The Experts below are selected from a list of 24408 Experts worldwide ranked by ideXlab platform
N Bartolo - One of the best experts on this subject based on the ideXlab platform.
-
planck intermediate results l evidence of spatial variation of the polarized thermal dust spectral energy distribution and implications for cmb b mode analysis
Astronomy and Astrophysics, 2017Co-Authors: N Aghanim, M Ashdown, J Aumont, C Baccigalupi, M Ballardini, A J Banday, R B Barreiro, N BartoloAbstract:The characterization of the Galactic foregrounds has been shown to be the main obstacle in thechallenging quest to detect primordial B -modes in the polarized microwave sky. We make use of the Planck -HFI 2015 data release at high frequencies to place new constraints on the properties of the polarized thermal dust emission at high Galactic latitudes. Here, we specifically study the spatial variability of the dust polarized spectral energy distribution (SED), and its potential impact on the determination of the tensor-to-scalar ratio, r . We use the correlation ratio of the C BB l angular power spectra between the 217 and 353 GHz channels as a tracer of these potential variations, computed on different high Galactic latitude regions, ranging from 80% to 20% of the sky. The new insight from Planck data is a departure of the correlation ratio from unity that cannot be attributed to a spurious Decorrelation due to the cosmic microwave background, instrumental noise, or instrumental systematics. The effect is marginally detected on each region, but the statistical combination of all the regions gives more than 99% confidence for this variation in polarized dust properties. In addition, we show that the Decorrelation increases when there is a decrease in the mean column density of the region of the sky being considered, and we propose a simple power-law empirical model for this dependence, which matches what is seen in the Planck data. We explore the effect that this measured Decorrelation has on simulations of the BICEP2-Keck Array/ Planck analysis and show that the 2015 constraints from these data still allow a Decorrelation between the dust at 150 and 353 GHz that is compatible with our measured value. Finally, using simplified models, we show that either spatial variation of the dust SED or of the dust polarization angle are able to produce Decorrelations between 217 and 353 GHz data similar to the values we observe in the data.
-
Planck intermediate results - L. Evidence of spatial variation of the polarized thermal dust spectral energy distribution and implications for CMB B-mode analysis
Astron.Astrophys., 2017Co-Authors: N Aghanim, M Ashdown, J Aumont, C Baccigalupi, M Ballardini, A J Banday, R B Barreiro, N Bartolo, S. Basak, K. BenabedAbstract:The characterization of the Galactic foregrounds has been shown to be the main obstacle in thechallenging quest to detect primordial B-modes in the polarized microwave sky. We make use of the Planck-HFI 2015 data release at high frequencies to place new constraints on the properties of the polarized thermal dust emission at high Galactic latitudes. Here, we specifically study the spatial variability of the dust polarized spectral energy distribution (SED), and its potential impact on the determination of the tensor-to-scalar ratio, r. We use the correlation ratio of the CBBℓ angular power spectra between the 217 and 353 GHz channels as a tracer of these potential variations, computed on different high Galactic latitude regions, ranging from 80% to 20% of the sky. The new insight from Planck data is a departure of the correlation ratio from unity that cannot be attributed to a spurious Decorrelation due to the cosmic microwave background, instrumental noise, or instrumental systematics. The effect is marginally detected on each region, but the statistical combination of all the regions gives more than 99% confidence for this variation in polarized dust properties. In addition, we show that the Decorrelation increases when there is a decrease in the mean column density of the region of the sky being considered, and we propose a simple power-law empirical model for this dependence, which matches what is seen in the Planck data. We explore the effect that this measured Decorrelation has on simulations of the BICEP2-Keck Array/Planck analysis and show that the 2015 constraints from these data still allow a Decorrelation between the dust at 150 and 353 GHz that is compatible with our measured value. Finally, using simplified models, we show that either spatial variation of the dust SED or of the dust polarization angle are able to produce Decorrelations between 217 and 353 GHz data similar to the values we observe in the data. Key words: cosmic background radiation / cosmology: observations / submillimeter: ISM / dust, extinction⋆ Corresponding author: L. Montier, e-mail: Ludovic.Montier@irap.omp.eu; J. Aumont, e-mail: jonathan.aumont@ias.u-psud.fr
Irena Hajnsek - One of the best experts on this subject based on the ideXlab platform.
