GNU Radio v3.6.2-149-ga6d285d9 C++ API
single_pole_iir_filter_cc.h
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00001 /* -*- c++ -*- */
00002 /*
00003  * Copyright 2004-2006,2012 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_SINGLE_POLE_IIR_FILTER_CC_H
00024 #define INCLUDED_SINGLE_POLE_IIR_FILTER_CC_H
00025 
00026 #include <filter/api.h>
00027 #include <filter/single_pole_iir.h>
00028 #include <gr_sync_block.h>
00029 #include <gr_complex.h>
00030 
00031 namespace gr {
00032   namespace filter {
00033     
00034     /*!
00035      * \brief  single pole IIR filter with complex input, complex output
00036      * \ingroup filter_blk
00037      *
00038      * The input and output satisfy a difference equation of the form
00039      \htmlonly
00040      \f{
00041      y[n] - (1-alpha) y[n-1] = alpha x[n]
00042      \f}
00043      \endhtmlonly
00044 
00045      \xmlonly
00046      y[n] - (1-alpha) y[n-1] = alpha x[n]
00047      \endxmlonly
00048 
00049      * with the corresponding rational system function
00050      \htmlonly
00051      \f{
00052      H(z) = \frac{alpha}{1 - (1-alpha) z^{-1}}
00053      \f}
00054      \endhtmlonly
00055 
00056      \xmlonly
00057      H(z) = \ frac{alpha}{1 - (1-alpha) z^{-1}}
00058      \endxmlonly
00059      
00060      * Note that some texts define the system function with a + in the
00061      * denominator. If you're using that convention, you'll need to
00062      * negate the feedback tap.
00063      */
00064     class FILTER_API single_pole_iir_filter_cc : virtual public gr_sync_block
00065     {
00066     public:
00067       // gr::filter::single_pole_iir_filter_cc::sptr
00068       typedef boost::shared_ptr<single_pole_iir_filter_cc> sptr;
00069 
00070       static sptr make(double alpha, unsigned int vlen=1);
00071 
00072       virtual void set_taps(double alpha) = 0;
00073     };
00074 
00075   } /* namespace filter */
00076 } /* namespace gr */
00077 
00078 #endif /* INCLUDED_SINGLE_POLE_IIR_FILTER_CC_H */