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Diffstat (limited to 'plugins/channel/nfm/nfmdemod.cpp')
| -rw-r--r-- | plugins/channel/nfm/nfmdemod.cpp | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/plugins/channel/nfm/nfmdemod.cpp b/plugins/channel/nfm/nfmdemod.cpp new file mode 100644 index 0000000..fde579b --- /dev/null +++ b/plugins/channel/nfm/nfmdemod.cpp @@ -0,0 +1,145 @@ +/////////////////////////////////////////////////////////////////////////////////// +// Copyright (C) 2012 maintech GmbH, Otto-Hahn-Str. 15, 97204 Hoechberg, Germany // +// written by Christian Daniel // +// // +// 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 as version 3 of the License, or // +// // +// 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 V3 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/>. // +/////////////////////////////////////////////////////////////////////////////////// + +#include <QTime> +#include <stdio.h> +#include "nfmdemod.h" +#include "audio/audiooutput.h" +#include "dsp/dspcommands.h" + +MessageRegistrator NFMDemod::MsgConfigureNFMDemod::ID("MsgConfigureNFMDemod"); + +NFMDemod::NFMDemod(AudioFifo* audioFifo, SampleSink* sampleSink) : + m_sampleSink(sampleSink), + m_audioFifo(audioFifo) +{ + m_rfBandwidth = 12500; + m_volume = 2.0; + m_squelchLevel = pow(10.0, -40.0 / 20.0); + m_sampleRate = 500000; + m_frequency = 0; + m_squelchLevel *= m_squelchLevel; + + m_nco.setFreq(m_frequency, m_sampleRate); + m_interpolator.create(16, m_sampleRate, 12500); + m_sampleDistanceRemain = (Real)m_sampleRate / 44100.0; + + m_lowpass.create(21, 44100, 3000); + + m_audioBuffer.resize(256); + m_audioBufferFill = 0; + + m_movingAverage.resize(16, 0); +} + +NFMDemod::~NFMDemod() +{ +} + +void NFMDemod::configure(MessageQueue* messageQueue, Real rfBandwidth, Real afBandwidth, Real volume, Real squelch) +{ + Message* cmd = MsgConfigureNFMDemod::create(rfBandwidth, afBandwidth, volume, squelch); + cmd->submit(messageQueue, this); +} + +void NFMDemod::feed(SampleVector::const_iterator begin, SampleVector::const_iterator end, bool firstOfBurst) +{ + Complex ci; + bool consumed; + + for(SampleVector::const_iterator it = begin; it < end; ++it) { + Complex c(it->real() / 32768.0, it->imag() / 32768.0); + c *= m_nco.nextIQ(); + + consumed = false; + if(m_interpolator.interpolate(&m_sampleDistanceRemain, c, &consumed, &ci)) { + m_sampleBuffer.push_back(Sample(ci.real() * 32768.0, ci.imag() * 32768.0)); + + m_movingAverage.feed(ci.real() * ci.real() + ci.imag() * ci.imag()); + + if(m_movingAverage.average() >= m_squelchLevel) + m_squelchState = m_sampleRate / 50; + + if(m_squelchState > 0) { + m_squelchState--; + Complex d = ci * conj(m_lastSample); + m_lastSample = ci; + Real demod = atan2(d.imag(), d.real()) / M_PI; + demod = m_lowpass.filter(demod); + demod *= m_volume; + qint16 sample = demod * 32767; + + m_audioBuffer[m_audioBufferFill].l = sample; + m_audioBuffer[m_audioBufferFill].r = sample; + ++m_audioBufferFill; + if(m_audioBufferFill >= m_audioBuffer.size()) { + uint res = m_audioFifo->write((const quint8*)&m_audioBuffer[0], m_audioBufferFill, 1); + /* + if(res != m_audioBufferFill) + qDebug("lost %u samples", m_audioBufferFill - res); + */ + m_audioBufferFill = 0; + } + } + + m_sampleDistanceRemain += (Real)m_sampleRate / 44100.0; + } + } + if(m_audioFifo->write((const quint8*)&m_audioBuffer[0], m_audioBufferFill, 0) != m_audioBufferFill) + ;//qDebug("lost samples"); + m_audioBufferFill = 0; + + if(m_sampleSink != NULL) + m_sampleSink->feed(m_sampleBuffer.begin(), m_sampleBuffer.end(), firstOfBurst); + m_sampleBuffer.clear(); +} + +void NFMDemod::start() +{ + m_squelchState = 0; +} + +void NFMDemod::stop() +{ +} + +bool NFMDemod::handleMessage(Message* cmd) +{ + if(cmd->id() == DSPSignalNotification::ID()) { + DSPSignalNotification* signal = (DSPSignalNotification*)cmd; + qDebug("%d samples/sec, %lld Hz offset", signal->getSampleRate(), signal->getFrequencyOffset()); + m_sampleRate = signal->getSampleRate(); + m_nco.setFreq(-signal->getFrequencyOffset(), m_sampleRate); + m_interpolator.create(16, m_sampleRate, m_rfBandwidth / 2.1); + m_sampleDistanceRemain = m_sampleRate / 44100.0; + m_squelchState = 0; + cmd->completed(); + return true; + } else if(cmd->id() == MsgConfigureNFMDemod::ID()) { + MsgConfigureNFMDemod* cfg = (MsgConfigureNFMDemod*)cmd; + m_rfBandwidth = cfg->getRFBandwidth(); + m_interpolator.create(16, m_sampleRate, m_rfBandwidth / 2.1); + m_lowpass.create(21, 44100, cfg->getAFBandwidth()); + m_squelchLevel = pow(10.0, cfg->getSquelch() / 20.0); + m_squelchLevel *= m_squelchLevel; + m_volume = cfg->getVolume(); + cmd->completed(); + return true; + } else { + return false; + } +} |