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NFM demod: corrections applied to the audio sample rate depedent parameters

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This commit is contained in:
f4exb 2018-04-11 01:31:48 +02:00
parent 4dc99f7ad8
commit dac48f9a6d
3 changed files with 25 additions and 17 deletions
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39
plugins/channelrx/demodnfm/nfmdemod.cpp
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@ -55,7 +55,8 @@ NFMDemod::NFMDemod(DeviceSourceAPI *devieAPI) :
m_ctcssIndex(0),
m_sampleCount(0),
m_squelchCount(0),
m_squelchGate(2),
m_squelchGate(4800),
m_squelchDecay(480),
m_squelchLevel(-990),
m_squelchOpen(false),
m_afSquelchOpen(false),
@ -75,12 +76,12 @@ NFMDemod::NFMDemod(DeviceSourceAPI *devieAPI) :
m_agcLevel = 1.0;
m_ctcssDetector.setCoefficients(3000, 6000.0); // 0.5s / 2 Hz resolution
m_afSquelch.setCoefficients(24, 600, 48000.0, 200, 0); // 0.5ms test period, 300ms average span, 48kS/s SR, 100ms attack, no decay
DSPEngine::instance()->getAudioDeviceManager()->addAudioSink(&m_audioFifo, getInputMessageQueue());
m_audioSampleRate = DSPEngine::instance()->getAudioDeviceManager()->getOutputSampleRate();
m_ctcssDetector.setCoefficients(m_audioSampleRate/16, m_audioSampleRate/8.0f); // 0.5s / 2 Hz resolution
m_afSquelch.setCoefficients(m_audioSampleRate/2000, 600, m_audioSampleRate, 200, 0); // 0.5ms test period, 300ms average span, audio SR, 100ms attack, no decay
m_lowpass.create(301, m_audioSampleRate, 250.0);
applyChannelSettings(m_inputSampleRate, m_inputFrequencyOffset, true);
@ -136,6 +137,7 @@ Real angleDist(Real a, Real b)
void NFMDemod::feed(const SampleVector::const_iterator& begin, const SampleVector::const_iterator& end, bool firstOfBurst __attribute__((unused)))
{
Complex ci;
float f = (m_audioSampleRate / 48000.0f);
if (!m_running) {
return;
@ -174,13 +176,13 @@ void NFMDemod::feed(const SampleVector::const_iterator& begin, const SampleVecto
if (m_settings.m_deltaSquelch)
{
if (m_afSquelch.analyze(demod)) {
m_afSquelchOpen = m_afSquelch.evaluate() ? m_squelchGate + 480 : 0;
if (m_afSquelch.analyze(demod * f)) {
m_afSquelchOpen = m_afSquelch.evaluate() ? m_squelchGate + m_squelchDecay : 0;
}
if (m_afSquelchOpen)
{
if (m_squelchCount < m_squelchGate + 480)
if (m_squelchCount < m_squelchGate + m_squelchDecay)
{
m_squelchCount++;
}
@ -204,7 +206,7 @@ void NFMDemod::feed(const SampleVector::const_iterator& begin, const SampleVecto
}
else
{
if (m_squelchCount < m_squelchGate + 480)
if (m_squelchCount < m_squelchGate + m_squelchDecay)
{
m_squelchCount++;
}
@ -217,7 +219,7 @@ void NFMDemod::feed(const SampleVector::const_iterator& begin, const SampleVecto
{
if (m_settings.m_ctcssOn)
{
Real ctcss_sample = m_lowpass.filter(demod);
Real ctcss_sample = m_lowpass.filter(demod * f);
if ((m_sampleCount & 7) == 7) // decimate 48k -> 6k
{
@ -257,8 +259,8 @@ void NFMDemod::feed(const SampleVector::const_iterator& begin, const SampleVecto
}
else
{
demod = m_bandpass.filter(demod);
Real squelchFactor = StepFunctions::smootherstep((Real) (m_squelchCount - m_squelchGate) / 480.0f);
