Lucian Anton

The synthesis of some NLFM laws using the stationary phase principle

In radar literature, the sidelobes reduction techniques using synthesis of some proper nonlinear FM (NLFM) laws represents a major scientific research direction. Accordingly, in order to assure the sidelobes suppression, the main objective of this paper is to present an adequate synthesis algorithm of some NLFM laws based on stationary phase principle. The achieved experimental results confirm a significant sidelobes reduction (i.e., more than -40 dB) without necessity to apply some weighting techniques. Finally, the analysis of the synthesized NLFM laws by ambiguity function tool was also discussed.

A TD-PSOLA based method for speech synthesis and compression

Mobility and cost restrictions of current text-to-speech systems stop them from being used by people with speech impairments all over the world. Therefore new ways to improve mobility and lower cost have to be developed. This can be done by decreasing the computational resources used by speech synthesis systems. Non-parametric concatenative synthesis techniques provide the easiest way to generate artificial speech with high quality. Although, they can be, in general, computationally efficient (e.g., TD-PSOLA) they are not always suited for implementation on embedded devices because they require rather large recorded speech data-bases. A big part of the recorded speech data is represented by the samples of the vowels. Therefore, compression ratios of at least 25% can be achieved for Romanian, by removing all these samples but one overlap-add (OLA) frame. At synthesis, the remaining vowel is used to generate the original sound. The paper presents a new method for the generation and the compression of vowels, starting from only one OLA frame and using TD-PSOLA in new way. Experiments show that by appropriately choosing pitch and amplitude jitter models, high quality synthetic speech can be achieved.

Sidelobes reduction using frequency predistortioning techniques on LFM signals

In the high resolution radar theory, a lot of powerful sidelobes reduction techniques are indicated. Belonging to this major research direction, the goal of this paper is to present some theoretical and experimental results achieved by applying on a LFM radio pulse with the low values of the basis, of the temporal frequency predistortioning techniques at the pulse ends using two proper nonlinear laws. Finally, some aspects concerning the optimization of the parameters assigned to the proposed frequency predistortioning laws are also discussed.

ICA-based information extraction method for PolSAR images

Identifying and characterizing objects in PolSAR images rely on proper backscattered signal models, correct segmentation algorithms and on exploiting the connections between the phisical structure of the considered objects and their radar echos. The paper presents an ICA-based approach for characterizing physical properties of the objects on the Earth surface. Segmentation of PolSAR image is based on stochastic models. Each segment is assimilated to an object or surface type and pixels of the segment are treated like realizations of the underlying target scattering mechanism. This scattering mechanism is characterized through ICA-based approach, thus providing information about the corresponding target. The TSVM decomposition is used to analyze the mixing matrix issued from ICA and to link its values to physical properties of the target.

Improving optimization of mobile networks by using fuzzy logic techniques

In order to improve the quality of service for data services in UMTS, complex analysis and optimization campaign must be made. Faster and reliable optimization is possible by using fuzzy logic modelling, in order to have an easier approach and understanding of the solution to implement.