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  • 1.
    Amin, Shoaib
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. KTH, Signalbehandling.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Händel, Peter
    Department of Signal Processing, KTH Royal Institute of Technology, Stockholm, Sweden .
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Characterization of concurrent dual-band power amplifiers using a dual two-tone excitation signal2015Ingår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 64, nr 10, s. 2781-2791, artikel-id 7104121Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A method to characterize the memory effects in a nonlinear concurrent dual-band transmitter is presented. It is an extension of the conventional two tone test for power amplifiers to concurrent dual band transmitters. The output signal of a concurrent dual-band transmitter is affected not only by intermodulation products but also by cross-modulation products. In one frequency band, the transmitter is excited by a two tone signal which frequency separation is swept. In the second band the transmitter is concurrently excited by an other two tone signal with slightly wider frequency separation. The frequency difference of the two signals is fixed during the frequency sweep. The two tone test is made at different power levels. The upper and lower third-order inter- and cross-modulation products are measured. The asymmetry between the upper and lower third-order inter- and cross-modulation products are measures of the transmitter's memory effects. The measurement results show that the memory effects are more dominant in the third-order intermodulation products than in the cross modulation products. An error analysis and system calibration was performed and measurement results for two different devices are presented.

  • 2.
    Amin, Shoaib
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Händel, Peter
    Department of Information Science and Engineering, KTH Royal Institute of Technology, Stockholm, Sweden.
    Rönnow, Daniel
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Rebuttal to "On Dual-Band Amplifications Using Dual Two-Tones Clarifications and Discussions"2017Ingår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 66, nr 10, s. 2795-2797Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This rebuttal is to "€œOn dual-band amplifications using dual two-tone: Clarifications and discussion". In the following, we provide our reply.

  • 3.
    Barbe, Kurt
    et al.
    Vrije Universiteit Brussel, Brussels, Belgium.
    Olarte, Oscar
    Vrije Universiteit Brussel, Brussels, Belgium.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Vrije Universiteit Brussel, Brussels, Belgium.
    Lauwers, Lieve
    Vrije Universiteit Brussel, Brussels, Belgium.
    Fractional models for modeling complex linear systems under poor frequency resolution measurements2013Ingår i: Digital signal processing (Print), ISSN 1051-2004, E-ISSN 1095-4333, Vol. 23, nr 4, s. 1084-1093Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    When modeling a linear system in a parametric way, one needs to deal with (i) model structure selection, (ii) model order selection as well as (iii) an accurate fit of the model. The most popular model structure for linear systems has a rational form which reveals crucial physical information and insight due to the accessibility of poles and zeros. In the model order selection step, one needs to specify the number of poles and zeros in the model. Automated model order selectors like Akaikeʼs Information Criterion (AIC) and the Minimum Description Length (MDL) are popular choices. A large model order in combination with poles and zeros lying closer to each other in frequency than the frequency resolution indicates that the modeled system exhibits some fractional behavior. Classical integer order techniques cannot handle this fractional behavior due to the fact that the poles and zeros are lying to close to each other to be resolvable and not enough data is available for the classical integer order identification procedure. In this paper, we study the use of fractional order poles and zeros and introduce a fully automated algorithm which (i) estimates a large integer order model, (ii) detects the fractional behavior, and (iii) identifies a fractional order system.

  • 4.
    Barbé, Kurt
    et al.
    Vrije Universiteit Brussel, ELEC.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Lauwers, L
    Vrije Universiteit Brussel.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    A Simple Nonparametric Preprocessing Technique to Correct for Nonstationary Effects in Measured Data2012Ingår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 61, nr 8, s. 2085-2094Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The general approach for modeling systems assumes that the measured signals are (weakly) stationary, i.e., the power spectrum is time invariant. However, the stationarity assumption is violated when: 1) transient effects due to experimental conditions are dominant; 2) data are missing due to, for instance, sensor failure; or 3) the amplitude of the excitation signals smoothly varies over time due to, for instance, actuator problems. Although different methods exist to deal with each of these nonstationary effects specifically, no unified approach is available. In this paper, a new and general technique is presented to handle nonstationary effects, based on processing overlapping subrecords of the measured data. The proposed method is a simple preprocessing step where the user does not need to specify which nonstationary effect is present, nor the time interval where the nonstationary effect appears. The merits of the proposed approach are demonstrated on an operational wireless system suffering from interrupted link effects.

