class IIRFilter : public Pipe

Digital IIR filter implementation API

Inheritance:

Public Methods

	IIRFilter (void) Default constructor.
explicit	IIRFilter (double design_sample_rate) Default constructor.
	IIRFilter (unsigned int npoles, const dComplex* pole, unsigned int nzeros, const dComplex* zero, double design_sample_rate) Constructor from poles and zeros
	IIRFilter (unsigned int npoles, const dComplex* pole, unsigned int nzeros, const dComplex* zero, double design_sample_rate, double gain) Constructor from poles and zeros
IIRFilter&	operator= (const IIRFilter& f) Assign filter characteristics from one IIR filter to another
IIRFilter&	operator*= ( const IIRFilter& f ) Add an other IIRFilter to this one
IIRFilter&	operator*= ( const IIRSos& sos ) Add a single second order section to an IIR filter
IIRFilter&	operator*= ( const double& gainfactor ) Multiply filter gain by a numerical factor
	IIRFilter (const IIRFilter& f) copy constructor
void	init (unsigned int npoles, const dComplex* pole, unsigned int nzeros, const dComplex* zero, double design_sample_rate, double gain) This function sets the pole and zero frequencies of the filter and the filter gain
int	dumpSosData (std::ostream& output) const Print the values of the second order section coefficients
int	dumpSPlaneRoots (std::ostream& output) const Print the root values
	~IIRFilter (void) Default destructor.
IIRFilter*	clone (void) const Clone the filter.
TSeries	apply (const TSeries& data_in) Apply filter to a timeseries.
void	dataCheck (const TSeries& data_in) const Check data integrity
void	reset (void) Not implemented.
bool	inUse (void) const Check filter for coefficients, history buffers.
Time	getStartTime (void) const Get data start time.
Time	getCurrentTime (void) const Get start time for current data.
unsigned	getOrder (void) const Filter order.
bool	hasSRepresentation (void) const Check if filter has s-plane representation.
const std::vector <double> &	getRealPoles (void) const Real pole list.
const std::vector <dComplex> &	getComplexPoles (void) const Complex pole list.
const std::vector <double> &	getRealZeros (void) const Real zero list.
const std::vector <dComplex> &	getComplexZeros (void) const Complex zero list.
double	getGain (void) const Gain.
double	getFSample (void) const Sampling rate .
bool	isInvertible (void) const Check if filter is invertible.
const std::vector <IIRSos> &	getSOS (void) const SOS list.

Protected Methods

bool	xfer (fComplex& coeff, double f) const Get a transfer coefficent of a Filter.

Inherited from Pipe:

Public Methods

virtual TSeries operator)(const TSeries& in)

FilterIO& operator)(const FilterIO& in)

virtual bool isDataValid(const TSeries& in) const

KeyChain& getInputKeys(void) const

KeyChain& getOutputKeys(void) const

virtual Interval getTimeDelay(void) const

virtual bool Xfer(fComplex& coeff, double f) const

virtual bool Xfer(fComplex* tf, const float* freqs, int points) const

virtual bool Xfer(FSeries& Fs, float Fmin = 0.0, float Fmax = 1000.0, float dF = 1.0) const

Inherited from FilterBase:

Public Methods

virtual bool rootGetStartTime(Time& t) const throw()

virtual bool rootGetCurrentTime(Time& t) const throw()

IIRFilter(void)

Default constructor. No coefficient or history storage is allocated.

explicit IIRFilter(double design_sample_rate)

Constructor. Makes a unity operator.

Parameters:

design_sample_rate - The sampling rate of the channel to be filtered, in Hz.

IIRFilter(unsigned int npoles, const dComplex* pole, unsigned int nzeros, const dComplex* zero, double design_sample_rate)

Constructor from S plane poles and zeros. The pole and zero positions are written to two arrays of type dComplex. For example, to initialize a filter with two poles at 10Hz and no zeros, you could type: dComplex pole0(-10,0); dComplex pole1(-10,0); dComplex poles[2]; pole[0]=pole0; pole[1]=pole1; IIRFilter myfilter(2,poles,0,0x0,256); This IIRFilter myfilter could be applied to any channel with a 256 Hz sampling rate. The gain of the filter is set to 1, so that the transfer function is

H(s) = \frac{(s - s_1)(s - s_2) \cdots}{(s - p_1)(s - p_2) \cdots}$$

Parameters:
npoles -  The number of poles. 

pole -  An array of type dComplex containing the list of poles.
Note that where a complex pole is in the list, its complex conjugate
must also be in the list. The convention for root specification is
the same as for Matlab, except that matlab expresses s plane values
in  whereas here s plane values are in Hz. 
So to enter
Matlab generated poles and zeros with this software, divide real and
imaginary parts by .

nzeros. -  The number of zeros.

zero -  An array of type dComplex containing the list of zeros. 
See comment above for pole specification.

design_sample_rate -  The sampling rate of the channel to be
filtered, in Hz.




