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| author | Josh Blum <josh@joshknows.com> | 2011-07-28 17:02:58 -0700 |
|---|---|---|
| committer | Josh Blum <josh@joshknows.com> | 2011-07-28 17:02:58 -0700 |
| commit | 8bc1c4dc5a8d31594e8768a10e05b4b0172e733e (patch) | |
| tree | fcb957028a108ca719a6cb879e7d62713b35ba1c /gr-digital/lib/digital_clock_recovery_mm_ff.cc | |
| parent | 8c824bf2e3e6758aff05ee4b5f4d3f106a13c672 (diff) | |
| parent | 8b3c4ccf922c602ae77dad7f3911b16bdd0112d3 (diff) | |
Merge branch 'digital' of https://github.com/trondeau/gnuradio into digital
Conflicts:
gnuradio-core/src/lib/filter/gr_cma_equalizer_cc.h
gnuradio-core/src/lib/general/gr_constellation_decoder_cb.h
gnuradio-core/src/lib/general/gr_costas_loop_cc.h
gnuradio-core/src/lib/general/gr_lms_dfe_cc.h
gnuradio-core/src/lib/general/gr_lms_dfe_ff.h
gr-digital/lib/Makefile.am
gr-digital/lib/digital_binary_slicer_fb.h
gr-digital/lib/digital_clock_recovery_mm_cc.h
gr-digital/lib/digital_clock_recovery_mm_ff.h
gr-digital/lib/digital_correlate_access_code_bb.h
gr-digital/lib/digital_crc32.h
gr-digital/lib/digital_mpsk_receiver_cc.h
gr-digital/python/Makefile.am
gr-digital/python/__init__.py
gr-digital/python/generic_mod_demod.py
gr-digital/python/pkt.py
gr-digital/python/psk2.py
gr-digital/python/qam.py
Diffstat (limited to 'gr-digital/lib/digital_clock_recovery_mm_ff.cc')
| -rw-r--r-- | gr-digital/lib/digital_clock_recovery_mm_ff.cc | 139 |
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 0000000000..04057f0e94 --- /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; +} |