ACFilterbank.h

//-*-C++-*-
/***************************************************************************
 *
 *   Copyright (C) 2005 by Willem van Straten
 *   Licensed under the Academic Free License version 2.1
 *
 ***************************************************************************/
 
// dspsr/Signal/General/dsp/ACFilterbank.h
 
#ifndef __ACFilterbank_h
#define __ACFilterbank_h
 
#include "dsp/Transformation.h"
#include "dsp/TimeSeries.h"
 
namespace dsp {
 
  class Apodization;
  class Response;
  
  /* This class can be used to form the power spectral density (PSD)
     or auto-correlation fuction (ACF) as a function of time.  There
     are two modes of operation:
 
     1) the PSD are stored in frequency-major order
     2) the ACF are mutliplexed into time-major order
 
     In order to compute the ACF (and not the cyclic ACF), the
     TimeSeries data must be zero padded before each Fourier
     transform.  For each good lag in the ACF, a zero is padded and,
     for each zero padded, the neighbouring FFTs will overlap.
     Therefore, in mode 1, the output will be larger than the input.
     However, in mode 2, an inverse FFT is required.
  */
 
  class ACFilterbank: public Transformation <TimeSeries, TimeSeries> {
 
  public:
 
    ACFilterbank ();
 
    void set_nchan (unsigned _nchan) { nchan = _nchan; }
 
    unsigned get_nchan () const { return nchan; }
 
    void set_nlag (unsigned _nlag) { nlag = _nlag; }
 
    unsigned get_nlag () const { return nlag; } 
 
    void set_form_acf (bool _flag) { form_acf = _flag; }
 
    bool get_form_acf () const { return form_acf; }
 
    void set_apodization (Apodization* function);
 
    bool has_passband () const;
 
    const Response* get_passband() const;
 
    void set_passband (Response* band);
 
  protected:
 
    virtual void transformation ();
 
    unsigned nchan;
 
    unsigned nlag;
 
    bool form_acf;
 
    Reference::To<Apodization> apodization;
 
    Reference::To<Response> passband;
 
  };
  
}
 
#endif