 764-769, artikkel-id 7943253Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents design and analysis of meta-material based bowtie-shaped fractal antenna for the frequency range of l.l-l.8 THz for futuristic Terahertz applications. A meta-material-inspired structure isinserted on ground plane to enhance overall performance of the proposed design. A comparative analysis of various iterated designs has been carried out in detail. Performance parameters e.g. return loss, antenna gain, radiation efficiency, radiation pattern are presented and discussed. Simulated resultsshow the multiband nature of designed antennas. Maximum gain of 6.59 dB and return loss of −21.00 dB are obtained at 1.5455 THz and 1.1787 THz respectively. HFSS simulation software is used for simulation of the designs.

  • 305.
    Kumar, Rajesh
    et al.
    Amity University, ASET, Department of Electronics & Communication Engineering, Noida, India; BSAITM, Faridabad, Haryana, India.
    Sarika,
    Amity University, ASET, Department of Electronics & Communication Engineering, Noida, India; BSAITM, Faridabad, Haryana, India.
    Tripathy, Malay Ranjan
    Amity University, ASET, Department of Electronics & Communication Engineering, Noida, India.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Orientation and Gap Independent Meta-surface Bowtie Antenna for WLAN Applications2017Inngår i: 2017 8TH INTERNATIONAL CONFERENCE ON COMPUTING, COMMUNICATION AND NETWORKING TECHNOLOGIES (ICCCNT), IEEE , 2017, artikkel-id 8203973Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A meta-surface loaded bowtie antenna with orientation and gap analysis depicting multi-band features from 1.5 GHz to 7.2 GHz is proposed. The orientation and the gap between the meta-surface unit cells are altered to investigate the effect on parameters like gain, bandwidth and directivity. The bowtie antenna uses FR4 material with relativity of 4.6, loss tangent of 0.02 and thickness h = 1.5 mm as substrate. The measured results of the fabricated antenna show a positive agreement with the simulation results. The proposed antenna shows the application in the range of WLAN. ANSYS High Frequency Structural Simulator (IIFSS) software is used to simulate the antenna.

  • 306.
    Kumar, Rajesh
    et al.
    Department of Electronics and Communication Engineering, ASET Amity University Uttar Pradesh, Noida, India.
    Sarika,
    Department of Electronics and Communication Engineering, ASET Amity University Uttar Pradesh, Noida, India.
    Tripathy, Malay Ranjan
    Department of Electronics and Communication Engineering, ASET Amity University Uttar Pradesh, Noida, India.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Performance analysis of 2 × 2 MIMO antenna with meta-material for ultra-wideband applications2017Inngår i: 2017 Progress In Electromagnetics Research Symposium - Fall (PIERS - FALL), Electromagnetics Academy , 2017, s. 593-597Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A 2 × 2 MIMO antenna based on meta-material is designed and analyzed for ultra-wideband (UWB) applications. The antenna is designed on 1.6 mm thick FR4 substrate having small dimensions of 40 mm × 40 mm. The leaf shape antenna structure with Full Ground (FG) is chosen which provides three wide bands from 0.1 GHz to 1.2 GHz, 1.2 GHz to 6.3 GHz and 6.5 GHz to 15.3 GHz. The composition of ground is varied from FG to Partial Ground (PG) to eventually PG with meta-material (PG with MM). The effect of PG with MM layer on the leaf structure shows that the return losses become smoother in nature with merging of first two bands into one, i.e., 0.1 GHz to 6.2 GHz. The structure designed provides good amount of isolation between four antenna elements. The compact size of antenna provides applications in portable UWB, X-band and Ku-band. © 2018 Electromagnetics Academy. All rights reserved.

  • 307.
    Kumar, Rajesh
    et al.
    Department of Electronics and Communication Engineering, ASET, Amity University Uttar Pradesh, Noida, India; Department of Electronics and Communication Engineering, BSAITM, Faridabad, Haryana, India .
    Sarika, n/a
    Department of Electronics and Communication Engineering, ASET, Amity University Uttar Pradesh, Noida, India; Department of Electronics and Communication Engineering, BSAITM, Faridabad, Haryana, India .
    Tripathy, Malay Ranjan
    Department of Electronics and Communication Engineering, ASET, Amity University Uttar Pradesh, Noida, India.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Multi-band slotted bowtie antenna for L, S and C band applications2017Inngår i: 2nd International Conference on Telecommunication and Networks (TEL-NET), 2017, s. 104-107Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A multi-band slotted bowtie antenna for L, S and C band applications is presented. The proposed antenna has the configuration of 40 mm58 mm1.5 mm. The slots are etched on the bowtie antenna to obtain multi-band features. The number of slots and spacing between them is varied for parametric study. The designed is fabricated on FR4 material and the measured and simulated results are in good agreement with each other thus confirming the proposed antenna design. High Frequency Structural Simulator (HFSS) is used for simulating the antenna design.

  • 308.
    Kumar, Rajesh
    et al.
    Amity University, Noida, India; BSAITM, Faridabad, Haryana, India.
    Tripathy, Malay Ranjan
    Amity University, Noida, India.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Multi Band Metamaterial Based Bowtie Antenna for Wireless Applications2015Inngår i: PIERS 2015 Prague: Progress in Electromagnetics Research Symposium : Proceedings, Cambridge, MA: Electromagnetics Academy , 2015, s. 2368-2371Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A new meta-material based bowtie antenna is proposed in this paper. Multi band response is observed in the simulated result of return loss for different frequencies (i.e., 1-12GHz). Apart from this it is seen that the return loss is improved in the case of metamaterial antenna in comparison to the conventional antenna. Simulated results of ζ and μ versus frequency are shown and it is observed that negative ζ and negative μ are obtained in different frequency bands respectively.

