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Changed NFM RF threshold squelch for after demod squelch

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This commit is contained in:
f4exb 2015-06-19 08:27:29 +02:00
parent 70cce80995
commit e66d9a417f
6 changed files with 370 additions and 55 deletions
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1
CMakeLists.txt
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@ -49,6 +49,7 @@ set(sdrbase_SOURCES
sdrbase/audio/audiofifo.cpp
sdrbase/audio/audiooutput.cpp
sdrbase/dsp/afsquelch.cpp
sdrbase/dsp/channelizer.cpp
sdrbase/dsp/channelmarker.cpp
sdrbase/dsp/ctcssdetector.cpp

87
include-gpl/dsp/afsquelch.h Normal file
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@ -0,0 +1,87 @@
///////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2015 Edouard Griffiths, F4EXB. //
// //
// 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/>. //
///////////////////////////////////////////////////////////////////////////////////
#ifndef INCLUDE_GPL_DSP_AFSQUELCH_H_
#define INCLUDE_GPL_DSP_AFSQUELCH_H_
#include "dsp/dsptypes.h"
/** AFSquelch: AF squelch class based on the Modified Goertzel
* algorithm.
*/
class AFSquelch {
public:
// Constructors and Destructor
AFSquelch();
// allows user defined tone pair
AFSquelch(unsigned int nbTones, const Real *tones);
virtual ~AFSquelch();
// setup the basic parameters and coefficients
void setCoefficients(
int N, // the algorithm "block" size
int SampleRate, // input signal sample rate
int _samplesAttack, // number of results before squelch opens
int _samplesDecay); // number of results keeping squelch open
// set the detection threshold
void setThreshold(double _threshold) {
threshold = _threshold;
}
// analyze a sample set and optionally filter
// the tone frequencies.
bool analyze(Real *sample); // input signal sample
// get the tone set
const Real *getToneSet() const
{
return toneSet;
}
bool open() const {
return isOpen;
}
void reset(); // reset the analysis algorithm
protected:
void feedback(Real sample);
void feedForward();
void evaluate();
private:
int N;
int sampleRate;
int samplesProcessed;
int maxPowerIndex;
int nTones;
int samplesAttack;
int attackCount;
int samplesDecay;
int decayCount;
bool isOpen;
double threshold;
double *k;
double *coef;
Real *toneSet;
double *u0;
double *u1;
double *power;
};
#endif /* INCLUDE_GPL_DSP_CTCSSDETECTOR_H_ */

