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  • 1. Ahnström, Ulrika
    et al.
    Falk, Johan
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Händel, Peter
    KTH, Tidigare Institutioner, Signaler, sensorer och system. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Wikström, Maria
    Detection and direction-finding of spread spectrum signals using correlation and narrowband interference rejection2003Ingår i: Nordic Matlab Conference 2003, 2003Konferensbidrag (Refereegranskat)
    Abstract [en]

    An algorithm for correlation-based detection of direct sequence spread spectrum signals with direction finding, including direction-filtering and narrow-band interference rejection, is implemented and evaluated in MATLAB. An analog noise-free signal is generated and sampled by a test-bed system. Numerical simulations are run based on data corrupted by mutually uncorrelated white Gaussian noise sequences, and also with recorded noise from two spatially separated HF radio receivers. The simulations and measurements show promising results for detection and direction-finding of covert wideband signals in low SNR and in presence of narrowband interferers. Direction filtering is shown to improve the results.

  • 2.
    Alayon Glasunov, Andrés
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Prasad, S.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Experimental characterization of the propagation channel along a very large virtual array in a reverberation chamber2014Ingår i: Progress in Electromagnetics Research B, ISSN 1937-6472, E-ISSN 1937-6472, nr 59, s. 205-217Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We show that the combined use of radio frequency absorbers and directive antennas can produce significant changes of the radio propagation channel properties along the positions of a virtual array inside a reverberation chamber. A multidimensional characterization of the channel was performed at 40 antenna positions with spacing of 0:233λ at 1 GHz. The average power, the Ricean K-factor, the coherence bandwidth, the r.m.s. delay spread, the mean delay, the beamforming power angle spectrum and array antenna correlation have been studied for different arrangements in the reverberation chamber. The analysis shows that the joint average over time and frequency channel behavior is, as expected, rather homogeneous along the very large array. However, individual realizations of the channel present a pronounced selective behavior in space, time and frequency with parameters varying along the positions of the virtual array suggesting that a heterogeneous behavior of the radio channels can be emulated in reverberation chambers. An important application of the presented study comprises testing of antenna array designs and algorithms in multipath environments. Further development may lead to Over The Air testing of Multiple Input Multiple Output antenna systems of various sizes, i.e., from small to very large arrays.

  • 3.
    Alayon Glazunov, Andres
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Prasad, Sathyaveer
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Bolin, Thomas
    Prytz, Kjell
    Impact of Scattering Within a Multipath Simulator Antenna Array on the Ricean Fading Distribution Parameters in OTA Testing2014Ingår i: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 62, nr 6, s. 3257-3269Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we investigate the unwanted scattering that exists within the multipath simulator (MPS) array antennas employed in over the air (OTA) testing of mobile terminals. The impact of scattering is evaluated in terms of the measurement uncertainty of the average received power and the Ricean K-factor. The maximum ratio combining diversity is investigated for a generic device under test comprising two half-wavelength dipole antennas. We provide closed-form expressions for the uncertainties of the average received power and the Ricean K-factor for a uniform circular array of MPS antennas and a 2-D uniformly distributed angle-of-arrival spectrum. We also derive the maximum number of MPS antennas and the minimum ring radius of the MPS system as a function of the separation between the most distant antenna elements if the device under test employs a uniform linear array. As a result, we provide design guidelines for MPS array in terms of the number antennas, the radius of the MPS array and the wavelength of the carrier frequency.

  • 4.
    Alizadeh, Mahmoud
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap. University of Gävle.
    Händel, Peter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    Rönnow, Daniel
    University of Gävle.
    Basis Function Decomposition Approach in Piece-Wise Modeling for RF Power Amplifiers2018Ingår i: 6th Telecommunications forum TELFOR 2018, Belgrade, Serbia, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, a new approach is proposed to decompose the basis functions in a piece-wise modeling technique for nonlinear radio frequency (RF) power amplifiers. The proposed technique treats the discontinuity problem of the model output at the joint points between different operating points, whereas preserves the linear and nonlinear properties of the original model within each region. Experimental results show that the proposed technique outperforms the conventional piece-wise model in terms of model errors.

  • 5.
    Alizadeh, Mahmoud
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap. Univ Gavle, Dept Elect Math & Nat Sci, SE-80176 Gavle, Sweden..
    Händel, Peter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    Rönnow, Daniel
    Univ Gavle, Dept Elect Math & Nat Sci, SE-80176 Gavle, Sweden..
    Basis Function Decomposition Approach in Piece-Wise Modeling for RF Power Amplifiers2018Ingår i: 2018 26TH TELECOMMUNICATIONS FORUM (TELFOR), IEEE , 2018, s. 140-143Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper a new approach is proposed to decompose the basis functions in a piece-wise modeling technique for nonlinear radio frequency (RF) power amplifiers. The proposed technique treats the discontinuity problem of the model output at the joint points between different operating points, whereas preserves the linear and nonlinear properties of the original model within each region. Experimental results show that the proposed technique outperforms the conventional piece-wise model in terms of model errors.

