121 lines
3.6 KiB
C++
121 lines
3.6 KiB
C++
/* -*- c++ -*- */
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/*
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* gr-satnogs: SatNOGS GNU Radio Out-Of-Tree Module
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*
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* Copyright (C) 2016, Libre Space Foundation <http://librespacefoundation.org/>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <gnuradio/io_signature.h>
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#include "coarse_doppler_correction_cc_impl.h"
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#include <volk/volk.h>
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#include <satnogs/log.h>
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namespace gr {
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namespace satnogs {
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coarse_doppler_correction_cc::sptr
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coarse_doppler_correction_cc::make(double target_freq,
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double offset,
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double sampling_rate)
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{
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return gnuradio::get_initial_sptr(
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new coarse_doppler_correction_cc_impl(target_freq, offset,
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sampling_rate));
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}
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/*
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* The private constructor
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*/
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coarse_doppler_correction_cc_impl::coarse_doppler_correction_cc_impl(
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double target_freq, double offset, double sampling_rate) :
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gr::sync_block("coarse_doppler_correction_cc",
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gr::io_signature::make(1, 1, sizeof(gr_complex)),
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gr::io_signature::make(1, 1, sizeof(gr_complex))),
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d_target_freq(target_freq),
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d_offset(offset),
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d_samp_rate(sampling_rate),
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d_buf_items(std::min((size_t)8192UL, (size_t)(d_samp_rate / 4))),
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d_freq_diff(d_offset),
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d_nco()
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{
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message_port_register_in(pmt::mp("freq"));
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/*
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* NOTE:
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* Set the maximum number of samples to be equivalent of half a second.
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* With this way we are sure that at least one frequency message
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* per second will be processed.
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*
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* This is taken into consideration due to the fact that the work()
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* and the input message handler are NOT reentrant.
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*/
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set_max_noutput_items(d_samp_rate / 4.0);
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set_alignment(8);
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set_msg_handler(
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pmt::mp("freq"),
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boost::bind(&coarse_doppler_correction_cc_impl::new_freq, this, _1));
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d_nco.set_freq((2 * M_PI * (-d_freq_diff)) / d_samp_rate);
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/* Allocate aligned memory for the NCO */
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d_nco_buff = (gr_complex *) volk_malloc(
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(d_samp_rate / 4) * sizeof(gr_complex), 32);
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if (!d_nco_buff) {
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throw std::runtime_error("Could not allocate NCO memory");
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}
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}
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void
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coarse_doppler_correction_cc_impl::new_freq(pmt::pmt_t msg)
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{
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double new_freq;
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new_freq = pmt::to_double(msg);
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d_freq_diff = new_freq - (d_target_freq - d_offset);
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d_nco.set_freq((2 * M_PI * (-d_freq_diff)) / d_samp_rate);
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}
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/*
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* Our virtual destructor.
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*/
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coarse_doppler_correction_cc_impl::~coarse_doppler_correction_cc_impl()
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{
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volk_free(d_nco_buff);
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}
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int
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coarse_doppler_correction_cc_impl::work(
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int noutput_items, gr_vector_const_void_star &input_items,
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gr_vector_void_star &output_items)
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{
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const gr_complex *in = (const gr_complex *) input_items[0];
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gr_complex *out = (gr_complex *) output_items[0];
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/* Perform the correction */
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d_nco.sincos(d_nco_buff, noutput_items, 1.0);
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volk_32fc_x2_multiply_32fc(out, in, d_nco_buff, noutput_items);
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// Tell runtime system how many output items we produced.
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return noutput_items;
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}
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} /* namespace satnogs */
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} /* namespace gr */
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