Design of Tunable One-Dimensional and Two-Dimensional Digital Comb Filters
Date Issued
2009
Date
2009
Author(s)
Lin, Shih-Hsin
Abstract
In many applications of signal processing, the harmonic interference rejection is required. An example is to cancel the power line interference in the electrocardiogram (ECG) signal in the biomedical area. The goal of the cancellation can be usually achieved through the use of comb filter, which is periodic with the stopband notches at 0 Hz. So far, several methods have been developed to design comb filter, and some of them are related to the design of fractional delay. As for fractional delay, the method of variable fractional delay (VFD) design has achieved a great attention due to the on-lining tuning property. In this thesis, we will propose a new approach to transform the specification of comb filter design into that of VFD design. Under this approach, the designing problem is simplified to find the optimized coefficients of some induced delay from VFD filter, and thus the designed comb filter will tend to be on-line tunable. In addition, a feed-back path containing FIR comb filter will be proposed to design multi-bandpass filter. Through the on-line tuning property of FIR comb filter, the designed multi-bandpass filter will be on-line tunable also. After the investigation of one-dimensional (1-D) comb filter, two-dimensional (2-D) comb filter is worth our while. Since only few literatures are related to 2-D comb filter, the goal in this thesis is to find the transfer function of 2-D comb filter, which is more complicated than 1-D comb filter. Through a lot of experience, it is found that some important issues are necessary to consider detail for the goal. From these considerations, finally, we will derive the transfer function of 2-D comb filter. In this thesis, the primary achievements are: the connection between comb filter and VFD filter, the design of tunable comb filter, the design of tunable multi-bandpass filter, and a closed-from of 2-D comb filter.
Subjects
Harmonic Interference
FIR Comb Filter
IIR Comb Filter
Variable Fractional Delay
Multi-Bandpass Filter
Weighted Least-Squares Approach
Type
thesis
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