filterkernel.cpp

Go to the documentation of this file.

//=============================================================================================================
 
//=============================================================================================================
// INCLUDES
//=============================================================================================================
 
#include "filterkernel.h"
 
#include <math/numerics.h>
 
#include "parksmcclellan.h"
#include "cosinefilter.h"
 
#include <algorithm>
 
//=============================================================================================================
// QT INCLUDES
//=============================================================================================================
 
#include <QDebug>
 
//=============================================================================================================
// EIGEN INCLUDES
//=============================================================================================================
 
#include <Eigen/SparseCore>
//#ifndef EIGEN_FFTW_DEFAULT
//#define EIGEN_FFTW_DEFAULT
//#endif
#include <unsupported/Eigen/FFT>
 
//=============================================================================================================
// USED NAMESPACES
//=============================================================================================================
 
using namespace UTILSLIB;
using namespace Eigen;
 
//=============================================================================================================
// INIT STATIC MEMBERS
//=============================================================================================================
 
QVector<UTILSLIB::FilterParameter> FilterKernel::m_designMethods({
    FilterParameter(QString("Cosine"), QString("A cosine filter")),
    FilterParameter(QString("Tschebyscheff"), QString("A tschebyscheff filter"))
    //    FilterParameter(QString("External"), QString("An external filter"))
});
QVector<UTILSLIB::FilterParameter> FilterKernel::m_filterTypes({FilterParameter(QString("LPF"), QString("An LPF filter")),
                                                                FilterParameter(QString("HPF"), QString("An HPF filter")),
                                                                FilterParameter(QString("BPF"), QString("A BPF filter")),
                                                                FilterParameter(QString("NOTCH"), QString("A NOTCH filter")),
                                                                FilterParameter(QString("UNKNOWN"), QString("An UNKNOWN filter"))});
 
//=============================================================================================================
// DEFINE MEMBER METHODS
//=============================================================================================================
 
FilterKernel::FilterKernel()
: m_sFreq(1000)
, m_dCenterFreq(0.5)
, m_dBandwidth(0.1)
, m_dParksWidth(0.1)
, m_dLowpassFreq(40)
, m_dHighpassFreq(4)
, m_iFilterOrder(80)
, m_iDesignMethod(m_designMethods.indexOf(FilterParameter("Cosine")))
, m_iFilterType(m_filterTypes.indexOf(FilterParameter("BPF")))
, m_sFilterName("Unknown")
, m_sFilterShortDescription("")
{
    designFilter();
}
 
//=============================================================================================================
 
FilterKernel::FilterKernel(const QString& sFilterName,
                           int iFilterType,
                           int iOrder,
                           double dCenterfreq,
                           double dBandwidth,
                           double dParkswidth,
                           double dSFreq,
                           int iDesignMethod)
: m_sFreq(dSFreq)
, m_dCenterFreq(dCenterfreq)
, m_dBandwidth(dBandwidth)
, m_dParksWidth(dParkswidth)
, m_iFilterOrder(iOrder)
, m_iDesignMethod(iDesignMethod)
, m_iFilterType(iFilterType)
, m_sFilterName(sFilterName)
, m_sFilterShortDescription()
{
    if (iOrder < 9) {
        qWarning() << "[FilterKernel::FilterKernel] Less than 9 taps were provided. Setting number of taps to 9.";
    }
 
    designFilter();
}
 
//=============================================================================================================
 
void FilterKernel::prepareFilter(int iDataSize)
{
    int iFftLength, exp;
 
    iFftLength = iDataSize + m_vecCoeff.cols();
    exp = ceil(Numerics::log2(iFftLength));
    iFftLength = pow(2, exp);
 
    // Transform coefficients anew if needed
    if (m_vecCoeff.cols() != (iFftLength / 2 + 1)) {
        fftTransformCoeffs(iFftLength);
    }
}
 
//=============================================================================================================
 
RowVectorXd FilterKernel::applyConvFilter(const RowVectorXd& vecData,
                                          bool bKeepOverhead) const
{
    //Do zero padding or mirroring depending on user input
    RowVectorXd vecDataZeroPad = RowVectorXd::Zero(2 * m_vecCoeff.cols() + vecData.cols());
    RowVectorXd vecFilteredTime = RowVectorXd::Zero(2 * m_vecCoeff.cols() + vecData.cols());
 
    vecDataZeroPad.segment(m_vecCoeff.cols(), vecData.cols()) = vecData;
 
