Chivapreecha, Sorawat
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Chivapreecha, Sorawat
Alternative Name
Chivapreecha, S.
Chivapreecha, Sorwat
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Email
sorawat.ch@kmitl.ac.th
15 results
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Item type:Publication, Generalized Pascal matrices, inverses, computations and properties using one-to-one rational polynomial s-z transformations(2008-01-01); Dejhan, KobchaiThis paper proposes a one-to-one mapping between the coefficients of continuous-time (s-domain) and discrete-time (z-domain) IIR transfer functions such that the s-domain numerator/denominator coefficients can be uniquely mapped to the z-domain numerator/denominator coefficients. The one-to-one mapping provides a firm basis for proving the inverses of the so-called generalized Pascal matrices from various first-order s-z transformations. We also derive recurrence formulas for recursively determining the inner elements of the generalized Pascal matrices from their boundary ones. Consequently, all the elements of the whole generalized Pascal matrix can be easily generated through utilizing their neighbourhood, which can be exploited for further simplifying the Pascal matrix generations. Finally, we reveal and prove some interesting properties of the generalized Pascal matrices. © 2008 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, An FPGA-based implementation of variable fractional delay filter(2009-10-19); Dejhan, KobchaiA variable fractional delay (VFD) filter is widely used in applications such as symbol timing recovery, arbitrary sampling rate conversion and echo cancellation. This paper presents an implementation of variable fractional delay filter on FPGA. The implementation utilizes an efficient structure so called Taylor structure. The main advantage of this structure is to reduce number of multiplier and adder when compared with Farrow structure or modified Farrow structure. The result of implementation will be reported as throughput and area utilization. ©2009 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Design of multiplierless elliptic narrowband IIR digital filter based on sensitivity analysis(2004-12-01); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Adaptive equalization architecture using distributed arithmetic for partial response channels(2006-12-01); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Bilinear s-z with frequency transformation using pascal matrix operation(2005-12-01); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Weighted least-squares design of variable recursive digital filters with guaranteed stability(2013-12-31); Dejhan, KobchaiThe stability guarantee is the most important issue in designing variable infinite-impulse-response (IIR) digital filters. This paper presents a new variable substitution method for transforming the denominator coefficients of a variable-IIR-filter into another set of variables such that arbitrary values of the new variables can guarantee the stability of the resulting variable-IIR-filter. That is, the design problem subject to stability guarantee (constrained non-linear design problem) is converted into an unconstrained design problem. As a consequence, the resulting variable-IIR-filters are always guaranteed theoretically. A lowpass variable-IIR-filter design example is given to illustrate the effectiveness of the design formulation. © 2013 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Bi-minimax design of even-order variable fractional-delay FIR digital filters(2012-01-01); Dejhan, KobchaiThis paper proposes a new minimax method for designing even-order finite-impulse-response (FIR) variable fractional-delay (VFD) digital filters with both the peak errors (maximum absolute errors) of variable frequency response (VFR) and VFD response being minimized. We call such a new minimax design the bi-minimax design, which minimizes a mixed error function that contains both the VFR peak error and VFD peak error. A relative weighting factor is used in the mixed error function for adjusting the relative weightings of the two peak errors. The central part of the biminimax design is how to formulate the biminimax design with highly non-linear constraints on the VFD errors as a solvable one. After linearizing the highly non-linear constraints as linear ones, the biminimax design problem can be easily solved by using the well-known efficient software SeDuMi. As a result, both the VFR peak error and VFD peak error can be simultaneously suppressed and the resulting VFR errors and VFD errors are made nearly equiripple (bi-equiripple). As compared with the existing SOCP-based minimax design that minimizes only the VFR peak error, the proposed biminimax method can achieve a nearly biequiripple design for both the VFR and VFD errors. A design example is given to illustrate the effectiveness of the biminimax design method. © 2004-2012 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Unified Pascal matrix for first-order s-z domain transformations(2009-06-16); Dejhan, KobchaiThe so-called generalized Pascal matrix is used for transforming a continuous-time (CT) linear system (filter) into a discrete-time (DT) one. This paper derives an explicit expression for a new generalized Pascal matrix called unified Pascal matrixfrom a unified first-order s-z transformation model and rigorously proves the inverses for various first-order s-z transformations. After deriving a recurrence formula for recursively generating the inner elements of the unified Pascal matrix from its boundary elements, we also show that the recurrence formula leads to computationally unstable solutions for high-order systems due to the so-called catastrophic cancellation in numerical computation, but the unstable problem can be solved through partitioning the whole unified Pascal matrix into several small matrices (submatrices) and then using the recurrence formula to compute the submatrices individually from their boundary elements. This operation almost retains the same computational complexity while guarantees numerically stable solutions. Moreover, an interesting property of the unified Pascal matrix is proved. © 2009 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, GISTDA EOC synthetic aperture radar data processing system(2010-09-17); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Even order biquad digital filter design using pascal matrix(2008-12-01); Dejhan, KobchaiThis paper presents new design method and structure of IIR digital filter. The new design method is based on bilinear s-z transformation and Pascal matrix theorem. These theories are used to transform the normalized analog transfer functions to digital transfer functions. The structure of IIR digital filter is modified for even order biquad digital filter which can give frequency response simultaneously as low-pass, high-pass, band-pass and band-stop filtering. The new structure use delay units the same as single frequency response IIR digital filters that has same order.I © 2008 IEEE.