The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
T Stezelberger - One of the best experts on this subject based on the ideXlab platform.
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radar absorption basal reflection thickness and polarization measurements from the ross ice shelf antarctica
Journal of Glaciology, 2015Co-Authors: J Hanson, Steven W. Barwick, Eric C. Berg, S R Klein, D Besson, T Duffin, S Kleinfelder, C Reed, M Roumi, T StezelbergerAbstract:Author(s): Hanson, JC; Barwick, SW; Berg, EC; Besson, DZ; Duffin, TJ; Klein, SR; Kleinfelder, SA; Reed, C; Roumi, M; Stezelberger, T; Tatar, J; Walker, JA; Zou, L | Abstract: Radio-glaciological parameters from the Moore's Bay region of the Ross Ice Shelf, Antarctica, have been measured. The thickness of the ice shelf in Moore's Bay was measured from reflection times of Radio-frequency pulses propagating vertically through the shelf and reflecting from the ocean, and is found to be 576± 8m. Introducing a baseline of 543 ±7m between Radio Transmitter and receiver allowed the computation of the basal reflection coefficient, R, separately from englacial loss. The depth-averaged attenuation length of the ice column, 〈L〉 is shown to depend linearly on frequency. The best fit (95% confidence level) is 〈L(v)〉 = (460± 20)-(180±40)vm (20 dB km-1), for the frequencies v = [0.100-0.850] GHz, assuming no reflection loss. The mean electric-field reflection coefficient is √R = 0.82 ±0.07 (1.7dB reflection loss) across [0.100-0.850] GHz, and is used to correct the attenuation length. Finally, the reflected power rotated into the orthogonal antenna polarization is l5% below 0.400 GHz, compatible with air propagation. The results imply that Moore's Bay serves as an appropriate medium for the ARIANNA high-energy neutrino detector.
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radar absorption basal reflection thickness and polarization measurements from the ross ice shelf
arXiv: Instrumentation and Methods for Astrophysics, 2014Co-Authors: Steven W. Barwick, Eric C. Berg, S R Klein, D Besson, T Duffin, J Hanson, S Kleinfelder, C Reed, M Roumi, T StezelbergerAbstract:Radio-glaciological parameters from Moore's Bay, in the Ross Ice Shelf, have been measured. The thickness of the ice shelf in Moore's Bay was measured from reflection times of Radio-frequency pulses propagating vertically through the shelf and reflecting from the ocean, and is found to be $576\pm8$ m. Introducing a baseline of 543$\pm$7 m between Radio Transmitter and receiver allowed the computation of the basal reflection coefficient, $R$, separately from englacial loss. The depth-averaged attenuation length of the ice column, $ $ is shown to depend linearly on frequency. The best fit (95% confidence level) is $ = (460\pm20)-(180\pm40)\nu$ m (20 dB/km), for the frequencies $\nu=$[0.100-0.850] GHz, assuming no reflection loss. The mean electric-field reflection coefficient is $\sqrt{R}=0.82\pm0.07$ (-1.7 dB reflection loss) across [0.100-0.850] GHz, and is used to correct the attenuation length. Finally, the reflected power rotated into the orthogonal antenna polarization is less than 5% below 0.400 GHz, compatible with air propagation. The results imply that Moore's Bay serves as an appropriate medium for the ARIANNA high energy neutrino detector.
Mikko Valkama - One of the best experts on this subject based on the ideXlab platform.
