Hamlib/gnuradio/wfm.h

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/*
* Hamlib GNUradio backend - Wide FM class
* Copyright (c) 2003 by Stephane Fillod
*
* $Id: wfm.h,v 1.2 2004-02-08 20:27:58 fillods Exp $
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Library General Public License as
* published by the Free Software Foundation; either version 2 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 Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#ifndef _WFM_H
#define _WFM_H 1
#include "demod.h"
#include <VrQuadratureDemod.h> /* WFM */
#include <GrFIRfilterFFF.h>
class WFMDemodChainCF : public DemodChainCF {
private:
VrQuadratureDemod<d_oType> *q_demod;
int RFIRdecimate;
GrFIRfilterFFF *audio_filter;
public:
WFMDemodChainCF (VrSource<d_iType> *src, VrSink<d_oType> *snk, rmode_t mode, pbwidth_t width, int input_rate, freq_t centerfreq = 0) :
DemodChainCF(src, snk, mode, width, input_rate, centerfreq) {
CFIRdecimate = 125;
RFIRdecimate = 5;
const int quadRate = input_rate / CFIRdecimate;
const int audioRate = quadRate / RFIRdecimate;
rig_debug(RIG_DEBUG_VERBOSE, "Input Sampling Rate: %d\n", input_rate);
rig_debug(RIG_DEBUG_VERBOSE, "Complex FIR decimation factor: %d\n", CFIRdecimate);
rig_debug(RIG_DEBUG_VERBOSE, "QuadDemod Sampling Rate: %d\n", quadRate);
rig_debug(RIG_DEBUG_VERBOSE, "Real FIR decimation factor: %d\n", RFIRdecimate);
rig_debug(RIG_DEBUG_VERBOSE, "Audio Sampling Rate: %d\n", audioRate);
// build channel filter
//
// note that the totally bogus transition width is because
// we don't have enough mips right now to really do the right thing.
// This results in a filter with 83 taps, which is just a few
// more than the original 75 in microtune_fm_demo.
if_width_of_transition_band = 8*100e3;
// float --> float
double width_of_transition_band = audioRate / 32;
vector<float> audio_coeffs =
gr_firdes::low_pass (1.0, // gain
quadRate, // sampling rate
audioRate/2 - width_of_transition_band, // low-pass cutoff freq
width_of_transition_band,
gr_firdes::WIN_HAMMING);
rig_debug(RIG_DEBUG_VERBOSE, "Number of audio_coeffs: %d\n", audio_coeffs.size ());
rig_debug(RIG_DEBUG_VERBOSE, "Low-pass cutoff freq: %d\n", audioRate/2 - (int)width_of_transition_band);
audio_filter = new GrFIRfilterFFF(RFIRdecimate, audio_coeffs);
q_demod = new VrQuadratureDemod<d_oType>(1.0);
demod_in = q_demod;
demod_out = audio_filter;
NWO_CONNECT(demod_in, audio_filter);
}
~WFMDemodChainCF() { delete q_demod; delete audio_filter; }
//void setWidth(pbwidth_t width) { }
//void setFreq(freq_t centerfreq) { }
void setRFgain(float gain) { q_demod->setGain(gain); }
};
#endif /* _WFM_H */