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authorTom Rondeau2011-03-28 17:36:51 -0400
committerTom Rondeau2011-03-28 17:36:51 -0400
commit485be49c4f81db57a78e333e9bd99cd2c77b1e7a (patch)
treeff9cf5ba5362054227fb118f09e579d4c6ebc743 /gr-digital/lib
parentd24a3fa25cd213b7a0aeab07da232bdce904af80 (diff)
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gr-digital: adding a new top-level block for digital comms work.
Diffstat (limited to 'gr-digital/lib')
-rw-r--r--gr-digital/lib/.gitignore4
-rw-r--r--gr-digital/lib/Makefile.am38
-rw-r--r--gr-digital/lib/gr_costas_loop_cc.cc186
-rw-r--r--gr-digital/lib/gr_costas_loop_cc.h145
4 files changed, 373 insertions, 0 deletions
diff --git a/gr-digital/lib/.gitignore b/gr-digital/lib/.gitignore
new file mode 100644
index 000000000..1b6114c39
--- /dev/null
+++ b/gr-digital/lib/.gitignore
@@ -0,0 +1,4 @@
+/.libs
+/.deps
+/Makefile
+/Makefile.in
diff --git a/gr-digital/lib/Makefile.am b/gr-digital/lib/Makefile.am
new file mode 100644
index 000000000..c37b48786
--- /dev/null
+++ b/gr-digital/lib/Makefile.am
@@ -0,0 +1,38 @@
+#
+# 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.
+#
+
+include $(top_srcdir)/Makefile.common
+
+AM_CPPFLAGS = $(STD_DEFINES_AND_INCLUDES) $(PYTHON_CPPFLAGS) $(WITH_INCLUDES)
+
+# These headers get installed in ${prefix}/include/gnuradio
+grinclude_HEADERS = \
+ gr_costas_loop_cc.h
+
+lib_LTLIBRARIES = libgnuradio-digital.la
+
+libgnuradio_digital_la_SOURCES = \
+ gr_costas_loop_cc.cc
+
+libgnuradio_digital_la_LIBADD = \
+ $(GNURADIO_CORE_LA)
+
+libgnuradio_digital_la_LDFLAGS = $(NO_UNDEFINED) $(LTVERSIONFLAGS)
diff --git a/gr-digital/lib/gr_costas_loop_cc.cc b/gr-digital/lib/gr_costas_loop_cc.cc
new file mode 100644
index 000000000..b77b19745
--- /dev/null
+++ b/gr-digital/lib/gr_costas_loop_cc.cc
@@ -0,0 +1,186 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2006,2010,2011 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_costas_loop_cc.h>
+#include <gr_io_signature.h>
+#include <gr_expj.h>
+#include <gr_sincos.h>
+#include <math.h>
+
+#define M_TWOPI (2*M_PI)
+
+gr_costas_loop_cc_sptr
+gr_make_costas_loop_cc (float alpha, float beta,
+ float max_freq, float min_freq,
+ int order
+ ) throw (std::invalid_argument)
+{
+ return gnuradio::get_initial_sptr(new gr_costas_loop_cc (alpha, beta,
+ max_freq, min_freq,
+ order));
+}
+
+gr_costas_loop_cc::gr_costas_loop_cc (float alpha, float beta,
+ float max_freq, float min_freq,
+ int order
+ ) throw (std::invalid_argument)
+ : gr_sync_block ("costas_loop_cc",
+ gr_make_io_signature (1, 1, sizeof (gr_complex)),
+ gr_make_io_signature (1, 2, sizeof (gr_complex))),
+ d_alpha(alpha), d_beta(beta),
+ d_max_freq(max_freq), d_min_freq(min_freq),
+ d_phase(0), d_freq((max_freq+min_freq)/2),
+ d_order(order), d_phase_detector(0)
+{
+ switch(d_order) {
+ case 2:
+ d_phase_detector = &gr_costas_loop_cc::phase_detector_2;
+ break;
+
+ case 4:
+ d_phase_detector = &gr_costas_loop_cc::phase_detector_4;
+ break;
+
+ case 8:
