1 files changed, 139 insertions, 0 deletions
diff --git a/gr-digital/lib/digital_clock_recovery_mm_ff.cc b/gr-digital/lib/digital_clock_recovery_mm_ff.cc
new file mode 100644
index 000000000..04057f0e9
--- /dev/null
+++ b/gr-digital/lib/digital_clock_recovery_mm_ff.cc
@@ -0,0 +1,139 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2004,2010,2011 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.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <gr_io_signature.h>
+#include <digital_clock_recovery_mm_ff.h>
+#include <gri_mmse_fir_interpolator.h>
+#include <stdexcept>
+
+#define DEBUG_CR_MM_FF	0		// must be defined as 0 or 1
+
+// Public constructor
+
+digital_clock_recovery_mm_ff_sptr 
+digital_make_clock_recovery_mm_ff(float omega, float gain_omega,
+				  float mu, float gain_mu,
+				  float omega_relative_limit)
+{
+  return gnuradio::get_initial_sptr(new digital_clock_recovery_mm_ff (omega,
+								      gain_omega, 
+								      mu,
+								      gain_mu,
+								      omega_relative_limit));
+}
+
+digital_clock_recovery_mm_ff::digital_clock_recovery_mm_ff (float omega, float gain_omega,
+							    float mu, float gain_mu,
+							    float omega_relative_limit)
+  : gr_block ("clock_recovery_mm_ff",
+	      gr_make_io_signature (1, 1, sizeof (float)),
+	      gr_make_io_signature (1, 1, sizeof (float))),
+    d_mu (mu), d_gain_omega(gain_omega), d_gain_mu(gain_mu),
+    d_last_sample(0), d_interp(new gri_mmse_fir_interpolator()),
+    d_logfile(0), d_omega_relative_limit(omega_relative_limit)
+{
+  if (omega <  1)
+    throw std::out_of_range ("clock rate must be > 0");
+  if (gain_mu <  0  || gain_omega < 0)
+    throw std::out_of_range ("Gains must be non-negative");
+
+  set_omega(omega);			// also sets min and max omega
+  set_relative_rate (1.0 / omega);
+
+  if (DEBUG_CR_MM_FF)
+    d_logfile = fopen("cr_mm_ff.dat", "wb");
+}
+
+digital_clock_recovery_mm_ff::~digital_clock_recovery_mm_ff ()
+{
+  delete d_interp;
+
+  if (DEBUG_CR_MM_FF && d_logfile){
+    fclose(d_logfile);
+    d_logfile = 0;
+  }
+}
+
+void
+digital_clock_recovery_mm_ff::forecast(int noutput_items, gr_vector_int &ninput_items_required)
+{
+  unsigned ninputs = ninput_items_required.size();
+  for (unsigned i=0; i < ninputs; i++)
+    ninput_items_required[i] =
+      (int) ceil((noutput_items * d_omega) + d_interp->ntaps());
+}
+
+static inline float
+slice(float x)
+{
+  return x < 0 ? -1.0F : 1.0F;
+}
+
+/*
+ * This implements the Mueller and Müller (M&M) discrete-time error-tracking synchronizer.
+ *
+ * See "Digital Communication Receivers: Synchronization, Channel
+ * Estimation and Signal Processing" by Heinrich Meyr, Marc Moeneclaey, & Stefan Fechtel.
+ * ISBN 0-471-50275-8.
+ */
+int
+digital_clock_recovery_mm_ff::general_work (int noutput_items,
+					    gr_vector_int &ninput_items,
+					    gr_vector_const_void_star &input_items,
+					    gr_vector_void_star &output_items)
+{
+  const float *in = (const float *) input_items[0];
+  float *out = (float *) output_items[0];
+
+  int 	ii = 0;				// input index
+  int  	oo = 0;				// output index
+  int   ni = ninput_items[0] - d_interp->ntaps(); // don't use more input than this
+  float mm_val;
+
+  while (oo < noutput_items && ii < ni ){
+
+    // produce output sample
+    out[oo] = d_interp->interpolate (&in[ii], d_mu);
+    mm_val = slice(d_last_sample) * out[oo] - slice(out[oo]) * d_last_sample;
+    d_last_sample = out[oo];
+
+    d_omega = d_omega + d_gain_omega * mm_val;
+    d_omega = d_omega_mid + gr_branchless_clip(d_omega-d_omega_mid, d_omega_relative_limit);   // make sure we don't walk away
+    d_mu = d_mu + d_omega + d_gain_mu * mm_val;
+
+    ii += (int) floor(d_mu);
+    d_mu = d_mu - floor(d_mu);
+    oo++;
+
+    if (DEBUG_CR_MM_FF && d_logfile){
+      fwrite(&d_omega, sizeof(d_omega), 1, d_logfile);
+    }
+  }
+
+  consume_each (ii);
+
+  return oo;
+}