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tri phasing modulation for efficient and wideband Radio Transmitters
IEEE Transactions on Circuits and Systems I-regular Papers, 2018Co-Authors: Jerry Lemberg, Mikko Martelius, Marko Kosunen, Enrico Roverato, Kari Stadius, Lauri Anttila, Mikko Valkama, Jussi RyynanenAbstract:In this paper, we show that amplitude transitions that are inherent to the multilevel outphasing Radio Transmitter architecture distort the transmitted signal due to time-domain discontinuities. In order to address this challenge, we propose a new Transmitter architecture called tri-phasing which avoids discontinuities in signal waveforms and thus achieves significantly better linearity than multilevel outphasing. The output waveform in tri-phasing can be made continuous by representing the baseband signal with three components. One of the three components is amplified by discrete amplitude steps, whereas the other two are used to compensate the instantaneous shift in the output waveform due to the discrete amplitude step and to provide fine amplitude resolution. An implementation of the tri-phasing Transmitter requires three phase modulators and additional digital signal processing. The system-level simulations performed in this paper demonstrate that the ACLR of a multilevel outphasing Transmitter with 4 amplitude levels and 10-bit phase resolution is limited to −48 dBc, when simulated with a 100 MHz carrier-aggregated LTE downlink signal at 2.46 GHz carrier frequency. The proposed tri-phasing Transmitter achieves −58 dBc ACLR with the same simulation parameters, indicating that continuous amplitude transitions can significantly improve the Transmitter linearity.
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low complexity subband digital predistortion for spurious emission suppression in noncontiguous spectrum access
IEEE Transactions on Microwave Theory and Techniques, 2016Co-Authors: Mahmoud Abdelaziz, Chance Tarver, Joseph R Cavallaro, Lauri Anttila, Kaipeng Li, Mikko ValkamaAbstract:Noncontiguous transmission schemes combined with high power-efficiency requirements pose big challenges for Radio Transmitter and power amplifier (PA) design and implementation. Due to the nonlinear nature of the PA, severe unwanted emissions can occur, which can potentially interfere with neighboring channel signals or even desensitize the own receiver in frequency division duplexing transceivers. In this paper, to suppress such unwanted emissions, a low-complexity subband digital predistortion solution, specifically tailored for spectrally noncontiguous transmission schemes in low-cost devices, is proposed. The proposed technique aims at mitigating only the selected spurious intermodulation distortion components at the PA output, hence allowing for substantially reduced processing complexity compared with classical linearization solutions. Furthermore, novel decorrelation-based parameter learning solutions are also proposed and formulated, which offer reduced computing complexity in parameter estimation as well as the ability to track time-varying features adaptively. Comprehensive simulation and RF measurement results are provided, using a commercial LTE-Advanced mobile PA, to evaluate and validate the effectiveness of the proposed solution in real-world scenarios. The obtained results demonstrate that highly efficient spurious component suppression can be obtained using the proposed solutions.
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low complexity sub band digital predistortion for spurious emission suppression in noncontiguous spectrum access
arXiv: Information Theory, 2016Co-Authors: Mahmoud Abdelaziz, Chance Tarver, Joseph R Cavallaro, Lauri Anttila, Mikko ValkamaAbstract:Noncontiguous transmission schemes combined with high power-efficiency requirements pose big challenges for Radio Transmitter and power amplifier (PA) design and implementation. Due to the nonlinear nature of the PA, severe unwanted emissions can occur, which can potentially interfere with neighboring channel signals or even desensitize the own receiver in frequency division duplexing (FDD) transceivers. In this article, to suppress such unwanted emissions, a low-complexity sub-band DPD solution, specifically tailored for spectrally noncontiguous transmission schemes in low-cost devices, is proposed. The proposed technique aims at mitigating only the selected spurious intermodulation distortion components at the PA output, hence allowing for substantially reduced processing complexity compared to classical linearization solutions. Furthermore, novel decorrelation based parameter learning solutions are also proposed and formulated, which offer reduced computing complexity in parameter estimation as well as the ability to track time-varying features adaptively. Comprehensive simulation and RF measurement results are provided, using a commercial LTE-Advanced mobile PA, to evaluate and validate the effectiveness of the proposed solution in real world scenarios. The obtained results demonstrate that highly efficient spurious component suppression can be obtained using the proposed solutions.
J Hanson - One of the best experts on this subject based on the ideXlab platform.