  • 6.
    Alizadeh, Mahmoud
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap. University of Gävle.
    Händel, Peter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    Rönnow, Daniel
    University of Gävle.
    Behavioural modelling and digital pre-distortion techniques for RF PAs in a 3x3 MIMO system2018Ingår i: International journal of microwave and wireless technologies, ISSN 1759-0795, E-ISSN 1759-0787Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Modern telecommunications are moving towards (massive) multi-input multi-output systems in 5th generation (5G) technology, increasing the dimensionality of the system dramatically. In this paper, the impairments of radio frequency (RF)power amplifiers (PAs) in a 3x3 MIMO system are compensated in both time and frequency domains. A three-dimensional(3D) time-domain memory polynomial-type model is proposed as an extension of conventional 2D models. Furthermore, a 3D frequency-domain technique is formulated based on the proposed time-domain model to reduce the dimensionality of the model, while preserving the performance in terms of model errors. In the 3D frequency-domain technique, the bandwidth of a system is split into several narrow sub-bands, and the parameters of the system are estimated for each subband. This approach requires less computational complexity, and also the procedure of the parameters estimation for each sub-band can be implemented independently. The device-under-test (DUT) consists of three RF PAs including input and output cross-talk channels. The proposed techniques are evaluated in both behavioural modelling and digital pre-distortion(DPD) perspectives. The results show that the proposed DPD technique can compensate the errors of non-linearity and memory effects by about 23.5 dB and 7 dB in terms of the normalized mean square error and adjacent channel leakage ratio, respectively.

  • 7.
    Alizadeh, Mahmoud
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap. University of Gävle.
    Rönnow, Daniel
    University of Gävle.
    Händel, Peter
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    A new Block-Structure Modeling Technique for RF Power Amplifiers in a 2×2 MIMO System2017Ingår i: 2017 13th International Conference on Advanced Technologies, Systems and Services in Telecommunications, TELSIKS 2017 - Proceeding, Nis, Serbia: IEEE, 2017, Vol. 2017, s. 224-227Konferensbidrag (Refereegranskat)
    Abstract [en]

    A new block-structure behavioral model is proposed for radio frequency power amplifiers in a 2×2 multiple-input multiple-output system including input cross-talk. The proposed model forms kernels of blocks of different nonlinear order that correspond to the significant frequency response of measured frequency domain Volterra kernels. The model can therefore well describe the input-output relationships of the nonlinear dynamic behavior of PAs. The proposed model outperforms conventional models in terms of model errors.

  • 8.
    Alizadeh, Mahmoud
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Teknisk informationsvetenskap. University of Gävle, Gävle, Sweden.
    Rönnow, Daniel
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Teknisk informationsvetenskap.
    Isaksson, Magnus
    A new Block-Structure Modeling Technique for RF Power Amplifiers in a 2x2 MIMO System2017Ingår i: 2017 13th International Conference on Advanced Technologies, Systems and Services in Telecommunications, TELSIKS 2017 - Proceeding / [ed] Milovanovic, BD Doncov, NS Stankovic, ZZ Dimitrijevic, TZ, Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 224-227Konferensbidrag (Refereegranskat)
    Abstract [en]

    A new block-structure behavioral model is proposed for radio frequency power amplifiers in a 2x2 multiple-input multiple-output system including input cross-talk. The proposed model forms kernels of blocks of different nonlinear order that correspond to the significant frequency response of measured frequency domain Volterra kernels. The model can therefore well describe the input-output relationships of the nonlinear dynamic behavior of PAs. The proposed model outperforms conventional models in terms of model errors.

  • 9.
    Amin, Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. University of Gävle, Sweden.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Rönnow, Daniel
    ATM, University of Gävle.
    Digital Predistortion of Single and Concurrent Dual BandRadio Frequency GaN Amplifiers with Strong NonlinearMemory Effects2017Ingår i: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 65, nr 7, s. 2453-2464Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electrical anomalies due to trapping effects in gallium nitride (GaN) power amplifiers (PAs) give rise to long-term or strong memory effects. We propose novel models based on infinite impulse response fixed pole expansion techniques for the behavioral modeling and digital predistortion of single-input single-output (SISO) and concurrent dual-band GaN PAs. Experimental results show that the proposed models outperform the corresponding finite impulse response (FIR) models by up to 17 dB for the same number of model parameters. For the linearization of a SISO GaN PA, the proposed models give adjacent channel power ratios (ACPRs) that are 7-17 dB lower than the FIR models. For the concurrent dual-band case, the proposed models give ACPRs that are 9-14 dB lower than the FIR models.

  • 10.
    Amin, Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Khan, Zain Ahmed
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Isaksson, Magnus
    Högskolan i Gävle.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Rönnow, Daniel
    Högskolan i Gävle.
    Concurrent Dual-band Power Amplifier Model Modification using Dual Two-Tone Test2016Ingår i: European Microwave Week 2016: "Microwaves Everywhere", EuMW 2016 - Conference Proceedings; 46th European Microwave Conference, EuMC 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, s. 186-189, artikel-id 7824309Konferensbidrag (Refereegranskat)
    Abstract [en]

    A dual two-tone technique for the characterization of memory effects in concurrent dual-band transmitters is revisited to modify a 2D-DPD model for the linearization of concurrent dual-band transmitters. By taking into account the individual nonlinear memory effects of the self- and cross-kernels, a new2D modified digital pre-distortion (2D-MDPD) model is proposed,which not only supersedes the linearization performance but also reduces the computational complexity compared to the 2DDPDmodel in terms of a number of floating point operations(FLOPs). Experimental results show an improvement of 1.7 dBin normalized mean square error (NMSE) and a 58% reduction in the number of FLOPs.

