Yukio Mori

A closed form transfer function of low delay bandpass FIR filters with maximally flat characteristics in the passband and the transmission zeros in the stopband

The large group delay of the high order FIR fillers is unacceptable in some applications. So, recently, how to reduce the group delay of FIR filters has been studied intensively. To reduce the ringing in the time domain and to maximize the stopband attenuation, it is useful to design FIR filters with maximally flat characteristics in the passband and transmission zeros in the stop band. We present a mathematically closed form transfer function of low delay bandpass FIR filters with maximally fiat amplitude in the passband and the transmission zeros in the stopband. Therefore, the designing filters are very simple.

Kernel with block structure for sampling rate converter

Sampling rate conversion using the filter banks is proposed in the field of digital signal processing. However, in sampling rate conversion with a rational factor, the computational complexity may become very large. Moreover whenever the sampling rate is changed, it is necessary to design the filter again. In this paper, hence, we present a kernel with block structure for sampling rate conversion. As the filter proposed has the impulse response approximated by polynomials, it is unnecessary to redesign whenever the sampling rate is changed. The kernel proposed has the block structure that the impulse response of the sampling section since the third is represented by the polynomial used for the second sampling section. Therefore, the filter has less memory. Moreover, the filter has the advantage that it is possible to correspond to arbitrary fractional sampling rate conversion.

Designing FIR filter with variable stopbands

In this paper, we define filters capable of changing frequency response as variable digital filters (VDFs). In the previous VDF having changed a piecewise large attenuation characteristic in the stopband, it is difficult to decrease the filter degree to two or more, changing noises. We propose a transfer function of FIR filters with changing some large attenuations in the stopband by using spectral parameters and its design method. The number of spectrum parameters used here uses the number of changing stopbands. In this method, the minimization problems are formulated as semidefinite programming (SDP) in the frequency domain. Moreover, we present that the proposed VDF can be implemented using Farrow structure. Finally, we confirm the effectiveness of this method through numerical examples.

A Design Method and Structure of Kernel for Sampling Rate Converter

In this paper, we propose arbitrary block structures of a kernel with nth polynomials and block ratio, and its design method for sampling rate converter. Because the proposed kernels are polynomial based, they can be efficiently implemented using the Farrow structure for the real time applications. In order to obtain a large attenuation, we design the kernel in the frequency domain using a modern optimization methodology known as semidefinite programming (SDP). The sampling rate changed fractional number is possible by the proposed kernel. Finally, effectiveness of the proposed kernel is verified through an example

The transfer function of low delay maximally flat lowpass FIR digital filters

This paper describes a closed form transfer function of low delay maximally flat lowpass finite impulse response (FIR) filters. It is possible to obtain the transfer function with the required degree of flatness in the passband and the stopband. In addition, the obtained transfer function has the required group delay at /spl omega/=0. The proposed design method is extremely simple, because of the closed form transfer function. We show the design examples of even and odd order filters.