#include <NotchFilter.h>

Inheritance diagram for Kwave::NotchFilter:

Collaboration diagram for Kwave::NotchFilter:

Public Slots
void	input (Kwave::SampleArray data)

void	setFrequency (const QVariant fc)

void	setBandwidth (const QVariant bw)

Signals
void	output (Kwave::SampleArray data)

Signals inherited from Kwave::StreamObject
void	attributeChanged (const QVariant value)

Public Member Functions
	NotchFilter ()

virtual	~NotchFilter () Q_DECL_OVERRIDE

virtual void	goOn () Q_DECL_OVERRIDE

virtual double	at (double f) Q_DECL_OVERRIDE

Public Member Functions inherited from Kwave::SampleSource
	SampleSource (QObject *parent=Q_NULLPTR)

virtual	~SampleSource ()

virtual bool	done () const

Public Member Functions inherited from Kwave::StreamObject
	StreamObject (QObject *parent=Q_NULLPTR)

virtual	~StreamObject ()

virtual unsigned int	tracks () const

virtual Kwave::StreamObject *	operator[] (unsigned int track)

virtual unsigned int	tracksOfPort (const char *port) const

virtual Kwave::StreamObject *	port (const char *port, unsigned int track)

virtual unsigned int	blockSize () const

void	setAttribute (const char *attribute, const QVariant &value)

Public Member Functions inherited from Kwave::TransmissionFunction
virtual	~TransmissionFunction ()

Private Member Functions
void	initFilter ()

void	setfilter_peaknotch2 (double freq, double bw)

Private Attributes
Kwave::SampleArray	m_buffer

double	m_f_cutoff

double	m_f_bw

struct {
double cx

double cx1

double cx2

double cy1

double cy2

double x

double x1

double x2

double y

double y1

double y2

}	m_filter

Additional Inherited Members
Static Public Member Functions inherited from Kwave::StreamObject
static void	setInteractive (bool interactive)

Detailed Description

Definition at line 35 of file NotchFilter.h.

Constructor & Destructor Documentation

◆ NotchFilter()

Kwave::NotchFilter::NotchFilter ( )

Constructor

Definition at line 28 of file NotchFilter.cpp.

References initFilter().

     :Kwave::SampleSource(Q_NULLPTR), Kwave::TransmissionFunction(),
      m_buffer(blockSize()), m_f_cutoff(M_PI), m_f_bw(M_PI / 2)
 {
     initFilter();
 }

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◆ ~NotchFilter()

Kwave::NotchFilter::~NotchFilter ( )

virtual

Destructor

Definition at line 36 of file NotchFilter.cpp.

37 {

38 }

Member Function Documentation

◆ at()

double Kwave::NotchFilter::at ( double f )

virtual

See also: TransmissionFunction::at()

Implements Kwave::TransmissionFunction.

Definition at line 47 of file NotchFilter.cpp.

References m_filter.

 {
     /*
      * filter function as extracted from the aRts code:
      *
      * y[t] = cx*x[t] + cx1*x[t-1] + cx2*x[t-2]
      *                + cy1*y[t-1] + cy2*y[t-2];
      *
      * convert filter coefficients to our notation:
      */
     double a0, a1, a2, b1, b2;
     a0 = m_filter.cx;
     a1 = m_filter.cx1;
     a2 = m_filter.cx2;
     b1 = m_filter.cy1;
     b2 = m_filter.cy2;
 
     /*
      *        a0*z^2 + a1*z + a2
      * H(z) = ------------------   | z = e ^ (j*2*pi*f)
      *          z^2 - b1*z - b0
      */
     std::complex<double> h;
     std::complex<double> w;
     std::complex<double> j(0.0,1.0);
     std::complex<double> z;
 
     w = f;
     z = std::exp(j*w);
 
     // get h[z] at z=e^jw
     h = 0.95 * (a0 * (z*z) + (a1*z) + a2) / ((z*z) - (b1*z) - b2);
 
     return sqrt(std::norm(h));
 }

◆ goOn()

void Kwave::NotchFilter::goOn ( )

virtual

does the calculation

Implements Kwave::SampleSource.