  • 5.
    Barbé, Kurt
    et al.
    Vrije Universiteit Brussel, ELEC.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Nagels, G
    Natl Ctr Multiple Sclerosis, Melsbroek, Belgium .
    Fractional-Order Time Series Models for Extracting the Haemodynamic Response From Functional Magnetic Resonance Imaging Data2012Ingår i: IEEE Transactions on Biomedical Engineering, ISSN 0018-9294, E-ISSN 1558-2531, Vol. 59, nr 8, s. 2264-2272Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The postprocessing of functional magnetic resonance imaging (fMRI) data to study the brain functions deals mainly with two objectives: signal detection and extraction of the haemodynamic response. Signal detection consists of exploring and detecting those areas of the brain that are triggered due to an external stimulus. Extraction of the haemodynamic response deals with describing and measuring the physiological process of activated regions in the brain due to stimulus. The haemodynamic response represents the change in oxygen levels since the brain functions require more glucose and oxygen upon stimulus that implies a change in blood flow. In the literature, different approaches to estimate and model the haemodynamic response have been proposed. These approaches can be discriminated in model structures that either provide a proper representation of the obtained measurements but provide no or a limited amount of physiological information, or provide physiological insight but lacks a proper fit to the data. In this paper, a novel model structure is studied for describing the haemodynamics in fMRI measurements: fractional models. We show that these models are flexible enough to describe the gathered data with the additional merit of providing physiological information.

  • 6.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Adding errors to reduce the PAPR and BER of OFDM-based transmissions2013Ingår i: 2013 IEEE International Instrumentation and Measurement Technology Conference (I2MTC 2013), New York: IEEE , 2013, s. 743-746Konferensbidrag (Refereegranskat)
    Abstract [en]

    When transmitting signals, one of the most important issues is to keep the transmission errors as low as possible. Or in other words, to obtain a reliable transmission link, the bit-error-rate (BER) should be kept within certain limits. However, the probability of transmission errors strongly depends on the signal-to-noise ratio (SNR) of the transmitted signals. Hence, the power amplifier plays a key role in the sender part: the more power, the higher the SNR, the lower the probability of transmission errors. Unfortunately, this is a too simple vision.

    One should take care to keep the peak-to-average power ratio (PAPR) of the transmitted signal low in order not to push the power amplifier into its nonlinear operation region. Classical techniques use clipping or backing-off the input signal to reduce the PAPR of the transmitted signal. However, these techniques have a negative influence on the SNR and hence on the BER.

    In this paper, we present a technique to reduce the PAPR of the transmitted signals and hence to reduce the BER, by introducing errors into Orthogonal Frequency Division Multiplexing (OFDM) signals in a controlled way. Channel coding will be used to compensate for the introduced errors.