  • 11.
    Amin, Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Ladin, Per N.
    ATM, University of Gävle.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Rönnow, Daniel
    ATM, University of Gävle.
    2D Extended Envelope Memory Polynomial Model forConcurrent Dual-band RF Transmitters2016Ingår i: International journal of microwave and wireless technologies, ISSN 1759-0795, E-ISSN 1759-0787Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The paper presents a 2D extended envelope memory polynomial (2D-EEMP) model for concurrent dual-band radio frequency (RF) power amplifiers (PAs). The model is derived based on the physical knowledge of a dual-band RF PA. The derived model contains cross-modulation terms not included in previously published models; these terms are found to be of importance for both behavioral modeling and digital pre-distortion (DPD). The performance of the derived model is evaluated both as the behavioral model and DPD, and the performance is compared with state-of-the-art2D-DPD and dual-band generalized memory polynomial (DB-GMP) models. Experimental result shows that the proposed model resulted in normalized mean square error (NMSE) of -51.7/-51.6dB and adjacent channel error power ratio (ACEPR) of -63.1/-63.4 dB, for channel 1/2, whereas the 2D-DPD resulted in the largest model error and DB-GMP resulted in model parameters that are 3 times more than those resulted with the proposed model with the same performance. As pre-distorter, the proposed model resulted in adjacent channel power ratio (ACPR) of -55.8/ -54.6 dB for channel 1/2 and is 7-10 dB lower than those resulted with the 2D-DPD model and2-4 dB lower compared to the DB-GMP model.

  • 12.
    Amin, Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. Högskolan i Gävle.
    Landin, Per
    Chalmers University of Technology.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Rönnow, Daniel
    Högskolan i Gävle.
    Behavioral modeling and linearization of crosstalk and memory effects in RF MIMO transmitters2014Ingår i: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 62, nr 4, s. 810-823Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper proposes three novel models for behavioral modeling and digital pre-distortion (DPD) of nonlinear 2 x 2 multiple-input multiple-output (MIMO) transmitters in the presence of crosstalk. The proposed models are extensions of the single-input single-output generalized memory polynomial model. Three types of crosstalk effects were studied and characterized as linear, nonlinear, and nonlinear & linear crosstalk. A comparative study was performed with previously published models for the linearization of crosstalk in a nonlinear 2 x 2 MIMO transmitter. The experiments indicate that, depending on the type of crosstalk, the selection of the correct model in the transmitter is necessary for behavioral modeling and sufficient DPD performance. The effects of coherent and partially noncoherent signal generation on the performance of DPD were also studied. For crosstalk levels of 30 dB, the difference in the normalized mean square error and adjacent channel power ratio was found to be 3-4 dB between coherent and partially noncoherent signal generation.

  • 13.
    Amin, Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. University of Gävle, Sweden.
    Landin, Per N.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Rönnow, Daniel
    2D Extended envelope memory polynomial model for concurrent dual-band RF transmitters2017Ingår i: International journal of microwave and wireless technologies, ISSN 1759-0795, E-ISSN 1759-0787, Vol. 9, nr 8, s. 1619-1627Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The paper presents a two-dimensional (2D) extended envelope memory polynomial model for concurrent dual-band radio frequency (RF) power amplifiers (PAs). The model is derived based on the physical knowledge of a dual-band RF PA. The derived model contains cross-modulation terms not included in previously published models; these terms are found to be of importance for both behavioral modeling and digital predistortion (DPD). The performance of the derived model is evaluated both as the behavioral model and DPD, and the performance is compared with state-of-the-art 2D-DPD and dual-band generalized memory polynomial (DB-GMP) models. Experimental result shows that the proposed model resulted in normalized mean square error of -51.7/-51.6 dB and adjacent channel error power ratio of -63.1/-63.4 dB, for channel 1/2, whereas the 2D-DPD resulted in the largest model error and DB-GMP resulted in model parameters that are three times more than those resulted with the proposed model with the same performance. As pre-distorter, the proposed model resulted in adjacent channel power ratio of -55.8/-54.6 dB for channel 1/2 and is 7-10 dB lower than those resulted with the 2D-DPD model and 2-4 dB lower compared with the DB-GMP model.

  • 14. Amin, Shoaib
    et al.
    van Moer, Wendy
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Teknisk informationsvetenskap.
    Ronnow, Daniel
    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 "On dual-band amplifications using dual two-tone: Clarifications and discussion." In the following, we provide our reply.

  • 15.
    Amin, Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. University of Gävle, Sweden.
    Van Moer, Wendy
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Rönnow, Daniel
    Characterization of a Concurrent dual-band Power Amplifier using a dual-tone excitation signals2014Ingår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662Artikel i tidskrift (Övrigt vetenskapligt)
  • 16.
    Amin, Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Van Moer, Wendy
    University of Gävle.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Rönnow, Daniel
    University of Gävle.
    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, nr 99Artikel 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.