Definition at line 41 of file NotchFilter.cpp.

References m_buffer, and output().

 {
     emit output(m_buffer);
 }

◆ initFilter()

void Kwave::NotchFilter::initFilter ( )

private

reset/initialize the filter coefficients

Definition at line 84 of file NotchFilter.cpp.

References m_filter.

Referenced by NotchFilter(), setBandwidth(), and setFrequency().

 {
     m_filter.x1 = 0.0;
     m_filter.x2 = 0.0;
     m_filter.y1 = 0.0;
     m_filter.y2 = 0.0;
     m_filter.y  = 0.0;
 }

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◆ input

void Kwave::NotchFilter::input ( Kwave::SampleArray data )

slot

receives input data

Definition at line 120 of file NotchFilter.cpp.

References double2sample(), m_buffer, m_f_bw, m_f_cutoff, m_filter, Kwave::SampleArray::resize(), sample2double(), setfilter_peaknotch2(), and Kwave::SampleArray::size().

 {
     const Kwave::SampleArray &in = data;
     bool ok = m_buffer.resize(in.size());
     Q_ASSERT(ok);
     Q_UNUSED(ok);
 
     setfilter_peaknotch2(m_f_cutoff, m_f_bw);
 
     for (unsigned i = 0; i < in.size(); ++i)
     {
         // do the filtering
         m_filter.x = sample2double(in[i]);
         m_filter.y =
             m_filter.cx  * m_filter.x  +
             m_filter.cx1 * m_filter.x1 +
             m_filter.cx2 * m_filter.x2 +
             m_filter.cy1 * m_filter.y1 +
             m_filter.cy2 * m_filter.y2;
         m_filter.x2 = m_filter.x1;
         m_filter.x1 = m_filter.x;
         m_filter.y2 = m_filter.y1;
         m_filter.y1 = m_filter.y;
         m_buffer[i] = double2sample(0.95 * m_filter.y);
     }
 }

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◆ output

void Kwave::NotchFilter::output ( Kwave::SampleArray data )

signal

emits a block with the filtered data

Referenced by goOn().

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◆ setBandwidth

void Kwave::NotchFilter::setBandwidth ( const QVariant bw )

slot

Sets the bandwidth, normed to [0...2Pi]. The calculation is: bw = bandwidth [Hz] * 2 * Pi / f_sample [Hz]. The default setting is 0.1.

Definition at line 159 of file NotchFilter.cpp.

References initFilter(), m_f_bw, m_f_cutoff, and setfilter_peaknotch2().

Referenced by Kwave::NotchFilterDialog::updateDisplay().

 {
     double new_bw = QVariant(bw).toDouble();
     if (qFuzzyCompare(new_bw, m_f_bw)) return; // nothing to do
 
     m_f_bw = new_bw;
     initFilter();
     setfilter_peaknotch2(m_f_cutoff, m_f_bw);
 }

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◆ setfilter_peaknotch2()

void Kwave::NotchFilter::setfilter_peaknotch2	(	double	freq,
		double	bw
	)

private

set the coefficients for a given frequency

Parameters

freq	normed frequency
bw	normed bandwidth

Definition at line 98 of file NotchFilter.cpp.

References m_filter.

Referenced by input(), setBandwidth(), and setFrequency().

