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157 lines
5.2 KiB
C++
157 lines
5.2 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2012 maintech GmbH, Otto-Hahn-Str. 15, 97204 Hoechberg, Germany //
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// written by Christian Daniel //
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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 as version 3 of the License, or //
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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 V3 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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#include <QTime>
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#include <stdio.h>
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#include "nfmdemod.h"
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#include "audio/audiooutput.h"
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#include "dsp/dspcommands.h"
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MESSAGE_CLASS_DEFINITION(NFMDemod::MsgConfigureNFMDemod, Message)
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NFMDemod::NFMDemod(AudioFifo* audioFifo, SampleSink* sampleSink) :
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m_sampleSink(sampleSink),
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m_audioFifo(audioFifo)
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{
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m_rfBandwidth = 12500;
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m_volume = 2.0;
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m_squelchLevel = pow(10.0, -40.0 / 10.0);
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m_sampleRate = 500000;
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m_frequency = 0;
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m_scale = 0;
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m_framedrop = 0;
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m_nco.setFreq(m_frequency, m_sampleRate);
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m_interpolator.create(16, m_sampleRate, 12500);
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m_sampleDistanceRemain = (Real)m_sampleRate / 48000.0;
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m_lowpass.create(21, 48000, 3000);
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m_audioBuffer.resize(256);
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m_audioBufferFill = 0;
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m_movingAverage.resize(16, 0);
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}
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NFMDemod::~NFMDemod()
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{
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}
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void NFMDemod::configure(MessageQueue* messageQueue, Real rfBandwidth, Real afBandwidth, Real volume, Real squelch)
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{
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Message* cmd = MsgConfigureNFMDemod::create(rfBandwidth, afBandwidth, volume, squelch);
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cmd->submit(messageQueue, this);
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}
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void NFMDemod::feed(SampleVector::const_iterator begin, SampleVector::const_iterator end, bool positiveOnly)
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{
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Complex ci;
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qint16 sample;
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Real a, b, s, demod;
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double meansqr = 1.0;
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for(SampleVector::const_iterator it = begin; it < end; ++it) {
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Complex c(it->real() / 32768.0, it->imag() / 32768.0);
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c *= m_nco.nextIQ();
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if(m_interpolator.interpolate(&m_sampleDistanceRemain, c, &ci)) {
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s = ci.real() * ci.real() + ci.imag() * ci.imag();
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meansqr += s;
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m_movingAverage.feed(s);
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if(m_movingAverage.average() >= m_squelchLevel)
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m_squelchState = m_sampleRate / 50;
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a = m_scale * m_this.real() * (m_last.imag() - ci.imag());
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b = m_scale * m_this.imag() * (m_last.real() - ci.real());
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m_last = m_this;
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m_this = Complex(ci.real(), ci.imag());
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demod = m_volume * m_lowpass.filter(b - a);
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sample = demod * 30000;
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// Display audio spectrum to 12kHz
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if (++m_framedrop & 1)
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m_sampleBuffer.push_back(Sample(sample, sample));
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if(m_squelchState > 0)
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m_squelchState--;
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else
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sample = 0;
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{
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m_audioBuffer[m_audioBufferFill].l = sample;
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m_audioBuffer[m_audioBufferFill].r = sample;
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++m_audioBufferFill;
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if(m_audioBufferFill >= m_audioBuffer.size()) {
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uint res = m_audioFifo->write((const quint8*)&m_audioBuffer[0], m_audioBufferFill, 1);
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if(res != m_audioBufferFill)
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qDebug("lost %u samples", m_audioBufferFill - res);
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m_audioBufferFill = 0;
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}
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}
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m_sampleDistanceRemain += (Real)m_sampleRate / 48000.0;
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}
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}
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if(m_audioFifo->write((const quint8*)&m_audioBuffer[0], m_audioBufferFill, 0) != m_audioBufferFill)
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;//qDebug("lost samples");
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m_audioBufferFill = 0;
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if(m_sampleSink != NULL)
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m_sampleSink->feed(m_sampleBuffer.begin(), m_sampleBuffer.end(), true);
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m_sampleBuffer.clear();
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// TODO: correct levels
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m_scale = ( end - begin) * m_sampleRate / 48000 / meansqr;
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}
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void NFMDemod::start()
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{
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m_squelchState = 0;
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}
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void NFMDemod::stop()
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{
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}
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bool NFMDemod::handleMessage(Message* cmd)
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{
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if(DSPSignalNotification::match(cmd)) {
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DSPSignalNotification* signal = (DSPSignalNotification*)cmd;
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qDebug("%d samples/sec, %lld Hz offset", signal->getSampleRate(), signal->getFrequencyOffset());
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m_sampleRate = signal->getSampleRate();
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m_nco.setFreq(-signal->getFrequencyOffset(), m_sampleRate);
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m_interpolator.create(16, m_sampleRate, m_rfBandwidth / 2.1);
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m_sampleDistanceRemain = m_sampleRate / 48000.0;
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m_squelchState = 0;
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cmd->completed();
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return true;
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} else if(MsgConfigureNFMDemod::match(cmd)) {
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MsgConfigureNFMDemod* cfg = (MsgConfigureNFMDemod*)cmd;
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m_rfBandwidth = cfg->getRFBandwidth();
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m_interpolator.create(16, m_sampleRate, m_rfBandwidth / 2.1);
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m_lowpass.create(21, 48000, cfg->getAFBandwidth());
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m_squelchLevel = pow(10.0, cfg->getSquelch() / 10.0);
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m_volume = cfg->getVolume();
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cmd->completed();
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return true;
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} else {
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if(m_sampleSink != NULL)
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return m_sampleSink->handleMessage(cmd);
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else return false;
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}
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}
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