filter: adding single_pole_iir_filter blocks.

QA, docs, and GRC.
author: Tom Rondeau <trondeau@vt.edu> 2012-06-15 15:58:28 -0400
committer: Tom Rondeau <trondeau@vt.edu> 2012-06-15 16:05:51 -0400
commit: 76a6a4c668579ff2e17f8fa44ceb0db381b9053f (patch)
tree: 7327b7ffb742d9cadf25c2303a03a378cd45c8ca /gr-filter/include
parent: 05c117f359b831513bbf6c4f43dca9cb181e5920 (diff)
4 files changed, 359 insertions, 0 deletions
diff --git a/gr-filter/include/filter/CMakeLists.txt b/gr-filter/include/filter/CMakeLists.txt
index 24e63dc0ca..49e946536d 100644
--- a/gr-filter/include/filter/CMakeLists.txt
+++ b/gr-filter/include/filter/CMakeLists.txt
@@ -81,6 +81,7 @@ install(FILES
     fft_filter.h
     pm_remez.h
     polyphase_filterbank.h
+    single_pole_iir.h
     ${generated_includes}
     adaptive_fir_ccc.h
     adaptive_fir_ccf.h
@@ -91,6 +92,8 @@ install(FILES
     fft_filter_fff.h
     hilbert_fc.h
     pfb_channelizer_ccf.h
+    single_pole_iir_filter_cc.h
+    single_pole_iir_filter_ff.h
     DESTINATION ${GR_INCLUDE_DIR}/gnuradio/filter
     COMPONENT "fft_devel"
 )
diff --git a/gr-filter/include/filter/single_pole_iir.h b/gr-filter/include/filter/single_pole_iir.h
new file mode 100644
index 0000000000..10d1b4791b
--- /dev/null
+++ b/gr-filter/include/filter/single_pole_iir.h
@@ -0,0 +1,200 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2002,2006,2012 Free Software Foundation, Inc.
+ *
+ * This file is part of GNU Radio
+ *
+ * GNU Radio is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3, or (at your option)
+ * any later version.
+ *
+ * GNU Radio is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Radio; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef INCLUDED_SINGLE_POLE_IIR_H
+#define INCLUDED_SINGLE_POLE_IIR_H
+
+#include <filter/api.h>
+#include <stdexcept>
+#include <gr_complex.h>
+
+namespace gr {
+  namespace filter {
+    
+    /*!
+     * \brief class template for single pole IIR filter
+     */
+    template<class o_type, class i_type, class tap_type>
+    class single_pole_iir
+    {
+    public:
+      /*!
+       * \brief construct new single pole IIR with given alpha
+       *
+       * computes y(i) = (1-alpha) * y(i-1) + alpha * x(i)
+       */
+      single_pole_iir(tap_type alpha = 1.0)
+      {
+	d_prev_output = 0;
+	set_taps(alpha);
+      }
+
+      /*!
+       * \brief compute a single output value.
+       * \returns the filtered input value.
+       */
+      o_type filter(const i_type input);
+
+      /*!
+       * \brief compute an array of N output values.
+       * \p input must have n valid entries.
+       */
+      void filterN(o_type output[], const i_type input[], unsigned long n);
+
+      /*!
+       * \brief install \p alpha as the current taps.
+       */
+      void set_taps(tap_type alpha)
+      {
+	if(alpha < 0 || alpha > 1)
+	  throw std::out_of_range("Alpha must be in [0, 1]\n");
+
+	d_alpha = alpha;
+	d_one_minus_alpha = 1.0 - alpha;
+      }
+
+      //! reset state to zero
+      void reset()
+      {
+	d_prev_output = 0;
+      }
+
+      o_type prev_output() const { return d_prev_output; }
+
+    protected:
+      tap_type	d_alpha;
+      tap_type	d_one_minus_alpha;
+      o_type	d_prev_output;
+    };
+
+    //
+    // general case.  We may want to specialize this
+    //
+    template<class o_type, class i_type, class tap_type>
+    o_type
+    single_pole_iir<o_type, i_type, tap_type>::filter(const i_type input)
+    {
+      o_type	output;
+
+      output = d_alpha * input + d_one_minus_alpha * d_prev_output;
+      d_prev_output = output;
+
+      return (o_type) output;
+    }
+
+
+    template<class o_type, class i_type, class tap_type>
+    void
+    single_pole_iir<o_type, i_type, tap_type>::filterN(o_type output[],
+						       const i_type input[],
+						       unsigned long n)
+    {
+      for(unsigned i = 0; i < n; i++)
+	output[i] = filter(input[i]);
+    }
+
+
+    //
+    // Specialized case for gr_complex output and double taps
+    // We need to have a gr_complexd type for the calculations and prev_output variable (in stead of double)
+
+    template<class i_type>
+    class single_pole_iir<gr_complex, i_type, double>
+    {
+    public:
+      /*!