  • 7.
    Björsell, Niclas
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Measuring and Characterizing Nonlinear RF Systems: Faculty Course Development Award 20132017Ingår i: IEEE Instrumentation & Measurement Magazine, ISSN 1094-6969, E-ISSN 1941-0123, Vol. 20, nr 4, s. 45-48Artikel i tidskrift (Refereegranskat)
  • 8.
    de la O Serna, Jose Antonio
    et al.
    Autonomous Univ Nuevo Leon, Monterrey, NL, Mexico.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Barbe, Kurt
    Vrije Universiteit Brussel, Brussels, Belgium.
    Using alternating Kalman filtering to analyze oscillometric blood pressure waveforms2013Ingår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 62, nr 10, s. 2621-2628Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Measuring the blood pressure as accurately as possible can save a lot of human lives. Hence, it is very important to find an optimal method to determine the systolic and diastolic pressures out of the measured oscillometric blood pressure waveform (OBPW). Recently, studies have shown that by working in the frequency domain, outperforming results could be obtained for the separation of breathing from cardiac activity. In this paper, we present a new implementation of the Kalman filtering algorithm to estimate the envelope of the cardiac activity. Even though the alternating Kalman filter algorithm has subharmonic infiltrations, it offers an envelope that, when applied together with the Windkessel model for calibration, substantially reduces the error of the calibrated systolic and diastolic pressures. This important result validates the non-linear model for the OBPW, as well as the Windkessel model for calibration.

  • 9. Esfeh, Babak Kazemi
    et al.
    Raskin, Jean-Pierre
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Low-cost wideband double-layer microstrip coupled-line directional coupler with high directivity2014Ingår i: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 56, nr 7, s. 1570-1575Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this article, a low-cost double-layer microstrip structure with a gap space between the two substrate layers is used to develop a microstrip coupled-line directional coupler with high directivity. The proposed design shows a high directivity (more than 20 dB) over a wide frequency bandwidth (more than 2 GHz). The double-layer directional coupler, designed on FR4 substrate material at 2.4 GHz provides more than 30 dB isolation. The simulation and measurement results are in good agreement. By applying a simple and low-cost fabrication process and design, the directivity of the directional coupler is enhanced by more than 10 dB compared with a microstrip structure. 

  • 10.
    Gonzales Fuentes, Lee
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap. Vrije Universiteit Brussel.
    Barbe, Kurt
    Vrije Universiteit Brussel.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Vrije Universiteit Brussel.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Cognitive radios: discriminant analysis finds the free space2012Ingår i: 2012 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), New York: IEEE conference proceedings, 2012, s. 2242-2247Konferensbidrag (Refereegranskat)
    Abstract [en]

    Spectrum sensing is an essential pre-processing step for cognitive radio technology. This paper presents a novel method to detect the significant spectral components in measured nonflat spectra, and to estimate the magnitude of the spectral components. Furthermore, the probability that the spectral component was incorrectly classified is available. The algorithm is able to detect the presence or absence of signals in any kind of spectrum since no prior knowledge about the measured signal is needed. Hence, this method becomes a strong basis for a high-quality operation mode of cognitive radios. Simulation results prove the advantages of the presented technique.

  • 11. Gonzales-Fuentes, L.
    et al.
    Barbé, K.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Adaptive noise tracking for Cognitive Radios under more realistic operation conditions2014Ingår i: IEEE Instrumentation and Measurement Technology Conference, 2014, s. 1339-1344Konferensbidrag (Refereegranskat)
    Abstract [en]

    Normal operation conditions of cognitive radio applications require signal processing techniques that can be executed in real time. One of the first steps is to sense the occupied or free frequency channels. Two major drawbacks in the current techniques are that they assume (i) the noise as white and (ii) the measured spectrum as time-invariant. In real world, the noise is (i) colored so it disturbs the signal unevenly and (ii) its spectrum changes over time. Hence, tracking the time-varying noise spectrum can become crucial to remove the noise contributions and enhance the estimate of the received signal. In this paper, we study an auto-regressive model to develop an adaptive noise tracking technique using a Kalman filter such that an extension of Boll's noise subtraction technique, designed for audio noise cancellation, becomes feasible when adjusted to cognitive radio scenarios. Simulation results show the performance of this technique. 

