216 lines
6.5 KiB
C++
216 lines
6.5 KiB
C++
/* -*- c++ -*- */
|
|
/*
|
|
* gr-satnogs: SatNOGS GNU Radio Out-Of-Tree Module
|
|
*
|
|
* Copyright (C) 2016, Libre Space Foundation <http://librespacefoundation.org/>
|
|
*
|
|
* This program 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 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#ifdef HAVE_CONFIG_H
|
|
#include "config.h"
|
|
#endif
|
|
|
|
#include <gnuradio/io_signature.h>
|
|
#include "doppler_correction_cc_impl.h"
|
|
#include <satnogs/log.h>
|
|
#include <volk/volk.h>
|
|
|
|
namespace gr
|
|
{
|
|
namespace satnogs
|
|
{
|
|
|
|
doppler_correction_cc::sptr
|
|
doppler_correction_cc::make (double target_freq, double sampling_rate,
|
|
size_t corrections_per_sec)
|
|
{
|
|
return gnuradio::get_initial_sptr (
|
|
new doppler_correction_cc_impl (target_freq, sampling_rate,
|
|
corrections_per_sec));
|
|
}
|
|
|
|
/*
|
|
* The private constructor
|
|
*/
|
|
doppler_correction_cc_impl::doppler_correction_cc_impl (
|
|
double target_freq, double sampling_rate, size_t corrections_per_sec) :
|
|
gr::sync_block ("doppler_correction_cc",
|
|
gr::io_signature::make (1, 1, sizeof(gr_complex)),
|
|
gr::io_signature::make (1, 1, sizeof(gr_complex))),
|
|
d_target_freq (target_freq),
|
|
d_samp_rate (sampling_rate),
|
|
d_update_period (sampling_rate / (double) corrections_per_sec),
|
|
d_est_thrhld (7),
|
|
d_corrections_per_sec (corrections_per_sec),
|
|
d_nco (),
|
|
/* A 3-rd order polynomial curve fitting is more than enough */
|
|
d_doppler_fit_engine (3),
|
|
d_freq_diff (0.0),
|
|
d_have_est (false),
|
|
d_freq_est_num (0),
|
|
d_corrections (0),
|
|
d_corrected_samples (0)
|
|
{
|
|
message_port_register_in (pmt::mp ("freq"));
|
|
message_port_register_in (pmt::mp ("reset"));
|
|
|
|
/*
|
|
* NOTE:
|
|
* Set the maximum number of samples to be equivalent of half a second.
|
|
* With this way we are sure that at least one frequency message
|
|
* per second will be processed.
|
|
*
|
|
* This is taken into consideration due to the fact that the work()
|
|
* and the input message handler are NOT reentrant.
|
|
*/
|
|
set_max_noutput_items (d_samp_rate / 2.0);
|
|
set_alignment (8);
|
|
|
|
set_msg_handler (
|
|
pmt::mp ("freq"),
|
|
boost::bind (&doppler_correction_cc_impl::new_freq, this, _1));
|
|
set_msg_handler (
|
|
pmt::mp ("reset"),
|
|
boost::bind (&doppler_correction_cc_impl::reset, this, _1));
|
|
|
|
/* Allocate the buffer that will hold the predicted frequency differences */
|
|
d_predicted_freqs = new double[d_corrections_per_sec];
|
|
|
|
/* Allocate aligned memory for the NCO */
|
|
d_nco_buff = (gr_complex *) volk_malloc (
|
|
d_update_period * sizeof(gr_complex), 32);
|
|
if (!d_nco_buff) {
|
|
throw std::runtime_error ("Could not allocate NCO memory");
|
|
}
|
|
}
|
|
|
|
void
|
|
doppler_correction_cc_impl::new_freq (pmt::pmt_t msg)
|
|
{
|
|
boost::mutex::scoped_lock lock (d_mutex);
|
|
double new_freq;
|
|
new_freq = pmt::to_double (msg);
|
|
d_freq_diff = new_freq - d_target_freq;
|
|
if (!d_have_est) {
|
|
d_freq_est_num++;
|
|
