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This paper proposes a chaos-based communication scheme which transmits a secret speech signal. To recover the states of the transmitter and the unknown message, the receiver uses a high order sliding mode observer. Its input is one of the states of the transmitter. The control parameters of the observer constitute the secret key of the transmission. The main aspect in which the present work differs...
The classical stereophonic acoustic echo cancellation (SAEC) scheme requires the identification of four echo paths using the same number of adaptive algorithms. The SAEC setup can be reinterpreted by employing the widely linear (WL) model, which recasts the two-input/two-output system with real random variables as a single-input/single-output system with complex random variables. The WL model improves...
The design of the finite impulse response (FIR) digital filters with linear phase is considered by cascading a prototype filter with complementary comb filters. The minimum attenuation in the stop band is increased and the complexity of implementation is reduced, because the complementary comb filters contain only adders and storage units. The prototype filter is designed by using grouped B-spline...
The regularization of the recursive least-squares (RLS) adaptive algorithm is a subject rarely approached in literature. The classical regularization method is implemented in the initial stages of the algorithm and has a time-limited effect on the corresponding correlation matrix. This paper proposes a new regularization technique for the RLS — dichotomous coordinate descent (DCD) algorithm, which...
This material proposes an efficient method for the design of the two channel quadrature mirror filters (QMF) bank, by using continuous polynomial functions. It is important to know that linear phase FIR filters cannot exactly satisfy the power complementarity condition. The proposal is to approximate the amplitudes of the two frequency transition bands by using continuous polynomial functions. The...
Radio resources have had higher demand in the last years. The frequency band licenses for most of the radio spectrum are sold for long periods of time and give exclusive rights to the owner. By using such an approach the spectrum seems overcrowded, but the reality shows that many frequency areas are actually used in a very small degree. We have demonstrated in [4] that cognitive radio (CR) technology...
We propose an improved spectral subtraction method for the reduction of colored acoustic noise added to the speech. Our implementation uses a time-recursive algorithm for estimation of the noise power spectral density and a multi-band spectral over subtraction method to reduce the colored noise. Simulations show a better quality in terms of Itakura Saito distance and perceptual evaluation of quality...
This paper proposes an algorithm for accurate detection of salient areas from a given scene. We used a complex model for the human visual system, in order to simulate the visual perception mechanisms. Human visual system modelling requires accurate knowledge about the entire visual pathways. This work focuses on the following features of the human vision: the color perception mechanism, the perceptual...
We propose an improved spectral subtraction method for reducing acoustic noise added to speech in noisy environments like helicopter cockpit or car engine. This implementation uses oversubtraction method for spectral subtraction. Residual noise can be masked by exploiting the masking properties of the human auditory system. A psychoacoustically motivated weighting filter was included to eliminate...
We propose an improved spectral subtraction method for the reduction of colored acoustic noise added to the speech in a helicopter cockpit or in a car caused by the engine sound. Our implementation uses an over-estimation subtraction method for spectral subtraction. The noise signal does not affect uniformly the speech signal over the whole spectrum. A nonlinear multi-band Bark scale frequency spacing...
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