+ d_phase_detector = &gr_costas_loop_cc::phase_detector_8;
+ break;
+
+ default:
+ throw std::invalid_argument("order must be 2, 4, or 8");
+ break;
+ }
+}
+
+float
+gr_costas_loop_cc::phase_detector_8(gr_complex sample) const
+{
+ float K = sqrt(2.0) - 1;
+
+ if(abs(sample.real()) >= abs(sample.imag())) {
+ return ((sample.real()>0 ? 1.0 : -1.0) * sample.imag() -
+ (sample.imag()>0 ? 1.0 : -1.0) * sample.real() * K);
+ }
+ else {
+ return ((sample.real()>0 ? 1.0 : -1.0) * sample.imag() * K -
+ (sample.imag()>0 ? 1.0 : -1.0) * sample.real());
+ }
+}
+
+float
+gr_costas_loop_cc::phase_detector_4(gr_complex sample) const
+{
+
+ return ((sample.real()>0 ? 1.0 : -1.0) * sample.imag() -
+ (sample.imag()>0 ? 1.0 : -1.0) * sample.real());
+}
+
+float
+gr_costas_loop_cc::phase_detector_2(gr_complex sample) const
+{
+ return (sample.real()*sample.imag());
+}
+
+void
+gr_costas_loop_cc::set_alpha(float alpha)
+{
+ d_alpha = alpha;
+}
+
+void
+gr_costas_loop_cc::set_beta(float beta)
+{
+ d_beta = beta;
+}
+
+int
+gr_costas_loop_cc::work (int noutput_items,
+ gr_vector_const_void_star &input_items,
+ gr_vector_void_star &output_items)
+{
+ const gr_complex *iptr = (gr_complex *) input_items[0];
+ gr_complex *optr = (gr_complex *) output_items[0];
+ gr_complex *foptr = (gr_complex *) output_items[1];
+
+ bool write_foptr = output_items.size() >= 2;
+
+ float error;
+ gr_complex nco_out;
+
+ if (write_foptr) {
+
+ for (int i = 0; i < noutput_items; i++){
+ nco_out = gr_expj(-d_phase);
+ optr[i] = iptr[i] * nco_out;
+
+ error = (*this.*d_phase_detector)(optr[i]);
+ if (error > 1)
+ error = 1;
+ else if (error < -1)
+ error = -1;
+
+ d_freq = d_freq + d_beta * error;
+ d_phase = d_phase + d_freq + d_alpha * error;
+
+ while(d_phase>M_TWOPI)
+ d_phase -= M_TWOPI;
+ while(d_phase<-M_TWOPI)
+ d_phase += M_TWOPI;
+
+ if (d_freq > d_max_freq)
+ d_freq = d_max_freq;
+ else if (d_freq < d_min_freq)
+ d_freq = d_min_freq;
+
+ foptr[i] = gr_complex(d_freq,0);
+ }
+ } else {
+ for (int i = 0; i < noutput_items; i++){
+ nco_out = gr_expj(-d_phase);
+ optr[i] = iptr[i] * nco_out;
+
+ error = (*this.*d_phase_detector)(optr[i]);
+ if (error > 1)
+ error = 1;
+ else if (error < -1)
+ error = -1;
+
+ d_freq = d_freq + d_beta * error;
+ d_phase = d_phase + d_freq + d_alpha * error;
+
+ while(d_phase>M_TWOPI)
+ d_phase -= M_TWOPI;
+ while(d_phase<-M_TWOPI)
+ d_phase += M_TWOPI;
+
+ if (d_freq > d_max_freq)
+ d_freq = d_max_freq;
+ else if (d_freq < d_min_freq)
+ d_freq = d_min_freq;
+
+ }
+ }
+ return noutput_items;
+}
diff --git a/gr-digital/lib/gr_costas_loop_cc.h b/gr-digital/lib/gr_costas_loop_cc.h
new file mode 100644
index 000000000..181880f1c
--- /dev/null
+++ b/gr-digital/lib/gr_costas_loop_cc.h
@@ -0,0 +1,145 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2006 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_GR_COSTAS_LOOP_CC_H
+#define INCLUDED_GR_COSTAS_LOOP_CC_H
+
+#include <gr_sync_block.h>
+#include <stdexcept>
+#include <fstream>
+
+
+/*! \brief A Costas loop carrier recovery module.