  • 12.
    Gonzales-Fuentes, Lee
    et al.
    Vrije Universiteit Brussel.
    Barbe, Kurt
    Vrije Universiteit Brussel.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Vrije Universiteit Brussel.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Cognitive Radios: Discriminant Analysis for Automatic Signal Detection in Measured Power Spectra2013Ingår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 62, nr 12, s. 3351-3360Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Signal detection of primary users for cognitive radios enables spectrum use agility. In normal operation conditions, the sensed spectrum is nonflat, i.e., the power spectrum is not constant. A novel method proposes the segmentation of the measured spectra into regions where the flatness condition is approximately valid. As a result, an automatic detection of the significant spectral components together with an estimate of the magnitude of the spectral component and a measure of the quality of classification becomes available. In this paper, we optimize the methodology for signal detection in cognitive radios such that the probability that a spectral component was incorrectly classified is iteratively reduced. Simulation and measurement results show the advantages of the presented technique in different types of spectra.

  • 13.
    Hamid, Mohamed
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Communications Systems Lab (CoS), Royal Institute of Technology (KTH), Stockholm, Sweden .
    Barbe, Kurt
    Vrije Universiteit Brussel, ELEC.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Communications Systems Lab (CoS), Royal Institute of Technology (KTH), Stockholm, Sweden .
    Van Moer, Wendy
    Vrije Universiteit Brussel.
    Spectrum sensing through spectrum discriminator and maximum minimum eigenvalue detector: a comparative study2012Ingår i: 2012 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), New York: IEEE conference proceedings, 2012, s. 2252-2256Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we present a new spectrum sensing technique for cognitive radios based on discriminant analysis called spectrum discriminator and compare it with the maximum minimum eigenvalue detector. The common feature between those two techniques is that neither prior knowledge about the system noise level nor the primary user signal, that might occupy the band under sensing, is required. Instead the system noise level will be derived from the received signal. The main difference between both techniques is that the spectrum discriminator is a non-parametric technique while the maximum minimum eigenvalue detector is a parametric technique. The comparative study between both has been done based on two performance metrics: the probability of false alarm and the probability of detection. For the spectrum discriminator an accuracy factor called noise uncertainty is defined as the level over which the noise energy may vary. Simulations are performed for different values of noise uncertainty for the spectrum discriminator and different values for the number of received samples and smoothing factor for the maximum minimum eigenvalue detector.

  • 14.
    Hamid, Mohamed
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. KTH.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Van Moer, Wendy
    Vrije Universiteit Brussel.
    Barbé, Kurt
    Vrije Universiteit Brussel.
    Slimane, Ben
    KTH.
    Blind Spectrum Sensing for Cognitive Radios Using Discriminant Analysis: A Novel Approach2013Ingår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 62, nr 11, s. 2912-2921Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we present a new spectrum sensing technique for cognitive radios based on discriminant analysis called spectrum discriminator. The presented technique uses the knowledge of the noise uncertainty and a probabilistic validation to overcome the limitations of the discriminant analysis. A comparative study between the proposed technique and the maximum-minimum eigenvalue detection has been performed based on two performance metrics: the probability of false alarm and the probability of detection. The spectrum discriminator has been further developed to a peel-off technique where all primary users can be detected. The performance of the spectrum discriminator and the peel-off technique has been tested on simulations and experimentally verified. The comparative study is based on simulations as well as measurements.

  • 15.
    Hamid, Mohamed
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. KTH.
    Ferrer Coll, Javier
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. KTH.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Chilo, José
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Van Moer, Wendy
    Vrije Universiteit Brussel, Brussels, Belgium .
    Multi-Interference Detection Algorithm using Discriminant Analysis in Industrial Environments2013Ingår i: 39th Annual Conference of the IEEE Industrial Electronics Society (IECON 2013), New York: IEEE conference proceedings, 2013, s. 5600-5604Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper a technique to detect multiple impulsive interference in an industrial environment is proposed and evaluated. The technique is based on discriminant analysis which iteratively peels-off the impulsive interferences. The probability of detection of the technique is tested with and without the iterative peeling-off part. The simulations show that the SIR can be improved by applying the detection technique and then blank or clip the impulsive interference components. The improvement in the SIR depends on the impulsive interference parameters and it can reach up to 17 dB.