107
plugins/channel/nfm/nfmdemod.cpp
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@ -26,11 +26,15 @@
#include <iostream>
static const Real afSqTones[2] = {2000.0, 8000.0};
MESSAGE_CLASS_DEFINITION(NFMDemod::MsgConfigureNFMDemod, Message)
NFMDemod::NFMDemod(AudioFifo* audioFifo, SampleSink* sampleSink) :
m_ctcssIndex(0),
m_sampleCount(0),
m_afSquelch(2, afSqTones),
m_squelchOpen(false),
m_sampleSink(sampleSink),
m_audioFifo(audioFifo)
{
@ -38,7 +42,7 @@ NFMDemod::NFMDemod(AudioFifo* audioFifo, SampleSink* sampleSink) :
m_config.m_inputFrequencyOffset = 0;
m_config.m_rfBandwidth = 12500;
m_config.m_afBandwidth = 3000;
m_config.m_squelch = -40.0;
m_config.m_squelch = -30.0;
m_config.m_volume = 2.0;
m_config.m_audioSampleRate = 48000;
@ -52,6 +56,8 @@ NFMDemod::NFMDemod(AudioFifo* audioFifo, SampleSink* sampleSink) :
m_AGC.resize(4096, m_agcLevel, 0, 0.1*m_agcLevel);
m_ctcssDetector.setCoefficients(3000, 6000.0); // 0.5s / 2 Hz resolution
m_afSquelch.setCoefficients(24, 48000.0, 1, 1); // 4000 Hz span, 250us
m_afSquelch.setThreshold(0.001);
}
NFMDemod::~NFMDemod()
@ -109,56 +115,52 @@ void NFMDemod::feed(SampleVector::const_iterator begin, SampleVector::const_iter
if(m_interpolator.interpolate(&m_interpolatorDistanceRemain, c, &ci)) {
m_sampleBuffer.push_back(Sample(ci.real() * 32767.0, ci.imag() * 32767.0));
m_movingAverage.feed(ci.real() * ci.real() + ci.imag() * ci.imag());
if(m_movingAverage.average() >= m_squelchLevel)
m_squelchState = m_running.m_audioSampleRate/ 20;
qint16 sample;
if(m_squelchState > 0)
m_AGC.feed(abs(ci));
ci *= (m_agcLevel / m_AGC.getValue());
// demod
/*
Real argument = arg(ci);
Real demod = argument - m_lastArgument;
m_lastArgument = argument;
*/
/*
// Original NFM
Complex d = conj(m_m1Sample) * ci;
Real demod = atan2(d.imag(), d.real());
demod /= M_PI;
*/
/*
Real argument1 = arg(ci);//atan2(ci.imag(), ci.real());
Real argument2 = m_lastSample.real();
Real demod = angleDist(argument2, argument1);
m_lastSample = Complex(argument1, 0);
*/
// Alternative without atan - needs AGC
// http://www.embedded.com/design/configurable-systems/4212086/DSP-Tricks--Frequency-demodulation-algorithms-
Real ip = ci.real() - m_m2Sample.real();
Real qp = ci.imag() - m_m2Sample.imag();
Real h1 = m_m1Sample.real() * qp;
Real h2 = m_m1Sample.imag() * ip;
Real demod = (h1 - h2) * 10000;
m_m2Sample = m_m1Sample;
m_m1Sample = ci;
m_sampleCount++;
// AF processing
if(m_afSquelch.analyze(&demod)) {
m_squelchOpen = m_afSquelch.open();
}
if (m_squelchOpen)
{
m_squelchState--;
m_AGC.feed(abs(ci));
ci *= (m_agcLevel / m_AGC.getValue());
// demod
/*
Real argument = arg(ci);
Real demod = argument - m_lastArgument;
m_lastArgument = argument;
*/
/*
// Original NFM
Complex d = conj(m_m1Sample) * ci;
Real demod = atan2(d.imag(), d.real());
demod /= M_PI;
*/
/*
Real argument1 = arg(ci);//atan2(ci.imag(), ci.real());
Real argument2 = m_lastSample.real();
Real demod = angleDist(argument2, argument1);
m_lastSample = Complex(argument1, 0);
*/
// Alternative without atan - needs AGC
// http://www.embedded.com/design/configurable-systems/4212086/DSP-Tricks--Frequency-demodulation-algorithms-
Real ip = ci.real() - m_m2Sample.real();
Real qp = ci.imag() - m_m2Sample.imag();
Real h1 = m_m1Sample.real() * qp;
Real h2 = m_m1Sample.imag() * ip;
Real demod = (h1 - h2) * 10000;
m_m2Sample = m_m1Sample;
m_m1Sample = ci;
m_sampleCount++;
// AF processing
//demod = m_lowpass.filter(demod);
//sample = demod * 32700;
Real ctcss_sample = m_lowpass.filter(demod);
if ((m_sampleCount & 7) == 7) // decimate 48k -> 6k
@ -186,7 +188,7 @@ void NFMDemod::feed(SampleVector::const_iterator begin, SampleVector::const_iter
if (m_ctcssIndexSelected && (m_ctcssIndexSelected != m_ctcssIndex))
{
sample = 0.0;
sample = 0;
}
else
{
@ -234,7 +236,6 @@ void NFMDemod::feed(SampleVector::const_iterator begin, SampleVector::const_iter
void NFMDemod::start()
{
m_squelchState = 0;
m_audioFifo->clear();
m_interpolatorRegulation = 0.9999;
m_interpolatorDistance = 1.0;
@ -292,8 +293,10 @@ void NFMDemod::apply()
}
if(m_config.m_squelch != m_running.m_squelch) {
m_squelchLevel = pow(10.0, m_config.m_squelch / 20.0);
m_squelchLevel = pow(10.0, m_config.m_squelch / 10.0);
m_squelchLevel *= m_squelchLevel;
m_afSquelch.setThreshold(m_squelchLevel);
m_afSquelch.reset();
}
m_running.m_inputSampleRate = m_config.m_inputSampleRate;

7
plugins/channel/nfm/nfmdemod.h
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@ -27,6 +27,7 @@
#include "dsp/movingaverage.h"
#include "dsp/agc.h"
#include "dsp/ctcssdetector.h"
#include "dsp/afsquelch.h"
#include "audio/audiofifo.h"
#include "util/message.h"
@ -136,8 +137,10 @@ private:
int m_ctcssIndexSelected;
int m_sampleCount;
Real m_squelchLevel;
int m_squelchState;
double m_squelchLevel;
//int m_squelchState;
AFSquelch m_afSquelch;
bool m_squelchOpen;
Real m_lastArgument;
Complex m_m1Sample;