 {
     const double gdb = -100;
     double k, w, bwr, abw, gain;
 
     k = pow(10.0, gdb / 20.0);
     /* w   = 2.0 * PI * freq / (double)SR; */
     /* bwr = 2.0 * PI * bw / (double)SR; */
     w = freq;
     bwr = bw;
     abw = (1.0 - tan(bwr / 2.0)) / (1.0 + tan(bwr / 2.0));
     gain = 0.5 * (1.0 + k + abw - k * abw);
     m_filter.cx = 1.0 * gain;
     m_filter.cx1 = gain * (-2.0 * cos(w) * (1.0 + abw)) /
                    (1.0 + k + abw - k * abw);
     m_filter.cx2 = gain * (abw + k * abw + 1.0 - k) /
                    (abw - k * abw + 1.0 + k);
     m_filter.cy1 = 2.0 * cos(w) / (1.0 + tan(bwr / 2.0));
     m_filter.cy2 = -abw;
 }

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◆ setFrequency

void Kwave::NotchFilter::setFrequency ( const QVariant fc )

slot

Sets the center frequency, normed to [0...2Pi]. The calculation is: fc = frequency [Hz] * 2 * Pi / f_sample [Hz]. The default setting is 0.5.

Definition at line 148 of file NotchFilter.cpp.

References initFilter(), m_f_bw, m_f_cutoff, and setfilter_peaknotch2().

Referenced by Kwave::NotchFilterDialog::updateDisplay().

 {
     double new_freq = QVariant(fc).toDouble();
     if (qFuzzyCompare(new_freq, m_f_cutoff)) return; // nothing to do
 
     m_f_cutoff = new_freq;
     initFilter();
     setfilter_peaknotch2(m_f_cutoff, m_f_bw);
 }

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Member Data Documentation

◆ cx

double Kwave::NotchFilter::cx

Definition at line 102 of file NotchFilter.h.

◆ cx1

double Kwave::NotchFilter::cx1

Definition at line 102 of file NotchFilter.h.

◆ cx2

double Kwave::NotchFilter::cx2

Definition at line 102 of file NotchFilter.h.

◆ cy1

double Kwave::NotchFilter::cy1

Definition at line 102 of file NotchFilter.h.

◆ cy2

double Kwave::NotchFilter::cy2

Definition at line 102 of file NotchFilter.h.

◆ m_buffer

Kwave::SampleArray Kwave::NotchFilter::m_buffer

private

buffer for input

Definition at line 92 of file NotchFilter.h.

Referenced by goOn(), and input().

◆ m_f_bw

double Kwave::NotchFilter::m_f_bw

private

bandwidth of the notch

Definition at line 98 of file NotchFilter.h.

Referenced by input(), setBandwidth(), and setFrequency().

◆ m_f_cutoff

double Kwave::NotchFilter::m_f_cutoff

private

cutoff frequency [0...PI]

Definition at line 95 of file NotchFilter.h.

Referenced by input(), setBandwidth(), and setFrequency().

◆ m_filter

struct { ... } Kwave::NotchFilter::m_filter

structure with the filter coefficients

Referenced by at(), initFilter(), input(), and setfilter_peaknotch2().

◆ x

double Kwave::NotchFilter::x

Definition at line 103 of file NotchFilter.h.

◆ x1

double Kwave::NotchFilter::x1

Definition at line 103 of file NotchFilter.h.

◆ x2

double Kwave::NotchFilter::x2

Definition at line 103 of file NotchFilter.h.

◆ y

double Kwave::NotchFilter::y

Definition at line 103 of file NotchFilter.h.

◆ y1

double Kwave::NotchFilter::y1

Definition at line 103 of file NotchFilter.h.

◆ y2

double Kwave::NotchFilter::y2

Definition at line 103 of file NotchFilter.h.

The documentation for this class was generated from the following files:

plugins/notch_filter/NotchFilter.h
plugins/notch_filter/NotchFilter.cpp

Public Slots

Signals

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ NotchFilter()

◆ ~NotchFilter()

Member Function Documentation

◆ at()

◆ goOn()

◆ initFilter()

◆ input

◆ output

◆ setBandwidth

◆ setfilter_peaknotch2()

◆ setFrequency

Member Data Documentation

◆ cx

◆ cx1

◆ cx2

◆ cy1

◆ cy2

◆ m_buffer

◆ m_f_bw

◆ m_f_cutoff

◆ m_filter

◆ x

◆ x1

◆ x2

◆ y

◆ y1

◆ y2