    //Do the convolution
    for (int i = m_vecCoeff.cols(); i < vecFilteredTime.cols(); i++) {
        vecFilteredTime(i - m_vecCoeff.cols()) = vecDataZeroPad.segment(i - m_vecCoeff.cols(), m_vecCoeff.cols()) * m_vecCoeff.transpose();
    }
 
    //Return filtered data
    if (!bKeepOverhead) {
        return vecFilteredTime.segment(m_vecCoeff.cols() / 2, vecData.cols());
    }
 
    return vecFilteredTime.head(vecData.cols() + m_vecCoeff.cols());
}
 
//=============================================================================================================
 
void FilterKernel::applyFftFilter(RowVectorXd& vecData,
                                  bool bKeepOverhead)
{
#ifdef EIGEN_FFTW_DEFAULT
    fftw_make_planner_thread_safe();
#endif
 
    // Make sure we always have the correct FFT length for the given input data and filter overlap
    int iFftLength = vecData.cols() + m_vecCoeff.cols();
    int exp = ceil(Numerics::log2(iFftLength));
    iFftLength = pow(2, exp);
 
    // Transform coefficients anew if needed
    if (m_vecFftCoeff.cols() != (iFftLength / 2 + 1)) {
        fftTransformCoeffs(iFftLength);
    }
 
    //generate fft object
    Eigen::FFT<double> fft;
    fft.SetFlag(fft.HalfSpectrum);
 
    // Zero padd if necessary. Please note: The zero padding in Eigen's FFT is only working for column vectors -> We have to zero pad manually here
    int iOriginalSize = vecData.cols();
    if (vecData.cols() < iFftLength) {
        int iResidual = iFftLength - vecData.cols();
        vecData.conservativeResize(iFftLength);
        vecData.tail(iResidual).setZero();
    }
 
    //fft-transform data sequence
    RowVectorXcd vecFreqData;
    fft.fwd(vecFreqData, vecData, iFftLength);
 
    //perform frequency-domain filtering
    vecFreqData = m_vecFftCoeff.array() * vecFreqData.array();
 
    //inverse-FFT
    fft.inv(vecData, vecFreqData);
 
    //Return filtered data
    if (!bKeepOverhead) {
        vecData = vecData.segment(m_vecCoeff.cols() / 2, iOriginalSize).eval();
    } else {
        vecData = vecData.head(iOriginalSize + m_vecCoeff.cols()).eval();
    }
}
 
//=============================================================================================================
 
QString FilterKernel::getName() const
{
    return m_sFilterName;
}
 
//=============================================================================================================
 
void FilterKernel::setName(const QString& sFilterName)
{
    m_sFilterName = sFilterName;
}
 
//=============================================================================================================
 
double FilterKernel::getSamplingFrequency() const
{
    return m_sFreq;
}
 
//=============================================================================================================
 
void FilterKernel::setSamplingFrequency(double dSFreq)
{
    m_sFreq = dSFreq;
}
 
//=============================================================================================================
 
int FilterKernel::getFilterOrder() const
{
    return m_iFilterOrder;
}
 
//=============================================================================================================
 
void FilterKernel::setFilterOrder(int iOrder)
{
    m_iFilterOrder = iOrder;
}
 
//=============================================================================================================
 
double FilterKernel::getCenterFrequency() const
{
    return m_dCenterFreq;
}
 
//=============================================================================================================
 
void FilterKernel::setCenterFrequency(double dCenterFreq)
{
    m_dCenterFreq = dCenterFreq;
}
 
//=============================================================================================================
 
double FilterKernel::getBandwidth() const
{
    return m_dBandwidth;
}
 
//=============================================================================================================
 
void FilterKernel::setBandwidth(double dBandwidth)
{
    m_dBandwidth = dBandwidth;
}
 
//=============================================================================================================
 
double FilterKernel::getParksWidth() const
{
    return m_dParksWidth;
}
 
//=============================================================================================================
 
void FilterKernel::setParksWidth(double dParksWidth)
{
    m_dParksWidth = dParksWidth;
}
 
//=============================================================================================================
 
double FilterKernel::getHighpassFreq() const
{
    return m_dHighpassFreq;
}
 
//=============================================================================================================
 
void FilterKernel::setHighpassFreq(double dHighpassFreq)
{
    m_dHighpassFreq = dHighpassFreq;
}
 
//=============================================================================================================
 
double FilterKernel::getLowpassFreq() const
{
    return m_dLowpassFreq;
}
 
//=============================================================================================================
 
void FilterKernel::setLowpassFreq(double dLowpassFreq)
{
    m_dLowpassFreq = dLowpassFreq;
}
 