  • 17.
    Amin, Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Zenteno, Efrain
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Landin, Per
    Dept. Electronics, Mathematics and Natural Sciences, Faculty of Engineering and Sustainable Development,University of Gävle .
    Rönnow, Daniel
    Dept. Electronics, Mathematics and Natural Sciences, Faculty of Engineering and Sustainable Development,University of Gävle .
    Isaksson, Magnus
    Dept. Electronics, Mathematics and Natural Sciences, Faculty of Engineering and Sustainable Development,University of Gävle .
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Noise Impact on the Identification of DigitalPredistorter Parameters in the Indirect LearningArchitecture2012Ingår i: Swedish Communication Technologies Workshop (Swe-CTW), 2012, IEEE conference proceedings, 2012, s. 36-39Konferensbidrag (Refereegranskat)
    Abstract [en]

    The indirect learning architecture (ILA) is the mostused methodology for the identification of Digital Pre-distorter(DPD) functions for nonlinear systems, particularly for highpower amplifiers. The ILA principle works in black box modelingrelying on the inversion of input and output signals of thenonlinear system, such that the inverse is estimated. This paperpresents the impact of disturbances, such as noise in the DPDidentification. Experiments were performed with a state-of-artDoherty power amplifier intended for base station operationin current telecommunication wireless networks. As expected,a degradation in the performance of the DPD (measured innormalized mean square error (NMSE)) is found in our experiments.However, adjacent channel power ratio (ACPR) canbe a misleading figure of merit showing improvement in theperformance for wrongly estimated DPD functions.

  • 18.
    Andersson, Tomas
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    IEEE standard 1057, Cramer-Rao bound and the parsimony principle2006Ingår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 55, nr 1, s. 44-53Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper deals with some fundamental properties of the sine-wave-fit algorithm included in IEEE Standards 1057 and 1241. Asymptotic Cramer-Rao bounds (CRBs) for three and four model parameters are derived under the Gaussian assumption. Further, the sine-wave-fitting properties of the algorithm are analyzed by the parsimony principle. A decision criterion whether to use the three- or four-parameter model is derived. It is shown that a three-parameter sine-wave fit produces a better fit than the four-parameter fit if the frequency is known to be within an interval related to the number of samples and the signal-to-noise ratio. By a numerical analysis, the theoretical results are shown to be also valid for the uniform noise model of quantization.

  • 19.
    Andersson, Tomas
    et al.
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Händel, Peter
    KTH, Tidigare Institutioner, Signaler, sensorer och system. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    IEEE Standard 1057, Cramér-Rao Bound and the Parsimony Principle2003Ingår i: International Workshop on ADC Modelling and Testing, 2003, s. 231-234Konferensbidrag (Refereegranskat)
  • 20.
    Andersson, Tomas
    et al.
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Multiple-tone estimation by IEEE standard 1057 and the expectation-maximization algorithm2003Ingår i: IMTC/O3: PROCEEDINGS OF THE 20TH IEEE INSTRUMENTATION AND MEASUREMENT TECHNOLOGY CONFERENCE, 2003, s. 739-742Konferensbidrag (Refereegranskat)
    Abstract [en]

    The aim of this work is to present an efficient algorithm for multiple-tone parameter estimation. The algorithm is inspired by the expectation-maximization algorithm, and it utilizes the IEEE standard 1057 for single tone parameter estimation. In the derivation of the algorithm it is assumed that the number of tones are known and that the frequencies are well separated The algorithm is evaluated using data consisting of multiple real-valued tones. The performance of the frequency estimator is studied and compared with the asymptotic Cramer-Rao bound (CRB). It is shown that the algorithm produces statistically efficient frequency estimates at high signal to noise ratios, that is the variance of the estimates reaches the CRB. Finally, it is shown that the algorithm can produce efficient estimates independent of the number of tones in the input signal.

  • 21.
    Andersson, Tomas
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Multiple-tone estimation by IEEE standard 1057 and the expectation-maximization algorithm2005Ingår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 54, nr 5, s. 1833-1839Artikel i tidskrift (Refereegranskat)
  • 22.
    Andersson, Tomas
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Robustness of wave-fitting with respect to uncertain parameter values2005Ingår i: Instrumentation and Measurement Technology Conference, 2005. IMTC 2005. Proceedings of the IEEE, 2005, Vol. 1, s. 662-665Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a criterion for model order selection. By usage of the parsimony principle the mean sum-squareerror is evaluated for models subject to imperfections inparameter values. In particular, model imperfections in different sinewavefitting scenarios have been analyzed. The analysis is carried out considering linear models. The obtained result is generalized to models incorporating non-linear parameters. Numerical illustrations are provided in order to gain insight of the behavior of model imperfections, as well as to numerically verify the theoretical results. The main contributions include a general result for linear signal models, as well as some novel results on sinewave-fitting. 

  • 23.
    Andersson, Tomas
    et al.
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Händel, Peter
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Standardized sine-wave fitting algorithms, extensions and applications2003Ingår i: Northern Light Workshop on Sensors, Signals and Systems, Björkliden, Sverige, April 7-9, 2003, 2003Konferensbidrag (Refereegranskat)
    Abstract [en]

    The objective of this paper is to present the statistical properties of the IEEE-STD-1057/IEEE-STD-1241 sine-wave fitting algorithms. The proper Cramér-Rao bound is derived for both the three-parameter and four-parameter algorithms. Further, we investigate the residual, and derive its statistical properties, in both the three- and four-parameter fitting case. In a practical setup were the frequency is almost known, we derive an analytical expression for the mean of the residual. By analysis we compare the two methods and state in which case one should use one over the other. Finally, we present some numerical evaluations confirming our analytical findings.

  • 24.
    Andersson, Tomas
    et al.
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Händel, Peter
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Toward a Standardized Multi-Sinewave Fit Algorithm2004Ingår i: 9th European Workshop on ADC Modelling and Testing, 2004, Vol. 1, s. 337-342Konferensbidrag (Refereegranskat)
    Abstract [en]

    Multi-sinewave test methods require algorithms for multiple-tone parameter estimation.There exist a vast amount of publications on the topic [1]. This paper presents a generalization ofthe IEEE four-parameter sinewave fit algorithm suitable to handle data comprising multiple sinewaves.The proposed method directly estimates the 3p + 1 parameters of a p-tone model. The algorithmis analyzed numerically with emphasize on its convergence properties and statistical efficiency. Theinitialization of the algorithm is of major importance and an attempt to formulate a proper initializationprocedure is presented.

