Implementation of the Variable Center Frequency Band-Pass Filter Based on FPGA

Abstract:

Digital band-pass filters play a very important role in instrument design. For some special applications, such as corrosion inspection of buried oil or gas pipeline, more than one band-pass filter with different center frequencies are needed to process different frequency signals. FPGA (Field-Programmable Gate Array) are widely used in these applications because of its high compute velocity and flexibility. For low cost and high reliability purposes, it is expected that one digital filter with a fixed configuration parameters can serve as multi different center frequency digital filter. In this paper a design method is proposed to realize two different center frequency band-pass filters which have the same filtering effect. Through analysis of design process for FIR band-pass filter, it’s easy to find that if the ratios (filter’ sample rate of input data to its cut-off frequency) of two filters keep equal, the normalized frequency will also equal. Thus according to this, two band-pass filters can have the same coefficients only if they have the same ratio of sample rate to cut-off frequency. This relationship is discussed here and MATLAB experiment is used to prove its effectiveness. This method is already used to design filters in pipeline current mapper instrument to inspect pipeline corrosion.

• Periodical: Advanced Materials Research (Volumes 1049-1050)
• Pages: 642-645
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1049-1050.642
• Online since: October 2014
• Authors: Dan Hua Hu*, Zhao Xiong Zeng, Jing Song Meng, Chang Hua Zhang
• Keywords: FIR Filter, FPGA, PCM, Pipeline Corrosion, Variable Center Frequency

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