demod = m_bandpass.filter(demod * f);
Real squelchFactor = StepFunctions::smootherstep((Real) (m_squelchCount - m_squelchGate) / (Real) m_squelchDecay);
sample = demod * m_settings.m_volume * squelchFactor;
}
}
@ -407,6 +409,12 @@ void NFMDemod::applyAudioSampleRate(int sampleRate)
m_interpolatorDistance = (Real) m_inputSampleRate / (Real) sampleRate;
m_lowpass.create(301, sampleRate, 250.0);
m_bandpass.create(301, sampleRate, 300.0, m_settings.m_afBandwidth);
m_squelchGate = (sampleRate / 100) * m_settings.m_squelchGate; // gate is given in 10s of ms at 48000 Hz audio sample rate
m_squelchDecay = (sampleRate / 100); // decay is fixed at 10ms
m_squelchCount = 0; // reset squelch open counter
m_ctcssDetector.setCoefficients(sampleRate/16, sampleRate/8.0f); // 0.5s / 2 Hz resolution
m_afSquelch.setCoefficients(sampleRate/2000, 600, sampleRate, 200, 0); // 0.5ms test period, 300ms average span, audio SR, 100ms attack, no decay
m_phaseDiscri.setFMScaling((8.0f*sampleRate) / static_cast<float>(m_settings.m_fmDeviation)); // integrate 4x factor
m_audioFifo.setSize(sampleRate);
m_settingsMutex.unlock();
@ -464,10 +472,9 @@ void NFMDemod::applySettings(const NFMDemodSettings& settings, bool force)
m_settingsMutex.unlock();
}
if ((settings.m_fmDeviation != m_settings.m_fmDeviation) ||
(settings.m_rfBandwidth != m_settings.m_rfBandwidth) || force)
if ((settings.m_fmDeviation != m_settings.m_fmDeviation) || force)
{
m_phaseDiscri.setFMScaling((8.0f*settings.m_rfBandwidth) / static_cast<float>(settings.m_fmDeviation)); // integrate 4x factor
m_phaseDiscri.setFMScaling((8.0f*m_audioSampleRate) / static_cast<float>(settings.m_fmDeviation)); // integrate 4x factor
}
if ((settings.m_afBandwidth != m_settings.m_afBandwidth) || force)
@ -479,7 +486,7 @@ void NFMDemod::applySettings(const NFMDemodSettings& settings, bool force)
if ((settings.m_squelchGate != m_settings.m_squelchGate) || force)
{
m_squelchGate = 480 * settings.m_squelchGate; // gate is given in 10s of ms at 48000 Hz audio sample rate
m_squelchGate = (m_audioSampleRate / 100) * settings.m_squelchGate; // gate is given in 10s of ms at 48000 Hz audio sample rate
m_squelchCount = 0; // reset squelch open counter
}
@ -614,7 +621,7 @@ int NFMDemod::webapiSettingsPutPatch(
if (frequencyOffsetChanged)
{
MsgConfigureChannelizer* channelConfigMsg = MsgConfigureChannelizer::create(
48000, settings.m_inputFrequencyOffset);
m_audioSampleRate, settings.m_inputFrequencyOffset);
m_inputMessageQueue.push(channelConfigMsg);
}

1
plugins/channelrx/demodnfm/nfmdemod.h
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@ -193,6 +193,7 @@ private:
int m_sampleCount;
int m_squelchCount;
int m_squelchGate;
int m_squelchDecay;
Real m_squelchLevel;
bool m_squelchOpen;

2
plugins/channelrx/demodnfm/nfmplugin.cpp
View File

@ -9,7 +9,7 @@
const PluginDescriptor NFMPlugin::m_pluginDescriptor = {
QString("NFM Demodulator"),
QString("3.14.1"),
QString("3.14.2"),
QString("(c) Edouard Griffiths, F4EXB"),
QString("https://github.com/f4exb/sdrangel"),
true,