+       * \brief construct new single pole IIR with given alpha
+       *
+       * computes y(i) = (1-alpha) * y(i-1) + alpha * x(i)
+       */
+      single_pole_iir(double alpha = 1.0)
+      {
+	d_prev_output = 0;
+	set_taps(alpha);
+      }
+
+      /*!
+       * \brief compute a single output value.
+       * \returns the filtered input value.
+       */
+      gr_complex filter(const i_type input);
+
+      /*!
+       * \brief compute an array of N output values.
+       * \p input must have n valid entries.
+       */
+      void filterN(gr_complex output[], const i_type input[], unsigned long n);
+
+      /*!
+       * \brief install \p alpha as the current taps.
+       */
+      void set_taps(double alpha)
+      {
+	if(alpha < 0 || alpha > 1)
+	  throw std::out_of_range("Alpha must be in [0, 1]\n");
+
+	d_alpha = alpha;
+	d_one_minus_alpha = 1.0 - alpha;
+      }
+
+      //! reset state to zero
+      void reset()
+      {
+	d_prev_output = 0;
+      }
+
+      gr_complexd prev_output() const { return d_prev_output; }
+
+    protected:
+      double	d_alpha;
+      double	d_one_minus_alpha;
+      gr_complexd	d_prev_output;
+    };
+
+    template< class i_type>
+    gr_complex
+    single_pole_iir<gr_complex, i_type, double>::filter(const i_type input)
+    {
+      gr_complexd	output;
+
+      output = d_alpha * (gr_complexd)input + d_one_minus_alpha * d_prev_output;
+      d_prev_output = output;
+
+      return (gr_complex) output;
+    }
+
+    //Do we need to specialize this, although it is the same as the general case?
+
+    template<class i_type>
+    void
+    single_pole_iir<gr_complex, i_type, double>::filterN(gr_complex output[],
+							 const i_type input[],
+							 unsigned long n)
+    {
+      for(unsigned i = 0; i < n; i++)
+	output[i] = filter(input[i]);
+    }
+
+  } /* namespace filter */
+} /* namespace gr */
+
+#endif /* INCLUDED_SINGLE_POLE_IIR_H */
diff --git a/gr-filter/include/filter/single_pole_iir_filter_cc.h b/gr-filter/include/filter/single_pole_iir_filter_cc.h
new file mode 100644
index 0000000000..37db7c65fb
--- /dev/null
+++ b/gr-filter/include/filter/single_pole_iir_filter_cc.h
@@ -0,0 +1,78 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2004-2006,2012 Free Software Foundation, Inc.
+ *
+ * This file is part of GNU Radio
+ *
+ * GNU Radio is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3, or (at your option)
+ * any later version.
+ *
+ * GNU Radio is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Radio; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef INCLUDED_SINGLE_POLE_IIR_FILTER_CC_H
+#define	INCLUDED_SINGLE_POLE_IIR_FILTER_CC_H
+
+#include <filter/api.h>
+#include <filter/single_pole_iir.h>
+#include <gr_sync_block.h>
+#include <gr_complex.h>
+
+namespace gr {
+  namespace filter {
+    
+    /*!