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radar absorption basal reflection thickness and polarization measurements from the ross ice shelf antarctica
Journal of Glaciology, 2015Co-Authors: J Hanson, Steven W. Barwick, Eric C. Berg, S R Klein, D Besson, T Duffin, S Kleinfelder, C Reed, M Roumi, T StezelbergerAbstract:Author(s): Hanson, JC; Barwick, SW; Berg, EC; Besson, DZ; Duffin, TJ; Klein, SR; Kleinfelder, SA; Reed, C; Roumi, M; Stezelberger, T; Tatar, J; Walker, JA; Zou, L | Abstract: Radio-glaciological parameters from the Moore's Bay region of the Ross Ice Shelf, Antarctica, have been measured. The thickness of the ice shelf in Moore's Bay was measured from reflection times of Radio-frequency pulses propagating vertically through the shelf and reflecting from the ocean, and is found to be 576± 8m. Introducing a baseline of 543 ±7m between Radio Transmitter and receiver allowed the computation of the basal reflection coefficient, R, separately from englacial loss. The depth-averaged attenuation length of the ice column, 〈L〉 is shown to depend linearly on frequency. The best fit (95% confidence level) is 〈L(v)〉 = (460± 20)-(180±40)vm (20 dB km-1), for the frequencies v = [0.100-0.850] GHz, assuming no reflection loss. The mean electric-field reflection coefficient is √R = 0.82 ±0.07 (1.7dB reflection loss) across [0.100-0.850] GHz, and is used to correct the attenuation length. Finally, the reflected power rotated into the orthogonal antenna polarization is l5% below 0.400 GHz, compatible with air propagation. The results imply that Moore's Bay serves as an appropriate medium for the ARIANNA high-energy neutrino detector.
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radar absorption basal reflection thickness and polarization measurements from the ross ice shelf
arXiv: Instrumentation and Methods for Astrophysics, 2014Co-Authors: Steven W. Barwick, Eric C. Berg, S R Klein, D Besson, T Duffin, J Hanson, S Kleinfelder, C Reed, M Roumi, T StezelbergerAbstract:Radio-glaciological parameters from Moore's Bay, in the Ross Ice Shelf, have been measured. The thickness of the ice shelf in Moore's Bay was measured from reflection times of Radio-frequency pulses propagating vertically through the shelf and reflecting from the ocean, and is found to be $576\pm8$ m. Introducing a baseline of 543$\pm$7 m between Radio Transmitter and receiver allowed the computation of the basal reflection coefficient, $R$, separately from englacial loss. The depth-averaged attenuation length of the ice column, $ $ is shown to depend linearly on frequency. The best fit (95% confidence level) is $ = (460\pm20)-(180\pm40)\nu$ m (20 dB/km), for the frequencies $\nu=$[0.100-0.850] GHz, assuming no reflection loss. The mean electric-field reflection coefficient is $\sqrt{R}=0.82\pm0.07$ (-1.7 dB reflection loss) across [0.100-0.850] GHz, and is used to correct the attenuation length. Finally, the reflected power rotated into the orthogonal antenna polarization is less than 5% below 0.400 GHz, compatible with air propagation. The results imply that Moore's Bay serves as an appropriate medium for the ARIANNA high energy neutrino detector.
Steven W. Barwick - One of the best experts on this subject based on the ideXlab platform.
