X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=gr-atsc%2Fsrc%2Flib%2FGrAtscFPLL.cc;fp=gr-atsc%2Fsrc%2Flib%2FGrAtscFPLL.cc;h=ce5b183e63ea5ce45b44ab319ee2177c6aef8d4a;hb=8a9ddbb0675f9bfcc6e03b457fba6c79474a3693;hp=0000000000000000000000000000000000000000;hpb=82d471b9b4a8b389b5da44b19c69c36420828382;p=debian%2Fgnuradio

diff --git a/gr-atsc/src/lib/GrAtscFPLL.cc b/gr-atsc/src/lib/GrAtscFPLL.cc
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+++ b/gr-atsc/src/lib/GrAtscFPLL.cc
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+/* -*- c++ -*- */
+/*
+ * Copyright 2002 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.
+ */
+
+#include <GrAtscFPLL.h>
+#include <algorithm>
+#include "fpll_btloop_coupling.h"
+
+/*
+ * I strongly suggest that you not mess with these...
+ *
+ * They are strongly coupled into the symbol timing code and
+ * their value also sets the level of the symbols going
+ * into the equalizer and viterbi decoder.
+ */
+static const float FPLL_AGC_REFERENCE = 2.5 * FPLL_BTLOOP_COUPLING_CONST;
+static const float FPLL_AGC_RATE = 0.25e-6;
+
+
+GrAtscFPLL::GrAtscFPLL (double a_initial_freq)
+  : VrSigProc (1, sizeof (iType), sizeof (oType)),
+    initial_phase(0), debug_no_update(false)
+{
+  initial_freq = a_initial_freq;
+  agc.set_rate (FPLL_AGC_RATE);
+  agc.set_reference (FPLL_AGC_REFERENCE);
+
+  if (_FPLL_DIAG_OUTPUT_){
+    fp = fopen ("fpll.out", "w");
+    if (fp == 0){
+      perror ("fpll.out");
+      exit (1);
+    }
+  }
+
+}
+
+void
+GrAtscFPLL::initialize ()
+{
+  float Fs = getInputSamplingFrequencyN (0);
+
+  float alpha = 1 - exp(-1.0 / Fs / 5e-6);
+  
+  afci.set_taps (alpha);
+  afcq.set_taps (alpha);
+
+  nco.set_freq (initial_freq / Fs * 2 * M_PI);
+  nco.set_phase (initial_phase);
+}
+
+int 
+GrAtscFPLL::work (VrSampleRange output, void *ao[],
+		  VrSampleRange inputs[], void *ai[])
+{
+  iType	 *in = ((iType **)ai)[0];
+  oType  *out = ((oType **)ao)[0];
+
+  unsigned int	k;
+
+  for (k = 0; k < output.size; k++){
+
+    float a_cos, a_sin;
+
+    float input = agc.scale (in[k]);
+
+    nco.step ();		// increment phase
+    nco.sincos (a_sin, a_cos);	// compute cos and sin
+
+    float I = input * a_sin;
+    float Q = input * a_cos;
+
+    out[k] = I;
+
+    float filtered_I = afci.filter (I);
+    float filtered_Q = afcq.filter (Q);
+
+    // phase detector
+
+    float x = atan2 (filtered_Q, filtered_I);
+
+    // avoid slamming filter with big transitions
+
+    static const float limit = M_PI / 2;
+
+    if (x > limit)
+      x = limit;
+    else if (x < -limit)
+      x = -limit;
+
+    // static const float alpha = 0.037;   // Max value
+    // static const float alpha = 0.005;   // takes about 5k samples to pull in, stddev = 323
+    // static const float alpha = 0.002;   // takes about 15k samples to pull in, stddev =  69
+				           //  or about 120k samples on noisy data, 
+    static const float alpha = 0.001;
+    static const float beta = alpha * alpha / 4;
+
+
+    if (!debug_no_update){
+      nco.adjust_phase (alpha * x);
+      nco.adjust_freq (beta * x);
+    }
+
+    if (_FPLL_DIAG_OUTPUT_){
+#if 0	// lots of data...
+      float	iodata[8];
+      iodata[0] = nco.get_freq () * getSamplingFrequency () * (1.0 / (2 * M_PI));
+      iodata[1] = in[k];
+      iodata[2] = input;
+      iodata[3] = I;
+      iodata[4] = Q;
+      iodata[5] = filtered_I;
+      iodata[6] = filtered_Q;
+      iodata[7] = x;
+      if (fwrite (iodata, sizeof (iodata), 1, fp) != 1){
+	perror ("fwrite: fpll");
+	exit (1);
+      }
+#else	// just the frequency
+      float	iodata[1];
+      iodata[0] = nco.get_freq () * getSamplingFrequency () * (1.0 / (2 * M_PI));
+      if (fwrite (iodata, sizeof (iodata), 1, fp) != 1){
+	perror ("fwrite: fpll");
+	exit (1);
+      }
+#endif
+    }
+  }
+
+  return output.size;
+}
+