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Version 4.4.0

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Gary Scavone
2013-09-29 23:11:39 +02:00
committed by Stephen Sinclair
parent d199342e86
commit eccd8c9981
287 changed files with 11712 additions and 7676 deletions
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doc/doxygen/filtering.txt
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@@ -1,9 +1,10 @@
/*! \page filtering Using Filters
In this section, we demonstrate the use of a few of the STK filter classes. The Filter class provides functionality to implement a generalized digital filter of any type, similar to the \c filter function in Matlab. In this example, we create a Filter instance and initialize it with specific numerator and denominator coefficients. We then compute its impulse response for 20 samples.
In this section, we demonstrate the use of a few of the STK filter classes. The stk::Iir class provides functionality to implement a generalized infinite impulse response (IIR) digital filter, similar to the \c filter function in Matlab. In this example, we create an stk::Iir instance and initialize it with specific numerator and denominator coefficients. We then compute its impulse response for 20 samples.
\code
#include "Filter.h"
#include "Iir.h"
using namespace stk;
int main()
{
@@ -16,7 +17,7 @@ int main()
denominator.push_back( 0.3 );
denominator.push_back( -0.5 );
Filter filter( numerator, denominator );
Iir filter( numerator, denominator );
filter.tick( output );
for ( unsigned int i=0; i<output.size(); i++ ) {
@@ -27,22 +28,23 @@ int main()
}
\endcode
The Filter class implements the standard difference equation
The stk::Iir class implements the standard difference equation
\code
a[0]*y[n] = b[0]*x[n] + ... + b[nb]*x[n-nb] - a[1]*y[n-1] - ... - a[na]*y[n-na],
\endcode
where "b" values are numerator coefficients and "a" values are denominator coefficients. Note that if the first denominator coefficient is not 1.0, the Filter class automatically normalizes all filter coefficients by that value. The coefficient values are passed to the Filter class via a C++ <a href="http://www.roguewave.com/support/docs/sourcepro/stdlibref/vector.html">vector</a>, a container object provided by the C++ Standard Library.
where "b" values are numerator coefficients and "a" values are denominator coefficients. Note that if the first denominator coefficient is not 1.0, the Iir class automatically normalizes all filter coefficients by that value. The coefficient values are passed to the Iir class via a C++ <a href="http://www.roguewave.com/support/docs/sourcepro/stdlibref/vector.html">vector</a>, a container object provided by the C++ Standard Library.
Most STK classes use more specific types of digital filters, such as the OneZero, OnePole, TwoPole, or BiQuad varieties. These classes inherit from the Filter class and provide specific functionality particular to their use, as well as functions to independently control individual coefficient values.
Most STK classes use more specific types of digital filters, such as the stk::OneZero, stk::OnePole, stk::TwoPole, or stk::BiQuad varieties. These classes inherit from the stk::Filter abstract base class and provide specific functionality particular to their use, as well as functions to independently control individual coefficient values.
\section reson Resonances:
The STK BiQuad and TwoPole classes provide functionality for creating resonance filters. The following example demonstrates how to create a resonance centered at 440 Hz that is used to filter the output of a Noise generator.
The STK stk::BiQuad and stk::TwoPole classes provide functionality for creating resonance filters. The following example demonstrates how to create a resonance centered at 440 Hz that is used to filter the output of a stk::Noise generator.
\code
#include "BiQuad.h"
#include "Noise.h"
using namespace stk;
int main()
{
@@ -61,11 +63,12 @@ int main()
}
\endcode
By passing a boolian value of \c true as the third argument to the BiQuad::setResonance() function, the filter coefficients are automatically scaled to achieve unity gain at the resonance peak frequency. The previous code could be easily modified for "vector-based" calculations:
By passing a boolian value of \c true as the third argument to the stk::BiQuad::setResonance() function, the filter coefficients are automatically scaled to achieve unity gain at the resonance peak frequency. The previous code could be easily modified for "vector-based" calculations:
\code
#include "BiQuad.h"
#include "Noise.h"
using namespace stk;
int main()
{