  • 309.
    Kumar, Rajesh
    et al.
    Department of Electronics and Communication Engineering, ASET, Amity University, Noida, Uttar Pradesh, India.
    Tripathy, Malay Ranjan
    Department of Electronics and Communication Engineering, ASET, Amity University, Noida, Uttar Pradesh, India.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Multi-resonant Bowtie Antenna with Modified Symmetric SRR for Wireless Applications2018Inngår i: IETE Journal of Research , E-ISSN 0974-780XArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A modified symmetric split ring resonator (MSSRR) loaded bowtie antenna with multi-band features over a range of 1.6–7.1 GHz is proposed in this paper. The antenna is designed on FR4 substrate with relative permittivity εr = 4.1 and thickness 1.5 mm. The fabricated antenna size is 40 mm × 58 mm. The Modified Symmetric SRR used beneath the substrate is novel and consists of two circles that are broken into four quarter circles by four rods. The effect of MSSRR location and its geometry is investigated and analysed thoroughly. The measurement results of the fabricated antenna are in good agreement with the simulation results, which confirms the proposed antenna design’s properties. ANSYS High Frequency Structural Simulator (HFSS) software is used for simulating the antenna.

  • 310.
    Kumar, Umesh
    et al.
    Amity University Uttar Pradesh, ASET, Dept Elect & Commun Engn, Noida, India.
    Kumar, Devesh
    Amity University Uttar Pradesh, ASET, Dept Elect & Commun Engn, Noida, India.
    Tripathy, Malay Ranjan
    Amity University Uttar Pradesh, ASET, Dept Elect & Commun Engn, Noida, India.
    Ranjan, Priya
    Amity University Uttar Pradesh, ASET, Dept Elect & Commun Engn, Noida, India.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Metamaterial Based Fractal Antenna for THz Application2016Inngår i: 2016 PROGRESS IN ELECTROMAGNETICS RESEARCH SYMPOSIUM (PIERS), IEEE , 2016, s. 3814-3814Konferansepaper (Fagfellevurdert)
  • 311.
    Kursu, Sami
    Högskolan i Gävle, Akademin för teknik och miljö.
    Adaptiv nivåreglering: Dynamisk expansion av ljudsignaler i en reell arbetsmiljö2013Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    För att implementera en adaptiv nivåreglering av ljudsignaler i en industriell miljö krävs hänsyn till många faktorer inför en reell implementering. Rapporten avser identifiera dessa faktorer, bedöma deras betydelse, samt presentera en grundläggande översiktlig implementeringsmetod. Förutsättningarna är ett verklighetsbaserat scenario, i form av ett nyinstallerat larmsystem i ett kontrollrum på ett pappersbruk, där ett av huvudmålen är att förtydliga ljudande larmsignaler för personalen.

    Då fysisk tillgång till implementeringsmiljön var begränsad, samplades ljudmiljön så att analys av påverkande bruskällors betydelse för nivåregleringen kunde utföras. Det samplade materialet användes även för att med hjälp av ljudredigeringsprogram belysa hur olika parameterinställningar påverkar dynamisk expansion i den aktuella ljudmiljön.

    Ett problem identifierades av det faktum att larmsignalerna själva påverkar graden av nivåreglering i det ögonblick signalerna exponeras för systemets detektormikrofoner, och möjliga metoder för att åtgärda problemet presenteras. Konstruktionen av en dynamisk expander beskrivs, och en modell och grundläggande algoritm för en eventuell framtida mjukvaruimplementering presenteras.

    Analysen visade att bestämning av lämpliga parameterinställningar är komplicerat och osäkert om det enbart görs med hjälp av samplat material, och en optimal reglering förutsätter justering efter gehör på plats i implementeringsmiljön. En relativt långsamt reagerande reglering baserat på RMS-detektering, med låg expansions-ratio och relativt högt tröskelvärde har de bästa förutsättningarna för en mjuk och transparent reglering utan påtagliga artefakter.

    En kompletterande passiv nivåreglering förbättrar möjligheterna/förutsättningarna att skapa en lyckad aktiv adaptiv nivåreglering.

    Den tillämpade analysmetodens lämplighet kan ifrågasättas med anledning av att samplingen möjligen inte representerar de förhållanden som kommer gälla vid en reell implementering, och att analysen försvåras av att den aurala perceptionen i den fysiska ljudmiljön inte nödvändigtvis med tillräcklig exakthet representeras av en samplad version av densamma. 

  • 312. Kus, Hulya
    et al.
    Norberg, Peter
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för byggnadskvalitet.
    Monitoring of moisture in rendered autoclaved aerated concrete wall by nail electrodes2001Inngår i: The international conference on building envelope systems and technologies (ICBEST) 2001, Vol 1, 2001, s. 237-242Konferansepaper (Annet vitenskapelig)
  • 313.
    Kuzmina, E. A.
    et al.
    Institute of Information Technologies, Moscow Technological University (MIREA), 86 Vernadsky Avenue, Moscow, Russian Federation.
    Shestopalov, Yury V.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Matematik.
    Complex waves in a dielectric rod and goubau line2017Inngår i: 2017 International Conference on Electromagnetics in Advanced Applications (ICEAA), Institute of Electrical and Electronics Engineers Inc. , 2017, s. 963-966, artikkel-id 8065417Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Existence of complex TM and TE waves in a dielectric waveguide of circular cross section and a Goubau line is proved by analyzing functional properties of the dispersion equations (DEs) using the theory of functions of several complex variables and validating the existence of complex roots of DE. The method proceeds from the analysis of general setting involving hybrid nonsymmetric azimuthally dependent real and complex waves.

  • 314. Kuzmina, E.
    et al.
    Shestopalov, Yury
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Matematik.
    Higher-order surface modes in the Goubau line2014Inngår i: Progress in Electromagnetics Research Symposium, Electromagnetics Academy , 2014, s. 2605-2609Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Existence of the higher-order surface waves of the Goubau line is proved and their structure is analyzed. An efficient computational approach is proposed based on numerical solution to initial-value problems obtained by the parameter differentiation. Several applications and further research directions are discussed.

