Methods for Simultaneous Improvement of Comb Pass Band and Folding Bands

2019 ◽  
pp. 978-994
Author(s):  
Gordana Jovanovic Dolecek
Keyword(s):  
Design Methods ◽  
Comb Filter ◽  
Signal Spectrum ◽  
Pass Band ◽  
Original Spectrum ◽  
Compensator Design ◽  
Decimation Filter

This decimation introduces the replicas of the main signal spectrum. If the signal is not properly filtered, the overlapping of the repeated replicas of the original spectrum, called aliasing, may occur. The aliasing may destroy the useful information of the decimated signal and must be eliminated by the filter which precedes the decimation, called decimation filter. The most popular decimation filter is a comb filter, usually used in the first stage of decimation. However, its magnitude characteristic is not flat in the pass band of interest and there is not enough attenuation in the folding bands. Different methods are proposed to improve comb magnitude characteristic. This chapter presents an overview of methods for simultaneous improvement of comb magnitude characteristic in both: pass band and folding bands. The methods are divided into three main groups: sharpening-based methods, corrector-based methods, and methods based on the combination of alias rejection and compensator design methods.

Methods for Simultaneous Improvement of Comb Pass Band and Folding Bands

2018 ◽  
pp. 6171-6183
Author(s):  
Gordana Jovanovic Dolecek
Keyword(s):  
Design Methods ◽  
Comb Filter ◽  
Signal Spectrum ◽  
Pass Band ◽  
Original Spectrum ◽  
Compensator Design ◽  
Decimation Filter

This decimation introduces the replicas of the main signal spectrum. If the signal is not properly filtered, the overlapping of the repeated replicas of the original spectrum, called aliasing, may occur. The aliasing may destroy the useful information of the decimated signal and must be eliminated by the filter which precedes the decimation, called decimation filter. The most popular decimation filter is a comb filter, usually used in the first stage of decimation. However its magnitude characteristic is not flat in the pass band of interest and there is not enough attenuation in the folding bands. Different methods are proposed to improve comb magnitude characteristic. This article presents an overview of methods for simultaneous improvement of comb magnitude characteristic in both: pass band and folding bands. The methods are divided into three main groups: Sharpening-based methods, Corrector–based methods, and Methods based on the combination of alias rejection and compensator design methods.

scholarly journals Sharpening of the multistage modified comb filters

2011 ◽  
Vol 8 (3) ◽  
pp. 281-291 ◽  
Author(s):  
Marko Nikolic ◽  
Miroslav Lutovac
Keyword(s):  
Comb Filter ◽  
Polyphase Filter ◽  
Filter Structure ◽  
Direct Form ◽  
Comb Filters ◽  
Decimation Filter ◽  
Last Stage ◽  
Positive Integers

This paper describes the application of filter sharpening method to the modified comb filter (MCF) in the case of decimation factor, which is product of two or more positive integers. It is shown that in the case of multistage decimation with MCF, filters in each stage are also MCF. Applying the sharpening to the decimation filter in the last stage provides very good results, with savings in the number of operations comparing to the case of sharpening of the complete filter. Direct-form FIR polyphase filter structure is proposed for the filters in each stage.

Methods for Improving Alias Rejections in Comb Filters

2018 ◽  
pp. 4746-4760
Author(s):  
Gordana Jovanovic Dolecek
Keyword(s):  
Chebyshev Polynomials ◽  
Sampling Rate ◽  
Comb Filter ◽  
Comb Filters ◽  
Decimation Filter

Downsampling is the process of decreasing the sampling rate of signal by an integer. This process may introduce the unwanted spectrum replica called aliasing. To avoid aliasing the signal must be filtered by decimation filter prior downsampling. Decimation consists of filtering and downsampling. The most simple decimation filter is comb filter usually used in the first stage of decimation. However, comb filter does not provide a good aliasing rejection. This paper presents the methods for improving alias rejection of comb filters. The methods are based on comb zero rotation, cosine filters, Chebyshev polynomials, and cascade of combs with different parameters.

Methods for Improving Alias Rejections in Comb Filters

2019 ◽  
pp. 891-909
Author(s):  
Gordana Jovanovic Dolecek
Keyword(s):  
Chebyshev Polynomials ◽  
Sampling Rate ◽  
Comb Filter ◽  
Comb Filters ◽  
Decimation Filter

Downsampling is the process of decreasing the sampling rate of signal by an integer. This process may introduce the unwanted spectrum replica called aliasing. To avoid aliasing, the signal must be filtered by decimation filter prior to downsampling. Decimation consists of filtering and downsampling. The simplest decimation filter is comb filter usually used in the first stage of decimation. However, comb filter does not provide a good aliasing rejection. This chapter presents methods for improving alias rejection of comb filters. The methods are based on comb zero rotation, cosine filters, Chebyshev polynomials, and cascade of combs with different parameters.

scholarly journals FPGA Based Performance Analysis of Multistage CIC Decimation Filter Design with former CIC Filter for WiMAX Applications

2019 ◽  
Vol 8 (6) ◽  
pp. 5084-5089
Keyword(s):  
Frequency Response ◽  
Filter Design ◽  
Stop Band ◽  
Pass Band ◽  
Two Stage ◽  
Simulink Model ◽  
Cic Filter ◽  
Decimation Filter ◽  
Two Stages ◽  
Kaiser Window

