GNU Radio 3.6.0 C++ API
gr_single_pole_iir_filter_cc.h
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00001 /* -*- c++ -*- */
00002 /*
00003  * Copyright 2004,2005,2006 Free Software Foundation, Inc.
00004  *
00005  * This file is part of GNU Radio
00006  *
00007  * GNU Radio is free software; you can redistribute it and/or modify
00008  * it under the terms of the GNU General Public License as published by
00009  * the Free Software Foundation; either version 3, or (at your option)
00010  * any later version.
00011  *
00012  * GNU Radio is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015  * GNU General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU General Public License
00018  * along with GNU Radio; see the file COPYING.  If not, write to
00019  * the Free Software Foundation, Inc., 51 Franklin Street,
00020  * Boston, MA 02110-1301, USA.
00021  */
00022 
00023 #ifndef INCLUDED_GR_SINGLE_POLE_IIR_FILTER_CC_H
00024 #define INCLUDED_GR_SINGLE_POLE_IIR_FILTER_CC_H
00025 
00026 #include <gr_core_api.h>
00027 #include <gr_sync_block.h>
00028 #include <gr_single_pole_iir.h>
00029 #include <gr_complex.h>
00030 #include <stdexcept>
00031 
00032 class gr_single_pole_iir_filter_cc;
00033 typedef boost::shared_ptr<gr_single_pole_iir_filter_cc> gr_single_pole_iir_filter_cc_sptr;
00034 
00035 GR_CORE_API gr_single_pole_iir_filter_cc_sptr
00036 gr_make_single_pole_iir_filter_cc (double alpha, unsigned int vlen=1);
00037 
00038 /*!
00039  * \brief  single pole IIR filter with complex input, complex output
00040  * \ingroup filter_blk
00041  *
00042  * The input and output satisfy a difference equation of the form
00043  \htmlonly
00044  \f{
00045  y[n] - (1-alpha) y[n-1] = alpha x[n]
00046  \f}
00047  \endhtmlonly
00048 
00049  \xmlonly
00050  y[n] - (1-alpha) y[n-1] = alpha x[n]
00051  \endxmlonly
00052 
00053  * with the corresponding rational system function
00054  \htmlonly
00055  \f{
00056  H(z) = \frac{alpha}{1 - (1-alpha) z^{-1}}
00057  \f}
00058  \endhtmlonly
00059 
00060  \xmlonly
00061  H(z) = \ frac{alpha}{1 - (1-alpha) z^{-1}}
00062  \endxmlonly
00063 
00064  * Note that some texts define the system function with a + in the denominator.
00065  * If you're using that convention, you'll need to negate the feedback tap.
00066  */
00067 class GR_CORE_API gr_single_pole_iir_filter_cc : public gr_sync_block
00068 {
00069  private:
00070   friend GR_CORE_API gr_single_pole_iir_filter_cc_sptr
00071   gr_make_single_pole_iir_filter_cc (double alpha, unsigned int vlen);
00072 
00073   unsigned int                                          d_vlen;
00074   std::vector<gr_single_pole_iir<gr_complex,gr_complex,double> >        d_iir;
00075 
00076   gr_single_pole_iir_filter_cc (double alpha, unsigned int vlen);
00077 
00078  public:
00079   ~gr_single_pole_iir_filter_cc ();
00080 
00081   void set_taps (double alpha);
00082 
00083   int work (int noutput_items,
00084             gr_vector_const_void_star &input_items,
00085             gr_vector_void_star &output_items);
00086 };
00087 
00088 #endif