  • 315.
    Kuzmina, Ekaterina
    et al.
    Moscow State Institute of Radio Engineering, Electronics and Automation, Technical University, Moscow, Russian Federation.
    Shestopalov, Yury
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Matematik.
    Waves in a lossy Goubau line2016Inngår i: 2016 10th European Conference on Antennas and Propagation: EuCAP 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, artikkel-id 7481368Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We consider a homogeneous Goubau line (GL) with a lossy cover. We analyze the dispersion equation for symmetric waves with respect to the problem parameters, find radially symmetric complex waves, and examine their behavior. We show that longitudinal wavenumbers of complex waves are regular perturbations of the propagation constants of eigenwaves of lossless GL, weakly depend om the imaginary part of permittivity of the cover, and that attenuation in GL is low at higher losses.

  • 316.
    Kylemark, Per
    et al.
    Photonics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden.
    Karlsson, Magnus
    Photonics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden.
    Torounidis, Thomas
    Högskolan i Gävle.
    Andrekson, Peter A.
    Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden.
    Noise statistics in fiber optical parametric amplifiers2007Inngår i: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 25, nr 2, s. 612-620Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we show both theoretically and experimentally that the probability density function of the intensity of an amplified signal by parametric amplifiers subject to a pump with excess noise is highly asymmetric. This is due to the nonlinear relationship between the optical pump power and the parametric gain. Because of this, the relationship between the noise figure (NF) and the bit error rate (BER) is modified, compared with that predicted by the chi(2) theory, which is an effect that is notable at large NFs and low BERs. The difference in predicted BER can be of several orders of magnitudes between the correct theory and the chi(2) approximation in single-stage parametric amplifiers. We also show that in the limit of many cascaded parametric amplifiers, the statistics of the noise of an amplified optical signal approaches chi(2). Furthermore, the BER of a parametric amplifier is generally lower compared with erbium-doped fiber amplifiers for the same NF values if we assume quantum-limited amplification.

  • 317.
    Lagovsky, B. A.
    et al.
    Deptartment of Applied Mathematics, Moscow Technological University, Moscow, Russian Federation.
    Samokhin, A. B.
    Deptartment of Applied Mathematics, Moscow Technological University, Moscow, Russian Federation.
    Shestopalov, Yury
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Matematik.
    Creating Two-Dimensional Images of Objects with High Angular Resolution2018Inngår i: Proceedings of 2018 IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP), 2018, s. 114-115Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A new method of digital radar signal processing for remote sensing is proposed. The technique allows one to obtain two-dimensional images of objects with super resolution. The method is based on solving a convolution-type two- dimensional linear integral equation of the first kind by algebraic methods.

  • 318.
    Lagovsky, B. A.
    et al.
    Moscow Technological University, Moscow, Russia.
    Samokhin, A. B.
    Moscow Technological University, Moscow, Russia.
    Shestopalov, Yury
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Matematik.
    Increasing accuracy of angular measurements using UWB signals2017Inngår i: 2017 11th European Conference on Antennas and Propagation, EUCAP 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 1083-1086Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We show that dispersion characteristics of antenna patterns should be taken into account when developing systems using UWB signals. The accuracy of measurement of angular coordinates of objects using UWB pulses is increased by optimizing their shape based on known characteristics of the antenna system and at least partially known characteristics of the investigated signal source. Optimization algorithms allow to minimize the width of the directional pattern for a given level of the useful signal.

  • 319.
    Lagovsky, B. A.
    et al.
    Moscow State Institute of Radio Engineering and Automation, Technical University, Moscow, Russian Federation.
    Samokhin, A. B.
    Moscow State Institute of Radio Engineering and Automation, Technical University, Moscow, Russian Federation.
    Shestopalov, Yury V.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Matematik.
    Pulse characteristics of antenna array radiating UWB signals2016Inngår i: 2016 10th European Conference on Antennas and Propagation: EuCAP 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, artikkel-id 7481624Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Dispersion properties of the mutual impedance of emitters significantly alter the shape and spectrum of ultra-wideband (UWB) signals which must be taken into account when forming the signal. In order to take into consideration mutual coupling of elements we propose to use pulse characteristics in the antenna performance analysis and calculations. This approach allows us to simplify calculations of UWB antenna systems and improve their accuracy.

  • 320. Lagovsky, Boris A.
    et al.
    Samokhin, Alexander B.
    Shestopalov, Yury V.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Matematik.
    Superresolution based on the methods of extrapolation2015Inngår i: PIERS 2015 Prague: Progress in Electromagnetics Research Symposium : Proceedings, Cambridge, MA: The Electromagnetics Academy , 2015, s. 1548-1551Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A new method of signal processing by smart antennas is proposed and justified. It allows to improve the accuracy of angle measurement and to restore the image of the object with superresolution. The method is based on the extrapolation of the signals received by each element of the antenna array, outside the aperture. This allows introducing new virtual elements and thus synthesizing significantly larger antenna array. The method is tested in numerical experiments using a mathematical model and the maximum effective angular resolution is found for different cases and objects. Algorithms based on the method of digital aperture synthesis provide angular superresolution 3-7 times greater than that according to the Rayleigh criterion for a signal/noise ratio of 12-13 dB.

  • 321.
    Lai, Jingou
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap.
    Liu, Che
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap.
    Use SNA instead of VNA to characterize indoor channel: implementing and rms theory2010Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    In this report we focus on the use of an economical way on how Scalar Network Analyzer (SNA) works instead of Vector Network Analyzer (VNA) to estimate the phase angle of signals in indoor channel. This is detailed in RMS delay theory and simulation section, experimental is designed in the according Experiment Design section, where we also state the required measurements known from the math part. In our work, data are recorded both from two different channel characteristics. Method of achieving amplitude is by using deconvolution theory. The condition of applying Hilbert transform are highlighted as impulse response h(t) in time domain should be causal.  The recorded data amplitude is computed by Hilbert Transform, and therefore validate the condition using Inverse Discrete Fourier Transform (IDFT) back to time domain to achieve h(t). Power delay profile P(t) is therefore presented afterwards. In paper calculations of rms delay τrms  of the channel which is the most important variable are also performed, the results calculated from different windowing truncation and the LOS and NLOS characteristics are compared in discussion and conclusion section, it also includes Opinions of window functions chosen for the phase estimation.