//=============================================================================================================
 
Eigen::RowVectorXd FilterKernel::getCoefficients() const
{
    return m_vecCoeff;
}
 
//=============================================================================================================
 
void FilterKernel::setCoefficients(const Eigen::RowVectorXd& vecCoeff)
{
    m_vecCoeff = vecCoeff;
}
 
//=============================================================================================================
 
Eigen::RowVectorXcd FilterKernel::getFftCoefficients() const
{
    return m_vecFftCoeff;
}
 
//=============================================================================================================
 
void FilterKernel::setFftCoefficients(const Eigen::RowVectorXcd& vecFftCoeff)
{
    m_vecFftCoeff = vecFftCoeff;
}
 
//=============================================================================================================
 
bool FilterKernel::fftTransformCoeffs(int iFftLength)
{
#ifdef EIGEN_FFTW_DEFAULT
    fftw_make_planner_thread_safe();
#endif
 
    if (m_vecCoeff.cols() > iFftLength) {
        qWarning().noquote().nospace() << "[FilterKernel::fftTransformCoeffs] The number of filter taps is bigger than the FFT length.";
        return false;
    }
 
    //generate fft object
    Eigen::FFT<double> fft;
    fft.SetFlag(fft.HalfSpectrum);
 
    // Zero padd if necessary. Please note: The zero padding in Eigen's FFT is only working for column vectors -> We have to zero pad manually here
    RowVectorXd vecInputFft;
    if (m_vecCoeff.cols() < iFftLength) {
        vecInputFft.setZero(iFftLength);
        vecInputFft.block(0, 0, 1, m_vecCoeff.cols()) = m_vecCoeff;
    } else {
        vecInputFft = m_vecCoeff;
    }
 
    //fft-transform filter coeffs
    RowVectorXcd vecFreqData;
    fft.fwd(vecFreqData, vecInputFft, iFftLength);
    m_vecFftCoeff = vecFreqData;
    ;
 
    return true;
}
 
//=============================================================================================================
 
void FilterKernel::designFilter()
{
    // Make sure we only use a minimum needed FFT size
    int iFftLength = m_iFilterOrder;
    int exp = ceil(Numerics::log2(iFftLength));
    iFftLength = pow(2, exp);
 
    if (m_iDesignMethod == 0) {
        double dSmallestFeatureHz = m_dParksWidth * (m_sFreq / 2.0);
        const double dLowEdgeHz = std::max(0.0, (m_dCenterFreq - m_dBandwidth / 2.0) * (m_sFreq / 2.0));
        const double dHighEdgeHz = std::max(0.0, (m_dCenterFreq + m_dBandwidth / 2.0) * (m_sFreq / 2.0));
        const double dSingleCutoffHz = std::max(0.0, m_dCenterFreq * (m_sFreq / 2.0));
 
        if (m_iFilterType == 0 || m_iFilterType == 1) {
            if (dSingleCutoffHz > 0.0) {
                dSmallestFeatureHz = std::min(dSmallestFeatureHz, dSingleCutoffHz);
            }
        } else {
            if (dLowEdgeHz > 0.0) {
                dSmallestFeatureHz = std::min(dSmallestFeatureHz, dLowEdgeHz);
            }
            if (dHighEdgeHz > 0.0) {
                dSmallestFeatureHz = std::min(dSmallestFeatureHz, dHighEdgeHz);
            }
        }
 
        dSmallestFeatureHz = std::max(0.5, dSmallestFeatureHz);
 
        const int iRecommendedFftLength = static_cast<int>(std::ceil((m_sFreq / dSmallestFeatureHz) * 8.0));
        if (iRecommendedFftLength > iFftLength) {
            int iRecommendedExp = ceil(Numerics::log2(iRecommendedFftLength));
            iFftLength = pow(2, iRecommendedExp);
        }
    }
 
    switch (m_iDesignMethod) {
        case 1: {
            ParksMcClellan filter(m_iFilterOrder,
                                  m_dCenterFreq,
                                  m_dBandwidth,
                                  m_dParksWidth,
                                  static_cast<ParksMcClellan::TPassType>(m_iFilterType));
            m_vecCoeff = filter.FirCoeff;
 
