gr-digital: adding CMA equalizer to gr-digital. This replaces the gr_cma_equalizer_cc in gnuradio-core and uses the complex-in, complex-out, complex-taps version of the gr_adaptive_filter.

1 files changed, 86 insertions, 0 deletions

diff --git a/gr-digital/lib/digital_cma_equalizer_cc.h b/gr-digital/lib/digital_cma_equalizer_cc.h
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+++ b/gr-digital/lib/digital_cma_equalizer_cc.h
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+/* -*- c++ -*- */
+/*
+ * Copyright 2011 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_DIGITAL_CMA_EQUALIZER_CC_H
+#define	INCLUDED_DIGITAL_CMA_EQUALIZER_CC_H
+
+#include <gr_adaptive_fir_ccc.h>
+#include <iostream>
+
+class digital_cma_equalizer_cc;
+typedef boost::shared_ptr<digital_cma_equalizer_cc> digital_cma_equalizer_cc_sptr;
+
+digital_cma_equalizer_cc_sptr 
+digital_make_cma_equalizer_cc(int num_taps, float modulus, float mu);
+
+/*!
+ * \brief Implements constant modulus adaptive filter on complex stream
+ * \ingroup eq_blk
+ *
+ * The error value and tap update equations (for p=2) can be found in:
+ *
+ * D. Godard, "Self-Recovering Equalization and Carrier Tracking in
+ * Two-Dimensional Data Communication Systems," IEEE Transactions on
+ * Communications, Vol. 28, No. 11, pp. 1867 - 1875, 1980,
+ */
+class digital_cma_equalizer_cc : public gr_adaptive_fir_ccc
+{
+private:
+  float d_modulus;
+  float d_mu;
+  
+  friend digital_cma_equalizer_cc_sptr digital_make_cma_equalizer_cc(int num_taps,
+								     float modulus,
+								     float mu);
+  digital_cma_equalizer_cc(int num_taps, float modulus, float mu);
+
+protected:
+
+  virtual gr_complex error(const gr_complex &out) 
+  { 
+    gr_complex error = out*(norm(out) - d_modulus);
+    return error;
+  }
+
+  virtual void update_tap(gr_complex &tap, const gr_complex &in) 
+  {
+    // Hn+1 = Hn - mu*conj(Xn)*zn*(|zn|^2 - 1)
+    tap -= d_mu*conj(in)*d_error;
+  }
+  
+public:
+  void set_gain(float mu) 
+  {
+    if(mu < 0)
+      throw std::out_of_range("digital_cma_equalizer::set_gain: Gain value must be >= 0");
+    d_mu = mu;
+  }
+
+  void set_modulus(float mod) 
+  {
+    if(mod < 0)
+      throw std::out_of_range("digital_cma_equalizer::set_modulus: Modulus value must be >= 0");
+    d_modulus = mod;
+  }
+};
+
+#endif