+ * \ingroup sync_blk
+ *
+ * The Costas loop locks to the center frequency of a signal and
+ * downconverts it to baseband. The second (order=2) order loop is
+ * used for BPSK where the real part of the output signal is the
+ * baseband BPSK signal and the imaginary part is the error
+ * signal. When order=4, it can be used for quadrature modulations
+ * where both I and Q (real and imaginary) are outputted.
+ *
+ * More details can be found online:
+ *
+ * J. Feigin, "Practical Costas loop design: Designing a simple and inexpensive
+ * BPSK Costas loop carrier recovery circuit," RF signal processing, pp. 20-36,
+ * 2002.
+ *
+ * http://rfdesign.com/images/archive/0102Feigin20.pdf
+ *
+ * \param alpha the loop gain used for phase adjustment
+ * \param beta the loop gain for frequency adjustments
+ * \param max_freq the maximum frequency deviation (radians/sample) the loop can handle
+ * \param min_freq the minimum frequency deviation (radians/sample) the loop can handle
+ * \param order the loop order, either 2 or 4
+ */
+class gr_costas_loop_cc;
+typedef boost::shared_ptr<gr_costas_loop_cc> gr_costas_loop_cc_sptr;
+
+
+gr_costas_loop_cc_sptr
+gr_make_costas_loop_cc (float alpha, float beta,
+ float max_freq, float min_freq,
+ int order
+ ) throw (std::invalid_argument);
+
+
+/*!
+ * \brief Carrier tracking PLL for QPSK
+ * \ingroup sync_blk
+ * input: complex; output: complex
+ * <br>The Costas loop can have two output streams:
+ * stream 1 is the baseband I and Q;
+ * stream 2 is the normalized frequency of the loop
+ *
+ * \p order must be 2 or 4.
+ */
+class gr_costas_loop_cc : public gr_sync_block
+{
+ friend gr_costas_loop_cc_sptr gr_make_costas_loop_cc (float alpha, float beta,
+ float max_freq, float min_freq,
+ int order
+ ) throw (std::invalid_argument);
+
+ float d_alpha, d_beta, d_max_freq, d_min_freq, d_phase, d_freq;
+ int d_order;
+
+ gr_costas_loop_cc (float alpha, float beta,
+ float max_freq, float min_freq,
+ int order
+ ) throw (std::invalid_argument);
+
+ /*! \brief the phase detector circuit for 8th-order PSK loops
+ * \param sample complex sample
+ * \return the phase error
+ */
+ float phase_detector_8(gr_complex sample) const; // for 8PSK
+
+ /*! \brief the phase detector circuit for fourth-order loops
+ * \param sample complex sample
+ * \return the phase error
+ */
+ float phase_detector_4(gr_complex sample) const; // for QPSK
+
+ /*! \brief the phase detector circuit for second-order loops
+ * \param sample a complex sample
+ * \return the phase error
+ */
+ float phase_detector_2(gr_complex sample) const; // for BPSK
+
+
+ float (gr_costas_loop_cc::*d_phase_detector)(gr_complex sample) const;
+
+public:
+
+ /*! \brief set the first order gain
+ * \param alpha
+ */
+ void set_alpha(float alpha);
+
+ /*! \brief get the first order gain
+ *
+ */
+ float alpha() const { return d_alpha; }
+
+ /*! \brief set the second order gain
+ * \param beta
+ */
+ void set_beta(float beta);
+
+ /*! \brief get the second order gain
+ *
+ */
+ float beta() const { return d_beta; }
+
+ int work (int noutput_items,
+ gr_vector_const_void_star &input_items,
+ gr_vector_void_star &output_items);
+
+ /*! \brief returns the current NCO frequency in radians/sample
+ *
+ */
+ float freq() const { return d_freq; }
+};
+
+#endif
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