145 research outputs found
High-resolution sinusoidal analysis for resolving harmonic collisions in music audio signal processing
Many music signals can largely be considered an additive combination of
multiple sources, such as musical instruments or voice. If the musical sources
are pitched instruments, the spectra they produce are predominantly harmonic,
and are thus well suited to an additive sinusoidal model. However,
due to resolution limits inherent in time-frequency analyses, when the harmonics
of multiple sources occupy equivalent time-frequency regions, their
individual properties are additively combined in the time-frequency representation
of the mixed signal. Any such time-frequency point in a mixture
where multiple harmonics overlap produces a single observation from which
the contributions owed to each of the individual harmonics cannot be trivially
deduced. These overlaps are referred to as overlapping partials or harmonic
collisions. If one wishes to infer some information about individual sources in
music mixtures, the information carried in regions where collided harmonics
exist becomes unreliable due to interference from other sources. This interference
has ramifications in a variety of music signal processing applications
such as multiple fundamental frequency estimation, source separation, and
instrumentation identification.
This thesis addresses harmonic collisions in music signal processing applications.
As a solution to the harmonic collision problem, a class of signal
subspace-based high-resolution sinusoidal parameter estimators is explored.
Specifically, the direct matrix pencil method, or equivalently, the Estimation
of Signal Parameters via Rotational Invariance Techniques (ESPRIT)
method, is used with the goal of producing estimates of the salient parameters
of individual harmonics that occupy equivalent time-frequency regions. This
estimation method is adapted here to be applicable to time-varying signals
such as musical audio. While high-resolution methods have been previously
explored in the context of music signal processing, previous work has not
addressed whether or not such methods truly produce high-resolution sinusoidal parameter estimates in real-world music audio signals. Therefore, this
thesis answers the question of whether high-resolution sinusoidal parameter
estimators are really high-resolution for real music signals.
This work directly explores the capabilities of this form of sinusoidal parameter
estimation to resolve collided harmonics. The capabilities of this
analysis method are also explored in the context of music signal processing
applications. Potential benefits of high-resolution sinusoidal analysis are
examined in experiments involving multiple fundamental frequency estimation
and audio source separation. This work shows that there are indeed
benefits to high-resolution sinusoidal analysis in music signal processing applications,
especially when compared to methods that produce sinusoidal
parameter estimates based on more traditional time-frequency representations.
The benefits of this form of sinusoidal analysis are made most evident
in multiple fundamental frequency estimation applications, where substantial
performance gains are seen. High-resolution analysis in the context of
computational auditory scene analysis-based source separation shows similar
performance to existing comparable methods
The DESAM toolbox: spectral analysis of musical audio
International audienceIn this paper is presented the DESAM Toolbox, a set of Matlab functions dedicated to the estimation of widely used spectral models for music signals. Although those models can be used in Music Information Retrieval (MIR) tasks, the core functions of the toolbox do not focus on any specific application. It is rather aimed at providing a range of state-of-the-art signal processing tools that decompose music files according to different signal models, giving rise to different ``mid-level'' representations. After motivating the need for such a toolbox, this paper offers an overview of the overall organization of the toolbox, and describes all available functionalities
Principled Design and Implementation of Steerable Detectors
We provide a complete pipeline for the detection of patterns of interest in
an image. In our approach, the patterns are assumed to be adequately modeled by
a known template, and are located at unknown position and orientation. We
propose a continuous-domain additive image model, where the analyzed image is
the sum of the template and an isotropic background signal with self-similar
isotropic power-spectrum. The method is able to learn an optimal steerable
filter fulfilling the SNR criterion based on one single template and background
pair, that therefore strongly responds to the template, while optimally
decoupling from the background model. The proposed filter then allows for a
fast detection process, with the unknown orientation estimation through the use
of steerability properties. In practice, the implementation requires to
discretize the continuous-domain formulation on polar grids, which is performed
using radial B-splines. We demonstrate the practical usefulness of our method
on a variety of template approximation and pattern detection experiments
Tunable transport with broken space-time symmetries
Transport properties of particles and waves in spatially periodic structures
that are driven by external time-dependent forces manifestly depend on the
space-time symmetries of the corresponding equations of motion. A systematic
analysis of these symmetries uncovers the conditions necessary for obtaining
directed transport. In this work we give a unified introduction into the
symmetry analysis and demonstrate its action on the motion in one-dimensional
periodic, both in time and space, potentials. We further generalize the
analysis to quasi-periodic drivings, higher space dimensions, and quantum
dynamics. Recent experimental results on the transport of cold and ultracold
atomic ensembles in ac-driven optical potentials are reviewed as illustrations
of theoretical considerations.Comment: Phys. Rep., in pres
Study on a miniaturized satellite payload for atmospheric temperature measurements
The atmospheric temperature reflects the thermal balance of the atmosphere and is a
valuable indicator of climate change. It has been widely recognized that the atmospheric
gravity wave activity has a profound effect on the large-scale circulation, thermal and
constituent structures in the mesosphere and lower thermosphere (MLT). Temperature
distribution in this region is an essential component to identify and quantify gravity
waves. Observation from remote sensing instruments on satellite platforms is an effective
way to measure the temperature in the MLT region.
A miniaturized satellite payload is developed to measure the atmospheric temperature
in the MLT region via observing the O2A-band emission. Following a Boltzmann
distribution, the relative intensities of the emission lines can be used to derive the temperature
profile. Based on the spatial heterodyne spectroscopy, this instrument is capable
of resolving individual emission lines in the O2A-band for the spatial and spectral
information simultaneously. The monolithic and compact feature of this spectrometer
makes it suitable for operating on satellite platforms.
In this work, the characterization of the instrument is investigated for the purpose
of simultaneously measuring multiple emission lines of the O2A-band. The instrument
is explored through a series of experimental methods, providing characteristics of the
instrument and evaluation of its performance. In spatial and spectral domain, Level-
0 and Level-1 data processors are developed to convert the raw data to the calibrated
spectral radiance for further temperature and gravity wave characterization.
Within this framework, the performance of the utilized detector is evaluated along
with its radiation tolerance in space environment. In the processor, the detector artifacts
are corrected based on the measurements in laboratory or in space. The radiometric
response of the instrument is characterized on a pixel-by-pixel basis using a blackbody.
An interferogram distortion correction algorithm is developed to correct for the spatial
and phase distortion induced by the detector optics. Further, localized phase distortion
correction is implemented to correct for the remaining phase error. Unwanted ghost
emission lines are removed based on two dimensional Fourier transform. In the spectral
domain, the processing steps mainly consist of wavelength calibration and instrument
spectral response correction, including filter response correction and modulation efficiency
correction.
As an in-orbit verification, the AtmoSHINE instrument was successfully deployed
in space on 22th of December, 2018. In the first test phase, the functionality and the
performance of the instrument in space were verified. The detector dark current measurement
in orbit is consistent with the ground-based results. Based on the the calibration
procedures and the developed data processing algorithms, the O2A-band emission
lines can be successfully resolved. A cross-verification of the AtmoSHINE limb radiance
profile with other satellite payload measurements indicates that the radiometric
performance of the instrument is within the expectation. The retrieved temperature parameters
are studied with respect to different number of samples and different objective
functions in the optimization. This work verifies the ability of the instrument to derive
the atmospheric temperature in the MLT region and its potential application in gravity
wave detections
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