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/* -*- c++ -*- */
/*
* Gqrx SDR: Software defined radio receiver powered by GNU Radio and Qt
* http://gqrx.dk/
*
* Copyright 2012 Alexandru Csete OZ9AEC.
*
* Gqrx 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.
*
* Gqrx 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 Gqrx; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#include <cmath>
#include <gnuradio/io_signature.h>
#include <gnuradio/filter/firdes.h>
#include "dsp/lpf.h"
static const int MIN_IN = 1; /* Mininum number of input streams. */
static const int MAX_IN = 1; /* Maximum number of input streams. */
static const int MIN_OUT = 1; /* Minimum number of output streams. */
static const int MAX_OUT = 1; /* Maximum number of output streams. */
/*
* Create a new instance of lpf and return
* a boost shared_ptr. This is effectively the public constructor.
*/
lpf_ff_sptr make_lpf_ff(double sample_rate, double cutoff_freq,
double trans_width, double gain)
{
return gnuradio::get_initial_sptr(new lpf_ff(sample_rate, cutoff_freq,
trans_width, gain));
}
lpf_ff::lpf_ff(double sample_rate, double cutoff_freq,
double trans_width, double gain)
: gr::hier_block2("lpf_ff",
gr::io_signature::make(MIN_IN, MAX_IN, sizeof (float)),
gr::io_signature::make(MIN_OUT, MAX_OUT, sizeof (float))),
d_sample_rate(sample_rate),
d_cutoff_freq(cutoff_freq),
d_trans_width(trans_width),
d_gain(gain)
{
/* generate taps */
d_taps = gr::filter::firdes::low_pass(d_gain, d_sample_rate,
d_cutoff_freq, d_trans_width);
/* create low-pass filter (decimation=1) */
lpf = gr::filter::fir_filter_fff::make(1, d_taps);
/* connect filter */
connect(self(), 0, lpf, 0);
connect(lpf, 0, self(), 0);
}
lpf_ff::~lpf_ff()
{
}
void lpf_ff::set_param(double cutoff_freq, double trans_width)
{
d_cutoff_freq = cutoff_freq;
d_trans_width = trans_width;
/* generate new taps */
d_taps = gr::filter::firdes::low_pass(d_gain, d_sample_rate,
d_cutoff_freq, d_trans_width);
lpf->set_taps(d_taps);
}
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