-
quantification of temporal Decorrelation effects at l band for polarimetric sar interferometry applications
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2013Co-Authors: Seungkuk Lee, Kostas Papathanassiou, Florian Kugler, Irena HajnsekAbstract:Temporal Decorrelation is the most critical issue for the successful inversion of polarimetric SAR interferometry (Pol-InSAR) data acquired in an interferometric repeat-pass mode, typical for satellite or lower frequency airborne SAR systems. This paper provides a quantitative estimation of temporal Decorrelation effects at L-band for a wide range of temporal baselines based on a unique set of multibaseline Pol-InSAR data. A new methodology that allows to quantify individual temporal Decorrelation components has been developed and applied. Temporal Decorrelation coefficients are estimated for temporal baselines ranging from 10 min to 54 days and converted to height inversion errors caused by them. The temporal Decorrelations of γTV (volume temporal Decorrelation) and γTG (ground temporal Decorrelation) depend not only on the wind-induced movement but also strongly on the rain-induced dielectric changes in volume and on the ground at temporal baseline on the order of day or longer. At temporal baselines on the order of minutes, the wind speed is a critical parameter and the speed of 2 m/s already hampers the application of Pol-InSAR forest parameter inversion. The approach is supported and validated by using L-band E-SAR repeat-pass data acquired in the frame of three dedicated campaigns, BioSAR 2007, TempoSAR 2008, and TempoSAR 2009.
-
IGARSS - Quantification and compensation of temporal Decorrelation effects in polarimetric SAR interferometry
2012 IEEE International Geoscience and Remote Sensing Symposium, 2012Co-Authors: Seungkuk Lee, Kostas Papathanassiou, Florian Kugler, Irena HajnsekAbstract:Temporal Decorrelation is a critical issue for a successful Pol-InSAR inversion in case of repeat-pass SAR data, as provided by conventional satellite or airborne SAR systems. This paper proposes estimation and compensation of temporal Decorrelation effects by using multi-baseline Pol-InSAR data. A new approach to quantify different temporal Decorrelation levels (one for volume and the other for the ground layer) is performed without resort to the special case of zero spatial baseline interferograms. Both temporal Decorrelation coefficients were separately estimated at temporal baselines ranging from 1 to 15 days and compared to height inversion errors caused by them.
-
TerraSAR-X: Exploration of Multitemporal PolSAR and Pol-InSAR Data
2007Co-Authors: Irena Hajnsek, Kostas PapathanassiouAbstract:In this paper two selected system modes of TerraSAR-X, polarimetric SAR and repeat pass interferometric SAR will be investigated with respect to multi- temporal X-band data acquisition. Even if the primary mission goal of TerraSAR-X was not SAR polarimetry and SAR interferometry, TerraSAR-X offers a number of new perspectives to polarimetric and interferometric SAR when compared to current SAR Sensors. The investigations are focused on the change of the observed bio- /geophysical parameters with time over an agricultural and urban area based using the partial polarimetric and repeat pass interferometric data sets. The potential of using X-band polarimetry for surface parameter estimation and coherent scatterer detection will be analysed. Further, the sensitivity of the interferometric coherences to volume decorelation of short vegetated crops will be explored using repeat pass interferometric modes and the effect of temporal Decorrelation using DLR's airborne E-SAR system X-band will be quantified. The TerraSAR-X data in single, dual will be explored in comparison with the X-band airborne data from the DLR's E-SAR system.
A J Banday - One of the best experts on this subject based on the ideXlab platform.