9
plugins/channel/nfm/nfmdemodgui.ui
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@ -253,10 +253,17 @@
</widget>
</item>
<item row="5" column="1">
<widget class="QComboBox" name="ctcss"/>
<widget class="QComboBox" name="ctcss">
<property name="toolTip">
<string>Set CTCSS</string>
</property>
</widget>
</item>
<item row="5" column="2">
<widget class="QLabel" name="ctcssText">
<property name="toolTip">
<string>CTCSS detected</string>
</property>
<property name="text">
<string>--</string>
</property>

214
sdrbase/dsp/afsquelch.cpp Normal file
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@ -0,0 +1,214 @@
///////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2015 Edouard Griffiths, F4EXB. //
// //
// 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 <cmath>
#include "dsp/afsquelch.h"
AFSquelch::AFSquelch() :
N(0),
sampleRate(0),
samplesProcessed(0),
maxPowerIndex(0),
nTones(2),
samplesAttack(0),
attackCount(0),
samplesDecay(0),
decayCount(0),
isOpen(false),
threshold(0.0)
{
k = new double[nTones];
coef = new double[nTones];
toneSet = new Real[nTones];
u0 = new double[nTones];
u1 = new double[nTones];
power = new double[nTones];
toneSet[0] = 2000.0;
toneSet[1] = 10000.0;
}
AFSquelch::AFSquelch(unsigned int nbTones, const Real *tones) :
N(0),
sampleRate(0),
samplesProcessed(0),
maxPowerIndex(0),
nTones(nbTones),
samplesAttack(0),
attackCount(0),
samplesDecay(0),
decayCount(0),
isOpen(false),
threshold(0.0)
{
k = new double[nTones];
coef = new double[nTones];
toneSet = new Real[nTones];
u0 = new double[nTones];
u1 = new double[nTones];
power = new double[nTones];
for (int j = 0; j < nTones; ++j)
{
toneSet[j] = tones[j];
}
}
AFSquelch::~AFSquelch()
{
delete[] k;
delete[] coef;
delete[] toneSet;
delete[] u0;
delete[] u1;
delete[] power;
}
void AFSquelch::setCoefficients(int _N, int _samplerate, int _samplesAttack, int _samplesDecay )
{
N = _N; // save the basic parameters for use during analysis
sampleRate = _samplerate;
samplesAttack = _samplesAttack;
samplesDecay = _samplesDecay;
// for each of the frequencies (tones) of interest calculate
// k and the associated filter coefficient as per the Goertzel
// algorithm. Note: we are using a real value (as apposed to
// an integer as described in some references. k is retained
// for later display. The tone set is specified in the
// constructor. Notice that the resulting coefficients are
// independent of N.
for (int j = 0; j < nTones; ++j)
{
k[j] = ((double)N * toneSet[j]) / (double)sampleRate;
coef[j] = 2.0 * cos((2.0 * M_PI * toneSet[j])/(double)sampleRate);
}
}
// Analyze an input signal
bool AFSquelch::analyze(Real *sample)
{
feedback(*sample); // Goertzel feedback
samplesProcessed += 1;
if (samplesProcessed == N) // completed a block of N
{
feedForward(); // calculate the power at each tone
samplesProcessed = 0;
return true; // have a result
}
else
{
return false;
}
}
void AFSquelch::feedback(Real in)
{
double t;
// feedback for each tone
for (int j = 0; j < nTones; ++j)
{
t = u0[j];
u0[j] = in + (coef[j] * u0[j]) - u1[j];
u1[j] = t;
}
}
void AFSquelch::feedForward()
{
for (int j = 0; j < nTones; ++j)
{
power[j] = (u0[j] * u0[j]) + (u1[j] * u1[j]) - (coef[j] * u0[j] * u1[j]);
u0[j] = u1[j] = 0.0; // reset for next block.
}
evaluate();
}
void AFSquelch::reset()
{
for (int j = 0; j < nTones; ++j)
{
power[j] = u0[j] = u1[j] = 0.0; // reset
}
samplesProcessed = 0;
maxPowerIndex = 0;
isOpen = false;
}
void AFSquelch::evaluate()
{
double maxPower = 0.0;
double minPower;
int minIndex = 0, maxIndex = 0;
for (int j = 0; j < nTones; ++j)
{
if (power[j] > maxPower) {
maxPower = power[j];
maxIndex = j;
}
}
minPower = maxPower;
for (int j = 0; j < nTones; ++j)
{
if (power[j] < minPower) {
minPower = power[j];
minIndex = j;
}
}
// principle is to open if power is uneven because noise gives even power
bool open = ((maxPower - minPower) > threshold) && (minIndex > maxIndex);
if (open)
{
if (attackCount < samplesAttack)
{
attackCount++;
}
else
{
isOpen = true;
decayCount = 0;
}
}
else
{
if (decayCount < samplesDecay)
{
decayCount++;
}
else
{
isOpen = false;
attackCount = 0;
}
}
}