  • 322.
    Landin, Per
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. KTH, Signalbehandling.
    Digital Baseband Modeling and Correction of Radio Frequency Power Amplifiers2012Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Aspects related to behavioral modeling and correction of distortions for radio frequency (RF) power amplifiers (PAs) are treated in the thesis.   

    When evaluating the performance of a behavioral model it is important to, first of all, use an evaluation criterion, and second, make sure that the criterion actually tells something about the behavior one wishes to describe. This is used in the weighted error spectral power ratio (WESPR) criterion by means of a frequency dependent weighting function. When the parameters of the models are estimated a suitable error criterion should likewise be used. The frequency weighting function in the WESPR is used in the extraction of the parameters. It is shown on two types of PAs that the model performance measured as WESPR can be improved while the model complexity is reduced compared to the standard frequency neutral criterion.   

    When building a model of a system it is advantageous to take account of the physical structure and incorporate this knowledge into the model. It can improve model performance and possibly reduce the number of parameters. By starting from a physically motivated nonlinear model of a RF PA, the commonly used memory polynomial (MP) models are derived. Additionally, three novel MP model structures are derived. Using data measured on a PA it is found that two of these model structures have lower model errors while using fewer parameters than models previously published in the literature.   

    Methods to increase the power efficiency and the linearity of RF PAs have been investigated. One of these methods is digital predistortion (DPD) which improves the linearity, thus facilitating operation at higher power levels which improves power efficiency. The other method is a signal shaping method that makes the signal more favorable to the PA by reducing the highest peaks to lower values. It is experimentally shown that the combination of DPD and signal shaping results in an increase of power efficiency in the order of 2-4 times. An instability in the feedback loop that updates the parameters of the DPD was also identified and two solutions were proposed. One solution changes the parameters of the DPD in such a way that the instability is avoided and the other changes the signal to avoid high amplitudes.   

    The nonlinear effects of class-D outphasing amplifiers are considered. Four model structures are proposed and evaluated on data measured from two amplifiers. In order to reduce the distortions in the output signal from the amplifiers an algorithm using constant envelope amplitude (purely phase-modulated) signals is proposed. The DPD is evaluated and found to reduce the distortions in a state-of-the-art 32 dBm class-D outphasing PA to make it fulfill the linearity requirements for downlink signals used in the universal mobile telecommunications system (UMTS).

  • 323.
    Landin, Per
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Barbé, Kurt
    Vrije Universiteit Brussel.
    Van Moer, Wendy
    Vrije Universiteit Brussel.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Händel, Peter
    KTH Royal Institute of Technology.
    Proofs of Derivations in Memory Polynomial Baseband Modeling of RF Power Amplifiers2011Rapport (Annet vitenskapelig)
    Abstract [en]

    This paper contains supporting derivations for the paperMemory Polynomial Baseband Modeling of RF Power Am-plifiers. All references to numbered equations, propositionsand assumptions are to the corresponding number inMemoryPolynomial Baseband Modeling of RF Power Amplifiers.

  • 324.
    Landin, Per
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Chalmers University of Technology, Gothenburg, Sweden .
    Eriksson, Thomas
    Chalmers University of Technology, Gothenburg, Sweden.
    Fritzin, Jonas
    Ericsson AB; Linköping University.
    Alvandpour, Atila
    Linköping University.
    Behavioral modeling of outphasing amplifiers considering memory effects2013Inngår i: 2013 IEEE MTT-S International Microwave Symposium Digest, IEEE conference proceedings, 2013, artikkel-id 6697764Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper proposes a behavioral model structure for outphasing amplifiers. The model performance is evaluated on a class-D CMOS outphasing amplifier and compared with two models found in the literature. The proposed model structure also allows the use of memory in a parallel Hammerstein-like setting. The proposed models show improvements in adjacent channel error power ratio (ACEPR) of approximately 5 dB in addition to being linear in the parameters. The lower model errors enable the use and design of improved predistorters taking frequency dependency (memory effects) in outphasing amplifiers into account. 

  • 325.
    Landin, Per
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Isaksson, Magnus
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Keskitalo, Niklas
    Högskolan i Gävle, Radio Center Gävle.
    Tornblad, Olof
    Infineon Technologies.
    Sideband asymmetries in RF Power LDMOS Before and After Digital Predistortion2009Konferansepaper (Annet vitenskapelig)
    Abstract [en]

     The merging of the fields of RF engineering and signal processing has introduced concepts such as behavioral modeling and enabled digital linearization schemes for wireless devices, such as power amplifiers (PAs). Despite that this process has been going on for a number of years much work remains to be done. The links between physical behavior and mathematical models are far from well-understood as are the optimum strategies for device design. This study focus on digital predistortion properties of a one-stage PA consisting of a power transistor mounted in a test fixture. The device under test (DUT) is an Infineon PTF210451E, a 45W transistor intended for usage in the frequency bands 2010-2025 MHz and 2110-2170 MHz. The test fixture is also designed by Infineon Technologies.  The signal types used in the measurements are single and double carrier wideband code division multiple access (WCDMA) signals. The double carrier WCDMA signals have tone-spacings of 5, 10 and 15 MHz. Normal two-tone measurements are also presented. 

  • 326.
    Landin, Per N.
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Chalmers University of Technology, Göteborg, Sweden; KTH Royal Institute of Technology, Stockholm, Sweden; Vrije Universiteit Brussel, Belgium.
    Barbé, Kurt
    Vrije Universiteit Brussel, Belgium.
    Van Moer, Wendy
    Vrije Universiteit Brussel, Belgium.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Händel, Peter
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Two novel memory polynomial models for modeling of RF power amplifiers2015Inngår i: International journal of microwave and wireless technologies, ISSN 1759-0795, E-ISSN 1759-0787, Vol. 7, nr 1, s. 19-29Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two novel memory polynomial models are derived based on physical knowledge of a general power amplifier (PA). The derivations are given in detail to facilitate derivations of other model structures. The model error in terms of normalized mean square error (NMSE) and adjacent channel error power ratio (ACEPR) of the novel model structures are compared to that of established models based on the number of parameters using data measured on two different amplifiers, one high-power base-station PA and one low-power general purpose amplifier. The novel models show both lower NMSE and ACEPR for any chosen number of parameters compared to the established models. The low model errors make the novel models suitable candidates for both modeling and digital predistortion.