  • 25. Andersson, Tomas
    et al.
    Skoglund, Mikael
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Frequency estimation by 1-bit quantization and table look-up processing2000Ingår i: Proceedings European Signal Processing Conference, 2000, s. 1807-1810Konferensbidrag (Refereegranskat)
  • 26.
    Andersson, Tomas
    et al.
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Skoglund, Mikael
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Händel, Peter
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Frequency estimation utilizing the Hadamard transform2001Ingår i: 2001 IEEE WORKSHOP ON STATISTICAL SIGNAL PROCESSING PROCEEDINGS, NEW YORK: IEEE , 2001, s. 409-412Konferensbidrag (Refereegranskat)
    Abstract [en]

    Fast analog to digital conversion with only one bit per sample does not only make high sampling rates possible but also reduces the required hardware complexity. For short data buffers or block lengths, it has been shown that tone frequency estimators can be implemented by a simple table look-up. In this paper we present an analysis of such tables using the Hadamard transform. As an outcome of the analysis, we propose a class of nonlinear estimators of low complexity. Their performance is evaluated using numerical simulations. Comparisons are made with the proper Cramer-Rao bound and with the table look-up approach.

  • 27. Anttila, L
    et al.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Mylläri, O
    Valkama, M
    Recursive learning-based joint digital predistorter for power amplifier and I/Q modulator impairments2010Ingår i: International Journal of Microwave and Wireless Technologies, ISSN 1759-0787, Vol. 2, nr 2, s. 173-182Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The main implementation impairments degrading the performance of direct-conversion radio transmitters are in-phase/quadrature (I/Q) mismatch, local oscillator (LO) leakage, and power amplifier (PA) nonlinear distortion. In this article, we propose a recursive least-squares-based learning algorithm for joint digital predistortion (PD) of frequency-dependent PA and I/Q modulator impairments. The predistorter is composed of a parallel connection of two parallel Hammerstein (PH) predistorters and an LO leakage compensator, yielding a predistorter which as a whole is fully linear in the parameters. In the parameter estimation stage, proper feedback signal from the transmitter radio frequency (RF) stage back to the digital parts is deployed, combined with the indirect learning architecture and recursive least-squares training. The proposed structure is one of the first techniques to explicitly consider the joint estimation and mitigation of frequency-dependent PA and I/Q modulator impairments. Extensive simulation and measurement analysis is carried out to verify the operation and efficiency of the proposed PD technique. In general, the obtained results demonstrate linearization and I/Q modulator calibration performance clearly exceeding the performance of current state-of-the-art reference techniques.

  • 28. Anttila, Lauri
    et al.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Valkama, Mikko
    Joint Mitigation of Power Amplifier and I/Q Modulator Impairments in Broadband Direct-Conversion Transmitters2010Ingår i: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 58, nr 4, s. 730-739Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we present a novel digital predistorter structure for joint mitigation of frequency-dependent power amplifier (PA) and in-phase and quadrature (I/Q) modulator impairments in direct-conversion radio transmitters. The predistorter is based on an extended parallel Hammerstein structure, yielding a predistorter that is fully linear in the parameters. In the parameter estimation stage, the indirect learning architecture is utilized. The proposed technique is the first technique in the literature to consider the joint estimation and mitigation of frequency-dependent PAand I/Q modulator impairments. Extensive simulation and measurement analysis is carried out to verify the operation and efficacy of the proposed predistortion structure. It is shown that the adjacent channel power ratio is increased by more than 20 dB in all experiments when using the proposed method, and that the performance of the reference techniques is clearly exceeded.

  • 29. Bergenheim, Jon
    et al.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Remle, Susanne
    Ekosläckning2002Patent (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    The present invention relates to a cancellation of echoes in telecommunications systems, more specifically it relates to adaptive alignment of a linear filter (500) used for echo cancellation. According to the invention, it is continuously determined, by means of control logic (520), if a reflection replica delay included in an echo replica signal (110), which delay is provided by a signal buffer (510), should be attempted to be increased or not. Similarly, it is continuously determined if the reflection replica delay should be attempted to be decreased or not. In this way it is possible to provide a delay of the reflection replica which corresponds to the pure delay of a corresponding reflection included in an echo signal (120) received over an echo path. The invention is advantageous since the filter (500) will continuously and quickly adapt to changes in the echo path delay by continuously increasing or decreasing, in an incremental and smooth manner, a present replica delay.

  • 30. Bjorsell, Niclas
    et al.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Post-correction of under-sampled analog to digital converters2007Ingår i: 2007 IEEE INSTRUMENTATION & MEASUREMENT TECHNOLOGY CONFERENCE, 2007, s. 58-62Konferensbidrag (Refereegranskat)
    Abstract [en]

    Applications with wide bandwidth and high center frequencies force the analog to digital converter (ADC) to be active in a working range with less dynamic performance in relation to lower frequency bands. However using under-sampling techniques in combination with post-correction methods enable a combination of high sampling rate, wide bandwidth and low distortion. In this paper the employed dynamic post-correction is a combination of look-up tables and model based correction. The results are mainly based on measurements on a 12-bit 210 MSPS ADC. The improvement in total harmonic distortion and spurious free dynamic range are acceptable over a wide frequency range and it is robust to variations in amplitude.

