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47 lines
1.7 KiB
C
47 lines
1.7 KiB
C
/**
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******************************************************************************
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* @addtogroup OpenPilot Math Utilities
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* @{
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* @addtogroup Butterworth low pass filter
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* @{
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*
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* @file butterworth.h
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* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2014.
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* @brief Direct form two of a second order Butterworth low pass filter
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*
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* @see The GNU Public License (GPL) Version 3
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*
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*****************************************************************************/
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/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifndef BUTTERWORTH_H
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#define BUTTERWORTH_H
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// Coefficients of second order Butterworth biquadratic filter in direct from 2
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struct ButterWorthDF2Filter {
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float b0;
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float a1;
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float a2;
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};
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// Function declarations
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void InitButterWorthDF2Filter(const float ff, struct ButterWorthDF2Filter *filterPtr);
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void InitButterWorthDF2Values(const float x0, const struct ButterWorthDF2Filter *filterPtr, float *wn1Ptr, float *wn2Ptr);
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float FilterButterWorthDF2(const float xn, const struct ButterWorthDF2Filter *filterPtr, float *wn1Ptr, float *wn2Ptr);
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#endif
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