+     * \brief  single pole IIR filter with complex input, complex output
+     * \ingroup filter_blk
+     *
+     * The input and output satisfy a difference equation of the form
+     \htmlonly
+     \f{
+     y[n] - (1-alpha) y[n-1] = alpha x[n]
+     \f}
+     \endhtmlonly
+
+     \xmlonly
+     y[n] - (1-alpha) y[n-1] = alpha x[n]
+     \endxmlonly
+
+     * with the corresponding rational system function
+     \htmlonly
+     \f{
+     H(z) = \frac{alpha}{1 - (1-alpha) z^{-1}}
+     \f}
+     \endhtmlonly
+
+     \xmlonly
+     H(z) = \ frac{alpha}{1 - (1-alpha) z^{-1}}
+     \endxmlonly
+     
+     * Note that some texts define the system function with a + in the
+     * denominator. If you're using that convention, you'll need to
+     * negate the feedback tap.
+     */
+    class FILTER_API single_pole_iir_filter_cc : virtual public gr_sync_block
+    {
+    public:
+      // gr::filter::single_pole_iir_filter_cc::sptr
+      typedef boost::shared_ptr<single_pole_iir_filter_cc> sptr;
+
+      static FILTER_API sptr make(double alpha, unsigned int vlen=1);
+
+      virtual void set_taps(double alpha) = 0;
+    };
+
+  } /* namespace filter */
+} /* namespace gr */
+
+#endif /* INCLUDED_SINGLE_POLE_IIR_FILTER_CC_H */
diff --git a/gr-filter/include/filter/single_pole_iir_filter_ff.h b/gr-filter/include/filter/single_pole_iir_filter_ff.h
new file mode 100644
index 0000000000..8abce94c90
--- /dev/null
+++ b/gr-filter/include/filter/single_pole_iir_filter_ff.h
@@ -0,0 +1,78 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2004,2005 Free Software Foundation, Inc.
+ *
+ * This file is part of GNU Radio
+ *
+ * GNU Radio is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3, or (at your option)
+ * any later version.
+ *
+ * GNU Radio is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Radio; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef INCLUDED_SINGLE_POLE_IIR_FILTER_FF_H
+#define	INCLUDED_SINGLE_POLE_IIR_FILTER_FF_H
+
+#include <filter/api.h>
+#include <filter/single_pole_iir.h>
+#include <gr_sync_block.h>
+#include <gr_complex.h>
+
+namespace gr {
+  namespace filter {
+    
+    /*!
+     * \brief  single pole IIR filter with float input, float output
+     * \ingroup filter_blk
+     *
+     * The input and output satisfy a difference equation of the form
+     \htmlonly
+     \f{
+     y[n] - (1-alpha) y[n-1] = alpha x[n]
+     \f}
+     \endhtmlonly
+
+     \xmlonly
+     y[n] - (1-alpha) y[n-1] = alpha x[n]
+     \endxmlonly
+
+     * with the corresponding rational system function
+     \htmlonly
+     \f{
+     H(z) = \frac{alpha}{1 - (1-alpha) z^{-1}}
+     \f}
+     \endhtmlonly
+
+     \xmlonly
+     H(z) = \ frac{alpha}{1 - (1-alpha) z^{-1}}
+     \endxmlonly
+
+     * Note that some texts define the system function with a + in the
+     * denominator. If you're using that convention, you'll need to
+     * negate the feedback tap.
+     */
+    class FILTER_API single_pole_iir_filter_ff : virtual public gr_sync_block
+    {
+    public:
+      // gr::filter::single_pole_iir_filter_ff::sptr
+      typedef boost::shared_ptr<single_pole_iir_filter_ff> sptr;
+
+      static FILTER_API sptr make(double alpha, unsigned int vlen=1);
+      
+      virtual void set_taps (double alpha) = 0;
+    };
+
+  } /* namespace filter */
+} /* namespace gr */
+
+#endif /* INCLUDED_SINGLE_POLE_IIR_FILTER_FF_H */
author	Tom Rondeau <trondeau@vt.edu>	2012-06-15 15:58:28 -0400
committer	Tom Rondeau <trondeau@vt.edu>	2012-06-15 16:05:51 -0400
commit	76a6a4c668579ff2e17f8fa44ceb0db381b9053f (patch)
tree	7327b7ffb742d9cadf25c2303a03a378cd45c8ca /gr-filter/include
parent	05c117f359b831513bbf6c4f43dca9cb181e5920 (diff)