Derk Reefman - Academia.edu (original) (raw)
Papers by Derk Reefman
Physica C: Superconductivity, 1992
Abstract—A mathematical framework, based on state-space modeling, for the description of limit cy... more Abstract—A mathematical framework, based on state-space modeling, for the description of limit cycles (LCs) of 1-bit sigma–delta modulators (SDMs) is presented. It is proved that periodicity in bit output pattern of the SDM implies a periodic orbit in state-space variables. While the state-space description is generally applicable for periodic inputs, the focus is on dc inputs, since this represents the most relevant practical condition. An outcome of the analysis is that, in general, for an th-order SDM, at least 1 initial conditions need to be fixed in order to have LC behavior. Expressions for the minimum disturbance of the input or initial conditions that is needed to break up a LC are also presented. Special focus is given to the case where the disturbance takes the form of “dithering the quantizer”, and it is shown that this form of dither is a suboptimal approach to remove LCs. The stability of LCs is determined, and it is demonstrated that a resonator section, as often emplo...
Journal of The Audio Engineering Society, 2003
Journal of The Audio Engineering Society, 2003
... Audio Engineering Society A new Digital-to-Analogue converter design technique for HiFi appli... more ... Audio Engineering Society A new Digital-to-Analogue converter design technique for HiFi applications Derk Reefman1 , John van den Homberg1 , Ed van ... For cheap IC processes, it reaches however its limits of performance close to SNR values of -110 dB because it does only ...
Journal of The Audio Engineering Society, 2003
Journal of The Audio Engineering Society, 2001
In this paper, an overview of Direct Stream Digital (DSD) signal processing is given. It is shown... more In this paper, an overview of Direct Stream Digital (DSD) signal processing is given. It is shown that 1-bit DSD signals can be dithered properly, so the resulting dithered DSD stream does not contain audible artifacts in a band from 0-100 kHz. It is also shown that signal processing can be done best in a high rate, multi-bit domain. Arguments are given that the minimal frequency span needed to comply with the human auditory system is roughly 0-300 kHz. Following the signal processing, nal conversion to DSD is made. It is demonstrated that Super Audio CD (SACD) is a very eÆcient consumer format: it is the format which, while maintaining all necessary psycho-acoustical characteristics such has high band width, ltering with wide transition bands etc., uses the least bits from the disk; hence o ering the longest playing time. INTRODUCTION In the past few years, there has been an evolving trend in the audio world to move from the standard CD-format (i.e., 16 bit resolution, and a sampli...
Journal of The Audio Engineering Society, 2007
In this listening test, two digital audio systems (X and Y), and one analog system (A) were teste... more In this listening test, two digital audio systems (X and Y), and one analog system (A) were tested by 10 test persons who listened to a surround sound scene “live” (without recording). The main question to be answered was: ”Which of the two digital systems best matches the audio quality of the analog system?” Both digital versions had 24bit dynamic resolution but differed in sampling rate with which the analog signal was sampled. One version (Y) was sampled with a CD rate of 44.1 kHz, the other (X) 8 times faster. There were also two test conditions, where in one condition there was a bandwidth cut off at 20 kHz instead of the 100 kHz that was possible with special 100 kHz microphones and added super-tweeters. For each subject, the experiment was replicated six times in random order, in each of the two conditions. The outcome of each experiment was a 0 or 1, where the 1 means that the, technically best, digital system X has been chosen as meeting the analog quality. The paper descri...
Journal of The Audio Engineering Society, 2004
A coding technique that is used to losslessly compress 1 bit audio data is introduced. The indivi... more A coding technique that is used to losslessly compress 1 bit audio data is introduced. The individual steps in the encoding and decoding process are detailed, and an example illustrating the complete algorithm is provided. The lossless compression performance of the algorithm is provided. The lossless compression performance of the algorithm and its dependence on various genres of music are discussed. To circumvent the classical problem of playing time uncertainty, intimately connected to any lossless coding technique, the concept of a playing time estimator is introduced, and feasibly of 1-bit compression is demonstrated.
