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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.
*/
#ifndef LPF_H
#define LPF_H
#include <gnuradio/hier_block2.h>
#include <gnuradio/filter/firdes.h>
#include <gnuradio/filter/fir_filter_fff.h>
class lpf_ff;
typedef boost::shared_ptr<lpf_ff> lpf_ff_sptr;
/*! \brief Return a shared_ptr to a new instance of lpf.
* \param sample_rate The sample rate (Hz).
* \param cutoff_freq Center of transition band (Hz).
* \param transition_width Width of transition band (Hz).
* \param .
* \param gain Overall gain of filter (typically 1.0).
*
* This is effectively the public constructor. To avoid accidental use
* of raw pointers, lpf's constructor is private.
* make_lpf is the public interface for creating new instances.
*/
lpf_ff_sptr make_lpf_ff(double sample_rate=48000.,
double cutoff_freq=5000.,
double trans_width=1000.,
double gain=1.0);
/*! \brief low-pass filter (LPF) with float taps.
* \ingroup DSP
*
* This class encapsulates a low-pass FIR filter and the code
* required to generate filter taps. It provides a simple
* interface to set the filter parameters.
*
* The user of this class is expected to provide valid parameters and no checks are
* performed by the accessors (though the taps generator from gr::filter::firdes does perform
* some sanity checks and throws std::out_of_range in case of bad parameter).
*/
class lpf_ff : public gr::hier_block2
{
friend lpf_ff_sptr make_lpf_ff(double sample_rate, double cutoff_freq,
double trans_width, double gain);
protected:
lpf_ff(double sample_rate, double cutoff_freq,
double trans_width, double gain);
public:
~lpf_ff();
void set_param(double cutoff_freq, double trans_width);
private:
/* GR blocks */
gr::filter::fir_filter_fff::sptr lpf;
/* other parameters */
std::vector<float> d_taps;
double d_sample_rate;
double d_cutoff_freq;
double d_trans_width;
double d_gain;
};
#endif // LPF_H
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