  • 327.
    Landin, Per
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Nader, Charles
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Van Moer, Wendy
    Vrije Universiteit Brussel.
    Björsell, Niklas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Händel, Peter
    KTH Royal Institute of Technology.
    Overview of Synergetic OFDM Crest Factor Reduction and DigitalPre-Distortion for RF PAs2011Inngår i: RFMTC11, 2011Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Digital baseband pre-distortion (DPD) is used tolinearize nonlinear RF PAs, crest factor reduction (CFR) toincrease the maximum output power level of RF PAs. Togetherthey result in increased output power with maintained, or even,better linearity. This paper discuss some of the techniquesfor DPD and CFR methods currently under investigation.Measured results for a class-AB PA using OFDM signalsindicate a possibility to increase the power added efficiency(PAE) by at least 15%-points, from 30%to 45%, and a poweroutput increase of 6 dB while maintaining specified ACLRrequirements.

  • 328.
    Landin, Per Niklas
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    On Radio Frequency Behavioral Modeling: Measurement Techniques, Devices and Validation Aspects2009Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [sv]

    Effektförstärkare för radiofrekvensapplikationer utgör fortfarande ett av de största problemen i trådlösa kommunikationssystem. Detta beror på att dessa förstärkare är ickelinjära, har låg energieffektivitet och ger mycket distortioner. Bättre verktyg för att förstå och korrigera dessa beteenden är nödvändiga. Ett sådant verktyg är beteendemodellering. En beteendemodell kanses som en svart låda med insignal(er) och utsignal(er). In detta fall är dessasignaler samplade basbandssignaler och den svarta lådan är en matematisk relation mellan en insignal och en utsignal.

    Avhandlingen behandlar några krav för beteendemodellering av nämnda system genom att presentera metoder för utvärdering och förbättring av modellernas prestanda. Detta åstadkoms genom att betrakta ett frekvensviktat felkriterium.

    Ett högpresterande mätsystem är också nödvändigt för experimenten. Prestandan hos det tillgängliga systemet jämförs med prestandan hos ett allmänt erkänt mätsystem, en s.k. storsignalsnätverksanalysator, genom att betrakta prestandan hos beteendemodellerna som extraheras och validerasmed data från respektive mätsystem. Resultatet visar att det existerande mätsystemet har god prestanda.

    Ett stort problem vid beteendemodellering är att kunna sampla med tillräckligt hög hastighet. Genom att använda Zhu-Franks generaliserade samplingsteorem vid beteendemodellering kan en del av detta problem undvikas. Teoremet medför att man kan sampla med en väsentligt lägre samlingsfrekvens än vad Nyquistteoremet säger. Modeller extraheras och prestandanutvärderas genom att använda kriteriet normalized mean square error (NMSE).

    För stabil prediktion och korrektion av utsignalen måste robustheten hos de använda modellerna verifieras. En sådan studie som berör robustheten mot variationer i lastimpedansen har genomförts. Prestandan på direkta modeller försämras med 7 dB mätt som adjacent channel error power ratio (ACEPR). Prestanda på inversmodellen, implementerad som digital predistortion, försämras med upp till 13 dB mätt som adjacent channel power ratio(ACPR).

  • 329.
    Landin, Per Niklas
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Barbé, Kurt
    Vrije Universiteit Brussel.
    Van Moer, Wendy
    Vrije Universiteit Brussel.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Händel, Peter
    KTH Royal Institute of Technology.
    Memory Polynomial Baseband Modeling of RF Power Amplifiers2012Inngår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662Artikkel i tidsskrift (Fagfellevurdert)
  • 330.
    Landin, Per Niklas
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Bengtsson, Olof
    Isaksson, Magnus
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Power Amplifier Behavioural Model Mismatch Sensitivity and the Impact on Digital Predistortion Performance2009Inngår i: Proc. 39th European Microwave Conference (EuMC), IEEE conference proceedings, 2009, s. 338-341Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents an investigation of poweramplifier behavioural model performance sensitivity to in-bandreflections. The measurement system and model extractionprocess is presented together with the results and an analysis ofthe effect of parameter variations in a digitally predistortedsystem. A load-pull system is used together with a digitalbaseband model extraction system to identify the impact onmodelling performance. The results show that the modelperformance varies greatly with in-band reflection magnitudeand phase on the amplifier output. It is also shown that a digitalpredistortion based on a model extracted at matched conditions,where it gives an excellent improvement of 20 dB in adjacentchannel leakage ratio (ACLR), gives a poor improvement of 7 dBfor miss-matched conditions with as low reflections as Γ=0.2(return loss 14 dB). This indicates that in-band reflections needto be considered and adaptive predistortion used also for lowVSWR system like base-stations for telecommunication.

  • 331.
    Landin, Per Niklas
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Fager, Christian
    Chalmers.
    Isaksson, Magnus
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Andersson, Kristoffer
    Chalmers.
    Power Amplifier Behavioral Modeling Performance Comparison of the LSNA and the Modulation-Domain System2008Inngår i: 72nd ARFTG Microwave Measurement Symposium, 2008, Portland, OR., 2008, s. 73-78Konferansepaper (Fagfellevurdert)
  • 332.
    Landin, Per Niklas
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Fritzin, Jonas
    Linköping University.
    Jung, Ylva
    Linköping University.
    Enqvist, Martin
    Linköping University.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Alvandpour, Atila
    Linköping University.
    Digital baseband pre-distortion of class-D outphasing amplifiers2012Inngår i: Proceedings Gigahertz Symposium 2012, 2012Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    This paper presents a novel structure and method for modeling and digitally pre-distorting outphasing amplifiers. The models and pre-distortion are evaluated on a CMOS low-power class-D outphasing amplifier using uplink WCDMA signals. Using the proposed pre-distorter improves the ACLR by no less than 12 dB making the amplifier fulfill the 3GPP requirements on ACLR.