-
planck intermediate results l evidence of spatial variation of the polarized thermal dust spectral energy distribution and implications for cmb b mode analysis
Astronomy and Astrophysics, 2017Co-Authors: N Aghanim, M Ashdown, J Aumont, C Baccigalupi, M Ballardini, A J Banday, R B Barreiro, N BartoloAbstract:The characterization of the Galactic foregrounds has been shown to be the main obstacle in thechallenging quest to detect primordial B -modes in the polarized microwave sky. We make use of the Planck -HFI 2015 data release at high frequencies to place new constraints on the properties of the polarized thermal dust emission at high Galactic latitudes. Here, we specifically study the spatial variability of the dust polarized spectral energy distribution (SED), and its potential impact on the determination of the tensor-to-scalar ratio, r . We use the correlation ratio of the C BB l angular power spectra between the 217 and 353 GHz channels as a tracer of these potential variations, computed on different high Galactic latitude regions, ranging from 80% to 20% of the sky. The new insight from Planck data is a departure of the correlation ratio from unity that cannot be attributed to a spurious Decorrelation due to the cosmic microwave background, instrumental noise, or instrumental systematics. The effect is marginally detected on each region, but the statistical combination of all the regions gives more than 99% confidence for this variation in polarized dust properties. In addition, we show that the Decorrelation increases when there is a decrease in the mean column density of the region of the sky being considered, and we propose a simple power-law empirical model for this dependence, which matches what is seen in the Planck data. We explore the effect that this measured Decorrelation has on simulations of the BICEP2-Keck Array/ Planck analysis and show that the 2015 constraints from these data still allow a Decorrelation between the dust at 150 and 353 GHz that is compatible with our measured value. Finally, using simplified models, we show that either spatial variation of the dust SED or of the dust polarization angle are able to produce Decorrelations between 217 and 353 GHz data similar to the values we observe in the data.
-
Planck intermediate results - L. Evidence of spatial variation of the polarized thermal dust spectral energy distribution and implications for CMB B-mode analysis
Astron.Astrophys., 2017Co-Authors: N Aghanim, M Ashdown, J Aumont, C Baccigalupi, M Ballardini, A J Banday, R B Barreiro, N Bartolo, S. Basak, K. BenabedAbstract:The characterization of the Galactic foregrounds has been shown to be the main obstacle in thechallenging quest to detect primordial B-modes in the polarized microwave sky. We make use of the Planck-HFI 2015 data release at high frequencies to place new constraints on the properties of the polarized thermal dust emission at high Galactic latitudes. Here, we specifically study the spatial variability of the dust polarized spectral energy distribution (SED), and its potential impact on the determination of the tensor-to-scalar ratio, r. We use the correlation ratio of the CBBℓ angular power spectra between the 217 and 353 GHz channels as a tracer of these potential variations, computed on different high Galactic latitude regions, ranging from 80% to 20% of the sky. The new insight from Planck data is a departure of the correlation ratio from unity that cannot be attributed to a spurious Decorrelation due to the cosmic microwave background, instrumental noise, or instrumental systematics. The effect is marginally detected on each region, but the statistical combination of all the regions gives more than 99% confidence for this variation in polarized dust properties. In addition, we show that the Decorrelation increases when there is a decrease in the mean column density of the region of the sky being considered, and we propose a simple power-law empirical model for this dependence, which matches what is seen in the Planck data. We explore the effect that this measured Decorrelation has on simulations of the BICEP2-Keck Array/Planck analysis and show that the 2015 constraints from these data still allow a Decorrelation between the dust at 150 and 353 GHz that is compatible with our measured value. Finally, using simplified models, we show that either spatial variation of the dust SED or of the dust polarization angle are able to produce Decorrelations between 217 and 353 GHz data similar to the values we observe in the data. Key words: cosmic background radiation / cosmology: observations / submillimeter: ISM / dust, extinction⋆ Corresponding author: L. Montier, e-mail: Ludovic.Montier@irap.omp.eu; J. Aumont, e-mail: jonathan.aumont@ias.u-psud.fr
Christopher Gribben - One of the best experts on this subject based on the ideXlab platform.
