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Diffstat (limited to 'src/modules/mathlib/math/filter/LowPassFilter2p.cpp')
| -rw-r--r-- | src/modules/mathlib/math/filter/LowPassFilter2p.cpp | 77 |
1 files changed, 0 insertions, 77 deletions
diff --git a/src/modules/mathlib/math/filter/LowPassFilter2p.cpp b/src/modules/mathlib/math/filter/LowPassFilter2p.cpp deleted file mode 100644 index efb17225d..000000000 --- a/src/modules/mathlib/math/filter/LowPassFilter2p.cpp +++ /dev/null @@ -1,77 +0,0 @@ -// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- - -/**************************************************************************** - * - * Copyright (C) 2012 PX4 Development Team. All rights reserved. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions - * are met: - * - * 1. Redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer. - * 2. Redistributions in binary form must reproduce the above copyright - * notice, this list of conditions and the following disclaimer in - * the documentation and/or other materials provided with the - * distribution. - * 3. Neither the name PX4 nor the names of its contributors may be - * used to endorse or promote products derived from this software - * without specific prior written permission. - * - * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS - * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT - * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS - * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE - * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, - * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, - * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS - * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED - * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT - * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN - * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE - * POSSIBILITY OF SUCH DAMAGE. - * - ****************************************************************************/ - -/// @file LowPassFilter.cpp -/// @brief A class to implement a second order low pass filter -/// Author: Leonard Hall <LeonardTHall@gmail.com> - -#include "LowPassFilter2p.hpp" -#include "math.h" - -namespace math -{ - -void LowPassFilter2p::set_cutoff_frequency(float sample_freq, float cutoff_freq) -{ - _cutoff_freq = cutoff_freq; - float fr = sample_freq/_cutoff_freq; - float ohm = tanf(M_PI_F/fr); - float c = 1.0f+2.0f*cosf(M_PI_F/4.0f)*ohm + ohm*ohm; - _b0 = ohm*ohm/c; - _b1 = 2.0f*_b0; - _b2 = _b0; - _a1 = 2.0f*(ohm*ohm-1.0f)/c; - _a2 = (1.0f-2.0f*cosf(M_PI_F/4.0f)*ohm+ohm*ohm)/c; -} - -float LowPassFilter2p::apply(float sample) -{ - // do the filtering - float delay_element_0 = sample - _delay_element_1 * _a1 - _delay_element_2 * _a2; - if (isnan(delay_element_0) || isinf(delay_element_0)) { - // don't allow bad values to propogate via the filter - delay_element_0 = sample; - } - float output = delay_element_0 * _b0 + _delay_element_1 * _b1 + _delay_element_2 * _b2; - - _delay_element_2 = _delay_element_1; - _delay_element_1 = delay_element_0; - - // return the value. Should be no need to check limits - return output; -} - -} // namespace math - |