  IIRFilter(unsigned int npoles, const dComplex* pole, unsigned int nzeros, const dComplex* zero, double design_sample_rate, double gain)
Constructor from S plane poles and zeros. The pole and zero positions
are written to two arrays of type dComplex. For example, to initialize
a filter with two poles at 10Hz and no zeros, you could type:
dComplex pole0(-10,0); dComplex pole1(-10,0); dComplex poles[2];
pole[0]=pole0; pole[1]=pole1; IIRFilter myfilter(2,poles,0,0x0,256);
This IIRFilter myfilter could be applied to any channel with a 256
Hz sampling rate. 

Parameters:
npoles -  The number of poles. 

pole -  An array of type dComplex containing the list of poles.
Note that where a complex pole is in the list, its complex conjugate
must also be in the list. The convention for root specification is
the same as for Matlab, except that matlab expresses s plane values
in  whereas here s plane values are in Hz. 
So to enter
Matlab generated poles and zeros with this software, divide real and
imaginary parts by .

nzeros. -  The number of zeros.

zero -  An array of type dComplex containing the list of zeros. 
See comment above for pole specification.

gain -  The gain of the filter. 

design_sample_rate -  The sampling rate of the channel to be
filtered, in Hz.




 IIRFilter&  operator=(const IIRFilter& f)
Assign filter characteristics from one
IIR filter to another



 IIRFilter&  operator*=( const IIRFilter& f )
Add an other IIRFilter to this one



 IIRFilter&  operator*=( const IIRSos& sos )
Add a single second order section to 
an IIR filter



 IIRFilter&  operator*=( const double& gainfactor )
Multiply filter gain by a numerical factor



  IIRFilter(const IIRFilter& f)
Copy an existing filter.




 void  init(unsigned int npoles, const dComplex* pole, unsigned int nzeros, const dComplex* zero, double design_sample_rate, double gain)
This function sets the pole and zero frequencies of the filter and
the filter gain. All values are in Hz. To input compute poles and zeros
from s plane parameters, divide the s plane parameters (poles and zeros)
by . See documentation for constructors for details on how to
initialize filters.



 int  dumpSosData(std::ostream& output) const 
Print the values of the second order section coefficients



 int  dumpSPlaneRoots(std::ostream& output) const 
Print the positions of the S plane poles and zeros in rad s^-1.




  ~IIRFilter(void)
Default destructor. Frees the history buffers.




 IIRFilter*  clone(void) const 
Clone an IIR Filter




 TSeries  apply(const TSeries& data_in)
Apply filter to a timeseries. No error trapping for gaps between
successive timeseries filtered. Note that a filter should always be
applied to the same channel.

Returns:
Filtered TSeries.




 void  dataCheck(const TSeries& data_in) const 
Check data before filtering. Not implemented.




 void  reset(void)
Clear history buffers, clear error flag. Not implemented.




 bool  inUse(void) const 
See if filter coefficients have been set and history buffers created.

Returns:
1 (true) if yes, 0 (false) if no




 Time  getStartTime(void) const 
Get data start time.
Returns:
Start time for first data set on which IIR filter applied.




 Time  getCurrentTime(void) const 
Get start time for current data.
Returns:
Current time for first data set on which IIR filter applied.




 unsigned  getOrder(void) const 
Get filter order. Implemented for pole/zero designs.
The filter order is defined as max(number of zeros,number of poles)

Returns:
Order of filter



 bool  hasSRepresentation(void) const 
Check if filter has s-plane representation.



 const  std::vector <double> &  getRealPoles(void) const 
Get real pole list.

Returns:
Real pole list



 const  std::vector <dComplex> &  getComplexPoles(void) const 
Get complex pole list.

Returns:
Complex pole list



 const  std::vector <double> &  getRealZeros(void) const 
Get real zero list.

Returns:
Real zero list



 const  std::vector <dComplex> &  getComplexZeros(void) const 
Get complex zero list.

Returns:
Complex zero list



 double  getGain(void) const 
Get gain.

Returns:
gain



 double  getFSample(void) const 
Get sampling rate.

Returns:
Sampling rate



 bool  isInvertible(void) const 
Check if filter is invertible.



 const  std::vector <IIRSos> &  getSOS(void) const 
Get SOS list.

Returns:
SOS list



 bool  xfer(fComplex& coeff, double f) const 
The transfer coefficient of the filter at the specified 
frequency is calculated and returned as a complex number. 
Filters that support a fast way to compute a transfer coefficient 
should implement this method and return true.

Returns:
true if successful       
Parameters:
coeff -  a complex number representing the Filter response 
at the specified frequency (return)

f -  Frequency at which to sample the transfer function.

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Please send questions and comments to zweizig_j@ligo.caltech.edu

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