Valentin Stanciu

Optimal grouped B-spline windows for power spectral density estimation

The solution, of minimizing the effect known as spectral leakage into the sidelobe of a window function is to obtain a continuous waveform, which results in lesser sidelobe level. Conventional windows are able to control these characteristics by only one parameter. To suppress the spectral leakage, a window function in the time domain is used to shape the finite time sampled measurement data. The higher order of continuity of the of the time window function can be obtained by using grouped B-spline functions with three control parameters for power spectral density estimation.

B-spline approach for the design of quadrature mirror filters

In this paper a design method of the optimum quadrature mirror filters (QMF), by using symmetric B-spline functions, is presented. It was shown that linear phase FIR filters cannot exactly satisfy the condition that the squared amplitude frequency responses are mirror images of each other about the line ω= π /2 which has led to the name quadrature mirror flters. It is important to have a flat frequency response for the filters. The solution is to approximate the response of each frequency band by using B-spline functions, that insures continuous superior order derivatives. In the proposed method, the prototype filter is optimized with the novelty of using spline functions in the transition band.

Continuous polynomials combination for the design of quadrature mirror filters

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 result is a good frequency selectivity. In the proposed approach, the prototype filter is optimized, by using continuous polynomials in the transition band. Many simulation results are presented to sustain the proposed method.

Grouped B-spline functions for the design of Quadrature Mirror Filters

The design of two channel Quadrature Mirror Filter (QMF) banks is considered with constraints on the peaks of the reconstruction error and that of the subband filter ripple sizes. In this paper a design method of the optimum quadrature mirror filters (QMF), by using grouped B-spline functions in each transition band, is presented. It was shown that linear phase FIR filters cannot exactly satisfy the condition that the squared amplitude frequency responses are mirror images of each other about the line ω = π / 2, which has led to the name quadrature mirror filters. It is important to have a flat frequency response for the filters. The solution is to approximate the response of each frequency band by using grouped B-spline functions, that insures continuous superior order derivatives.

FPGA implementation for power spectral estimation using grouped B-Spline windows

Spectrum sensing is an essential component in radio systems such as cognitive networks, which aim for opportunistic usage of unutilized radio spectrum. In order to perform an accurate estimation and reduce spectral leakage, grouped B-Spline windows can be used. The amplitude of the windows can be modified using three control parameters. A hardware implementation solution is presented and the performance of the proposed system is verified. The analyzed structure is attractive for hardware implementations with spectral sensing features.

Digital apodizing filters design by using B-spline functions and continuous polynomials

This paper presents a design method of the audio digital appodizing filters, by using B-spline and continuous polynomial functions in the transition frequency band. It is known that an appodizing filter can be used to control the time smear for a recording and a reproducing chain. The choice of the frequency response above 20 kHz can reduce the time extent of the impulse response. In the proposed approach, the appodizing filter is optimized with the novelty of using spline functions and continuous polynomials in the transition band. Several design examples are included to illustrate the proposed algorithm.

Grouped B-spline functions for the design of improved FIR filters

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 windows and a modified transfer function. In the proposed method, the composite filter maintains the linear phase, because the complementary comb filters have linear phase responses.