Journal of The Audio Engineering Society, 2002
A method is presented for improving current coding efficiency in DSD signals. The goal of this wo... more A method is presented for improving current coding efficiency in DSD signals. The goal of this work is to explore new compression techniques which are tailored to the DSD format and which are meant to complement the current lossless DST compression practice used for SACD. The new technique builds on principles illustrated in previous papers. The method makes use of the highly oversampled character of DSD. Example implementations and results have been obtained. Losses to stability and signal-to-noise ratio have been measured and their audio effects have been minimised and quantified. Lower bounds are established on the compression ratio of these methods. This is viewed as a first step for a potentially constant bitrate compression scheme.
Journal of The Audio Engineering Society, 2009
Acta Crystallographica Section A Foundations of Crystallography, 1996
2005 European Conference on Power Electronics and Applications, 2005
ABSTRACT
Physical review. B, Condensed matter, 1993
ABSTRACT
Acta Crystallographica Section C-crystal Structure Communications, 1987
Le compose du titre cristallise dans le systeme orthorhombique avec le groupe d'espace Pbca. ... more Le compose du titre cristallise dans le systeme orthorhombique avec le groupe d'espace Pbca. Affinement de la structure jusqu'a 0,063. Les atomes Mn sont entoures octaedriquement par 2 moles d'eau orientees en trans et 4 atomes N du coordinat
Physical Review B, 1990
ABSTRACT
MRS …, 1997
ABSTRACTThin Ag-Ni and Ag-Co layers with compositions of 0, 15, 22 to 28 at% Ni or Co were made b... more ABSTRACTThin Ag-Ni and Ag-Co layers with compositions of 0, 15, 22 to 28 at% Ni or Co were made by magnetron sputtering. TEM experiments revealed that the layers exhibited a {111} fiber texture with a high density of twins, always with the twinning plane parallel to the layer surface. X-ray diffraction and TEM results indicate that all Ni or Co is dissolved in the Ag, although some compositional inhomogeneity occurs: the layers are highly supersaturated with Ni or Co. Unlike the pure Ag layer, the Ag-Ni and Ag-Co layers exhibited high strains in the as prepared state.Upon annealing Ni or Co precipitated. The Ni precipitates were small, spherical particles oriented parallel to the surrounding Ag. The strains in the Ag-Ni and Ag-Co layers after annealing were less than the calculated thermal strains, but they were larger than the strain in the pure Ag layer after an equal annealing treatment.
Solid State Communications, 1990
ABSTRACT
Physical Review Letters, 1994
ABSTRACT
Physica C: Superconductivity, 1992
Abstract—A mathematical framework, based on state-space modeling, for the description of limit cy... more Abstract—A mathematical framework, based on state-space modeling, for the description of limit cycles (LCs) of 1-bit sigma–delta modulators (SDMs) is presented. It is proved that periodicity in bit output pattern of the SDM implies a periodic orbit in state-space variables. While the state-space description is generally applicable for periodic inputs, the focus is on dc inputs, since this represents the most relevant practical condition. An outcome of the analysis is that, in general, for an th-order SDM, at least 1 initial conditions need to be fixed in order to have LC behavior. Expressions for the minimum disturbance of the input or initial conditions that is needed to break up a LC are also presented. Special focus is given to the case where the disturbance takes the form of “dithering the quantizer”, and it is shown that this form of dither is a suboptimal approach to remove LCs. The stability of LCs is determined, and it is demonstrated that a resonator section, as often emplo...
Journal of The Audio Engineering Society, 2003
Journal of The Audio Engineering Society, 2003
... Audio Engineering Society A new Digital-to-Analogue converter design technique for HiFi appli... more ... Audio Engineering Society A new Digital-to-Analogue converter design technique for HiFi applications Derk Reefman1 , John van den Homberg1 , Ed van ... For cheap IC processes, it reaches however its limits of performance close to SNR values of -110 dB because it does only ...
Journal of The Audio Engineering Society, 2003
Journal of The Audio Engineering Society, 2001
In this paper, an overview of Direct Stream Digital (DSD) signal processing is given. It is shown... more In this paper, an overview of Direct Stream Digital (DSD) signal processing is given. It is shown that 1-bit DSD signals can be dithered properly, so the resulting dithered DSD stream does not contain audible artifacts in a band from 0-100 kHz. It is also shown that signal processing can be done best in a high rate, multi-bit domain. Arguments are given that the minimal frequency span needed to comply with the human auditory system is roughly 0-300 kHz. Following the signal processing, nal conversion to DSD is made. It is demonstrated that Super Audio CD (SACD) is a very eÆcient consumer format: it is the format which, while maintaining all necessary psycho-acoustical characteristics such has high band width, ltering with wide transition bands etc., uses the least bits from the disk; hence o ering the longest playing time. INTRODUCTION In the past few years, there has been an evolving trend in the audio world to move from the standard CD-format (i.e., 16 bit resolution, and a sampli...