-
The Perception of Band-Limited Decorrelation Between Vertically Oriented Loudspeakers
IEEE ACM Transactions on Audio Speech and Language Processing, 2020Co-Authors: Christopher GribbenAbstract:Two experiments have been conducted to investigate the perceptual effect of band-limited interchannel Decorrelation between vertically oriented loudspeakers. The perceived vertical image spread (VIS) and tonal quality (TQ) of phantom auditory images have been subjectively assessed in multiple comparison trials. The aim of the article was to find a lower Decorrelation boundary that provides a significant increase of VIS, whilst maintaining TQ close to that of the original source. For test stimuli, Decorrelation was applied to natural sound sources and pink noise in groups of octave-bands, where the lowest band was varied between 63 Hz and 8 kHz and the upper band was fixed at 16 kHz, resulting in eight decorrelated conditions for each source. Unprocessed octave-bands below the lower boundary were reproduced simultaneously through the lower main-layer loudspeaker only, and a monophonic main-layer only condition was also included in the comparison alongside the decorrelated stimuli. Results reveal that vertical Decorrelation of the 500 Hz octave-band and above tends to significantly increase VIS, similar to that of broadband Decorrelation, with little impact on TQ. In some cases, Decorrelation of higher octave-bands and above can also produce similar increases of VIS with less impact on TQ, however, this is shown to be largely source-dependent. These results suggest that vertical Decorrelation of lower frequencies has little perceptual benefit, and band-limiting vertical Decorrelation to higher frequencies is likely to reduce low frequency phase cancellation. Applications of such an approach include 2D-to-3D upmixing and binaural audio rendering, with additional implications for 3D audio recording.
-
Investigations into the perception of vertical interchannel Decorrelation in 3D surround sound reproduction
2018Co-Authors: Christopher GribbenAbstract:The use of three-dimensional (3D) surround sound systems has seen a rapid increase over recent years. In two-dimensional (2D) loudspeaker formats (i.e. two-channel stereophony (stereo) and 5.1 Surround), horizontal interchannel Decorrelation is a well-established technique for controlling the horizontal spread of a phantom image. Use of interchannel Decorrelation can also be found within established two-to-five channel upmixing methods (stereo to 5.1). More recently, proprietary algorithms have been developed that perform 2D-to-3D upmixing, which presumably make use of interchannel Decorrelation as well; however, it is not currently known how interchannel Decorrelation is perceived in the vertical domain. From this, it is considered that formal investigations into the perception of vertical interchannel Decorrelation are necessary. Findings from such experiments may contribute to the improved control of a sound source within 3D surround systems (i.e. the vertical spread), in addition to aiding the optimisation of 2D-to-3D upmixing algorithms. The current thesis presents a series of experiments that systematically assess vertical interchannel Decorrelation under various conditions. Firstly, a comparison is made between horizontal and vertical interchannel Decorrelation, where it is found that vertical Decorrelation is weaker than horizontal Decorrelation. However, it is also seen that vertical Decorrelation can generate a significant increase of vertical image spread (VIS) for some conditions. Following this, vertical Decorrelation is assessed for octave-band pink noise stimuli at various azimuth angles to the listener. The results demonstrate that vertical Decorrelation is dependent on both frequency and presentation angle – a general relationship between the interchannel cross-correlation (ICC) and VIS is observed for the 500 Hz octave-band and above, and strongest for the 8 kHz octave-band. Objective analysis of these stimuli signals determined that spectral changes at higher frequencies appear to be associated with VIS perception – at 0° azimuth, the 8 and 16 kHz octave-bands demonstrate potential spectral cues, at ±30°, similar cues are seen in the 4, 8 and 16 kHz bands, and from ±110°, cues are featured in the 2, 4, 8 and 16 kHz bands. In the case of the 8 kHz octave-band, it seems that vertical Decorrelation causes a ‘filling in’ of vertical localisation notch cues, potentially resulting in ambiguous perception of vertical extent. In contrast, the objective analysis suggests that VIS perception of the 500 Hz and 1 kHz bands may have been related to early reflections in the listening room. From the experiments above, it is demonstrated that the perception of VIS from vertical interchannel Decorrelation is frequency-dependent, with high frequencies playing a particularly important role. A following experiment explores the vertical Decorrelation of high frequencies only, where it is seen that Decorrelation of the 500 Hz octave-band and above produces a similar perception of VIS to broadband Decorrelation, whilst improving tonal quality. The results also indicate that Decorrelation of the 8 kHz octave-band and above alone can significantly increase VIS, provided the source signal has sufficient high frequency energy. The final experimental chapter of the present thesis aims to provide a controlled assessment of 2D-to-3D upmixing, taking into account the findings of the previous experiments. In general, 2D-to-3D upmixing by vertical interchannel Decorrelation had little impact on listener envelopment (LEV), when compared against a level-matched 2D 5.1 reference. Furthermore, amplitude-based Decorrelation appeared to be marginally more effective, and ‘high-pass Decorrelation’ resulted in slightly better tonal quality for sources that featured greater low frequency energy.