  • 31. Bjorsell, Niclas
    et al.
    Ronnow, Daniel
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Measuring Volterra kernels of analog to digital converters using a stepped three-tone scan2006Ingår i: 2006 IEEE INSTRUMENTATION AND MEASUREMENT TECHNOLOGY CONFERENCE PROCEEDINGS, 2006, s. 1047-1050Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Volterra theory can be used to mathematically model nonlinear dynamic components such as analog-to-digital converter (ADC). This paper describes how frequency domain Volterra kernels of an ADC are determined from measurements. The elements of Volterra theory are given and practical issues are considered, such as methods for signal conditioning, finding the appropriate test signals scenario and suitable sampling frequency. The results show that for the used pipeline ADC, the frequency dependence is significantly stronger for second order difference products than for sum products and the linear frequency dependence was not as pronounced as that of the second order Volterra kernel.

  • 32.
    Björsell, Niclas
    et al.
    Gävle Universitet, Sweden.
    Andersen, Olav
    Ericsson AB, Gävle.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    High dynamic range test-bed for characterization of analog-to-digital converters up to 500 MSPS2005Ingår i: 14th Symposium on New Technologies in Measurement and Instrumentation and 10th Workshop on ADC Modelling and Testing, IMEKO-International Measurement Federation Secretariat , 2005, s. 601-604Konferensbidrag (Refereegranskat)
    Abstract [en]

    A measurement set-up of for the characterization of analog-to-digital converters (ADCs) is described. The measurement set-up characterizes ADCs up to 16 bits at 350 MHz (option for >500 MHz). Testing dynamic performance of high-speed ADCs is regarded as difficult and expensive. By using existing state-of-the-art instruments in combination with specially designed amplifiers and filters, a high performance, cost efficient test-bed has been built-up. Practical performance corresponds to ADC datasheet and exceeds the performance obtained if using commercial instruments only. Consequently, the measurement results represent the true performance of the ADC without impact from the test-bed

  • 33. Björsell, Niclas
    et al.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    A Statistical Evaluation of ADC Histogram Tests with Arbitrary Stimuli Signal2005Ingår i: ADDA 2005, 2005, s. 259-264Konferensbidrag (Refereegranskat)
  • 34.
    Björsell, Niclas
    et al.
    Gävle Universitet.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Achievable ADC Performance by Post-Correction Utilizing Dynamic Modeling of the Integral Nonlinearity2008Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1110-8657, s. 497187-1-497187-10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is a need for a universal dynamic model of analog-to-digital converters (ADC’s) aimed for postcorrection. However, it is complicated to fully describe the properties of an ADC by a single model. An alternative is to split up the ADC model in different components, where each component has unique properties. In this paper, a model based on three components is used, and a performance analysis for each component is presented. Each component can be postcorrected individually and by the method that best suits the application. The purpose of postcorrection of an ADC is to improve the performance. Hence, for each component, expressions for the potential improvement have been developed. The measures of performance are total harmonic distortion (THD) and signal to noise and distortion (SINAD), and to some extent spurious-free dynamic range (SFDR).

  • 35. Björsell, Niclas
    et al.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Analog-to-Digital Converters for High-Speed Applications2005Ingår i: GigaHz 2005, 2005, s. 151-154Konferensbidrag (Refereegranskat)
  • 36. Björsell, Niclas
    et al.
    Händel, Peter
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Benefits with Truncated Gaussian Noise in ADC Histogram Tests2004Ingår i: 9th IMEKO Workshop on ADC Modeling and Testing, IWADC 2004, Held Together with the 13th IMEKO TC4 Symposium on Measurements for Research and Industrial Applications, IMEKO-International Measurement Federation Secretariat , 2004, s. 787-792Konferensbidrag (Refereegranskat)
    Abstract [en]

    One method to characterize ADCs is to use a histogram, where Gaussian noise may be used as stimulus signal. However, a Gaussian noise signal that excites all transition levels also generates input values outside working range of the ADC. Modern signal generators can generate arbitrary signals. Hence, excluding undesired values outside the ADC full scale can minimize test sequences. Truncating the signal to the working range gives further advantages, which are explored in this paper. The statistical properties is theoretically evaluated and compared. It is shown that accuracy increases for a fixed sample length and that variation over transition levels decrease.

  • 37. Björsell, Niclas
    et al.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dynamic behavior models of analog to digital converters aimed for post-correction in wideband applications2006Ingår i: 18th IMEKO World Congress 2006: Metrology for a Sustainable Development, 2006, s. 1344-1348Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper a dynamic behavior model of analog to digital converters is proposed. The model is aimed for post correction in wideband applications. The suggested post correction method is a combination of look up tables and model based correction.The model consists of three components. The first is a component represented by a Hammerstein model; that is a static nonlinearity followed by a time invariant linear filter. The second component is a nonparametric model caused by significant deviation from the characterized integral nonlinearity and the output from the Hammerstein model. The third component contains of the remaining deviation and is considered as a random model error.Results from simulations verify that the examined ADC can be described by an ordinary Hammerstein model and a static look-up table.