  • 333.
    Landin, Per Niklas
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Fritzin, Jonas
    Linköping University.
    Van Moer, Wendy
    Vrije Universiteit Brussel.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Alvandpour, Atila
    Linköping University.
    Modeling and digital predistortion of class-D outphasing RF power amplifiers2012Inngår i: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 60, nr 6, s. 1907-1915Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a direct model structure for describing class-D outphasing power amplifiers (PAs) and a method for digitally predistorting these amplifiers. The direct model structure is based on modeling differences in gain and delay, nonlinear interactions between the two paths, and differences in the amplifier behavior. The digital predistortion method is designed to operate only on the input signals' phases, to correct for both amplitude and phase mismatches. This eliminates the need for additional voltage supplies to compensate for gain mismatch. Model and predistortion performance are evaluated on a 32-dBm peak-output-power class-D outphasing PA in CMOS with on-chip transformers. The excitation signal is a 5-MHz downlink WCDMA signal with peak-to-average power ratio of 9.5 dB. Using the proposed digital predistorter, the 5-MHz adjacent channel leakage power ratio (ACLR) was improved by 13.5 dB, from -32.1 to -45.6 dBc. The 10-MHz ACLR was improved by 6.4 dB, from -44.3 to -50.7 dBc, making the amplifier pass the 3GPP ACLR requirements.

  • 334.
    Landin, Per Niklas
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Isaksson, Magnus
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    A review of validation criteria for behavioral power amplifier models2008Konferansepaper (Annet vitenskapelig)
  • 335.
    Landin, Per Niklas
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Isaksson, Magnus
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Händel, Peter
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Comparison of Evaluation Criteria for Power Amplifier Behavioral Modeling2008Inngår i: IEEE MTT-S International Microwave Symposium Digest; 2008, Atlanta, GA, USA, 2008, s. 1441-1444Konferansepaper (Fagfellevurdert)
  • 336.
    Landin, Per Niklas
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Händel, Peter
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Parameter Extraction and Performance Evaluation Method for Increased Performance in RF Power Amplifier Behavioral Modeling2010Inngår i: International Journal of RF and Microwave Computer-Aided Engineering, ISSN 1096-4290, E-ISSN 1099-047X, Vol. 20, nr 2, s. 200-208Artikkel i tidsskrift (Fagfellevurdert)
  • 337.
    Landin, Per Niklas
    et al.
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Högskolan i Gävle, Radio Center Gävle.
    Isaksson, Magnus
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik. Högskolan i Gävle, Radio Center Gävle.
    Keskitalo, Niclas
    Högskolan i Gävle, Radio Center Gävle.
    Tornblad, Olof
    A Study of memory effects of RF power LDMOS before and after digital predistortion2009Inngår i: Wireless and Microwave Technology Conference, 2009. WAMICON '09. IEEE 10th Annual, 2009, s. 1-5Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Sideband asymmetries in distortion products are created due to electrical and thermal memory effects and this can be difficult to correct for in a digital predistortion algorithm. In this study, sideband asymmetries in third-order intermodulation distortion products before and after digital predistortion were investigated using 2-tone and 2-carrier WCDMA signals. The parallel Hammerstein (PH) model was used in the digital predistortion algorithm. The sign of the asymmetries before correction were found to depend on power level. Memoryless correction lead to an increase in asymmetries for some power ranges whereas using a PH model of order 13 with only one order of memory length lead to good correction over a large power range.

  • 338.
    Landin, Per Niklas
    et al.
    Högskolan i Gävle, Radio Center Gävle.
    Nader, Charles
    Högskolan i Gävle, Radio Center Gävle.
    Björsell, Niclas
    Högskolan i Gävle, Radio Center Gävle.
    Isaksson, Magnus
    Högskolan i Gävle, Radio Center Gävle.
    Wisell, David
    Ericsson AB.
    Händel, Peter
    Högskolan i Gävle, Radio Center Gävle.
    Andersen, Olav
    Ericsson AB.
    Keskitalo, Niclas
    Högskolan i Gävle, Radio Center Gävle.
    Wideband Characterization of Power Amplifiers Using Undersampling2009Inngår i: 2009 IEEE MTT-S International Microwave Symposium, Boston: IEEE MTT , 2009, s. 1365-1368Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper a radio frequency power amplifier is measured and characterized by the use of undersampling based on the generalized Zhu-Frank sampling theorem. A test system has been designed allowing the bandwidth of the stimuli signal to be 100 MHz in the characterization process. That would not be possible with any vector signal analyzer on the market. One of the more challenging problem within the proposed concept is the model validation process. Here, two different techniques for model validation are proposed, the multitone and the spectrum scan validation methods.

  • 339.
    Landin, Per Niklas
    et al.
    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.
    Odd and Odd-Even Memory Polynomial Representations2013Rapport (Annet vitenskapelig)
    Abstract [en]

    It is shown that the absolute value of a complex-valued function can be expressed as a polynomial in the square of the absolute value of the function. A series expansion is given and related to the Volterra-series. The results find application in explaining and improving the understanding of the “even” order memory polynomial models.

  • 340.
    Landin, Per Niklas
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Van Moer, Wendy
    Vrije Universiteit Brussel.
    Isaksson, Magnus
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Händel, Peter
    KTH Royal Institute of Technology.
    Peak-Power Controlled Digital Predistorters for RF Power Amplifiers2012Inngår i: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 60, nr 11, s. 3582-3590Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper investigates the issue of “predistorter blow-up,” i.e., uncontrolled peak expansion caused by the predistorter. To control the peak expansion, an extension of the multistep indirect learning architecture (MS-ILA) is proposed by adding a constraint that describes the allowed peak power of the predistortion signal. The resulting optimization problem is shown to be convex and an optimization method is formulated to solve it. Measurements on a class-AB power amplifier (PA) using orthogonal frequency-division multiplex signals show that the peak control works as intended and prevents the MS-ILA from generating high peaks when the PA is operated in compression. The restriction on the peak power also prevents the performance degradation occurring due to the “blow-up” problem. This makes the proposed controlled MS-ILA a safer option than the standard MS-ILA. In addition to controlling the peak input power to the PA, using the proposed method it was possible to increase the output power by 1.3 dB while fulfilling requirements of less than 40-dB adjacent channel leakage power ratio, compared to the standard five-step MS-ILA. Reduced peak power also reduces the requirements on linearity in signal generation, resolution in computations, and analog-to-digital and digital-to-analog conversion.