  • 16.
    Hamid, Mohamed
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. KTH, Stockholm, Sweden; University of Agder, Kristiansand, Norway.
    Slimane, Ben
    KTH, Stockholm, Sweden.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Spectrum Sensing Challenges: Blind Sensing and Sensing Optimization2016Ingår i: IEEE Instrumentation & Measurement Magazine, ISSN 1094-6969, E-ISSN 1941-0123, Vol. 19, nr 2, s. 44-52Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    By any measure, wireless communications is one of the most evolving fields in engineering. This, in return, has imposed many challenges, especially in handling the hunger for higher data rates in the next generation wireless networks. Among these challenges is how to provide the needed resources in terms of the electromagnetic radio spectrum for these networks. In this regard, cognitive radio (CR) based on dynamic spectrum access (DSA) has been attracting huge attention as a promising solution for more efficient utilization of the available radio spectrum. DSA is based on finding and opportunistically accessing the free-of-use portions of spectrum. To facilitate DSA, spectrum sensing can be used. However, spectrum sensing faces many challenges in different aspects. Such aspects include blind sensing and sensing optimization, which are both to a great extent measurement challenges. We discuss different contributions in addressing these two challenges in this article.

  • 17.
    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 amplifiers2015Ingår i: International journal of microwave and wireless technologies, ISSN 1759-0795, E-ISSN 1759-0787, Vol. 7, nr 1, s. 19-29Artikel i tidskrift (Refereegranskat)
    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.

  • 18.
    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 PAs2011Ingår i: RFMTC11, 2011Konferensbidrag (Övrigt vetenskapligt)
    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.

  • 19.
    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 conditions2012Ingår i: Instrumentation and Measurement Technology Conference (I2MTC), 2012 IEEE International, 2012Konferensbidrag (Refereegranskat)
    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.

  • 20.
    Nader, Charles
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Björsell, Niclas
    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.
    Wideband Radio Frequency Measurements: From Instrumentation to Sampling Theory2013Ingår i: IEEE Microwave Magazine, ISSN 1527-3342, E-ISSN 1557-9581, Vol. 14, nr 2, s. 85-98Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Whether listening to broadcast radio or testing developed wireless devices, for civilian or military applications, based on terrestrial or spatial links, a radio frequency (RF) receiver with good measurement capabilities that preserves the received signal information is required. Todays RF measurement receivers with wideband capabilities are split into two groups based on the measurement strategy they adopt. Both groups produce a time domain waveform with both amplitude and phase information that is constructed either from a transformation of its frequency contents or directly from its time-domain samples.

  • 21. Olarte, O.
    et al.
    Barbé, K.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Vrije Universiteit Brussel.
    Van Ingelgem, Y.
    Glucose characterization based on electrochemical impedance spectroscopy2014Ingår i: IEEE Instrumentation and Measurement Technology Conference, 2014, s. 833-837Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper an equivalent circuit model is employed in the characterization of the impedance measurements of saline solutions at physiological glucose concentrations. The impedance data are obtained using a three electrodes cell configuration since it allows measuring the potential accurately in the working electrode independently from the counter electrode. As excitation signal an odd random phase multisine is employed which allows identifying the best linear approximation, the noise level and the non-linear distortions present in the system. The results show a significant change in the impedance as a function of the glucose at the interphase electrode-electrolyte as well as in the bulk solution. This is an important step towards the development of glucose measurement systems based in electrochemical impedance spectroscopy (EIS). 

