From f6e8da2d7cb16c68a3e3683a0e81c84eda73dabf Mon Sep 17 00:00:00 2001 From: Tom Rondeau Date: Mon, 28 Mar 2011 22:20:03 -0400 Subject: gr-digital: renaming block to avoid name collision with stuff in gnuradio-core. --- gr-digital/lib/digital_costas_loop_cc.h | 146 ++++++++++++++++++++++++++++++++ 1 file changed, 146 insertions(+) create mode 100644 gr-digital/lib/digital_costas_loop_cc.h (limited to 'gr-digital/lib/digital_costas_loop_cc.h') diff --git a/gr-digital/lib/digital_costas_loop_cc.h b/gr-digital/lib/digital_costas_loop_cc.h new file mode 100644 index 000000000..256423aae --- /dev/null +++ b/gr-digital/lib/digital_costas_loop_cc.h @@ -0,0 +1,146 @@ +/* -*- c++ -*- */ +/* + * Copyright 2006,2011 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_COSTAS_LOOP_CC_H +#define INCLUDED_DIGITAL_COSTAS_LOOP_CC_H + +#include +#include +#include + + +/*! \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 digital_costas_loop_cc; +typedef boost::shared_ptr digital_costas_loop_cc_sptr; + + +digital_costas_loop_cc_sptr +digital_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 + *
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 digital_costas_loop_cc : public gr_sync_block +{ + friend digital_costas_loop_cc_sptr + digital_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; + + digital_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 (digital_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 -- cgit From b30c79326c3eedf5ebf20be62306f0511b98a0e7 Mon Sep 17 00:00:00 2001 From: Tom Rondeau Date: Tue, 29 Mar 2011 00:48:49 -0400 Subject: gr-digital: restructured Costas loop to be specified in terms of the damping factor and natural frequency instead of randomly setting the gains. Much more robust in simulation. --- gr-digital/lib/digital_costas_loop_cc.h | 38 ++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 17 deletions(-) (limited to 'gr-digital/lib/digital_costas_loop_cc.h') diff --git a/gr-digital/lib/digital_costas_loop_cc.h b/gr-digital/lib/digital_costas_loop_cc.h index 256423aae..9c112d328 100644 --- a/gr-digital/lib/digital_costas_loop_cc.h +++ b/gr-digital/lib/digital_costas_loop_cc.h @@ -58,8 +58,7 @@ typedef boost::shared_ptr digital_costas_loop_cc_sptr; digital_costas_loop_cc_sptr -digital_make_costas_loop_cc (float alpha, float beta, - float max_freq, float min_freq, +digital_make_costas_loop_cc (float damping, float nat_freq, int order ) throw (std::invalid_argument); @@ -77,18 +76,30 @@ digital_make_costas_loop_cc (float alpha, float beta, class digital_costas_loop_cc : public gr_sync_block { friend digital_costas_loop_cc_sptr - digital_make_costas_loop_cc (float alpha, float beta, - float max_freq, float min_freq, + digital_make_costas_loop_cc (float damping, float nat_freq, int order ) throw (std::invalid_argument); float d_alpha, d_beta, d_max_freq, d_min_freq, d_phase, d_freq; + float d_nat_freq, d_damping; int d_order; - digital_costas_loop_cc (float alpha, float beta, - float max_freq, float min_freq, - int order - ) throw (std::invalid_argument); + digital_costas_loop_cc (float damping, float nat_freq, + int order + ) throw (std::invalid_argument); + + + /*! \brief update the system gains from omega and eta + * + * This function updates the system gains based on the natural + * frequency (omega) and damping factor (eta) of the system. + * These two factors can be set separately through their own + * set functions. + * + * These equations are summarized nicely in this paper from Berkeley: + * http://www.complextoreal.com/chapters/pll.pdf + */ + void update_gains(); /*! \brief the phase detector circuit for 8th-order PSK loops * \param sample complex sample @@ -113,21 +124,14 @@ class digital_costas_loop_cc : public gr_sync_block public: - /*! \brief set the first order gain - * \param alpha - */ - void set_alpha(float alpha); + void set_natural_freq(float w); + void set_damping_factor(float eta); /*! \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 * */ -- cgit From 1a43b1c6d705710a58b4bbd3bcb4000766425091 Mon Sep 17 00:00:00 2001 From: Tom Rondeau Date: Wed, 30 Mar 2011 00:01:01 -0400 Subject: gr-digital: cleaning up and commenting. --- gr-digital/lib/digital_costas_loop_cc.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'gr-digital/lib/digital_costas_loop_cc.h') diff --git a/gr-digital/lib/digital_costas_loop_cc.h b/gr-digital/lib/digital_costas_loop_cc.h index 9c112d328..2c4c38e8b 100644 --- a/gr-digital/lib/digital_costas_loop_cc.h +++ b/gr-digital/lib/digital_costas_loop_cc.h @@ -81,7 +81,7 @@ class digital_costas_loop_cc : public gr_sync_block ) throw (std::invalid_argument); float d_alpha, d_beta, d_max_freq, d_min_freq, d_phase, d_freq; - float d_nat_freq, d_damping; + float d_damping, d_nat_freq; int d_order; digital_costas_loop_cc (float damping, float nat_freq, -- cgit From 7dfb50a3deec474bb8896cfbfc8d51928908bd17 Mon Sep 17 00:00:00 2001 From: Tom Rondeau Date: Sun, 10 Jul 2011 20:28:47 -0400 Subject: digital: fixed variable ordering to remove warning. --- gr-digital/lib/digital_costas_loop_cc.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'gr-digital/lib/digital_costas_loop_cc.h') diff --git a/gr-digital/lib/digital_costas_loop_cc.h b/gr-digital/lib/digital_costas_loop_cc.h index 2c4c38e8b..9c112d328 100644 --- a/gr-digital/lib/digital_costas_loop_cc.h +++ b/gr-digital/lib/digital_costas_loop_cc.h @@ -81,7 +81,7 @@ class digital_costas_loop_cc : public gr_sync_block ) throw (std::invalid_argument); float d_alpha, d_beta, d_max_freq, d_min_freq, d_phase, d_freq; - float d_damping, d_nat_freq; + float d_nat_freq, d_damping; int d_order; digital_costas_loop_cc (float damping, float nat_freq, -- cgit