d_doppler_freqs.push_back (
|
|
freq_drift (nitems_written (0), d_freq_diff));
|
|
if (d_freq_est_num > d_est_thrhld - 1) {
|
|
d_doppler_fit_engine.fit (d_doppler_freqs);
|
|
d_doppler_fit_engine.predict_freqs (d_predicted_freqs,
|
|
d_corrections_per_sec,
|
|
d_update_period);
|
|
d_have_est = true;
|
|
}
|
|
}
|
|
else {
|
|
d_doppler_freqs.pop_front ();
|
|
d_doppler_freqs.push_back (
|
|
freq_drift (nitems_written (0), d_freq_diff));
|
|
|
|
/* Fit the doppler drift based on the new estimated frequency */
|
|
d_doppler_fit_engine.fit (d_doppler_freqs);
|
|
/* Predict the frequency differences for the near future */
|
|
d_doppler_fit_engine.predict_freqs (d_predicted_freqs,
|
|
d_corrections_per_sec,
|
|
d_update_period);
|
|
d_corrections = 0;
|
|
}
|
|
}
|
|
|
|
void
|
|
doppler_correction_cc_impl::reset (pmt::pmt_t msg)
|
|
{
|
|
boost::mutex::scoped_lock lock (d_mutex);
|
|
d_doppler_freqs.clear ();
|
|
d_freq_est_num = 0;
|
|
d_corrections = 0;
|
|
d_have_est = false;
|
|
}
|
|
|
|
/*
|
|
* Our virtual destructor.
|
|
*/
|
|
doppler_correction_cc_impl::~doppler_correction_cc_impl ()
|
|
{
|
|
delete[] d_predicted_freqs;
|
|
volk_free (d_nco_buff);
|
|
}
|
|
|
|
int
|
|
doppler_correction_cc_impl::work (int noutput_items,
|
|
gr_vector_const_void_star &input_items,
|
|
gr_vector_void_star &output_items)
|
|
{
|
|
const gr_complex *in = (const gr_complex *) input_items[0];
|
|
gr_complex *out = (gr_complex *) output_items[0];
|
|
int produced = 0;
|
|
size_t cnt;
|
|
|
|
/*
|
|
* If we do not have an estimation yet, just copy the input to the output.
|
|
* Otherwise perform Doppler correction, using the fitted curve indicating
|
|
* the frequency drift.
|
|
*/
|
|
if (d_have_est) {
|
|
while (produced < noutput_items) {
|
|
/*
|
|
* If no samples have been corrected from the current correction step
|
|
* compute and store the NCO buffer with the corresponding frequency
|
|
*/
|
|
if (d_corrected_samples == 0) {
|
|
d_nco.set_freq (
|
|
2 * M_PI * (-d_predicted_freqs[d_corrections]) / d_samp_rate);
|
|
d_nco.sincos (d_nco_buff, d_update_period, 1.0);
|
|
d_corrections++;
|
|
|
|
/*
|
|
* The doppler estimation may fail/delay. In such a case the block
|
|
* should continue using the predicted frequencies
|
|
*/
|
|
if (d_corrections == d_corrections_per_sec) {
|
|
d_doppler_fit_engine.predict_freqs (d_predicted_freqs,
|
|
d_corrections_per_sec,
|
|
d_update_period);
|
|
d_corrections = 0;
|
|
}
|
|
}
|
|
|
|
cnt = std::min (d_update_period - d_corrected_samples,
|
|
(size_t) (noutput_items - produced));
|
|
/* Perform the doppler shift correction */
|
|
volk_32fc_x2_multiply_32fc (out + produced, in + produced,
|
|
d_nco_buff + d_corrected_samples, cnt);
|
|
|
|
/* Make the proper advances */
|
|
produced += (int) cnt;
|
|
d_corrected_samples += cnt;
|
|
|
|
if (d_corrected_samples == d_update_period) {
|
|
d_corrected_samples = 0;
|
|
}
|
|
}
|
|
}
|
|
else {
|
|
memcpy (out, in, noutput_items * sizeof(gr_complex));
|
|
}
|
|
|
|
return noutput_items;
|
|
}
|
|
|
|
} /* namespace satnogs */
|
|
} /* namespace gr */
|
|
|