9,126 research outputs found
Bandwidth extension of narrowband speech
Recently, 4G mobile phone systems have been
designed to process wideband speech signals whose
sampling frequency is 16 kHz. However, most part of
mobile and classical phone network, and current 3G
mobile phones, still process narrowband speech signals
whose sampling frequency is 8 kHz. During next future,
all these systems must be living together. Therefore,
sometimes a wideband speech signal (with a bandwidth up
to 7,2 kHz) should be estimated from an available
narrowband one (whose frequency band is 300-3400 Hz).
In this work, different techniques of audio bandwidth
extension have been implemented and evaluated. First, a
simple non-model-based algorithm (interpolation
algorithm) has been implemented. Second, a model-based
algorithm (linear mapping) have been designed and
evaluated in comparison to previous one. Several CMOS
(Comparison Mean Opinion Score) [6] listening tests show
that performance of Linear Mapping algorithm clearly
overcomes the other one. Results of these tests are very
close to those corresponding to original wideband speech
signal.Postprint (published version
Least squares DOA estimation with an informed phase unwrapping and full bandwidth robustness
The weighted least-squares (WLS) direction-of-arrival estimator that minimizes an error based on interchannel phase differences is both computationally simple and flexible. However, the approach has several limitations, including an inability to cope with spatial aliasing and a sensitivity to phase wrapping. The recently proposed phase wrapping robust (PWR)-WLS estimator addresses the latter of these issues, but requires solving a nonconvex optimization problem. In this contribution, we focus on both of the described shortcomings. First, a conceptually simpler alternative to PWR is presented that performs comparably given a good initial estimate. This newly proposed method relies on an unwrapping of the phase differences vector. Secondly, it is demonstrated that all microphone pairs can be utilized at all frequencies with both estimators. When incorporating information from other frequency bins, this permits a localization above the spatial aliasing frequency of the array. Experimental results show that a considerable performance improvement is possible, particularly for arrays with a large microphone spacing
A study and experiment plan for digital mobile communication via satellite
The viability of mobile communications is examined within the context of a frequency division multiple access, single channel per carrier satellite system emphasizing digital techniques to serve a large population of users. The intent is to provide the mobile users with a grade of service consistant with the requirements for remote, rural (perhaps emergency) voice communications, but which approaches toll quality speech. A traffic model is derived on which to base the determination of the required maximum number of satellite channels to provide the anticipated level of service. Various voice digitalization and digital modulation schemes are reviewed along with a general link analysis of the mobile system. Demand assignment multiple access considerations and analysis tradeoffs are presented. Finally, a completed configuration is described
Frame Theory for Signal Processing in Psychoacoustics
This review chapter aims to strengthen the link between frame theory and
signal processing tasks in psychoacoustics. On the one side, the basic concepts
of frame theory are presented and some proofs are provided to explain those
concepts in some detail. The goal is to reveal to hearing scientists how this
mathematical theory could be relevant for their research. In particular, we
focus on frame theory in a filter bank approach, which is probably the most
relevant view-point for audio signal processing. On the other side, basic
psychoacoustic concepts are presented to stimulate mathematicians to apply
their knowledge in this field
Communications
The communications sector of an economy comprises a range of technologies, physical media, and institutions/rules that facilitate the storage of information through means other than a society\u27s oral tradition and the transmission of that information over distances beyond the normal reach of human conversation. This chapter provides data on the historical evolution of a disparate range of industries and institutions contributing to the movement and storage of information in the United States over the past two centuries. These include the U.S. Postal Service, the newspaper industry, book publishing, the telegraph, wired and cellular telephone service, radio and television, and the Internet
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