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Radio-frequency Attenuation Length, Basal Reflectivity, Depth, and Polarization Measurements from Moore’s Bay in the Ross Ice-Shelf
2016Co-Authors: Steven W. Barwick, Eric C. Berg, Dave Z. Besson, Thorin JAbstract:ABSTRACT. Radio-glaciological parameters from Moore’s Bay, in the Ross Ice Shelf, have been measured. The thickness of the ice shelf in Moore’s Bay was measured from reflection times of Radio-frequency pulses propagating vertically through the shelf and reflecting from the ocean. The average depth obtained is 576 ± 8 m. The temperature-averaged attenuation length of the ice column, 〈L〉, is derived from the returned power assuming 100 % reflection. A linear fit to the data yields 〈L(ν) 〉 = (460 ± 20) − (180 ± 40)ν, for the frequencies ν =[0.100-0.850] GHz, at 95 % confidence. Introducing a baseline of 543±7 m between Radio Transmitter and receiver allowed the computation of the basal reflection coefficient, R, separately from attenuation. The electric-field reflection coefficient is R = 0.82 ± 0.07 across [0.100-0.850] GHz. Finally, the reflected power rotated into the orthogonal antenna polarization is less than 5 % below 0.400 GHz, compatible with air propagation. These results suggest that Moore’s Bay will serve as an appropriate medium for the ARIANNA high energy neutrino telescope
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radar absorption basal reflection thickness and polarization measurements from the ross ice shelf antarctica
Journal of Glaciology, 2015Co-Authors: J Hanson, Steven W. Barwick, Eric C. Berg, S R Klein, D Besson, T Duffin, S Kleinfelder, C Reed, M Roumi, T StezelbergerAbstract:Author(s): Hanson, JC; Barwick, SW; Berg, EC; Besson, DZ; Duffin, TJ; Klein, SR; Kleinfelder, SA; Reed, C; Roumi, M; Stezelberger, T; Tatar, J; Walker, JA; Zou, L | Abstract: Radio-glaciological parameters from the Moore's Bay region of the Ross Ice Shelf, Antarctica, have been measured. The thickness of the ice shelf in Moore's Bay was measured from reflection times of Radio-frequency pulses propagating vertically through the shelf and reflecting from the ocean, and is found to be 576± 8m. Introducing a baseline of 543 ±7m between Radio Transmitter and receiver allowed the computation of the basal reflection coefficient, R, separately from englacial loss. The depth-averaged attenuation length of the ice column, 〈L〉 is shown to depend linearly on frequency. The best fit (95% confidence level) is 〈L(v)〉 = (460± 20)-(180±40)vm (20 dB km-1), for the frequencies v = [0.100-0.850] GHz, assuming no reflection loss. The mean electric-field reflection coefficient is √R = 0.82 ±0.07 (1.7dB reflection loss) across [0.100-0.850] GHz, and is used to correct the attenuation length. Finally, the reflected power rotated into the orthogonal antenna polarization is l5% below 0.400 GHz, compatible with air propagation. The results imply that Moore's Bay serves as an appropriate medium for the ARIANNA high-energy neutrino detector.
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radar absorption basal reflection thickness and polarization measurements from the ross ice shelf
arXiv: Instrumentation and Methods for Astrophysics, 2014Co-Authors: Steven W. Barwick, Eric C. Berg, S R Klein, D Besson, T Duffin, J Hanson, S Kleinfelder, C Reed, M Roumi, T StezelbergerAbstract:Radio-glaciological parameters from Moore's Bay, in the Ross Ice Shelf, have been measured. The thickness of the ice shelf in Moore's Bay was measured from reflection times of Radio-frequency pulses propagating vertically through the shelf and reflecting from the ocean, and is found to be $576\pm8$ m. Introducing a baseline of 543$\pm$7 m between Radio Transmitter and receiver allowed the computation of the basal reflection coefficient, $R$, separately from englacial loss. The depth-averaged attenuation length of the ice column, $ $ is shown to depend linearly on frequency. The best fit (95% confidence level) is $ = (460\pm20)-(180\pm40)\nu$ m (20 dB/km), for the frequencies $\nu=$[0.100-0.850] GHz, assuming no reflection loss. The mean electric-field reflection coefficient is $\sqrt{R}=0.82\pm0.07$ (-1.7 dB reflection loss) across [0.100-0.850] GHz, and is used to correct the attenuation length. Finally, the reflected power rotated into the orthogonal antenna polarization is less than 5% below 0.400 GHz, compatible with air propagation. The results imply that Moore's Bay serves as an appropriate medium for the ARIANNA high energy neutrino detector.
Eric C. Berg - One of the best experts on this subject based on the ideXlab platform.