  • 22. Olarte, O.
    et al.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Barbe, K.
    Van Ingelgem, Y.
    Hubin, A.
    FREQUENCY DOMAIN IDENTIFICATION OF GLUCOSE AQUEOUS SOLUTIONS AT PHYSIOLOGICAL LEVELS2013Ingår i: Diabetes Technology & Therapeutics, ISSN 1520-9156, E-ISSN 1557-8593, Vol. 15, s. A68-A68Artikel i tidskrift (Övrigt vetenskapligt)
  • 23. Olarte, Oscar
    et al.
    Barbé, Kurt
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Vrije Universiteit Brussel.
    Van Ingelgem, Yves
    Fractional frequency domain identification of NaCl-glucose solutions at physiological levels2014Ingår i: Measurement, ISSN 0263-2241, E-ISSN 1873-412X, Vol. 50, nr 1, s. 213-221Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electrical impedance spectroscopy (EIS) has been used to characterize different biological materials. This article exposes a methodology oriented to estimate glucose levels of a solution based on a rational fractional parametric model of the impedance data. The methodology is applied over saline-glucose solutions at five physiological glucose levels, using three sensors and five repetitions for each glucose concentration and employed sensor. The results suggest that changes in the glucose concentration produce significant changes in the impedance that should be reflected in the parametric model. The modeling procedure shows that the poles and zeros of an integer model presents a degree of correlation. However, the correlation is clearly explicit employing fractional models where the mean location of the complex zeros is highly related to the glucose content in the sample. 

  • 24.
    Olarte, Oscar
    et al.
    Vrije University of Brussels, Belgium.
    Barbé, Kurt
    Vrije University of Brussels, Belgium.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Vrije University of Brussels, Belgium.
    Van Ingelgem, Yves
    Vrije University of Brussels, Belgium.
    Hubin, Annick
    Vrije University of Brussels, Belgium.
    Measurement and characterization of glucose in NaCl aqueous solutions by electrochemical impedance spectroscopy2014Ingår i: Biomedical Signal Processing and Control, ISSN 1746-8094, Vol. 14, nr 1, s. 9-18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electrochemical impedance spectroscopy (EIS) allows measuring the properties of the system as a function of the frequency as well as distinguishing between processes that could be involved: resistance, reactance, relaxation times, amplitudes, etc. Although it is possible to find related literature to in vitro and in vivo experiments to estimate glucose concentration, no clear information regarding the condition and precision of the measurements are easily available. This article first address the problem of the condition and precision of the measurements, as well as the effect of the glucose over the impedance spectra at some physiological (normal and pathological) levels. The significance of the measurements and the glucose effect over the impedance are assessment regarding the noise level of the system, the experimental error and the effect of using different sensors. Once the data measurements are analyzed the problem of the glucose estimation is addressed. A rational parametric model in the Laplace domain is proposed to track the glucose concentration. The electrochemical spectrum is measured employing odd random phase multisine excitation signals. This type of signals provides short acquisition time, broadband measurements and allows identifying the best linear approximation of the impedance as well as estimating the level of noise and non-linearities present in the system. All the experiments were repeated five times employing three different sensors from the same brand in order to estimate the significance of the experimental error, the effects of the sensors and the effect of the glucose over the impedance. 

  • 25.
    Olarte, Oscar
    et al.
    Vrije Univ. Brussel.
    Chilo, José
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Pelegri-Sebastia, José
    Univ. Pol. de Valencia.
    Barbé, Kurt
    Vrije Univ. Brussel.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Vrije Univ. Brussel.
    Glucose detection in human sweat using an electronic nose2013Ingår i: Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS, New York: IEEE conference proceedings, 2013, s. 1462-1465Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the last years attempts to develop a non-invasive glucose system based on the glucose levels in sweat have been studied. In this paper, 32 metal oxide semiconductor (MOS) sensors operating at different temperatures have been used to develop a multisensor olfactory system that allows to study the glucose levels in sweat. In order to develop repeatable experiments, artificial sweat at different glucose concentrations were developed in the laboratory. The obtained results suggest high viability of the approach. Although, the sensitivity of the sensors system needs to be improved.