  • 341.
    Landin, Per
    et al.
    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.
    RF PA Modeling Considering Odd-Even and Odd Order Polynomials2016Inngår i: 2015 IEEE Symposium on Communications and Vehicular Technology in the Benelux (SCVT), New York: Institute of Electrical and Electronics Engineers (IEEE), 2016, artikkel-id 7374233Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The use of “even” order polynomial terms in radio frequency power amplifier behavioral modeling and digital pre-distortion linearization has long been discussed. This contribution mathematically shows that the purely odd polynomials and the odd-even polynomials are equivalent up to the truncation error inherent in the model itself. The choice of odd or odd-even polynomial is equivalent to a choice of basis functions wherein the odd-even representation does not provide a richer set of basis functions, as earlier has been claimed. Modeling using measured data from a power amplifier shows that the difference in performance between the odd and odd-even polynomials is negligible for models at high nonlinear order. These findings are important to explain the appearance and use of the odd and odd-even models in power amplifier modeling and digital pre-distortion.

  • 342.
    Larsson, Oskar
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap.
    Arduinobaserad hundpejl2017Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    En hundpejl är idag något absolut nödvändigt vid löshundsjakt. Anledningen är att jägaren måste veta vart hunden är och helst också vad som sker. Idag när trafiken ökar allt mer är det av vikt att i tid kunna avgöra om hunden är på väg mot en trafikerad väg. Om hunden blir still har man möjlighet att i tid avgöra om den fastnat eller har gått i vatten och har möjlighet att hinna fram i tid för att hjälpa. Och då hundpejlar ofta kostar mer än 2000 kronor så finns det ett önskemål om att ta fram billigare varianter av hundpejlar.

    Målet i detta projekt är därför att konstruera, montera och programmera en pejl av Arduino UNO och Adafruit FONA 808 som uppfyller de krav, såsom en batteritid på minst 8 timmar och ett precisionsfel på max 5 meter, som en jägare ställer på en pejl som samtidigt är billigare en kommersiell produkt med liknande prestanda. Tillgångavägssättet var sådant att först studerades relevant litteratur såsom Adafruits produktbeskrivning och testkod, sedan testades de olika enskilt funktionerna, skicka, ta bort och läsa SMS samt hämta GPS-koordinater. När det var klart att funktionerna fungerade programmerades en kod som erhåller de egenskaper som en användare önskar sig.  Därefter utvärderades pejlen för att se om den uppfyller de ställda kraven. Det som testades var pejlens vikt, batteritid och positionsnoggrannhet. Vikten mättes på en köksvåg, batteritiden mättes genom att testa batteriladdningen en gång i timmen över tre timmar och positionsnoggrannheten mättes på sådant sätt att pejlens koordinater jämfördes med resultatet från Google Maps och Eniro.

    Det visade sig att pejlen inte helt uppfyller alla krav, då positionsnoggrannheten inte direkt uppfyller de kraven som är ställda. Dock är enheten fortfarande användningsbar för spårning då den ger en tillräcklig generell area för att kunna hitta en hund på. Pejlen kan även användas i andra syften, till exempel placera den i en bil utifall stöld. Den ger även en bas att vidareutveckla en hundpejl ifrån till exempel skicka ljud till en telefon vilket även intresserar jägare.

  • 343.
    Lastras-Martí­nez, L. F.
    et al.
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Santos, P. V.
    Paul-Drude-Institut für Festkörperelektronik, Berlin, Germany.
    Rönnow, Daniel
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Cardona, M.
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Specht, P.
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Eberl, K.
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Reflectance difference spectroscopy of GaAs asymmetric surface quantum wells above the fundamental gap1998Inngår i: Physica status solidi. A, Applied research, ISSN 0031-8965, E-ISSN 1521-396X, Vol. 170, nr 2, s. 317-321Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report Reflectance Difference (RD) measurement on (001) GaAs surface quantum wells (QW) under Ultra High Vacuum (UHV) conditions from 1.7 to 5.0eV. The QW is embedded between an arsenic-rich reconstructed GaAs surface and an AlAs barrier. The samples, grown by MBE with a protective arsenic cap layer, were heated to 320 and 430°C to desorb the As layer and form c(4 x 4) and (2 x 4) surface reconstructions, respectively. By modifying the surface reconstructure, we are able to separate the contributions to the optical anisotropy from the surface region (mainly associated with the As dimers) from those originating below the surface.

  • 344.
    Lauwers, L
    et al.
    Vrije Universiteit Brussel.
    Barbé, Kurt
    Vrije Universiteit Brussel.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    A robust signal detection method for fMRI data under correct Rice conditions2012Inngår i: Instrumentation and Measurement Technology Conference (I2MTC), 2012 IEEE International, 2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we tackle the problem of signal detection in functional Magnetic Resonance Imaging (fMRI) data by means of a statistical analysis. The main problem of the commonly used statistical tests is that they are based on the assumption that the data are Gaussian distributed, which is only valid for high signal-to-noise ratios (SNRs). Hence, for low SNRs the classical statistical tests are inadequate due to the wrong normality assumption, since it is known from literature that fMRI data follow a Rice distribution. In order to handle both high and low SNRs, we present in this paper a correction for the simplest and most widely used t-test by incorporating the correct Rice conditions. The performance of the Rice-corrected statistical test is shown through simulations and compared with its uncorrected counterpart.

  • 345.
    Lejarza, Lander
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Gas Data Acquisition using Arduino2017Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    The aim of this project is to acquire gas data using an Arduino microcontroller. This project is part of a bigger project called The electronic nose where mechanical, thermal, electrical, electronic and software parts work together. It is the continuation of a project handled before where mainly the mechanical, thermal and electrical parts were done.