  • 38.
    Björsell, Niclas
    et al.
    Gävle Universitet.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Histogram Tests for Wideband Applications2008Ingår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 57, nr 1, s. 70-75Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Characterization and testing of analog-to-digital converters (ADCs) are important for many reasons. A histogram test is a common method to characterize the linearity features of an ADC. Two commonly used stimulus signals are sine waves and Gaussian noise. This paper presents a metrological comparison between Gaussian and sine-wave histogram tests for wide-band applications, that is, we evaluate the performance of the characterization of the ADC and the usability of postcorrection. A postcorrection procedure involves the characterization of the ADC nonlinearity and then the use of this information by processing the ADC output samples to remove the distortion. The results show that the Gaussian histogram test gives reasonable accuracy in measuring nonlinearities. However, it does not result in a suitable model for postcorrection in wideband applications. A single-tone sine-wave histogram will be a better basis for postcorrection. The best result can be obtained if the lookup table is trained with several single-tone sine waves in the frequency band.

  • 39. Björsell, Niclas
    et al.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    On Gaussian and Sine Wave Histogram Tests for Wideband Applications2005Ingår i: Proceedings of the IEEE Instrumentation and Measurement Technology Conference, IEEE , 2005, s. 677-682Konferensbidrag (Refereegranskat)
    Abstract [en]

    Characterization and testing of analog-to-digital converters (ADCs) are interesting in many different aspects. Histogram test is a common method to characterize the linearity features of an ADC. Two commonly used stimuli signals are sine waves and Gaussian noise. This paper will present a metrological comparison between Gaussian and sine wave histogram tests for wideband applications; that is evaluate the performance in characterization of the ADC and the usability of post-correction. A post-correction procedure involves characterization of the ADC non-linearity and then utilization of this information by processing the ADC output samples to remove the distortion. The results indicates that even though the Gaussian histogram test seems to give reasonable accuracy to measure non-linearities it is not thereby a suitable model for post-correction. A single-tone sine wave histogram will most likely be a better solution. Best result is to train the look-up table with several single-tone sine waves in the frequency band.

  • 40.
    Björsell, Niclas
    et al.
    Gävle Universitet.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Truncated Gaussian Noise in ADC Histogram Tests2007Ingår i: Measurement, ISSN 0263-2241, E-ISSN 1873-412X, Vol. 40, nr 1, s. 36-42Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One method to characterize analogue to digital converters (ADCs) is to use a histogram, where Gaussian noise may be used as stimulus signal. However, a Gaussian noise signal that excites all transition levels also generates input values outside working range of the ADC. Modern signal generators can generate arbitrary signals. Hence, excluding undesired values outside the ADC full scale can minimize test sequences. Truncating the signal to the working range gives further advantages, which are explored in this paper. The Cramer-Rao lower bound and a minimum variance estimator for histogram tests with an arbitrary stimulus are derived. These are applied for truncated Gaussian noise and the result is theoretically evaluated and compared to untruncated noise. It is shown that accuracy increases for a fixed sample length and that variation over transition levels decrease.

  • 41.
    Björsell, Niclas
    et al.
    University of Gävle.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Jansson, Magnus
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Medawar, Samer
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Improved estimate of parametric models for analogue to digital converters by using weighted integral nonlinearity data2010Ingår i: 17th Symposium IMEKO TC4 - Measurement of Electrical Quantities, 15th International Workshop on ADC Modelling and Testing, and 3rd Symposium IMEKO TC19 - Environmental Measurements, 2010, s. 597-600Konferensbidrag (Refereegranskat)
    Abstract [en]

    Error modelling has played a major role in generating post-corrections of analogue to digital converters (ADC). Benefits by using parametric models for post-correction are that they requires less memory and that they are easier to identify for arbitrary signals. However, the parameters are estimated in two steps; firstly, the integral nonlinearity (INL) is estimated and secondly, the model parameters. In this paper we propose a method to improve the performance in the second step, by utilizing information about the statistical properties of the first step.

  • 42.
    Björsell, Niclas
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Isaksson, Magnus
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Rönnow, Daniel
    Kautz-Volterra modelling of an analogue-to-digital converter using a stepped three-tone excitation2007Ingår i: 12th IMEKO TC-4 International Workshop on ADC MODELLING AND TESTING, 2007, s. 107-112Konferensbidrag (Refereegranskat)
    Abstract [en]

    In many test and measurement applications, the analogue-to-digital converter (ADC) is the limiting component. Using post-correction methods can improve the performance of the component as well as the over all measurement system. In this paper an ADC is characterised by a Kautz-Volterra (KV) model, which utilises a model-based post-correction of the ADC with general properties and a reasonable number of parameters. Results that are based on measurements on a high-speed 12-bit ADC, shows good results for a third order model.

  • 43.
    Björsell, Niclas
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Isaksson, Magnus
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Rönnow, Daniel
    Gävle Universitet.
    Kautz-Volterra modelling of analogue-to-digital converters2010Ingår i: Computer Standards & Interfaces, ISSN 0920-5489, E-ISSN 1872-7018, Vol. 32, nr 3, s. 126-129Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In many test and measurement applications, the analogue-to-digital converter (ADC) is the limiting component. Using post-correction methods can improve the performance of the component as well as the overall measurement system. In this paper an ADC is characterised by a Kautz–Volterra (KV) model, which utilises a model-based post-correction of the ADC with general properties and a reasonable number of parameters. It is also shown that the inverse model has the same dynamic properties as the direct KV model. Results that are based on measurements on a high-speed 12-bit ADC show good results for a third-order model.