  • 26. Olarte, Oscar
    et al.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Barbé, Kurt
    Van Ingelgem, Yves
    Rubin, Annick
    Influence of the type and position of the sensor on the precision of impedance glucose measurements2013Ingår i: 2013 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), New York: IEEE conference proceedings, 2013, s. 1750-1754Konferensbidrag (Refereegranskat)
    Abstract [en]

    Electrochemistry Impedance Spectroscopy has been proposed as a promising technique for non-invasive glucose monitoring. Although it is possible to find related literature to in-vitro and in-vivo experiments, no clear information is available regarding the precision of the measurements. In this paper, we address the problem of the precision due to different samples of the same sensor type and different sensor positions. We will show that the precision of the measurements is high for different sensor positions (over 96 %) but can drop significantly when different sensors are used (around 90 %), even when these sensors belong to the same brand.

  • 27.
    Olarte, Oscar
    et al.
    Vrije Univ. Brussel, Brussels, Belgium .
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Vrije Univ. Brussel, Brussels, Belgium .
    Barbé, Kurt
    Vrije Univ. Brussel, Brussels, Belgium .
    Verguts, Sven
    Vrije Univ. Brussel, Brussels, Belgium .
    Van Ingelgem, Yves
    Vrije Univ. Brussel, Brussels, Belgium .
    Hubin, Annick
    Vrije Univ. Brussel, Brussels, Belgium .
    Using the Best Linear Approximation as a First Step to a New Non-Invasive Glucose Measurement2012Ingår i: 2012 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), 2012, s. 2747-2751Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper an approach to develop a non-invasive glucose measured system based on the best linear approximation (BLA) and electrical impedance spectroscopy (EIS) is presented. In order to test the advantages of the technique, three blood components at reference blood concentration are tested. In these solutions the level of glucose was varied from normal to pathological concentrations. The results show the ability of BLA-EIS to detect the glucose changes by combining the amplitude and phase behavior of the impedance.

  • 28.
    Shirmohammadi, Shervin
    et al.
    University of Ottawa, Canada.
    Daponte, Pasquale
    University of Sannio, Italy.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Guest Editorial Special Issue on the 2015 IEEE International Instrumentation and Measurement Technology Conference: Pisa, Italy, May 11-14, 20152016Ingår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 65, nr 5, s. 958-959Artikel i tidskrift (Refereegranskat)
  • 29.
    Tellini, Bernardo
    et al.
    University of Pisa, Italy .
    Lehmann, Pascale
    French-German Research Institute of Saint-Louis, France.
    Daponte, Pasquale
    University of Sannio, Benevento, Italy .
    Shirmohammadi, Shervin
    University of Ottawa, Canada .
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Welcome Message from the Chairpersons2015Ingår i: Instrumentation and Measurement Technology Conference (I2MTC), 2015 IEEE International, IEEE conference proceedings, 2015, s. iiv-iv, artikel-id 7151229Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 30.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    2018?? Already??2018Ingår i: IEEE Instrumentation & Measurement Magazine, ISSN 1094-6969, E-ISSN 1941-0123, Vol. 21, nr 1, s. 2-Artikel i tidskrift (Övrigt vetenskapligt)
  • 31.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Back to Basics2016Ingår i: IEEE Instrumentation & Measurement Magazine, ISSN 1094-6969, E-ISSN 1941-0123, Vol. 19, nr 6, s. 4-, artikel-id 7777642Artikel i tidskrift (Refereegranskat)
  • 32.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Big Data in I&M2017Ingår i: IEEE Instrumentation & Measurement Magazine, ISSN 1094-6969, E-ISSN 1941-0123, Vol. 20, nr 5, s. 2-2Artikel i tidskrift (Övrigt vetenskapligt)
  • 33.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    I&M for farmers2017Ingår i: IEEE Instrumentation & Measurement Magazine, ISSN 1094-6969, E-ISSN 1941-0123, Vol. 20, nr 3, s. 2-2Artikel i tidskrift (Övrigt vetenskapligt)
  • 34.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Industry 4.0 and IoT2018Ingår i: IEEE Instrumentation & Measurement Magazine, ISSN 1094-6969, E-ISSN 1941-0123, Vol. 21, nr 6, s. 2-Artikel i tidskrift (Refereegranskat)
  • 35.
    Van Moer, Wendy
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Welcome 20172017Ingår i: IEEE Instrumentation & Measurement Magazine, ISSN 1094-6969, E-ISSN 1941-0123, Vol. 20, nr 1, s. 2-Artikel i tidskrift (Refereegranskat)
  • 36.
    Van Moer, Wendy
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Vrije Universiteit Brussel.
    Barbe, Kurt
    Vrije Universiteit Brussel.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    A novel spectral subtraction technique for cognitive radios2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the past a lot of work has been done to remove noise from speech. Most of the presented techniques were derived from Boll's spectral subtraction technique. Roughly speaking the spectral subtraction techniques consists of estimating the noise power during the periods when no speech is present and subtracting this estimate of the noise power from the signal when speech is present. This spectral subtraction technique could be a very good in-band de-noising technique for communication signals measured by cognitive radios. However, there is one major drawback: one can never turn off the spectrum so that no communication signals are present. This paper presents an extended version of the spectral subtraction technique which does not require `speech free?? periods, but can determine the noise power from the empty frequency bins in the spectrum. The presented method is based on an autoregressive (AR) model, which is linear in the parameters. Simulation results show that the presented technique is as performing as the original spectral subtraction techniques without the need to turn off the signals.

