Browsing by Author "Rajan, P. K."

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Efficient design of delta operator based 2-D IIR filters using symmetrical decomposition
(2008)
Khoo, I-Hung
;
Reddy, Hari C.
;
Rajan, P. K.
;
資訊工程學系
;
Department of Computer Science
A method based on symmetrical decomposition is presented for the design of 2-D IIR filters through optimization. This technique allows a filter with non-symmetric magnitude specification to benefit from the savings in parameters provided by symmetry. The procedure is developed for the delta operator based design to take advantage of its better coefficient sensitivity compared to the z-domain design when the filter is narrowband.
Unified theory of symmetry for two-dimensional complex polynomials using delta discrete-time operator
(2011-03-01)
Khoo, I. -Hung
;
Reddy, Hari C.
;
Rajan, P. K.
;
資訊學院
;
College of Computer Science
The complexity in the design and implementation of 2-D filters can be reduced considerably if the symmetries that might be present in the frequency responses of these filters are utilized. As the delta operator (gamma-domain) formulation of digital filters offers better numerical accuracy and lower coefficient sensitivity in narrow-band filter designs when compared to the traditional shift-operator formulation, it is desirable to have efficient design and implementation techniques in gamma-domain which utilize the various symmetries in the filter specifications. Furthermore, with the delta operator formulation, the discrete-time systems and results converge to their continuous-time counterparts as the sampling periods tend to zero. So a unifying theory can be established for both discrete- and continuous-time systems using the delta operator approach. With these motivations, we comprehensively establish the unifying symmetry theory for delta-operator formulated discrete-time complex-coefficient 2-D polynomials and functions, arising out of the many types of symmetries in their magnitude responses. The derived symmetry results merge with the s-domain results when the sampling periods tend to zero, and are more general than the real-coefficient results presented earlier. An example is provided to illustrate the use of the symmetry constraints in the design of a 2-D IIR filter with complex coefficients. For the narrow-band filter in the example, it can be seen that the gamma-domain transfer function possesses better sensitivity to coefficient rounding than the z-domain counterpart.