  • 44.
    Björsell, Niclas
    et al.
    University of Gävle, Radio center for measurement technology.
    Nader, Charles
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Multi-tone design for out-of-band characterization of nonlinear RF modules using harmonic sampling2010Ingår i: 2010 IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2010 - Proceedings, IEEE , 2010, s. 620-623Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we evaluate the generation of a multi-tone set for characterizing the behavior of nonlinear radio frequency (RF) modules in its out-of-band when harmonic sampling is used as digitizer. The purpose is to provide the reader with a tool to select proper frequencies and record length for a given application and test-bed. The method is based on simulations and the use of Sidon sequences. The proposed method is applicable to sparse discrete frequency multi-tones.

  • 45. Björsell, Niklas
    et al.
    Suchánek, Petr
    Czech Tech Univ Prague.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Rönnow, Daniel
    Gävle Universitet.
    Measuring Volterra Kernels of Analog To Digital Converters Using a Stepped Three-Tone Scan2008Ingår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 57, nr 4, s. 666-671Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Volterra theory can be used to mathematically model nonlinear dynamic components such as analog-to-digital converters (ADCs). This paper describes how frequency-domain Volterra kernels of an ADC are determined from measurements. The elements of the Volterra theory are given, and practical issues are considered, such as methods for signal conditioning and finding the appropriate test signals scenario and suitable sampling frequency. The results show that, for the used pipeline ADC, the frequency dependence is significantly stronger for second-order difference products than for sum products and the linear frequency dependence was not as pronounced as that of the second-order Volterra kernel. It is suggested that the Volterra kernels have the symmetry properties of a specific box model, namely, the parallel Hammerstein system.

  • 46. Bose, Subhojyoti
    et al.
    Gupta, Amit K.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Teknisk informationsvetenskap.
    On The Noise And Power Performance Of A Shoe-Mounted Multi-Imu Inertial Positioning System2017Ingår i: 2017 INTERNATIONAL CONFERENCE ON INDOOR POSITIONING AND INDOOR NAVIGATION (IPIN), IEEE, 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Shoe-mounted inertial navigation systems, aka pedestrian dead reckoning or PDR sensors, are being preferred for pedestrian navigation because of the accuracy offered by them. Such shoe sensors are, for example, the obvious choice for real time location systems of first responders. The opensource platform OpenShoe has reported application of multiple IMUs in shoe-mounted PDR sensors to enhance noise performance. In this paper, we present an experimental study of the noise performance and the operating clocks based power consumption of multi-IMU platforms. The noise performances of a multi-IMU system with different combinations of IMUs are studied. It is observed that four-IMU system is best optimized for cost, area and power. Experiments with varying operating clocks frequency are performed on an in-house four-IMU shoe-mounted inertial navigation module (the Oblu module). Based on the outcome, power-optimized operating clock frequencies are obtained. Thus the overall study suggests that by selecting a well-designed operating point, a multi-IMU system can be made cost, size and power efficient without practically affecting its superior positioning performance.

  • 47. Carlsson, B
    et al.
    Händel, Peter
    Uppsala universitet.
    A NOTCH FILTER BASED ON RECURSIVE LEAST-SQUARES MODELING1994Ingår i: Signal Processing, ISSN 0165-1684, E-ISSN 1872-7557, Vol. 35, nr 3, s. 231-239Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents a notch filter based on recursive least-squares sinusoidal modelling. This gives analytical insight both into least-squares modelling of sine waves in noise and the use of constrained notch filters. Especially, the derived filter corresponds to a commonly used notch filter with constrained poles and zeros.

  • 48. Carlsson, B.
    et al.
    Händel, Peter
    Analysis and interpretation of a constrained notch filter1992Ingår i: Acoustics, Speech, and Signal Processing, 1992. ICASSP-92., 1992 IEEE International Conference on, 1992, Vol. 4, s. 293-296Konferensbidrag (Refereegranskat)
    Abstract [en]

    A notch filter based on discounted recursive least squares sinusoidal modeling is presented. This gives analytical insight both into least squares modeling of sine waves in noise and the use of constrained notch filters. Especially, it is shown that the discounted least squares solution converges to a commonly used notch filter with constrained poles and zeros, where the forgetting factor in the criterion corresponds to the pole radii in the filter. Also a Kalman filter interpretation is given for the derived constrained notch filter

  • 49. Cazzorla, Alessandro
    et al.
    De Angelis, Alessio
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    De Angelis, Guido
    Dwivedi, Satyam
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Moschitta, Antonio
    Dionigi, Marco
    Alimenti, Federico
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Carbone, Paolo
    Localizzazione in ambienti chiusi mediante trasmissione di segnali a banda ultra larga ed elaborazione statistica2013Konferensbidrag (Refereegranskat)
  • 50.
    Chatterjee, Saikat
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Hari, K. V. S.
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Projection-based atom selection in orthogonal matching pursuit for compressive sensing2012Ingår i: 2012 National Conference on Communications, NCC 2012, IEEE , 2012, s. 6176797-Konferensbidrag (Refereegranskat)
    Abstract [en]

    For compressive sensing, we endeavor to improve the atom selection strategy of the existing orthogonal matching pursuit (OMP) algorithm. To achieve a better estimate of the underlying support set progressively through iterations, we use a least squares solution based atom selection method. From a set of promising atoms, the choice of an atom is performed through a new method that uses orthogonal projection along-with a standard matched filter. Through experimental evaluations, the effect of projection based atom selection strategy is shown to provide a significant improvement for the support set recovery performance, in turn, the compressive sensing recovery.

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