  • 37.
    Van Moer, Wendy
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Hamid, Mohamed
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Barbe, Kurt
    Vrije Universiteit Brussel, ELEC.
    Nader, Charles
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Saving lives by integrating cognitive radios into ambulances2012Ingår i: Medical Measurements and Applications Proceedings (MeMeA), 2012 IEEE International Symposium on, Budapest, 2012, s. 1-4Konferensbidrag (Refereegranskat)
    Abstract [en]

    A brain stroke is defined as a disturbance in the blood supply of the brain. This can be due to either an obstruction in the blood vessels of the brain or a rupture in the blood vessels which causes a leakage of blood in the brain. In many cases, a stroke results in the death of the patient within 24 hours. Hence, it is crucial that the neurologist has immediately contact with the patient in the first 30 minutes after the stroke. This means that a direct broadband communication link between the ambulance and the hospital is needed in order to transmit all necessary physiological parameters, such as blood pressure and glucose level as well as video images. In this paper, we present a new architecture of a wireless communication link between the ambulance and the hospital based on the concept of cognitive radios. The sender/receiver module in the ambulance will allow measuring the wideband spectrum and search for a suitable empty frequency band to send the data.

  • 38.
    Voet, Kevin
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik. Vrije Universiteit Brussel, Brussels, Belgium; Signal Processing Lab, Royal Institute of Technology, Stockholm, Sweden.
    Händel, Peter
    Signal Processing Lab, Royal Institute of Technology, Stockholm, Sweden.
    Björsell, Niclas
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för elektronik, matematik och naturvetenskap, Elektronik.
    Van Moer, Wendy
    Vrije Universiteit Brussel, Brussels, Belgium.
    Mirrored parallel Hammerstein predistortion for multitone generation2011Ingår i: 2011 IEEE INTERNATIONAL INSTRUMENTATION AND MEASUREMENT TECHNOLOGY CONFERENCE (I2MTC), 2011, s. 814-817Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper discusses the approach tested for digital pre-distortion of radio frequency vector signal generators, where joint mitigation of impairments is considered stemming from the inphase/quadrature modulator, local oscillator, and power amplifier. A predistorter structure, linear in its parameters, was taken and the parameters were estimated by the least-squares method. The proposed method is validated by demonstrating improvement in the performance of the Rohde & Schwarz SMU200 by about 8 dB reduction in mirror-frequency interference, 17 dB reduction in leakage from the local oscillator, and 6 dB improvement in inter-modulation products. Thus, the tested approach is considered useful for several instrumentation and measurement applications.

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