Browsing by Author "Kao, MC"

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A new approach to the design of QMF banks
(1998)
Kao, MC
;
Chen, SG
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
New L-2 objective functions for the design of quadrature-mirror-filter (QMF) banks are proposed. They are based on the derivative information of the reconstruction error. Simple and explicit matrix-form expressions for the proposed objective functions are derived. An efficient design method is proposed by incorporating a separability technique into the derived optimality conditions on prototype filters. The proposed method only needs to solve linear equations iteratively without nonlinear optimization. Design examples demonstrate that good low-delay QMF banks and linear-phase QMF banks can be obtained after a few iterations. Compared to the conventional approach, the new approach leads to QMF banks with larger stopband attenuation and smaller reconstruction errors.
A new type of perfect-reconstruction QMF banks
(1997)
Chen, SG
;
Kao, MC
;
Chen, SP
;
交大名義發表
;
電子工程學系及電子研究所
A new type of perfect-reconstruction QMF system is proposed. The filter system is based on half-band filters so that it has lower complexity and group delay than the known QMF systems, with a comparable performance. It is shown that the new PR QMF system achieves zero phase distortion and zero amplitude distortion, in addition to producing aliase-free outputs. A filter optimization technique is also proposed for its prototype low pass filter. For realization, its polyphase architecture is derived, which has very simple structure.
A novel iterative design technique for linear-phase FIR half-band filters
(2000)
Kao, MC
;
Chen, SG
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper proposes a novel iterative design scheme for generating linear-phase, half-band FIR filters with considerably reduced arithmetic operations and narrow transition bandwidth. Starting from a short half-band subfilter, preferably a multiplier-free one, the scheme can evolve this subfilter to a better composite half-band filter by using simple algebraic composition transformation iteratively. Compared to the existing design methods, the proposed scheme is free of filter optimization process and is much simpler. In implementation, the designed half-band filters can be realized as a multi-stage cascaded structure, composed of several short half-band subfilters and delay elements. Since its building elements have trivial coefficients with short wordlengths, the proposed structure for half-band filters has low complexity and low coefficient dynamic range. Thus it is suitable for finite-precision implementation. Furthermore, the structure is highly modular, repetitive in all stages, and suitable for VLSI implementation.
Design of QMF banks based on derivative information
(1999-10-01)
Kao, MC
;
Chen, SG
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
New L-2 objective functions for the design of quadrature mirror filter (QMF) banks are proposed. They are based on the derivative information of the reconstruction error Simple and explicit matrix-form formulas for the proposed objective functions are derived. Efficient design methods are proposed by incorporating a separability technique into the derived optimality conditions on prototype filters. The proposed design methods need only solve linear equation iteratively without nonlinear optimisation. Design examples demonstrate that good low-delay QMF banks and linear-phase QMF banks can be obtained in only a few iterations. Compared with the conventional approach, the new approach leads to QMF banks with larger stopband attenuation and smaller reconstruction errors.
Low-complexity, perfect reconstruction FIR QMF bank
(1998-07-23)
Chen, SG
;
Kao, MC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A low-complexity, perfect reconstruction quadrature mirror filter (QMF) bank is proposed, which requires only 50% of the multiplications and additions of the existing QMF banks per output sample. In addition, the new QMF bank only needs to solve a set of linear equations instead of the commonly required nonlinear optimisation technique for the prototype filter.
Modeling of the response of midbrain auditory neurons in the rat to their vocalization sounds based on FM sensitivities
(1997)
Kao, MC
;
Poon, PWF
;
Sun, X
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Single units were recorded from the inferior colliculus (IC) of anaesthetized rats in response to: (a) an FM tone, the frequency of which was randomly varied, and (b) a digitized rat vocalization sound. We hypothesized that these neurons may have 'orientation-specific' spectrotemporal receptive field (STRF) that can be used to estimate their responses to complex communication signals. Based on the FM response, we first estimated the cell's STRF which was then convolved with the spectrogram of the rat's vocalization call. A simple convolution gave only crude prediction of the cell's response to the vocalization sound. When inhibitory areas were added around certain parts of the STRF, a better match was found. We conclude that for some FM-sensitive neurons of the IC, STRF with inhibitory areas may account for their responses to vocalization sounds.