Tomas Nordström

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This paper reports on a comparative study of several automatic speaker verification systems using the Polycost database. Polycost is a multi-lingual database with non-native English and mother-tongue speech by subjects from 14 countries. We present results for the first three baseline experiments defined for the database as well as explore the multi-lingual(More)
This thesis investigates the iterative application of Monte Carlo methods to the problem of parameter estimation for models of maximum entropy, minimum divergence, and maximum likelihood among the class of exponential-family densities. It describes a suite of tools for applying such models to large domains in which exact computation is not practically(More)
In this paper we introduce Epiphany as a highperformance energy-efficient manycore architecture suitable for real-time embedded systems. This scalable architecture supports floating point operations in hardware and achieves 50 GFLOPS/W in 28 nm technology, making it suitable for high performance streaming applications like radio base stations and radar(More)
The common-mode (CM) signal in wireline transmission systems has proven to provide valuable information exploited for mitigating narrowband noise at the receive side. In this paper, we focus on the case of broadband noise. Treating the CM signal as an additional receive signal, we investigate the capacity of the copper cable channel for different levels of(More)
Narrowband radio transmitters like radio amateurs and broadcast radio stations are considered to be a serious problem for highbitrate data transmission over twisted pairs. Due to its high power level, radio frequency interference (RFI) has the potential of overloading the receiver’s analog-to-digital converter (ADC). Once the ADC is in saturation, any(More)
Among all noise sources present in wireline transmission systems we focus on one special type: narrowband radio frequency interference generated by radio amateurs (HAM) and broadcast radio stations. This disturbance, characterized by high power and narrow bandwidth, has the potential of overloading the receiver’s analog-to-digital converter (ADC). Once the(More)
To better utilize the capacity of the twisted-pair access networks, operators deploying very high-speed digital subscriber line (VDSL) systems need accurate parameters for power back-off (PBO). However, VDSL standards give almost no guidance on how these parameters should be established for a particular network. In this paper we present a new technique for(More)
Self organizing maps (SOM) are a class of artificial neural network (ANN) models developed by Kohonen. There are a number of variants, where the self organizing feature map (SOFM) is one of the most used ANN models with unsupervised learning. Learning vector quantifiers (LVQ) is another group of SOM which can be used as very efficient classifiers. SOM have(More)
Dynamic spectrum management (DSM) is an important technique for mitigating crosstalk noise in multi-user digital subscriber line (DSL) environments. Until now, most of the proposed algorithms for DSM have been designed solely for the purpose of bitrate maximization. These algorithms assume a fixed maximum total power and neglect the energy consumption in(More)