From f232855f93d4bccf08b9836943b55c25c2ef0055 Mon Sep 17 00:00:00 2001
From: Tom Rondeau <trondeau@vt.edu>
Date: Sun, 10 Jul 2011 20:29:27 -0400
Subject: digital: moving more constellation blocks into gr-digital. Builds,
make check needs work.
---
.../lib/digital_constellation_receiver_cb.cc | 131 +++++++++++++++++++++
1 file changed, 131 insertions(+)
create mode 100644 gr-digital/lib/digital_constellation_receiver_cb.cc
(limited to 'gr-digital/lib/digital_constellation_receiver_cb.cc')
diff --git a/gr-digital/lib/digital_constellation_receiver_cb.cc b/gr-digital/lib/digital_constellation_receiver_cb.cc
new file mode 100644
index 0000000000..56385f11e6
--- /dev/null
+++ b/gr-digital/lib/digital_constellation_receiver_cb.cc
@@ -0,0 +1,131 @@
+/* -*- 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.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <gr_io_signature.h>
+#include <gr_prefs.h>
+#include <digital_constellation_receiver_cb.h>
+#include <stdexcept>
+#include <gr_math.h>
+#include <gr_expj.h>
+
+
+#define M_TWOPI (2*M_PI)
+#define VERBOSE_MM 0 // Used for debugging symbol timing loop
+#define VERBOSE_COSTAS 0 // Used for debugging phase and frequency tracking
+
+// Public constructor
+
+digital_constellation_receiver_cb_sptr
+digital_make_constellation_receiver_cb(digital_constellation_sptr constell,
+ float alpha, float beta,
+ float fmin, float fmax)
+{
+ return gnuradio::get_initial_sptr(new digital_constellation_receiver_cb (constell,
+ alpha, beta,
+ fmin, fmax));
+}
+
+static int ios[] = {sizeof(char), sizeof(float), sizeof(float), sizeof(float)};
+static std::vector<int> iosig(ios, ios+sizeof(ios)/sizeof(int));
+digital_constellation_receiver_cb::digital_constellation_receiver_cb (digital_constellation_sptr constellation,
+ float alpha, float beta,
+ float fmin, float fmax)
+ : gr_block ("constellation_receiver_cb",
+ gr_make_io_signature (1, 1, sizeof (gr_complex)),
+ gr_make_io_signaturev (1, 4, iosig)),
+ d_constellation(constellation),
+ d_alpha(alpha), d_beta(beta), d_freq(0), d_max_freq(fmax), d_min_freq(fmin), d_phase(0),
+ d_current_const_point(0)
+{
+ if (d_constellation->dimensionality() != 1)
+ throw std::runtime_error ("This receiver only works with constellations of dimension 1.");
+}
+
+void
+digital_constellation_receiver_cb::phase_error_tracking(float phase_error)
+{
+ d_freq += d_beta*phase_error; // adjust frequency based on error
+ d_phase += d_freq + d_alpha*phase_error; // adjust phase based on error
+
+ // Make sure we stay within +-2pi
+ while(d_phase > M_TWOPI)
+ d_phase -= M_TWOPI;
+ while(d_phase < -M_TWOPI)
+ d_phase += M_TWOPI;
+
+ // Limit the frequency range
+ d_freq = gr_branchless_clip(d_freq, d_max_freq);
+
+#if VERBOSE_COSTAS
+ printf("cl: phase_error: %f phase: %f freq: %f sample: %f+j%f constellation: %f+j%f\n",
+ phase_error, d_phase, d_freq, sample.real(), sample.imag(),
+ d_constellation->points()[d_current_const_point].real(),
+ d_constellation->points()[d_current_const_point].imag());
+#endif
+}
+
+int
+digital_constellation_receiver_cb::general_work (int noutput_items,
+ gr_vector_int &ninput_items,
+ gr_vector_const_void_star &input_items,
+ gr_vector_void_star &output_items)
+{
+ const gr_complex *in = (const gr_complex *) input_items[0];
+ unsigned char *out = (unsigned char *) output_items[0];
+
+ int i=0;
+
+ float phase_error;
+ unsigned int sym_value;
+ gr_complex sample, nco;
+
+ float *out_err = 0, *out_phase = 0, *out_freq = 0;
+ if(output_items.size() == 4) {
+ out_err = (float *) output_items[1];
+ out_phase = (float *) output_items[2];
+ out_freq = (float *) output_items[3];
+ }
+
+ while((i < noutput_items) && (i < ninput_items[0])) {
+ sample = in[i];
+ nco = gr_expj(d_phase); // get the NCO value for derotating the current sample
+ sample = nco*sample; // get the downconverted symbol
+ sym_value = d_constellation->decision_maker_pe(&sample, &phase_error);
+ // phase_error = -arg(sample*conj(d_constellation->points()[sym_value]));
+ phase_error_tracking(phase_error); // corrects phase and frequency offsets
+ out[i] = sym_value;
+ if(output_items.size() == 4) {
+ out_err[i] = phase_error;
+ out_phase[i] = d_phase;
+ out_freq[i] = d_freq;
+ }
+ i++;
+ }
+
+ consume_each(i);
+ return i;
+}
+
--
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