-
A Comparison between Horizontal and Vertical Interchannel Decorrelation
Applied Sciences, 2017Co-Authors: Christopher Gribben, Hyunkook LeeAbstract:The perceptual effects of interchannel Decorrelation on perceived image spread have been investigated subjectively in both horizontal and vertical stereophonic reproductions, looking specifically at the frequency dependency of Decorrelation. Fourteen and thirteen subjects graded the horizontal and vertical image spreads of a pink noise sample, respectively. The pink noise signal had been decorrelated by a complementary comb-filter Decorrelation algorithm, varying the frequency-band, time-delay and Decorrelation factor for each sample. Results generally indicated that interchannel Decorrelation had a significant effect on auditory image spread both horizontally and vertically, with spread increasing as correlation decreases. However, it was found that the effect of vertical Decorrelation was less effective than that of horizontal Decorrelation. The results also suggest that the Decorrelation effect was frequency-dependent; changes in horizontal image spread were more apparent in the high frequency band, whereas those in vertical image spread were in the low band. Furthermore, objective analysis suggests that the perception of vertical image spread for the low and middle frequency bands could be associated with a floor reflection; whereas for the high band, the results appear to be related to spectral notches in the ear input signals.
-
The Perception of Vertical Image Spread by Interchannel Decorrelation
Journal of The Audio Engineering Society, 2016Co-Authors: Christopher Gribben, Hyunkook LeeAbstract:Subjective listening tests were conducted to assess the general perception of Decorrelation in the vertical domain. Interchannel Decorrelation was performed between a pair of loudspeakers in the median plane; one at ear level and the other elevated 30° above. The test stimuli consisted of decorrelated octave-band pink noise samples (63–8000 Hz), generated using three Decorrelation techniques—each method featured three degrees of the interchannel cross-correlation coefficient (ICCC): 0.1, 0.4, and 0.7. Thirteen subjects participated in the experiment, using a pairwise comparison method to grade the sample with the greater perceived vertical image spread (VIS). Results suggest there is broadly little difference of overall VIS between Decorrelation methods, and changes to vertical interchannel Decorrelation appear to be better perceived in the upper-middle-frequencies.
-
The Perceptual Effects of Horizontal and Vertical Interchannel Decorrelation Using the Lauridsen Decorrelator
Journal of The Audio Engineering Society, 2014Co-Authors: Christopher Gribben, Hyunkook LeeAbstract:The perceptual effects of interchannel Decorrelation, using a method proposed by Lauridsen, have been investigated subjectively, looking specifically at the frequency dependency of Decorrelation. Twelve subjects graded the perceived auditory image width of a pink noise sample that had been decorrelated by a Lauridsen decorrelator algorithm, varying the frequency-band, time-delay and Decorrelation factor for each sample. The same test has been carried out in both the horizontal and vertical planes. Results generally indicate that Decorrelation is more effective horizontally than vertically. For horizontal Decorrelation, the higher the frequency, the more effective the Decorrelation, with a longer time-delay required for lower frequencies. In contrast, the vertical width produced by vertical Decorrelation is better perceived at lower frequencies than higher ones.
N Aghanim - One of the best experts on this subject based on the ideXlab platform.