The motto of this paper is to design and realize decimation filter using CIC filter. The main drawback of this filter is there is large droop in pass band and very less attenuation in stop band. So, to improve the frequency response of CIC filter we go for two stage realization of CIC filter. At the initial stage we use CIC filter and in the last stage we use Kaiser Window and improve the characteristics of filter design. When we design a filter using multistage methodology the order of the filter as well as power also decreases. Tools used are MATLAB Simulink Model and Xilinx system generator and realization is done on Virtex V-XC5VLX110T-3ff136. In this paper the proposed two stage realization is compared with respect to two stages Kaiser window realization in the terms of number of LUT’s required, slices as well as power dissipation and improvements in frequency response with respect to conventional CIC filter are compared

Compensation Design of CIC Decimation Filter for Seismic Prospecting

2011 ◽  
Vol 52-54 ◽  
pp. 829-833
Author(s):  
Jian Zhong Qi ◽  
Li Jun Cao
Keyword(s):  
High Speed ◽  
Seismic Survey ◽  
Pass Band ◽  
Low Resolution ◽  
Seismic Prospecting ◽  
Analog Signals ◽  
Survey System ◽  
Cic Filter ◽  
Decimation Filter ◽  
Compensation Design

In seismic prospecting, the over sample combined with low quantity is used to converter input analog signals to 1-bit data flow. In order to realize decimation filtering for the high speed low resolution signal produced in the process of seismic prospecting, the CIC decimation filter is introduced into seismic survey system to achieve decimation and filting. The principle and the shortcoming were analyzed; finally an ISOP filter is introduced to compensate the pass-band attenuation, Simulation showed it could improve the performance of CIC filter, the cascade of CIC and ISOP is suitable for seismic prospecting system.

Design and Research of Digital Decimation Filter Based on FPGA

2011 ◽  
Vol 105-107 ◽  
pp. 2086-2091
Author(s):  
Yao Li
Keyword(s):  
High Speed ◽  
Sampling Rate ◽  
Comb Filter ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Cic Filter ◽  
Decimation Filter ◽  
Fpga Chip ◽  
Digital Down Conversion

This paper studies and analyses various digital filter and decimation structure. On this basis, by using QUARTUS development system design the decimation device modules, through the waveform simulation validated its correctness. Finally,a program is written into FPGA chip by the hardware platform. In the digital down conversion (DDC), CIC (cascade integral comb) filter plays an important role. It is mainly used for sampling rate, as well as low-pass filter effect. The main characteristics of CIC filter, using only adders, subtractor and register (no multiplier), so fewer resources occupied, implementation is simple and high speed. Based on the analysis of the principle of CIC filter,simulate and synthesize based on the theory of using VHDL language in FPGA. And successful application in the development of DDC chip. Keyword: CIC (cascade integral comb) filter,FPGA,VHDL

Design of a Digital Decimation Filter for High-Precision 4-Order Sigma-Delta ADC

2012 ◽  
Vol 503 ◽  
pp. 415-419 ◽  
Author(s):  
Wei Ping Chen ◽  
Qiang Fu ◽  
Xiao Wei Liu ◽  
Yan Xiao ◽  
Bin Zhang ◽  
...  
Keyword(s):  
High Precision ◽  
Sampling Rate ◽  
Stop Band ◽  
Cutoff Frequency ◽  
Pass Band ◽  
Sigma Delta ◽  
Band Filter ◽  
Cic Filter ◽  
Decimation Filter ◽  
Sigma Delta Adc

In this paper, a design of a digital decimation filter which has a output of 24 bits for high-precision 4-ordes Σ-Δ ADC is proposed. The digital decimation filter includes a CIC filter, a compensation filter and a half band filter. The over-sampling rate of the digital decimation filter is 256, the cutoff frequency is 1kHz, the coefficient of the pass-band ripple is -0.25dB, the stop-band attenuation is -162dB, simulation results using Matlab and modelsim are correct, the result of the FPGA verification shows that the design meet the requirement of the high-precision 4-ordes Σ-Δ ADC.

A Dosimetric Comparison of Three Compensator Design Methods for the Mantle Field

1989 ◽  
Vol 14 (4) ◽  
pp. 257-263 ◽  
Author(s):  
Jane P. Cantwell ◽  
Wendel D. Renner ◽  
Thomas P. O’Connor ◽  
Nini M. Bermudez
Keyword(s):  
Design Methods ◽  
Dosimetric Comparison ◽  
Compensator Design

scholarly journals Improving Comb Aliasing Rejection Using Sharpening of Modified Comb

2021 ◽  
Vol 1208 (1) ◽  
pp. 012031
Author(s):  
Gordana Jovanovic Dolecek
Keyword(s):  
Impulse Response ◽  
Efficient Method ◽  
Comb Filter ◽  
Two Stage ◽  
First Order ◽  
Comb Structure ◽  
Second Stage ◽  
Decimation Filter ◽  
Passband Droop

Abstract This paper presents an efficient method to improve the comb aliasing rejection in a comb decimation filter without increasing its passband droop. This problem is important since aliasing and comb passband droop may deteriorate the decimated signal. We propose here to apply sharpening of the modified comb in the second stage of a two-stage comb structure. The modified comb is obtained by decreasing the middle coefficient of the impulse response of the cascade of two combs by 1/2. The sharpening polynomial with the first order tangencies is used here. As a result, the comb folding bands, where the aliasing occur, become wider and with an increased attenuation in comparison with the original comb filter. However, this improvement in the folding bands did not result in an increased passband droop. The compensator from literature is used to further decrease passband droop. The method is illustrated with examples and compared with the original comb and the methods proposed in literature for increasing aliasing rejection.

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