            //fft-transform m_vecCoeff in order to be able to perform frequency-domain filtering
            fftTransformCoeffs(iFftLength);
 
            break;
        }
 
        case 0: {
            CosineFilter filtercos;
 
            switch (m_iFilterType) {
                case 0:
                    filtercos = CosineFilter(iFftLength,
                                             (m_dCenterFreq) * (m_sFreq / 2.),
                                             m_dParksWidth * (m_sFreq / 2),
                                             (m_dCenterFreq) * (m_sFreq / 2),
                                             m_dParksWidth * (m_sFreq / 2),
                                             m_sFreq,
                                             static_cast<CosineFilter::TPassType>(m_iFilterType));
 
                    break;
 
                case 1:
                    filtercos = CosineFilter(iFftLength,
                                             (m_dCenterFreq) * (m_sFreq / 2),
                                             m_dParksWidth * (m_sFreq / 2),
                                             (m_dCenterFreq) * (m_sFreq / 2),
                                             m_dParksWidth * (m_sFreq / 2),
                                             m_sFreq,
                                             static_cast<CosineFilter::TPassType>(m_iFilterType));
 
                    break;
 
                case 2:
                    filtercos = CosineFilter(iFftLength,
                                             (m_dCenterFreq + m_dBandwidth / 2) * (m_sFreq / 2),
                                             m_dParksWidth * (m_sFreq / 2),
                                             (m_dCenterFreq - m_dBandwidth / 2) * (m_sFreq / 2),
                                             m_dParksWidth * (m_sFreq / 2),
                                             m_sFreq,
                                             static_cast<CosineFilter::TPassType>(m_iFilterType));
 
                    break;
            }
 
            //This filter is designed in the frequency domain, hence the time domain impulse response need to be shortend by the users dependent number of taps
            m_vecCoeff.resize(m_iFilterOrder);
 
            m_vecCoeff.head(m_iFilterOrder / 2) = filtercos.m_vecCoeff.tail(m_iFilterOrder / 2);
            m_vecCoeff.tail(m_iFilterOrder / 2) = filtercos.m_vecCoeff.head(m_iFilterOrder / 2);
 
            //Now generate the fft version of the shortened impulse response
            fftTransformCoeffs(iFftLength);
 
            break;
        }
    }
 
    switch (m_iFilterType) {
        case 0:
            m_dLowpassFreq = 0;
            m_dHighpassFreq = m_dCenterFreq * (m_sFreq / 2);
            break;
 
        case 1:
            m_dLowpassFreq = m_dCenterFreq * (m_sFreq / 2);
            m_dHighpassFreq = 0;
            break;
 
        case 2:
            m_dLowpassFreq = (m_dCenterFreq + m_dBandwidth / 2) * (m_sFreq / 2);
            m_dHighpassFreq = (m_dCenterFreq - m_dBandwidth / 2) * (m_sFreq / 2);
            break;
    }
    getShortDescription();
}
 
//=============================================================================================================
 
QString FilterKernel::getShortDescription() const
{
    QString description(m_designMethods.at(m_iDesignMethod).getName() + "  -  " +
                        QString::number(m_dHighpassFreq, 'g', 4) + "Hz to " + QString::number(m_dLowpassFreq, 'g', 4) + "Hz  -  "
                                                                                                                        "Ord: " +
                        QString::number(m_iFilterOrder));
    return description;
}
 
//=============================================================================================================
 
UTILSLIB::FilterParameter FilterKernel::getDesignMethod() const
{
    if (m_iDesignMethod < 0) {
        return m_designMethods.at(0);
    }
    return m_designMethods.at(m_iDesignMethod);
}
 
//=============================================================================================================
 
UTILSLIB::FilterParameter FilterKernel::getFilterType() const
{
    if (m_iFilterType < 0) {
        return m_filterTypes.at(0);
    }
    return m_filterTypes.at(m_iFilterType);
}
 
//=============================================================================================================
 
void FilterKernel::setDesignMethod(int iDesignMethod)
{
    m_iDesignMethod = (iDesignMethod >= 0 && iDesignMethod < m_designMethods.size()) ? iDesignMethod : 0;
}
 
//=============================================================================================================
 
void FilterKernel::setFilterType(int iFilterType)
{
    m_iFilterType = (iFilterType >= 0 && iFilterType < m_filterTypes.size()) ? iFilterType : 0;
}
 
//=============================================================================================================
 
FilterParameter::FilterParameter()
: FilterParameter("Unknown", "")
{
}
 
//=============================================================================================================
 
FilterParameter::FilterParameter(QString sName)
: FilterParameter(sName, "")
{
}
 
//=============================================================================================================
 
FilterParameter::FilterParameter(QString sName,
                                 QString sDescription)
: m_sName(sName)
, m_sDescription(sDescription)
{
}
 
//=============================================================================================================
 
QString FilterParameter::getName() const
{
    return m_sName;
}
 
//=============================================================================================================