-
planck intermediate results l evidence of spatial variation of the polarized thermal dust spectral energy distribution and implications for cmb b mode analysis
Astronomy and Astrophysics, 2017Co-Authors: N Aghanim, M Ashdown, J Aumont, C Baccigalupi, M Ballardini, A J Banday, R B Barreiro, N BartoloAbstract:The characterization of the Galactic foregrounds has been shown to be the main obstacle in thechallenging quest to detect primordial B -modes in the polarized microwave sky. We make use of the Planck -HFI 2015 data release at high frequencies to place new constraints on the properties of the polarized thermal dust emission at high Galactic latitudes. Here, we specifically study the spatial variability of the dust polarized spectral energy distribution (SED), and its potential impact on the determination of the tensor-to-scalar ratio, r . We use the correlation ratio of the C BB l angular power spectra between the 217 and 353 GHz channels as a tracer of these potential variations, computed on different high Galactic latitude regions, ranging from 80% to 20% of the sky. The new insight from Planck data is a departure of the correlation ratio from unity that cannot be attributed to a spurious Decorrelation due to the cosmic microwave background, instrumental noise, or instrumental systematics. The effect is marginally detected on each region, but the statistical combination of all the regions gives more than 99% confidence for this variation in polarized dust properties. In addition, we show that the Decorrelation increases when there is a decrease in the mean column density of the region of the sky being considered, and we propose a simple power-law empirical model for this dependence, which matches what is seen in the Planck data. We explore the effect that this measured Decorrelation has on simulations of the BICEP2-Keck Array/ Planck analysis and show that the 2015 constraints from these data still allow a Decorrelation between the dust at 150 and 353 GHz that is compatible with our measured value. Finally, using simplified models, we show that either spatial variation of the dust SED or of the dust polarization angle are able to produce Decorrelations between 217 and 353 GHz data similar to the values we observe in the data.
-
Planck intermediate results - L. Evidence of spatial variation of the polarized thermal dust spectral energy distribution and implications for CMB B-mode analysis
Astron.Astrophys., 2017Co-Authors: N Aghanim, M Ashdown, J Aumont, C Baccigalupi, M Ballardini, A J Banday, R B Barreiro, N Bartolo, S. Basak, K. BenabedAbstract:The characterization of the Galactic foregrounds has been shown to be the main obstacle in thechallenging quest to detect primordial B-modes in the polarized microwave sky. We make use of the Planck-HFI 2015 data release at high frequencies to place new constraints on the properties of the polarized thermal dust emission at high Galactic latitudes. Here, we specifically study the spatial variability of the dust polarized spectral energy distribution (SED), and its potential impact on the determination of the tensor-to-scalar ratio, r. We use the correlation ratio of the CBBℓ angular power spectra between the 217 and 353 GHz channels as a tracer of these potential variations, computed on different high Galactic latitude regions, ranging from 80% to 20% of the sky. The new insight from Planck data is a departure of the correlation ratio from unity that cannot be attributed to a spurious Decorrelation due to the cosmic microwave background, instrumental noise, or instrumental systematics. The effect is marginally detected on each region, but the statistical combination of all the regions gives more than 99% confidence for this variation in polarized dust properties. In addition, we show that the Decorrelation increases when there is a decrease in the mean column density of the region of the sky being considered, and we propose a simple power-law empirical model for this dependence, which matches what is seen in the Planck data. We explore the effect that this measured Decorrelation has on simulations of the BICEP2-Keck Array/Planck analysis and show that the 2015 constraints from these data still allow a Decorrelation between the dust at 150 and 353 GHz that is compatible with our measured value. Finally, using simplified models, we show that either spatial variation of the dust SED or of the dust polarization angle are able to produce Decorrelations between 217 and 353 GHz data similar to the values we observe in the data. Key words: cosmic background radiation / cosmology: observations / submillimeter: ISM / dust, extinction⋆ Corresponding author: L. Montier, e-mail: Ludovic.Montier@irap.omp.eu; J. Aumont, e-mail: jonathan.aumont@ias.u-psud.fr
