Due to the periodical motions of most machinery in steady state operation, many diagnosis techniques are based on frequency analysis. This is often performed through Fourier transform. Some extensions of these techniques to the more general case of non stationary operation have been proposed. They are based on signal processing advances such as time-frequency representations and adaptive filter...

In the last decade it has become clear that one of the central themes within Gabor analysis (with respect to general timefrequency lattices) is a duality theory for Gabor frames, including the Wexler-Raz biorthogonality condition, the Ron-Shen’s duality principle or Janssen’s representation of a Gabor frame operator. All these results are closely connected with the so-called Fundamental Identit...

While Independent Subspace Analysis provides a means of blindly separating sound sources from a single channel signal, it does have a number of problems. In particular the amount of information required for separation of sources varies with the signal. This is as a result of the variance-based nature of Principal Component Analysis, which is used for dimensional reduction in the Independent Sub...

A technique using the time-frequency phase information of two microphones is proposed to estimate an ideal timefrequency mask using time-delay-of-arrival (TDOA) of the signal of interest. At a signal-to-noise ratio (SNR) of 0dB, the proposed technique using two microphones achieves a digit recognition rate (average over 5 speakers, each speaking 20-30 digits) of 71%. In contrast, delayand-sum b...

Time-frequency distributions (TFDs) have proven useful in a wide variety of nonstationary signal processing applications. While sophisticated optimal bilinear TFDs have been developed to extract the maximum possible timefrequency information from signals, certain applications dictate simpler linear, running-FFT processing techniques. In this paper, we propose a signal-dependent short-time Fouri...

Within the EU FP6 Integrated Project WINNER, adaptive transmission is investigated as a key technology for boosting the spectral efficiency of a new radio interface for 4G systems. Adaptive allocation of timefrequency bins in an OFDM-based system offers a significant potential, but also poses challenges. Within work package 2 of WINNER, we study critical issues such as the feasibility of adapti...

This paper presents the theoretical background for the Model Based Underdetermined Source Separation presented in [5]. We show that for a given frequency band, in contrast to customary assumption, the observed Short-Time Fourier Transform (STFT) ratio coming from one source is not constant in time, but is a random variable whose distribution we have obtained. Using this distribution and the Tim...

we present a general theory of $ilii~ear/ quadratic signal representations t h a t a l e coiianant to timefrequency (TF) displacement operators resentations are developed in the CY,,^') dQmaiiB and iio the e e o ~ ~ u ~ a ~ e case, covariant representa,tions can also be formulated in an eigenfunction parameter domain ( ( a , b ) domain). The relations connecting the (0, p), TF, and (U, b) domai...

In this paper, we consider a random network in which the nodes are deployed as a Poisson Point Process. Under this model, we find the medium access rate of nodes using a CSMA-type MAC protocol. For finite network areas this is a timefrequency parameter, while for infinite network areas it translates into a spatial parameter since stationarity can be assumed. The expressions found here make the ...