     

    The whole e-Nose project is divided in 4 main subcategories: general mechanical structure, thermal and piston electric circuit, gas sensors and software. My work will be focused in the last two subcategories of the general project.

     

    The sample to be measured is placed inside of a moving cylinder, which will lift up the sample reaching near the sensors and warming it using a thermal resistance, to release more odor. That is where the sensors act, synchronized with the piston, will get the data through the Arduino and sends it to the computer to be analysed. The sensors will be activated using an Arduino Mega 2560 and transferred to the computer to be analysed with MatLab.

     

    To control the measurement, a push button, a LCD display and a LED will be placed; having like this a full control of the project and an easy interface for the user. Six gas sensors will be used, which will be enough to be able to differentiate between different kind of gases. With such variety it is possible to categorize between combustible gas (methane, propane, LPG etc.), NH3, alcohol and more gases.

     

    The e-Nose will be able to measure different gases in more than ways depending on the program we choose. For a more accurate response, more sensors would be needed using a sensor fusion method or more accurate sensors.

  • 346.
    Lempart, Michael
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap.
    Machine learning and augmented data for automated treatment planning in complex external beam radiation therapy2019Independent thesis Advanced level (degree of Master (Two Years)), 10 poäng / 15 hpOppgave
    Abstract [en]

    External beam radiation therapy is currently one of the most commonly used modalities for treating cancer. With the rise of new technologies and increasing computational power, machine learning, deep learning and artificial intelligence applications used for classification and regression problems have begun to find their way into the field of radiation oncology. One such application is the automated generation of radiotherapy treatment plans, which must be optimized for every single patient. The department of radiation physics in Lund, Sweden, has developed an autoplanning software, which in combination with a commercially available treatment planning system (TPS), can be used for automatic creation of clinical treatment plans. The parameters of a multivariable cost function are changed iteratively, making it possible to generate a great amount of different treatment plans for a single patient. The output leads to optimal, near-optimal, clinically acceptable or even non-acceptable treatment plans. In this thesis, the possibility of using machine and deep learning to minimize the amount of treatment plans generated by the autoplanning software as well as the possibility of finding cost function parameters that lead to clinically acceptable optimal or near-optimal plans is evaluated. Data augmentation is used to create matrices of optimal treatment plan parameters, which are stored in a training database.  Patient specific training features are extracted from the TPS, as well as from the bottleneck layer of a trained deep neural network autoencoder. The training features are then matched against the same features extracted for test patients, using a k-nearest neighbor algorithm. Finally, treatment plans for a new patient are generated using the output plan parameter matrices of its nearest neighbors. This allows for a reduction in computation time as well as for finding suitable cost function parameters for a new patient.

  • 347.
    Lian 连, Xiangyu 翔宇
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö.
    Jiang 姜, Chunguang 春光
    Högskolan i Gävle, Akademin för teknik och miljö.
    Building a simple spectrum analyzer with dsPIC30F4013  2011Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    FFT-based digital spectral analyzer has become more and more widely used as a result of the development of Digital Signal Processing (DSP) techniques. Modern Analog-to-Digital Converters (ADC) and processors have made it possible to make fast measurements with a limited number of hardware.

     

    In this thesis, a design of a simple low-cost FFT-based digital spectrum analyzer was presented. The author discusses the design of each components of the system in qualitatively and quantitatively. The report presents the whole system design in detail which contains filter design, micro-controller design, UART transmission design and MATLAB GUI design. Some satisfying measurement result of the system were presented in the paper. The system can provide fast measurement with good accuracy. But the measured result has a limited range and resolution of the display is not very high. At last, the advantages and disadvantages of the system was discussed which is considered as guidelines for further work.

  • 348.
    Liang, Hao
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap.
    Data acquisition and analysis of a novel SPR biosensor using a laser line generator2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 349.
    Lindström, T.
    et al.
    Department of Technology, Uppsala University, Uppsala, Sweden.
    Kullman, L.
    Department of Technology, Uppsala University, Uppsala, Sweden.
    Rönnow, Daniel
    Max-Planck-Institut für Festkörperforschung, Stuttgart ,Germany.
    Ribbing, C. G.
    Department of Technology, Uppsala University, Uppsala, Sweden.
    Granqvist, C. G.
    Department of Technology, Uppsala University, Uppsala, Sweden.
    Electrochromic control of thin film light scattering1997Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 81, nr 3, s. 1464-69Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Total and diffuse reflectance spectra were measured on Al surfaces covered with electrochromic W oxide films in colored and bleached states. Vector perturbation theory was used for analyzing the spectra. The diffuse reflectance appeared to originate from correlated (uncorrelated) interface roughness when the W oxide film was fully colored (bleached). Assuming partially correlated interfaces led to agreement between experimental and calculated spectra. The use of an electrochromic film appears a promising method to control the relative contributions of the interfaces to the resulting scattering.

  • 350. Litwin, Andrej
    et al.
    Bengtsson, Olof
    Högskolan i Gävle, Institutionen för teknik och byggd miljö, Ämnesavdelningen för elektronik.
    Olsson, Jörgen
    Novell BiCMOS Compatible, Short Channel LDMOS Technology for Medium Voltage RF & Power Applications2002Inngår i: IEEE MTT-S Digest, 2002, s. 35-38Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We describe a very short channel, 0.15 μm, LDMOS transistor, with a breakdown voltage of up to 45 V, manufactured in a standard 0.35 μm BiCMOS process. At 1900 MHz and a 12V supply voltage the 0.4mm gate width device gives 100 mW output power P1 dB at a drain efficiency of 43%. It has a transducer power gain of more than 20dB and a current gain cutoff frequency, fT, of 13 GHz. The maximum available gain cutoff frequency, fMAX, is 27 GHz. The LDMOS process module does not affect the performance or models of other devices. We present for the first time a simple way to create high voltage, high performance LDMOS transistors for RF power amplifier use even in a very downscaled silicon technology.

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