In this paper, the alignment of noisy high-resolution radar signals using the maximum position method is studied. The relationship between the shift estimation and the signal-to-noise ratio is considered. As a result, two analytical expressions are obtained that approximate the root-mean-square error of the difference in the shift estimation with and without noise. These two expressions allow us to improve the understanding of the sensitivity to noise of the Maximum Position alignment method.

Hearing loss may disqualify many people from leading a normal life, though the majority do not make use of hearing aids. This is because most hearing aids on the market cannot automatically adapt to the changing acoustical environment the user faces daily. This paper focuses on the development of an automatic sound classifier for digital hearing aids that aims to enhance listening comprehension when the user goes from one sound environment to another. Given the strong complexity constraints of these devices, reducing the number of signal-describing features which feed the automatic classifier is of great importance and becomes a challenging topic. Thus, the use of genetic algorithms with restricted search is explored for the mentioned feature selection. In an effort to evaluate its performance, the algorithm is compared with a standard unconstrained genetic algorithm and with sequential methods. The restricted search driven by the implemented genetic algorithm performs better than both the sequential methods and unconstrained genetic algorithms. It thus allows a subset of signal-describing features with lower cardinality to be selected. This may permit these selected features to be programmed on the digital signal processor that the hearing aid is based on, and to make efficient use of its limited computational facilities.

This paper presents an automatic road-sign detection and recognition system based on support vector machines (SVMs). In automatic traffic-sign maintenance and in a visual driver-assistance system, road-sign detection and recognition are two of the most important functions. Our system is able to detect and recognize circular, rectangular, triangular, and octagonal signs and, hence, covers all existing Spanish traffic-sign shapes. Road signs provide drivers important information and help them to drive more safely and more easily by guiding and warning them and thus regulating their actions. The proposed recognition system is based on the generalization properties of SVMs. The system consists of three stages: 1) segmentation according to the color of the pixel; 2) traffic-sign detection by shape classification using linear SVMs; and 3) content recognition based on Gaussian-kernel SVMs. Because of the used segmentation stage by red, blue, yellow, white, or combinations of these colors, all traffic signs can be detected, and some of them can be detected by several colors. Results show a high success rate and a very low amount of false positives in the final recognition stage. From these results, we can conclude that the proposed algorithm is invariant to translation, rotation, scale, and, in many situations, even to partial occlusions

In this letter, we propose a novel matching pursuit-based method for transient modeling with application to parametric audio coding. The overcomplete dictionary for the matching pursuit is composed of wavelet functions that implement a wavelet-packet filter bank. The proposed transient modeling method is suitable to be integrated into a parametric audio coder based on the three-part model of sines, transients, and noise (STN model). Comparative analysis between wavelet and exponentially damped sinusoidal functions are shown in experimental results. The mean-squared-error performance of the proposed approach is better than that obtained with damped sinusoids.

A new approach to designing nearly perfect transmultiplexers based on cosine-modulated filter banks for xDSL applications is presented. We propose a new way of designing the prototype filter from which the transmitting and receiving filters are derived. The resulting TMUX systems do not have phase distortion, and amplitude distortion is almost null. The importance of the prototype filter design technique on the performance of the TMUX system is evaluated and a comparative analysis with other very efficient methods is realized.

We present an efficient way to extract the illumination from the images by exploring only the low frequencies into them jointly with the use of the illumination model from the homomorphic filter. This illumination information may be used to code images in a sequence with only illumination changes. We take an image from the sequence as a reference. Any other image to be coded is approximated by changing the low pass band of the discrete wavelet transform of the reference with that from the image to be coded. To improve the recovering process it is possible to modify the high frequencies into the reference image according to the differences between the illumination from the reference and from the image to be recovered. The results obtained show us a new way to code illumination changes when used with video sequences.

Pseudo-QMF banks in which there is no optimization involved in order to obtain the prototype filter used in the cosine modulation are an advance that simplifies the system design. In this paper, three filter bank design methods that satisfy this requirement-all of them employ any conventional designing technique-are proposed. These filter banks do not introduce phase distortion, their aliasing is comparable to the stopband gain of the prototype filter and amplitude distortion can be really minimized. The differences among them are prototype filter specifications and the initial phase factor election. When the prototype filters are appropriately designed, the total error on the reconstructed output signal is reduced. An example where an audio signal is the input signal is included.

A new method for still image coding that tries to exploit intra and inter-band relations in the wavelet-transformed matrix is presented. An intuitive study of the relation between coefficients is done. The conclusion is that it is more important to exploit intra-band relations than inter-band relations. Results achieved are even better than those obtained with the best embedded published algorithms.