Toma Miyata

A design method for separable-denominator 2D IIR filters using a stability criterion based on the system matrix

In this paper, we propose designing method for separable-denominator two-dimensional Infinite Impulse Response (IIR) filters (separable 2D IIR filters) by Successive Projection (SP) methods using a stability criterion based on the system matrix. It is generally known that separable 2D IIR filters are stable if and only if each of the denominators is stable. Therefore, the stability criteria of 1D IIR filters can be used for separable 2D IIR filters. A stability criterion based on the system matrix is a necessary and sufficient condition to guarantee stability in 1D IIR filters. Therefore, separable 2D IIR filters obtained by the proposed method have a smaller error ripple than those obtained by the conventional method.

A reducing the number of polynomial coefficients method for variable notches FIR filters

In this paper, we propose a design method for finite impulse response (FIR) variable digital filters (VDFs) obtaining quasi-equiripple characteristic even if notch frequencies change. The change in filter coefficients, which depends on the change in notch frequencies, is approximated by a polynomial using variable parameters. In this method, the minimization problem for the polynomial coefficients with variable notches is formulated as semidefinite programming (SDP) in the frequency domain. However, the number of polynomial coefficients increases when variable parameters are plural number. Therefore, we also propose a method for reducing the number of polynomial coefficients. The usefulness of the proposed VDF is demonstrated through examples.

Designing two-channel nonuniform-division FIR filter banks with variable notches

In this paper, we propose a design method for a variable two-channel nonuniform-division FIR filter bank. The proposed filter bank can change the notch frequency in the stopband for each filter to reduce these noise. For changing notch frequencies, filter coefficients are approximated by polynomials using variable parameters in the proposed filter bank. In addition, the proposed filter bank satisfies approximately perfect reconstruction condition, and the filter bank exhibits quasi-equiripple characteristics in the passband and stopband. Linear programming is used to design the proposed filter bank in the frequency domain. The usefulness of the proposed filter bank is demonstrated through an example.

Nonuniform-division FIR filter bank with variable transmission zeros using Farrow structure

In this paper, we propose a design method for two-channel nonuniform-division FIR filter bank with variable transmission zeros in the stopband at each filters. For changing transmission variable parameters. In addition, the proposed filter bank satisfies approximately perfect reconstruction condition, and exhibits quasi-equiripple characteristics in the passband and stopband. Linear programming is used to design the proposed filter bank in the frequency domain. The proposed variable two-channel nonuniform-division FIR filter bank can be implemented using the Farrow structure, which is suitable for real time signal processing. The usefulness of the proposed filter bank is demonstrated through an example.

A design method for IIR digital filters with variable stopband using semidefinite programming

Several application in digital signal processing demand variable digital filters with arbitrary variable frequency response. For example, in dynamic gravimetry, the main vibration noise is changed by kinds or size of measurement and spec of conveying means. In this case, if a part of main noise is changed, it is important that changing characteristics of filter at once. FIR digital filter are always stable. However, because FIR digital filter generally needs high order, the delay is increased and it is problem in high speed and high accuracy signal processing. Then this paper describes a design method for IIR digital filters with variable stopbands. Numerator filter coefficients are approximated by polynomials using a variable parameter. We solve its transfer function by semidefinite programming in the frequency domain. Finally, a design example is given to demonstrate the proposed techniques.

A successive projections method with a changeable maximum allowable deviation

A applicability of Successive Projections (SP) method is wide. In the previous SP method which is an iterative approximation method, only one extreme frequency point at which the deviation from the given specification is maximized is used in the update of the filter coefficients. We extended to SP method which can update the filter coefficients by the multiple extreme frequency points using Fritz Johns theorem. In this method, the solution is obtained less iteration number than the previous method. However, because it is necessary to decide the maximum allowable error experientially, there is the case that the solution does not converge and the obtained filter does not have equiripple characteristics. In this paper, we present a design method of linear phase FIR filters by SP method updating maximum allowable error. The updating maximum allowable error analytically solves such as Remez algorithm. Finally, we confirm the effectiveness of propose method through several examples.

A design method of FIR digital filters with variable stop bands using iterative WLS

In the field of measurement signal processing, we should often change the characteristic of the stopband instantaneously. Such the filter that can change the frequency response instantaneously is called variable filter. We propose the design of FIR digital filters with variable stopbands. In this paper, the quasi-chebyshev characteristic is obtained by using an iterative weighted least square (WLS) method. Moreover, a memory required for the calculation for computing filter coefficients in the proposed method has the feature of being fewer than the conventional method. The usefulness of the proposed design method is verified through some examples.

Semidefinite programming for variable notch FIR filters

In this paper, we propose a transfer function of filters which does not change filter characteristics even if notch frequency changes. A change in filter coefficient which depends on change in a notch frequency is approximated by the polynomial which used a variable parameter. In this method, the minimization problems for the coefficients of the filter with a variable notch are formulated as semidefinite programming (SDP) in the frequency domain. Moreover we present that the proposed VDF can be implemented using the Farrow structure suitable for high-speed signal processing.

Designing FIR filters with variable notch

In this paper, we propose a transfer function of filters which does not change filter characteristics even if notch frequency changes. A change in filter coefficient which depends on change in a notch frequency is approximated by the polynomial which used a variable parameter. In this method, the minimization problems for the coefficients of the filter with a variable notch are formulated as semidefinite programming (SDP) in the frequency domain. Moreover we present that the proposed VDF can be implemented using the Farrow structure suitable for high-speed signal processing.