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Radio-frequency Attenuation Length, Basal Reflectivity, Depth, and Polarization Measurements from Moore’s Bay in the Ross Ice-Shelf
2016Co-Authors: Steven W. Barwick, Eric C. Berg, Dave Z. Besson, Thorin JAbstract:ABSTRACT. Radio-glaciological parameters from Moore’s Bay, in the Ross Ice Shelf, have been measured. The thickness of the ice shelf in Moore’s Bay was measured from reflection times of Radio-frequency pulses propagating vertically through the shelf and reflecting from the ocean. The average depth obtained is 576 ± 8 m. The temperature-averaged attenuation length of the ice column, 〈L〉, is derived from the returned power assuming 100 % reflection. A linear fit to the data yields 〈L(ν) 〉 = (460 ± 20) − (180 ± 40)ν, for the frequencies ν =[0.100-0.850] GHz, at 95 % confidence. Introducing a baseline of 543±7 m between Radio Transmitter and receiver allowed the computation of the basal reflection coefficient, R, separately from attenuation. The electric-field reflection coefficient is R = 0.82 ± 0.07 across [0.100-0.850] GHz. Finally, the reflected power rotated into the orthogonal antenna polarization is less than 5 % below 0.400 GHz, compatible with air propagation. These results suggest that Moore’s Bay will serve as an appropriate medium for the ARIANNA high energy neutrino telescope
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radar absorption basal reflection thickness and polarization measurements from the ross ice shelf antarctica
Journal of Glaciology, 2015Co-Authors: J Hanson, Steven W. Barwick, Eric C. Berg, S R Klein, D Besson, T Duffin, S Kleinfelder, C Reed, M Roumi, T StezelbergerAbstract:Author(s): Hanson, JC; Barwick, SW; Berg, EC; Besson, DZ; Duffin, TJ; Klein, SR; Kleinfelder, SA; Reed, C; Roumi, M; Stezelberger, T; Tatar, J; Walker, JA; Zou, L | Abstract: Radio-glaciological parameters from the Moore's Bay region of the Ross Ice Shelf, Antarctica, have been measured. The thickness of the ice shelf in Moore's Bay was measured from reflection times of Radio-frequency pulses propagating vertically through the shelf and reflecting from the ocean, and is found to be 576± 8m. Introducing a baseline of 543 ±7m between Radio Transmitter and receiver allowed the computation of the basal reflection coefficient, R, separately from englacial loss. The depth-averaged attenuation length of the ice column, 〈L〉 is shown to depend linearly on frequency. The best fit (95% confidence level) is 〈L(v)〉 = (460± 20)-(180±40)vm (20 dB km-1), for the frequencies v = [0.100-0.850] GHz, assuming no reflection loss. The mean electric-field reflection coefficient is √R = 0.82 ±0.07 (1.7dB reflection loss) across [0.100-0.850] GHz, and is used to correct the attenuation length. Finally, the reflected power rotated into the orthogonal antenna polarization is l5% below 0.400 GHz, compatible with air propagation. The results imply that Moore's Bay serves as an appropriate medium for the ARIANNA high-energy neutrino detector.
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radar absorption basal reflection thickness and polarization measurements from the ross ice shelf
arXiv: Instrumentation and Methods for Astrophysics, 2014Co-Authors: Steven W. Barwick, Eric C. Berg, S R Klein, D Besson, T Duffin, J Hanson, S Kleinfelder, C Reed, M Roumi, T StezelbergerAbstract:Radio-glaciological parameters from Moore's Bay, in the Ross Ice Shelf, have been measured. The thickness of the ice shelf in Moore's Bay was measured from reflection times of Radio-frequency pulses propagating vertically through the shelf and reflecting from the ocean, and is found to be $576\pm8$ m. Introducing a baseline of 543$\pm$7 m between Radio Transmitter and receiver allowed the computation of the basal reflection coefficient, $R$, separately from englacial loss. The depth-averaged attenuation length of the ice column, $ $ is shown to depend linearly on frequency. The best fit (95% confidence level) is $ = (460\pm20)-(180\pm40)\nu$ m (20 dB/km), for the frequencies $\nu=$[0.100-0.850] GHz, assuming no reflection loss. The mean electric-field reflection coefficient is $\sqrt{R}=0.82\pm0.07$ (-1.7 dB reflection loss) across [0.100-0.850] GHz, and is used to correct the attenuation length. Finally, the reflected power rotated into the orthogonal antenna polarization is less than 5% below 0.400 GHz, compatible with air propagation. The results imply that Moore's Bay serves as an appropriate medium for the ARIANNA high energy neutrino detector.