Journal of The Audio Engineering Society, 2007
In this listening test, two digital audio systems (X and Y), and one analog system (A) were teste... more In this listening test, two digital audio systems (X and Y), and one analog system (A) were tested by 10 test persons who listened to a surround sound scene “live” (without recording). The main question to be answered was: ”Which of the two digital systems best matches the audio quality of the analog system?” Both digital versions had 24bit dynamic resolution but differed in sampling rate with which the analog signal was sampled. One version (Y) was sampled with a CD rate of 44.1 kHz, the other (X) 8 times faster. There were also two test conditions, where in one condition there was a bandwidth cut off at 20 kHz instead of the 100 kHz that was possible with special 100 kHz microphones and added super-tweeters. For each subject, the experiment was replicated six times in random order, in each of the two conditions. The outcome of each experiment was a 0 or 1, where the 1 means that the, technically best, digital system X has been chosen as meeting the analog quality. The paper descri...
Journal of The Audio Engineering Society, 2004
A coding technique that is used to losslessly compress 1 bit audio data is introduced. The indivi... more A coding technique that is used to losslessly compress 1 bit audio data is introduced. The individual steps in the encoding and decoding process are detailed, and an example illustrating the complete algorithm is provided. The lossless compression performance of the algorithm is provided. The lossless compression performance of the algorithm and its dependence on various genres of music are discussed. To circumvent the classical problem of playing time uncertainty, intimately connected to any lossless coding technique, the concept of a playing time estimator is introduced, and feasibly of 1-bit compression is demonstrated.
Journal of The Audio Engineering Society, 2002
A method is presented for improving current coding efficiency in DSD signals. The goal of this wo... more A method is presented for improving current coding efficiency in DSD signals. The goal of this work is to explore new compression techniques which are tailored to the DSD format and which are meant to complement the current lossless DST compression practice used for SACD. The new technique builds on principles illustrated in previous papers. The method makes use of the highly oversampled character of DSD. Example implementations and results have been obtained. Losses to stability and signal-to-noise ratio have been measured and their audio effects have been minimised and quantified. Lower bounds are established on the compression ratio of these methods. This is viewed as a first step for a potentially constant bitrate compression scheme.
Journal of The Audio Engineering Society, 2009
Acta Crystallographica Section A Foundations of Crystallography, 1996
2005 European Conference on Power Electronics and Applications, 2005
ABSTRACT
Physical review. B, Condensed matter, 1993
ABSTRACT
Acta Crystallographica Section C-crystal Structure Communications, 1987
Le compose du titre cristallise dans le systeme orthorhombique avec le groupe d'espace Pbca. ... more Le compose du titre cristallise dans le systeme orthorhombique avec le groupe d'espace Pbca. Affinement de la structure jusqu'a 0,063. Les atomes Mn sont entoures octaedriquement par 2 moles d'eau orientees en trans et 4 atomes N du coordinat
Physical Review B, 1990
ABSTRACT
MRS …, 1997
ABSTRACTThin Ag-Ni and Ag-Co layers with compositions of 0, 15, 22 to 28 at% Ni or Co were made b... more ABSTRACTThin Ag-Ni and Ag-Co layers with compositions of 0, 15, 22 to 28 at% Ni or Co were made by magnetron sputtering. TEM experiments revealed that the layers exhibited a {111} fiber texture with a high density of twins, always with the twinning plane parallel to the layer surface. X-ray diffraction and TEM results indicate that all Ni or Co is dissolved in the Ag, although some compositional inhomogeneity occurs: the layers are highly supersaturated with Ni or Co. Unlike the pure Ag layer, the Ag-Ni and Ag-Co layers exhibited high strains in the as prepared state.Upon annealing Ni or Co precipitated. The Ni precipitates were small, spherical particles oriented parallel to the surrounding Ag. The strains in the Ag-Ni and Ag-Co layers after annealing were less than the calculated thermal strains, but they were larger than the strain in the pure Ag layer after an equal annealing treatment.
Solid State Communications, 1990
ABSTRACT
Physical Review Letters, 1994
ABSTRACT